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Archive for the ‘Male Genetics’ Category

sex chromosome | genetics | Britannica.com

Sex chromosome, either of a pair of chromosomes that determine whether an individual is male or female. The sex chromosomes of human beings and other mammals are designated by scientists as X and Y. In humans the sex chromosomes comprise one pair of the total of 23 pairs of chromosomes. The other 22 pairs of chromosomes are called autosomes.

Individuals having two X chromosomes (XX) are female; individuals having one X chromosome and one Y chromosome (XY) are male. The X chromosome resembles a large autosomal chromosome with a long and a short arm. The Y chromosome has one long arm and a very short second arm. This path to maleness or femaleness originates at the moment of meiosis, when a cell divides to produce gametes, or sex cells having half the normal number of chromosomes. During meiosis the male XY sex-chromosome pair separates and passes on an X or a Y to separate gametes; the result is that one-half of the gametes (sperm) that are formed contains the X chromosome and the other half contains the Y chromosome. The female has two X chromosomes, and all female egg cells normally carry a single X. The eggs fertilized by X-bearing sperm become females (XX), whereas those fertilized by Y-bearing sperm become males (XY).

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sex: Sex chromosomes

In most species of animals the sex of individuals is determined decisively at the time of fertilization of the egg, by means of chromosomal distribution. This process is the most clear-cut form of sex determination. When any cell in the body divides, except during the formation of the sex cells, each daughter cell receives the full complement of chromosomes; i.e., copies of the two sets...

Unlike the paired autosomes, in which each member normally carries alleles (forms) of the same genes, the paired sex chromosomes do not carry an identical complement of genetic information. The X chromosome, being larger, carries many more genes than does the Y. Traits controlled by genes found only on the X chromosome are said to be sex-linked (see linkage group). Recessive sex-linked traits, such as hemophilia and redgreen colour blindness, occur far more frequently in men than in women. This is because the male who inherits the recessive allele on his X chromosome has no allele on his Y chromosome to counteract its effects. The female, on the other hand, must inherit the recessive allele on both of her X chromosomes in order to fully display the trait. A woman who inherits the recessive allele for a sex-linked disorder on one of her X chromosomes may, however, show a limited expression of the trait. The reason for this is that, in each somatic cell of a normal female, one of the X chromosomes is randomly deactivated. This deactivated X chromosome can be seen as a small, dark-staining structurethe Barr bodyin the cell nucleus.

The effects of genes carried only on the Y chromosome are, of course, expressed only in males. Most of these genes are the so-called maleness determiners, which are necessary for development of the testes in the fetus.

Several disorders are known to be associated with abnormal numbers of sex chromosomes. Turners syndrome and Klinefelters syndrome are among the most common of these. See also X trisomy; XYY-trisomy.

sex chromosome disorder of human females, in which three X chromosomes are present, rather than the normal pair. More common than Turners syndrome, where only one X chromosome is present, X-trisomy usually remains undetected because affected individuals appear normal, experience puberty,...

relatively common human sex chromosome anomaly in which a male has two Y chromosomes rather than one. It occurs in 1 in 5001,000 live male births, and individuals with the anomaly are often characterized by tallness and severe acne and sometimes by skeletal malformations and mental...

the sum of features by which members of species can be divided into two groupsmale and femalethat complement each other reproductively.

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sex chromosome | genetics | Britannica.com

Scientific studies favor male miceand that could hurt a lot of humans – Popular Science

The biological differences between men and women can affect the way they react to certain drugs and treatments, according to a new study in Nature Communications. If this sounds like a no brainer, you probably haven't looked at many biomedical studies. As PopSci noted earlier this year, biomedical researchers experiment almost exclusively on male animal subjects. A 2011 study found that animals in medical research are up to five times more likely to be male than female.

That's a problem, because what happens in men is not necessarily a template for what happens in the whole population. Results in rodents are already difficult to translate to potential outcomes in humans, but leaving female animals out of the mix could make for even less predictable reactions. The new study indicates that sex has an impact on 56.6 percent of quantitative traits (things like bone density) and roughly 10 percent of qualitative traits (like whether or not a mouses head was shaped normally). All of which makes sense. We know that certain diseaseslupus and urinary tract infections, for exampleare more prevalent in human women than in men. Other diseases, like heart disease, have different qualities depending on sex. The protective effects of estrogen on the cardiovascular system mean that biologically female patients tend to develop heart disease later in life than male patients, for example. As estrogen declines with menopause, the likelihood of heart disease increases.

While its long been known that this blind spot exists in the scientific world, the actual impact on results has been less clear. The new study aims to quantify the differences between male and female study subjects, known as sexual dimorphism. The team analyzed up to 234 physical characteristics in more than 60,000 mice14,250 wildtype animals, or animals as they typically occur in nature, and 40,192 mutant mice from 2,186 single gene knockout lines. Knockout mice have been genetically engineered, with researchers making a single gene inactive to show what role it plays. The 40,192 mice had a total of 2,186 genes knocked out (though no more than one single gene was knocked out per mouse).

As it turned out, sex altered the mutation effects by 17.7 percent in quantitative traits, and 13.3 percent in qualitative traits. And in some cases, the only way to discover the difference was to study both sexes. So while gene therapies may hold promise for treating and curing human disease, a sex bias in rodent trials could mean that biological men benefit much more from these advances than their female counterparts.

The researchers are simply working to confirm something that an increasing number of scientists acknowledge: sex matters. People who menstruate, can potentially have children, have organs that biological males do not, and metabolize drugs differently can have drastically different responses to all manner of medical interventions. In fact, medications are most likely to be pulled off the market because of adverse reactions in womensomething that could easily be avoided if drug manufacturers were equally rigorous in testing drugs for both sexes.

When female subjects are included in studies, they tend to be tested (as PopSci noted in our recent article on sunscreen) when they are at their most "male-like", biologically speakingeither when they're menopausal or in the period before ovulation and menstruation. Researchers say that doing so makes their experiments simpler, because hormonal cycles add too many variables to the mix. The fact that this fails to account for the conditions under which many patients will actually take these medications is apparently inconsequential.

Its been just under 27 years since the National Institutes of Health created the Office of Research on Womens Health as a step to overcome the systemic exclusion of women from biomedical studies. Their worry was that clinical decisions in healthcare were being made for everyone based only on findings from studies conducted on male subjects. For over two decades, the National Institutes of Health has required that clinical trialsthe last step before drugs make it to marketinclude women. While the number of women in clinical trials has increased, from nine percent in 1970 to 41 percent in 2006, women are still underrepresented in clinical trials and, as this new study makes clear, woefully underrepresented in animal trials.

"This study illustrates how often sex differences occur in traits that we would otherwise assume to be the same in males and females, says study author Judith Manka, a geneticist at University College London. More importantly, the fact that a mouse's sex influenced the effects of genetic modification indicates that males and females differ right down to the underlying genetics behind many traits. This means that only studying males paints half the picture."

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Scientific studies favor male miceand that could hurt a lot of humans - Popular Science

So Cal mountain lions’ low genetic diversity threatens population – Davis Enterprise

If a dangerously inbred puma population in Southern California is to survive in the future, an urgent need for genetic connectivity must be met, according to two scientific papers from a team of researchers coordinated by UC Davis and involving scientists at the University of Wyoming and the University of Massachusetts-Amherst.

The first paper, published in the journal Royal Society Open Science in May, reports that the puma population of about 20 adults in the Santa Ana Mountains has the lowest genetic diversity ever reported for pumas besides the Florida panther, which nearly went extinct from genetic causes. Read the journal report at http://bit.ly/2sew1LT.

The pumas isolation is primarily due to surrounding urbanization from Los Angeles and San Diego.

The only hope for puma movements in and out of the Santa Ana Mountains is to cross I-15 an eight- to 10-lane interstate highway which poses a major barrier for pumas attempting to migrate between the Santa Ana Mountains and the rural Eastern Peninsular Mountains, said lead author Kyle Gustafson, a postdoctoral conservation geneticist from the University of Wyoming.

University of Wyoming researchers conducted genetic analyses of both radio-collared and uncollared pumas to develop a multigeneration pedigree. This showed where pumas and their offspring were born, and whether they successfully migrated and reproduced after crossing I-15, which separates the Santa Ana Mountains from other mountain ranges to the east.

The power of one Although seven males crossed I-15 over the past 20 years, only one male puma #86 (M86) was able to successfully produce offspring in the Santa Anas after migrating from the genetically diverse population to the east. By producing a total of 11 detected offspring, M86 rapidly disseminated unique genes into the inbred population, which reduced the level of inbreeding and significantly increased genetic diversity.

Unfortunately, M86 was hit by a car between 2014 and 2015, and more than half of his offspring are either now deceased or in captivity.

This is consistent with mortality rates we found previously in the region, said Winston Vickers, a wildlife veterinarian from UCDs Karen C. Drayer Wildlife Health Center who conducted most of the field research. Only one other migrant, named M119, remains in the Santa Ana Mountains, but whether he is alive or produced offspring is uncertain.

Senior author Holly Ernest, a wildlife population geneticist and research veterinarian at the University of Wyoming, said that by introducing new genetic material and raising the level of genetic diversity in this population, that single male mountain lion, M86, performed what amounts to a genetic rescue.

Our study also shows how quickly his genetics were lost by high mortality levels of his offspring, Ernest said. A message here is that this population needs help to regain healthy genetics and persist in the Southern California landscape. That help can come in the form of just a few individuals over time adding new blood to the population.

Connectivity is key The second paper, published in June in the journal PLOS ONE, provides a potential solution to this issue. In it, the researchers propose a conservation network for pumas spanning the Santa Ana Mountains and the Eastern Peninsular Mountains. Read the journal report at http://bit.ly/2rYuYv3.

Using genetic data and data from GPS radio-collared pumas, this analysis identified critical habitat patches, movement corridors, and key road crossing locations across I-15 that would allow pumas to persist and increase genetic diversity.

Without continued emigration into the Santa Ana Mountains by pumas coming from the east of I-15, eroding genetic diversity and continued inbreeding are expected to resume, said veterinarian Walter Boyce, co-director of the Wildlife Health Centers Southern California Mountain Lion Study with Vickers.

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So Cal mountain lions' low genetic diversity threatens population - Davis Enterprise

Horse Tale: Oriental Stallions Dominate Horse DNA, Gene Study Shows – NBCNews.com

A Lipizzan stallion named Conversano Sessana, born in 2001.The Y sequence that is needed as a template to detect variants in any horse is generated from a stallion of this breed. Spanische Hofreitschule Wien

A group of researchers led by Barbara Wallner of the Institute of Animal Breeding and Genetics in Vienna, Austria sampled the genes of 52 modern horses representing 21 different breeds for their study. They included the famous white dancing Lipizzaners, quarter horses, cobs, Thoroughbreds and Arabians.

The team focused on the male specific

The findings were startling. Most of the horses in common use descend from just two lineages, the Arabian lineage from the Arabian Peninsula and the Turkoman lineage from the steppes of Central Asia, also widely known as "Oriental" among horse breeders, as reported in the Journal of Current Biology.

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"Apart from stallion lines in Northern European breeds, all stallion lines detected in other modern breeds derive from more recently introduced Oriental ancestors," Wallner said.

Its not surprising that a few studs would have a large number of progeny. Females can have one or two foals a year, while males can sire many.

It seems medieval horse breeders made great use of a few very strong specimens, Wallner said, breeding them with local mares.

The qualities they were looking for are still the same qualities people still admire today.

They wanted them because they were beautiful. They wanted them to be faster and stronger and lighter, Wallner told NBC News.

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Theres plenty of history about horse breeding and its no secret that Arabian stallions were desired and shipped long distances for breeding.

Of particular importance was the trend to import stallions from foreign studs to improve local herds. In central Europe, this practice started in the 16th century with the popularity of Spanish and Neapolitan stallions. Until the end of the 18th century, the Central European horse population was shaped by the introduction of Oriental stallions, they wrote.

A person riding a Lipizzan stallion. They perform in the Spanish Riding School in Vienna. Spanische Hofreitschule Wien

Wallners study shows just how few male lines ended up surviving the process.

Other research has looked at mitochondrial DNA, which females pass down virtually unchanged to their children. This collection of DNA is particularly diverse in horses, demonstrating that many, many mares are ancestors of modern horses.

Now Wallner wants to collect DNA from the remains of ancient horses to see if she can determine when wild horse were first domesticated, and where.

Similar recent studies have shown the surprising

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Horse Tale: Oriental Stallions Dominate Horse DNA, Gene Study Shows - NBCNews.com

Twins Separated at Birth Reveal Staggering Influence of …

WASHINGTON Jim Lewis and Jim Springer were identical twins raised apart from the age of 4 weeks. When the twins were finally reunited at the age of 39 in 1979, they discovered they both suffered from tension headaches, were prone to nail biting, smoked Salem cigarettes, drove the same type of car and even vacationed at the same beach in Florida.

The culprit for the odd similarities? Genes.

Genes can help explain why someone is gay or straight, religious or not, brainy or not, and even whether they're likely to develop gum disease, one psychologist explains.

Such broad-ranging genetic effects first came to light in a landmark study Minnesota Twin Family Study conducted from 1979 to 1999, which followed identical and fraternal twins who were separated at an early age. [Seeing Double: 8 Fascinating Facts About Twins]

"We were surprised by certain behaviors that showed a genetic influence, such as religiosity [and] social attitudes," said Nancy Segal, an evolutionary psychologist at California State University, Fullerton, who was part of the study for nine years. "Those surprised us, because we thought those certainly must come from the family [environment]," Segal told Live Science. Segal described the groundbreaking research on Aug. 7 here at a meeting of the American Psychological Association.

Born together, raised apart

Researchers at the University of Minnesota, led by Thomas Bouchard, launched the landmark study in 1979. Over the course of 20 years, they studied 137 pairs of twins 81 pairs of identical twins (twins who developed from one egg that split in two), and 56 pairs of fraternal twins (twins who developed from two eggs fertilized by two different sperm).

The Jim twins were probably the most famous set of twins involved in the study, but other pairs were equally fascinating. One pair of female twins in the study were separated from each other at 5 months old, and weren't reunited until age 78, making them the world's longest separated pair in Guinness World Records.

The Minnesota study resulted in more than 170 individual studies focusing on different medical and psychological characteristics.

In one study, the researchers took photographs of the twins, and found that identical twins would stand the same way, while fraternal twins had different postures.

Another study of four pairs of twins found that genetics had a stronger influence on sexual orientation in male twins than in female twins. A recent study in Sweden of 4,000 pairs of twins has replicated these findings, Segal said. [5 Myths About Gay People Debunked]

Nature vs. nurture

A 1986 study that was part of the larger Minnesota study found that genetics plays a larger role on personality than previously thought. Environment affected personality when twins were raised apart, but not when they were raised together, the study suggested.

Reporter Daniel Goleman wrote in The New York Times at the time that genetic makeup was more influential on personality than child rearing a finding he said would launch "fierce debate."

"We never said [family environment] didn't matter," Segal said at the APA meeting. "We just made the point that environment works in ways we hadn't expected."

Another study, commissioned by the editor of the journal Science, looked at genetics and IQ. The Minnesota researchers found that about 70 percent of IQ variation across the twin population was due to genetic differences among people, and 30 percent was due to environmental differences. The finding received both praise and criticism, but an updated study in 2009 containing new sets of twins found a similar correlation between genetics and IQ.

Moreover, a study in 1990 found that genetics account for 50 percent of the religiosity among the population in other words, both identical twins raised apart were more likely to be religious or to be not religious, compared with unrelated individuals.

Other studies found a strong genetic influence on dental or gum health. That research helped to show that gum disease isn't just caused by bacteria, it also has a genetic component, Segal said.

Another study found that happiness and well-being had a 50 percent genetic influence.

In another study, researchers surveyed the separated twins about how close they felt to their newfound sibling. Among identical twins, 80 percent of those surveyed reported feeling closer and more familiar with their twin than they did to their best friends, suggesting a strong genetic component in the bond between identical twins.

The Minnesota study gave scientists a new understanding of the role of genes and environment on human development, Segal said. In the future, twin studies will aim to link specific genes to specific behaviors, as well as investigate epigenetics what turns genes on or off, she said.

Segal, who wrote a book about the study called "Born Together Reared Apart: The Landmark Minnesota Twins Study" (Harvard University Press, 2012), is now doing a prospective study of Chinese twins raised apart, often in different countries, by adoptive families.

Follow Tanya Lewis on Twitterand Google+. Follow us @livescience, Facebook& Google+. Original article onLive Science.

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Twins Separated at Birth Reveal Staggering Influence of ...

Cohen wins Gates grant for her new take on male contraception – Cornell Chronicle

In time, men may have a new way to prevent pregnancy, thanks to the innovative thinking of a Cornell geneticist.

Paula Cohen, professor of genetics in the College of Veterinary Medicine, has won a $100,000 grant from the Bill & Melinda Gates Foundation to develop a radical approach to contraception an area that has remained static for many years.

Thats whats truly innovative here: We are targeting a stage in the reproductive cycle thats poorly understood, Cohen said.

An expert in the genetics of fertility, Cohen was one of 28 researchers, chosen from 1,600 applicants from around the world, awarded a Grand Challenges Explorations grant, funded by the Gates Foundation. The grant supports innovative thinkers worldwide to explore ideas that can break the mold in how we solve persistent global health and development challenges. Successful projects have the opportunity to receive a follow-on grant of up to $1 million.

Cohens project will look at meiosis, a poorly understood stage of development in which a sperm cells DNA is halved. When the sperm fertilizes an egg which also contains only one half of its chromosomes the resulting embryo is restored to the full number of chromosomes.

Ive always thought that if we can stop those cells from actually getting into meiosis, youd have a really good contraceptive, Cohen said.

There are several reasons why this stage of sperm cell development is a better target for contraception than others, she said.

Traditionally, contraceptives have tried to block the sperm from getting to the egg, with barriers like condoms and spermicide. Thats shutting the stable door after the horse has bolted, Cohen said. If a single swimmer gets out, it still has the potential to fertilize an egg, and you cant always prevent that from happening.

Hormonal approaches, like birth control pills, have their own drawbacks. Cohen believes they are not always good for women. And the development of a male birth control pill has always been scorned by men who fear that their libido and/or male sexual characteristics will be diminished.

And contraceptives that target the sperm cell in the testis at a late stage of development might result in mutant sperm and thus birth defects.

Her new approach, centering on the sperm cells entry into meiosis, before it even leaves the testis, offers several benefits.

For example, should one sperm sneak its way through to meiosis, the surveillance machinery present during meiosis would get rid of that solitary cell; in other words, the meiotic process itself would check for escapers. And unlike later stages of sperm cell development, the cells entry into meiosis is accessible to blood-borne factors such as drugs.

The problem is, we know very little about meiosis, because its a very hard stage to target biologically or molecularly, she said. Only recently have we started to gather the tools to be able to look at it. One tool Cohen will use is called CRISPR/Cas9, a genome editing technology that allows genes to be modified permanently and very rapidly.

She has three goals. First, shell try to prove she can get the sperm cells to go into meiosis in culture. Second, shell monitor the cells entry, by engineering what are known as reporter mice, whose cells turn green or red depending on whether or not they have entered meiosis. Third, and as proof-of-principle, shell try to manipulate two genes that are known to affect a cells entry into meiosis.

One gene is required for sperm stem cell maintenance in the testes; if it is deleted, cells rapidly progress into meiosis. The second gene is required for the sperm cell to enter meiosis; it if is blocked, the cells stop developing. So weve got a gene that should accelerate their entry into meiosis and one that should slow it down, Cohen said.

If she can manipulate those genes, that opens the door to the possibility of finding others. There could be hundreds of genes that control this process, she said. We just need to find them and begin to ask whether they are potential contraceptive targets.

This is not the type of science that would qualify for funding through traditional agencies like the National Institutes of Health, Cohen said.

Its very out there, its very risky, and thats what the Gates Foundation is going for, she said. They want you to come up with ideas that are truly revolutionary.

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Cohen wins Gates grant for her new take on male contraception - Cornell Chronicle

A Florida higher-ed official said women’s genetics may be keeping … – Washington Post

A Florida college official said Tuesday that women make less money than men because genetically they might lack the skills to negotiate for better pay.

Edward Morton ofthe State University System of Florida made the comments during a board meeting in which members talked about closing the wage gap between male and femalegraduates of the states public university system.Morton, chair of the boards Strategic Planning Committee and a financial adviser from Naples, Fla., said,according to Politico:

Something that were doing in Naples some of our high school students, were actually talking about incorporating negotiating and negotiating skill into curriculum so that the women are given maybe some of it is genetic, I dont know, Im not smart enough to know the difference but I do know that negotiating skills can be something that can be honed, and they can improve. Perhaps we can address than in all of our various curriculums through the introduction of negotiating skill, and maybe that would have a bearing on these things.

Morton apologized for his comment in an email sent to fellow board members shortly after the meeting.

I chose my words poorly. My belief is that women and men should be valued equally in the workplace, he said, adding that the universitys goal is to teach all students how to better negotiate their salaries.

[Utah Republican argues against equal pay for women: Its bad for families and society]

Gov. Rick Scott, who appointed Morton to the board, was among those who quickly criticized Morton for hiscomments. Lauren Schenone, a spokeswoman for Scott, said in a statement that as a father of two daughters, the governorabsolutely does not agree with Mortonscomments.

Gwen Graham, whos seeking the Democratic nomination for governor,tweeted Tuesday night:When I sat at the negotiation table, nothing about my gender or genetics held me back. THIS is why we need more women in state government.

Morton did not return a call seeking comment Wednesday.

Politico reported that during the meeting board members were reviewing areport on gender wage gaps among students who graduated from the university system in 2015.The report, which looked at what students did after graduation and how much theyre earning, found that female graduates from various fieldshave an annual median salary of $37,000, which is $5,500 less than the median salary of male graduates. African American graduates make even less, with an annual median wage of $35,600.

[Here are the facts behind that 79 cent pay gap factoid]

Femalegraduates make less than men even though they account fornearly 60 percent of the graduating class, according to the report.Blacks, Hispanics and whites make up 12 percent, 25 percent and 52 percent of the graduating class, respectively.

During the meeting, Morton said that the wage gap will in some way be self-correcting because the university system has more female graduates than men, according to Politico.

The report also found significant discrepancies in pay among men and women who graduated with the same degrees.The median salaries of women with degrees in biological sciences, business and marketing, communication and journalism, security and protective services, social sciences, and visual and performing arts are from$1,200to $4,400 lower than those of men with similar credentials.The gap among agriculture, liberal arts and physical sciences graduates is even greater from $6,400to $9,400.

Yet the report also found that women with degrees in education, engineering, health professions and psychology make from$500 to$3,100 more than their male counterparts annually.

A history of the long fight for gender wage equality. (Daron Taylor/The Washington Post)

Florida is among more than a dozen states with equal pay laws that haveloopholes that allow employers to continue to pay women less, according to the American Association of University Women.Two states, Alabama and Mississippi, have no equal paylaws. And only a handful California, Illinois, Minnesota, Vermont, Massachusetts and Maryland have strong equal pay laws.

Nationally, womens annual earnings are about 80 percent of what men make, according to a recent report by the association.

The report attributes the wage gap partly to differences in career choices and to the fact that parenting more often puts womens professional lives at a disadvantage than it does mens. Twenty-three percent of mothers left the workforce 10 years after graduation, while 17 percent worked part-time, according to the association. Those numbers among fathers were 1 percent and 2 percent, respectively.

Despite factors such as life choices and parenting, women facepay gaps at every education level and in nearly every line of work, the report said.

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In the federal government, how likely is it that a woman will make more than a man?

The poor just dont want health care: Republican congressman faces backlash over comments

Nobody dies because they dont have access to health care, GOP lawmaker says. He got booed.

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A Florida higher-ed official said women's genetics may be keeping ... - Washington Post

Florida higher education official said women may earn less than men because of genetics – New York Daily News

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Genetic data show mainly men migrated from the Pontic steppe to … – Science Daily


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Genetic data show mainly men migrated from the Pontic steppe to ...
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A new study, looking at the sex-specifically inherited X chromosome of prehistoric human remains, shows that hardly any women took part in the extensive ...

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Genetic data show mainly men migrated from the Pontic steppe to ... - Science Daily

Thousands of horsemen may have swept into Bronze Age Europe, transforming the local population – Science Magazine

A Yamnaya skeleton from a grave in the Russian steppe, which was the homeland of men who migrated to Europe.

XVodolazx/Wikimedia Commons

By Ann GibbonsFeb. 21, 2017 , 12:00 PM

Call it an ancient thousand man march. Early Bronze Age men from the vast grasslands of the Eurasian steppe swept into Europe on horseback about 5000 years agoand may have left most women behind. This mostly male migration may have persisted for several generations, sending men into the arms of European women who interbred with them, and leaving a lasting impact on the genomes of living Europeans.

It looks like males migrating in war, with horses and wagons, says lead author and population geneticist Mattias Jakobsson of Uppsala University in Sweden.

Europeans are the descendants of at least three major migrations of prehistoric people. First, a group of hunter-gatherers arrived in Europe about 37,000 years ago. Then, farmers began migrating from Anatolia (a region including present-day Turkey) into Europe 9000 years ago, but they initially didnt intermingle much with the local hunter-gatherers because they brought their own families with them. Finally, 5000 to 4800 years ago, nomadic herders known as the Yamnaya swept into Europe. They were an early Bronze Age culture that came from the grasslands, or steppes, of modern-day Russia and Ukraine, bringing with them metallurgy and animal herding skills and, possibly,Proto-Indo-European, themysterious ancestral tonguefrom which all of todays 400 Indo-European languages spring. Theyimmediately interbred with local Europeans, who were descendants of both the farmers and hunter-gatherers. Within a few hundred years, the Yamnaya contributed to at least half of central Europeans genetic ancestry.

To find out why this migration of Yamnaya had such a big impact on European ancestry, researchers turned to genetic data from earlier studies of archaeological samples. They analyzed differences in DNA inherited by 20 ancient Europeans who lived just after the migration of Anatolian farmers (6000 to 4500 years ago) and 16 who lived just after the influx of Yamnaya (3000 to 1000 years ago). The team zeroed in on differences in the ratio of DNA inherited on their X chromosomes compared with the 22 chromosomes that do not determine sex, the so-called autosomes. This ratio can reveal the proportion of men and women in an ancestral population, because women carry two X chromosomes, whereas men have only one.

Europeans who were alive from before the Yamnaya migration inherited equal amounts of DNA from Anatolian farmers on their X chromosome and their autosomes, the team reports today in the Proceedings of the National Academy of Sciences. This means roughly equal numbers of men and women took part in the migration of Anatolian farmers into Europe.

But when the researchers looked at the DNA later Europeans inherited from the Yamnaya, they found that Bronze Age Europeans had far less Yamnaya DNA on their X than on their other chromosomes. Using a statistical method developed by graduate student Amy Goldberg in the lab of population geneticist Noah Rosenberg at Stanford University in Palo Alto, California, the team calculated that there were perhaps 10 men for every woman in the migration of Yamnaya men to Europe (with a range of five to 14 migrating men for every woman). That ratio is extremeeven more lopsided than the mostly male wave of Spanish conquistadores who came by ship to the Americas in the late 1500s, Goldberg says.

Such a skewed ratio raises red flags for some researchers, who warn it is notoriously difficult to estimate the ratio of men to women accurately in ancient populations. But if confirmed, one explanation is that the Yamnaya men were warriors who swept into Europe on horses or drove horse-drawn wagons; horses had been recently domesticated in the steppe and the wheel was a recent invention. They may have been more focused on warfare, with faster dispersal because of technological inventions says population geneticist Rasmus Nielsen of the University of California, Berkeley, who is not part of the study.

But warfare isnt the only explanation. The Yamnaya men could have been more attractive mates than European farmers because they had horses and new technologies, such as copper hammers that gave them an advantage, Goldberg says.

The finding that Yamnaya men migrated for many generations also suggests that all was not right back home in the steppe. It would imply a continuing strongly negative push factor within the steppes, such as chronic epidemics or diseases, says archaeologist David Anthony of Hartwick College in Oneonta, New York, who was not an author of the new study. Or, he says it could be the beginning of cultures that sent out bands of men to establish new politically aligned colonies in distant lands, as in later groups of Romans or Vikings.

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Thousands of horsemen may have swept into Bronze Age Europe, transforming the local population - Science Magazine

Genetic basis for male baldness identified in large-scale study – Medical News Today

Although common, male baldness can have negative psychological effects and some studies have even linked it to a handful of serious illnesses. New research identifies the genetic variants involved in the condition, which could eventually enable researchers to predict a person's chances of hair loss.

Male baldness - also referred to as androgenetic alopecia or male pattern baldness (MPB) - affects a significant number of people in the United States, as the condition accounts for over 95 percent of all hair loss in men.

According to the American Hair Loss Association, two thirds of U.S. adults will be affected by MPB to a certain degree by the age of 35, and around 85 percent of men will have experienced significant hair loss by the age of 50.

A lot of these men are seriously affected by the condition, which can have a negative effect on a person's self-image, as well as on their interpersonal relationships.

Additionally, some genetic studies have even associated MPB with negative clinical outcomes such as prostate cancer and cardiovascular disease.

A new study - led by Saskia Hagenaars and David Hill of the University of Edinburgh in the United Kingdom - explores the genetic basis for the condition. The findings were published in the journal PLOS Genetics.

Scientists analyzed the genomic and health data of more than 52,000 men enrolled in the UK Biobank - an international health resource offering health information on more than 500,000 individuals.

The team located more than 250 independent genetic regions linked to severe hair loss.

The researchers split the 52,000 participants into two groups: a so-called discovery sample of 40,000 people and a target sample of 12,000 individuals. Based on the genetic variants that separated those with no hair loss from those with severe hair loss, the team designed an algorithm aimed to predict who would develop MPB.

The algorithmic baldness predictor is based on a genetic score, and although accurate predictions are still a long way off, the results of this study might soon enable researchers to identify subgroups of the population that are particularly prone to hair loss.

In the present study, researchers found that 14 percent of the participants with a submedian genetic score had severe MPB, and 39 percent had no hair loss. By contrast, 58 percent of those scoring in the top 10 percent on the polygenic score had moderate to severe MPB.

Co-lead author Saskia Hagenaars - a Ph.D. student at the University of Edinburgh's Centre for Cognitive Aging and Cognitive Epidemiology - comments on the findings:

"We identified hundreds of new genetic signals," Hagenaars says. "It was interesting to find that many of the genetics signals for male pattern baldness came from the X chromosome, which men inherit from their mothers."

The study's other lead author, Dr. David Hill, notes that the study did not collect data on the age of baldness onset, but only on hair loss pattern. However, he adds that, "we would expect to see an even stronger genetic signal if we were able to identify those with early-onset hair loss."

To the authors' knowledge, this is the largest genetic study of MPB to date.

The study's principal investigator, Dr. Riccardo Marioni, from the University of Edinburgh's Centre for Genomic and Experimental Medicine, explains the significance of the findings:

"We are still a long way from making an accurate prediction for an individual's hair loss pattern. However, these results take us one step closer. The findings pave the way for an improved understanding of the genetic causes of hair loss."

Learn how a drug promises robust new hair growth.

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Genetic basis for male baldness identified in large-scale study - Medical News Today

Baldness linked to over 280 genes – BioNews

A new study has found over 280 genes associated with male-pattern baldness.

These genes could be used to predict a man's chance of hair loss or possibly provide targets for drug development in the future.

The research, published in PLOS Genetics, is the largest genomic study of baldness to date. Researchers studied the DNA of more than 52,000 men aged between 4069 years old enrolled in the UK Biobank, looking for genes associated with baldness.

'We identified hundreds of new genetic signals,' Saskia Hagenaars, a PhD student at the University of Edinburgh and co-lead author, said. 'It was interesting to find that many of the genetics signals for male-pattern baldness came from the X chromosome, which men inherit from their mothers.'

Many of the 287 genes linked with hair loss were related to hair growth and development. The researchers used these genes to try to predict the chance that a man will go bald, and found that almost 60 percent of those with the most number of hair loss genes showed signs of moderate to serious balding. However, the authors state that predictions for individuals are still 'relatively crude'.

'Data were collected on hair-loss pattern but not age of onset; we would expect to see an even stronger genetic signal if we were able to identify those with early-onset hair loss,' said Dr David Hill, University of Edinburgh, who co-led the research.

Male-pattern baldness affects around half of all men by the age of 50. The condition is hereditary and thought to be linked to levels of a certain male sex hormone. Previous genetic studies have also associated male-pattern baldness with prostate cancer and heart disease.

The study's principal investigator, Dr Riccardo Marioniof theUniversity of Edinburgh, said: 'We are still a long way from making an accurate prediction for an individual's hair-loss pattern. However, these results take us one step closer. The findings pave the way for an improved understanding of the genetic causes of hair loss.'

The study was based on information from the first release of data from the UK Biobank in 2015. The authors say that the release of data from the full cohort will enable them to further refine their predictions of male-pattern baldness and investigate its genetic basis.

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Baldness linked to over 280 genes - BioNews

Genetic data show mainly men migrated from the Pontic steppe to Europe 5000 years ago – Phys.Org

February 21, 2017

A new study, looking at the sex-specifically inherited X chromosome of prehistoric human remains, shows that hardly any women took part in the extensive migration from the Pontic-Caspian Steppe approximately 5,000 years ago. The great migration that brought farming practices to Europe 4,000 years earlier, on the other hand, consisted of both women and men. The difference in sex bias suggests that different social and cultural processes drove the two migrations.

Genetic data suggest that modern European ancestry represents a mosaic of ancestral contributions from multiple waves of prehistoric migration events. Recent studies of genomic variation in prehistoric human remains have demonstrated that two mass migration events are particularly important to understanding European prehistory: the Neolithic spread of agriculture from Anatolia starting around 9,000 years ago, and migration from the Pontic-Caspian Steppe around 5,000 years ago. These migrations are coincident with large social, cultural, and linguistic changes, and each has been inferred to have replaced more than half of the contemporaneous gene pool of resident Central Europeans.

Dramatic events in human prehistory can be investigated using patterns of genetic variation among the people that lived in those times. In particular, studies of differing female and male demographic histories on the basis of ancient genomes can provide information about complexities of social structures and cultural interactions in prehistoric populations.

Researchers from Uppsala and Stanford University investigated the genetic ancestry on the sex-specifically inherited X chromosome and the autosomes in 20 early Neolithic and 16 Late Neolithic/Bronze Age human remains. Contrary to previous hypotheses suggesting patrilocality (social system in which a family resides near the man's parents) of many agricultural populations, they found no evidence of sex-biased admixture during the migration that spread farming across Europe during the early Neolithic.

For later migrations from the Pontic steppe during the early Bronze Age, however, we find a dramatic male bias. There are simply too few X-chromosomes from the migrants, which points to around ten migrating males for every migrating female, says Mattias Jakobsson, professor of Genetics at the Department of Organismal Biology, Uppsala University.

The research group found evidence of ongoing, primarily male, migration from the steppe to central Europe over a period of multiple generations, with a level of sex bias that excludes a pulse migration during a single generation.

The contrasting patterns of sex-specific migration during these two migrations suggest a view of differing cultural histories in which the Neolithic transition was driven by mass migration of both males and females in roughly equal numbersperhaps whole familieswhereas the later Bronze Age migration and cultural shift were instead driven by male migration.

Explore further: Baltic hunter-gatherers began farming without influence of migration, ancient DNA suggests

More information: "Ancient X chromosomes reveal contrasting sex bias in Neolithic and Bronze Age Eurasian migrations," PNAS, DOI: 10.1073/pnas.1616392114 , http://www.pnas.org/content/early/2017/02/17/1616392114.abstract

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Genetic data show mainly men migrated from the Pontic steppe to Europe 5000 years ago - Phys.Org

Men inherit male pattern baldness from their mum’s side of the family … – Metro

It all comes from your X chromosome (Picture: Getty)

Getting a bit smooth up top? Judging on how you feel about it, your mum is the one you should be blaming /thanking.

Researchers at the University of Edinburgh have found that men inherit most of their baldness genes from their mums side of the family.

For what is the largest ever analysis of hair loss, scientists looked at the DNA of 52,000 men.

They identified almost 300 genes that could contribute to male pattern baldness most of which come from the X chromosome.

Saskia Hagenaars, who jointly led the research, said: We identified hundreds of new genetic signals.

It was interesting to find that many of the genetics signals for male pattern baldness came from the X chromosome, which men inherit from their mothers.

Before this research, published in PLOS Genetics, scientists had only identified a handful of genes related to baldness.

The studys principle investigator, Dr Riccardo Marioni, added: We are still a long way from making an accurate prediction for an individuals hair loss pattern.

However, these results take us one step closer.

The findings pave the way for an improved understanding of the genetic causes of hair loss.

More here:
Men inherit male pattern baldness from their mum's side of the family ... - Metro

Experts Are One Step Closer To Predicting A Man’s Risk For Hair Loss – Huffington Post

More than 200 new genetic markers linked with male pattern baldness have been identified, according to a new study from the United Kingdom.

The findings greatly increase the number of known genetic markers linked with baldness in men; a previous large study identified just eight such markers.

The researchers in the new study were also able to use their set of genetic markers to predict mens chances of severe hair loss, although the scientists noted that their results apply more to large populations of people than to any given individual.

We are still a long way from making an accurate prediction for an individuals hair-loss pattern. However, these results take us one step closer, study co-author Riccardo Marioni, of the University of Edinburghs Centre for Genomic and Experimental Medicine, said in a statement. The findings pave the way for an improved understanding of the genetic causes of hair loss, Marioni said. [5 Myths About the Male Body]

In the study, the researchers analyzed information from more than 52,000 men ages 40 to 69 years in the United Kingdom. Of these men, about 32 percent said they had no hair loss, 23 percent said they had slight hair loss, 27 percent said they had moderate hair loss and 18 percent said they had severe hair loss

The researchers then analyzed participants genomes, looking for genetic variations, known as single-nucleotide polymorphisms, or SNPs, that were linked with severe hair loss. That search revealed 287 genetic variations, located on more than 100 genes, that were linked with severe hair loss.

Many of the genetic variations were located on or near genes that have previously been linked with hair growth, hair graying or the biological structures involved in making hair, the researchers said.

Forty of the genetic variations were located on the X chromosome, which men inherit from their mothers, the researchers said. One of the genes on the X chromosome the gene for the androgen receptor, which binds to the hormone testosterone was strongly linked with severe hair loss. Previous studies have also pinpointed this gene as tied to male pattern baldness.

The researchers then created a formula, which resulted in a genetic risk score, to try to predict the chances of severe hair loss in the men. Among those men with a below-average score, 39 percent had no hair loss and 14 percent had severe hair loss. In contrast, among those with a high score that put them in the top 10 percent of those in the study, 58 percent had moderate-to-severe hair loss.

The researchers noted that in the study, they did not collect information on the age at which the men started losing their hair. The scientists said they would expect to see even stronger genetic associations with hair loss if they were able to include information about which men experienced early onset hair loss.

As more information from these participants becomes available, the researchers may be able to further refine their predictions, they said.

The study was published today (Feb. 14) in the journal PLOS Genetics.

Original article on Live Science.

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Experts Are One Step Closer To Predicting A Man's Risk For Hair Loss - Huffington Post

More Than 200 Baldness-Linked Genetic Markers Found – Yahoo News

More than 200 new genetic markers linked with male pattern baldness have been identified, according to a new study from the United Kingdom.

The findings greatly increase the number of known genetic markers linked with baldness in men; a previous large study identified just eight such markers.

The researchers in the new study were also able to use their set of genetic markers to predict men's chances of severe hair loss, although the scientists noted that their results apply more to large populations of people than to any given individual.

"We are still a long way from making an accurate prediction for an individual's hair-loss pattern. However, these results take us one step closer," study co-author Riccardo Marioni, of the University of Edinburgh's Centre for Genomic and Experimental Medicine, said in a statement. "The findings pave the way for an improved understanding of the genetic causes of hair loss," Marioni said. [5 Myths About the Male Body]

In the study, the researchers analyzed information from more than 52,000 men ages 40 to 69 years in the United Kingdom. Of these men, about 32 percent said they had no hair loss, 23 percent said they had slight hair loss, 27 percent said they had moderate hair loss and 18 percent said they had severe hair loss

The researchers then analyzed participants' genomes, looking for genetic variations, known as single-nucleotide polymorphisms, or SNPs, that were linked with severe hair loss. That search revealed 287 genetic variations, located on more than 100 genes, that were linked with severe hair loss.

Many of the genetic variations were located on or near genes that have previously been linked with hair growth, hair graying or the biological structures involved in making hair, the researchers said.

Forty of the genetic variations were located on the X chromosome, which men inherit from their mothers, the researchers said. One of the genes on the X chromosome the gene for the androgen receptor, which binds to the hormone testosterone was strongly linked with severe hair loss. Previous studies have also pinpointed this gene as tied to male pattern baldness.

The researchers then created a formula, which resulted in a genetic "risk score," to try to predict the chances of severe hair loss in the men. Among those men with a below-average score, 39 percent had no hair loss and 14 percent had severe hair loss. In contrast, among those with a high score that put them in the top 10 percent of those in the study, 58 percent had moderate-to-severe hair loss.

The researchers noted that in the study, they did not collect information on the age at which the men started losing their hair. The scientists said they would expect to see even stronger genetic associations with hair loss if they were able to include information about which men experienced early onset hair loss.

As more information from these participants becomes available, the researchers may be able to further refine their predictions, they said.

The study was published today (Feb. 14) in the journal PLOS Genetics.

Original article on Live Science.

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More Than 200 Baldness-Linked Genetic Markers Found - Yahoo News

Can Your Anxiety Impact How Long You Last In Bed? – Men’s Health


Men's Health
Can Your Anxiety Impact How Long You Last In Bed?
Men's Health
To rule out the influence of genetics, the researchers only studied male twins and brothers of twins. After analyzing their responses, the researchers found no link between anxiety symptoms reported in 2006 with later reports of premature ejaculation ...

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Can Your Anxiety Impact How Long You Last In Bed? - Men's Health

Women in Data Science conference highlights female participation in male-dominated field – Daily Free Press (subscription)


Daily Free Press (subscription)
Women in Data Science conference highlights female participation in male-dominated field
Daily Free Press (subscription)
Later in the day, Caroline Uhler, a professor at MIT's Institute for Data, Systems, and Society, shared her research on weather forecasting models and her work with genetics. Audience members listened, taking notes on Uhler's data-driven research and ...

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Women in Data Science conference highlights female participation in male-dominated field - Daily Free Press (subscription)

Male Contraceptives Have A Messy History And A Bright Future – Yahoo News

Shutterstock/UPROXX

Why is contraception the burden of women? Male contraception would seem to be a much easier way of having sex for fun and not sticking a woman with the baby, but its rarely been on the minds of scientists in the past. That may be about to change, especially with the recent success of Vasalgel in a clinical trial. But why did it take so long, and why is it going so slowly?

Currently contraception takes three forms when it comes to men: Withdrawal, vascetomy, or condoms. Pulling out requires experience and control, making it less than ideal for an act all about losing control. Vasectomy works, but is, well, a rather permanent solution most people dont want to resort to. And condoms generally work, and have the bonus of helping prevent STIs.

That said, contraceptive options for women tend to be riskier, healthwise. Hormonal birth control may, depending on your genetics, increase your risk of stroke, and other side effects of the pill, especially the psychological ones, had been downplayed or even covered up for years or decades. Tubal ligation is more dangerous than vasectomy, albeit only by a small margin, and also a permanent solution where one may not be wanted. And IUDs have rare, but potentially serious, risks. Simply put, biology makes it much easier for men to use contraceptives, but historically, its been the womans job.

The main issue is that where women produce one cell a month, men crank out literally over a thousand sperm per second. That makes male birth control inherently more hit-or-miss since, despite making millions of them, you only need one to get pregnant. And, it has to be said, theres also the social aspect: Men dont get pregnant, and its easier to simply stick the woman with the responsibility and walk away. The history of birth control is littered with ugly incidents where sex without babies was seen as more important than womens health.

That doesnt mean, however, that men havent been trying, and even succeeding to some degree. The ancient Greeks mixed hemp seeds and rue in alcohol to lower sperm count, a method which worked in rat studies conducted thousands of years later. Gossypol, a polymer found in cottonseed oil used for cooking, turned out to be effective, but had a high risk of permanent infertility. And recently, the folklore that papaya seeds reduce fertility turned out to be accurate.

The problem is that the fields had several high profile failures. For example, a few months ago, Facebook had a good giggle at the idea of fragile men unable to handle the side effects of an experimental set of hormonal birth control shots. But that ignored that as the study has scaled up, it had gotten more and more reports of excessively increased libido from more than a third of study participants and 20% reporting mood disorders. That meant one of two things: The drug was riskier than previously thought, or something in the trial had gone wrong.

Shutterstock

There are, however, a host of other options. Calcium channel blockers, encouraging the immune system to attack sperm, and even an alpha blocker that simply prevents ejaculation are all out there and being tested. And noninvasive surgical options, like the aforementioned Vasalgel, which is already in human trials in India, and a treatment blasting the testicles with ultrasound to kill sperm, are also showing promise.

So whats the issue? Why is research so slow? In a word? Trust. Women have repeatedly expressed a discomfort in trusting men to be in charge of their reproductive destiny. In fact, it can even be a form of domestic violence: In 2010, 10% of men and 9% of women report theyve been the targets of reproductive coercion, in which someone is forced into a pregnancy by means of sabotaging their birth control, or being impregnated without their consent. And only recently have the courts viewed removing a condom during sex as a serious crime.

That, combined with the fears of some men that male birth control will make them less of a man, can be a difficult hurdle for some to jump. That said, men should be allowed to take more control of their reproductive destiny. And medical science finally seems ready to give them just that.

Excerpt from:
Male Contraceptives Have A Messy History And A Bright Future - Yahoo News

The impact of RABL2B gene (rs144944885) on human male infertility in patients with oligoasthenoteratozoospermia … – UroToday

Male infertility is a multifactorial disorder with impressively genetic basis; besides, sperm abnormalities are the cause of numerous cases of male infertility. In this study, we evaluated the genetic variants in exons 4 and 5 and their intron-exon boundaries in RABL2B gene in infertile men with oligoasthenoteratozoospermia (OAT) and immotile short tail sperm (ISTS) defects to define if there is any association between these variants and human male infertility.

To this purpose, DNA was extracted from peripheral blood and after PCR reaction and sequencing, the results of sequenced segments were analyzed. In the present study, 30 infertile men with ISTS defect and 30 oligoasthenoteratozoospermic infertile men were recruited. All men were of Iranian origin and it took 3years to collect patient's samples with ISTS defect.

As a result, the 50776482 delC intronic variant (rs144944885) was identified in five patients with oligoasthenoteratozoospermia defect and one patient with ISTS defect in heterozygote form. This variant was not identified in controls. The allelic frequency of the 50776482 delC variant was significantly statistically higher in oligoasthenoteratozoospermic infertile men (p

According to the present study, 50776482 delC allele in the RABL2B gene could be a risk factor in Iranian infertile men with oligoasthenoteratozoospermia defect, but more genetic studies are required to understand the accurate role of this variant in pathogenesis of human male infertility.

Journal of assisted reproduction and genetics. 2017 Jan 30 [Epub ahead of print]

Seyedeh Hanieh Hosseini, Mohammad Ali Sadighi Gilani, Anahita Mohseni Meybodi, Marjan Sabbaghian

Department of Andrology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran., Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran., Department of Andrology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran. .

PubMed http://www.ncbi.nlm.nih.gov/pubmed/28138870

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The impact of RABL2B gene (rs144944885) on human male infertility in patients with oligoasthenoteratozoospermia ... - UroToday

Entrepreneurship Is Genetic, And South Africa Is The Ideal Environment For Young Entrepreneurs To Thrive – Huffington Post South Africa (blog)

Knowing the real South Africa is to know, and be familiar with, the ambitious entrepreneurial spirit that runs through its tributaries and flows like a river into the heart of a nation. South Africans have always been opportunistic, from J.B.M Hertzog who founded Naspers, which is now Africa's largest company and globally the 7th largest internet company, to MTN and Discovery, both of which can now be found all over the world. We can even highlight the contributions of one of the world's most foremost thinkers and innovators, Elon Musk, the driving force behind SpaceX.

Recently, Ventureburn did an article on the Top Entrepreneurs Under 40 in South Africa, highlighting how this spirit continues to grow and is a far cry from fading anytime soon. But what differentiates the men and women who started these companies from those of us 'normal' people who would not regard ourselves as entrepreneurs?

Entrepreneurs are a rare breed of humans who choose to innovate and forge their ideas into successful business from the ground up. They're fearless and believe that what they are creating is going to change the world forever. And guess what, research shows that this could be genetic.

A recent study at Kings College in London, headed up by Scott Shane, identified that 37 to 48 per cent of the tendency to be an entrepreneur is genetic, and that the tendency to identify new business opportunities is in your genes. If you take this study as anything to go by, then this is remarkable as genetics account for almost half of what is a determining factor in becoming an entrepreneur.

What we know about genetics is that in some cases almost half of who we are is genetic, or how we are made, and the rest is down to environmental factors (in other words, what we do and how we live). This presents us all with an incredible opportunity to take control of our environment to use our genetic strengths to reach our goal. For some, and I would encourage any young South African with ambition to consider this path, that goal is entrepreneurship.

Take the environment in South Africa, for instance. South Africa is still a young country that is constantly growing, discovering who it is, and where its place in the world will be. This is what makes it the ideal environment for those predisposed, by either genetics, environment or desire, to entrepreneurship to thrive. It's not all dependent on your genotype, but a large proportion of it could be, according to this study, and this could be what drives certain people to tackle new, exciting business ventures that other people may be dissuaded from due to fear of failure and the unknown.

This isn't the only study that associates entrepreneurship with being genetics.

Nicos Nicolaou is a researcher who has been heading up these new discoveries that attempt to link genetics to entrepreneurship. Although they still require more research, which will come as the science around the human genome develops, their findings are interesting. They explain that there is a "single nucleotide polymorphism (rs1486011) of the DRD3 gene on chromosome 3 to be significantly associated with the tendency to be an entrepreneur. This result is the first evidence of the association of a specific gene with entrepreneurship."

Wouldn't you like to know if you had this gene, especially if you can already be considered an entrepreneur? I know I would, as it would be interesting to discover if my genes influenced me to start DNAFit, or any of my other business ventures.

I would also like to know if this gene is related to not requiring as much sleep as the average person - entrepreneurs never rest while there is opportunity to innovate and expand our ideas!

Going even deeper, Zhang did twin studies to find out if personality and gender play a role in the development of entrepreneurship as well. Their study can be regarded as verging on epigenetic as it uses the environmental impact, as well as genes.

It is based on "1285 pairs of identical twins (449 male and 836 female pairs) and 849 pairs of same-sex fraternal twins (283 male and 566 female pairs), we found that females have a strong genetic influence and zero shared-environmental influences on their tendency to become entrepreneurs. In contrast, males show zero genetic influence, but a large shared-environmental influence... such individuals appear to be 'both born and made'."

The difference in gender also make clear the notion that genes influence females and males differently, but they still eventually reach the same conclusion on their journey. As with everything, we still do not know enough about our genes to get conclusive, definite answers, and, even then, never forget environmental effects could re-direct people in a variety of ways.

How much start-up capital are you able to attain? How dedicated is your work force to your vision so that make it a success? How well-received are you not only by the market but by the influential people who rely on to believe in your brand as well?

And those are just a few factors...

Studies like the ones above do show how genetics are becoming more important than ever before when it comes to our understanding of the world. It's not only about predisposition to disease, ancestry, and race.

We are becoming more and more capable of harnessing the power of genetics and applying it to our daily lives, and there is an opportunity to make South Africa the best environment for entrepreneurship in the world. Take the example of other great startup cities, such as Lisbon. In Lisbon, they went to great lengths to provide great access to capital, human resource, and cut red-tape for new businesses. Now, Lisbon is one of the top startup cities in the world - nominated European Capital of Entrepreneurship in 2015.

In South Africa, we have the ability to follow Lisbon, and go even further. With a talented, ambitious, and abundant workforce, great access to high quality office space and a low cost of living, we have everything the country needs to be the next Silicon Valley. Coupled with our incredible quality of life (and weather!), it seems to me that for all South Africans, this a time where nothing should be holding you back.

It's inspirational to think that our entrepreneurial fire has only been started, and we as a country should do everything we can to foster an environment supportive of entrepreneurship and startup culture for everybody no matter how or where they were born. With this approach, we can make South Africa a world leader in both our genetic talent pool, and our fostering environment for entrepreneurship.

See the rest here:
Entrepreneurship Is Genetic, And South Africa Is The Ideal Environment For Young Entrepreneurs To Thrive - Huffington Post South Africa (blog)

Tortoiseshell cat – Wikipedia

Tortoiseshell is a cat coat coloring named for its similarity to tortoiseshell material. Tortoiseshell cats are almost exclusively female.[1][2][3] Male tortoiseshells are rare and are usually sterile.[4][a]

Also called torties for short, tortoiseshell cats combine two colors other than white, either closely mixed or in larger patches.[2] The colors are often described as red and black, but the "red" patches can instead be orange, yellow, or cream,[2] and the "black" can instead be chocolate, grey, tabby, or blue.[2] Tortoiseshell cats with the tabby pattern as one of their colors are sometimes referred to as a torbie.[6]

"Tortoiseshell" is typically reserved for particolored cats with relatively small or no white markings. Those that are largely white with tortoiseshell patches are described as tricolor,[2] tortoiseshell-and-white (in the United Kingdom), or calico (in Canada and the United States).[7]

Tortoiseshell markings appear in many different breeds, as well as in non-purebred domestic cats.[7] This pattern is especially preferred in the Japanese Bobtail breed,[8] and exists in the Cornish Rex group.[9]

Tortoiseshell cats have particolored coats with patches of various shades of red and black, and sometimes white. A tortoiseshell can also have splotches of orange or gold, but these colors are rarer on the breed.[4] The size of the patches can vary from a fine speckled pattern to large areas of color. Typically, the more white a cat has, the more solid the patches of color. Dilution genes may modify the coloring, lightening the fur to a mix of cream and blue, lilac or fawn; and the markings on tortoiseshell cats are usually asymmetrical.[10]

Occasionally tabby patterns of black and brown (eumelanistic) and red (phaeomelanistic) colors are also seen. These patched tabbies are often called a tortie-tabby, torbie or, with large white areas, a caliby.[10] Not uncommonly there will be a "split face" pattern with black on one side of the face and orange on the other, with a dividing line running down the bridge of the nose. Tortoiseshell coloring can also be expressed in the point pattern, referred to as a "tortie point".[10]

Tortoiseshell and calico coats result from an interaction between genetic and developmental factors. The primary gene for coat color (B) for the colors brown, chocolate, cinnamon, etc., can be masked by the co-dominant gene for the orange color (O) which is on the X Chromosome and has two alleles, the orange (XO) and not-orange (Xo), that produce orange phaeomelanin and black eumelanin pigments, respectively. (NOTE: Typically, the X for the chromosome is assumed from context and the alleles are referred to by just the uppercase O for the orange, or lower case o for the not-orange.) The tortoiseshell and calico cats are indicated: Oo to indicate they are heterozygous on the O gene. The (B) and (O) genes can be further modified by a recessive dilute gene (dd) which softens the colors. Orange becomes cream, black becomes gray, etc. Various terms are used for specific colors, for example, gray is also called blue, orange is also called ginger. Therefore, a tortoiseshell cat may be a chocolate tortoiseshell or a blue/cream tortoiseshell or the like, based on the alleles for the (B) and (D) genes.

The cells of female cats, which like other mammalian females have two X chromosomes (XX), undergo the phenomenon of X-inactivation,[11][12] in which one or the other of the X-chromosomes is turned off at random in each cell in very early development. The inactivated X becomes a Barr body. Cells in which the chromosome carrying the orange (O) allele is inactivated express the alternative non-orange (o) allele, determined by the (B) gene. Cells in which the non-orange (o) allele is inactivated express the orange (O) allele. Pigment genes are expressed in melanocytes that migrate to the skin surface later in development. In bi-colored tortoiseshell cats, the melanocytes arrive relatively early, and the two cell types become intermingled, producing the characteristic brindled appearance consisting of an intimate mixture of orange and black cells, with occasional small diffuse spots of orange and black.

In tri-colored calico cats, a separate gene interacts developmentally with the coat color gene. This spotting gene produces white, unpigmented patches by delaying the migration of the melanocytes to the skin surface. There are a number of alleles of this gene that produce greater or lesser delays. The amount of white is artificially divided into mitted, bicolor, harlequin, and van, going from almost no white to almost completely white. In the extreme case, no melanocytes make it to the skin and the cat is entirely white (but not an albino). In intermediate cases, melanocyte migration is slowed, so that the pigment cells arrive late in development and have less time to intermingle. Observation of tri-color cats will show that, with a little white color, the orange and black patches become more defined, and with still more white, the patches become completely distinct. Each patch represents a clone of cells derived from one original cell in the early embryo.[13]

A male cat, like males of other therian mammals, has only one X and one Y chromosome (XY). That X chromosome does not undergo X-inactivation, and coat color is determined by which allele is present on the X. Accordingly, the cat's coat will be either entirely orange or non-orange. Very rarely (approximately 1 in 3,000[14]) a male tortoiseshell or calico is born. These animals typically have an extra X chromosome (XXY), a condition known in humans as Klinefelter syndrome, and their cells undergo an X-inactivation process like that in females. As in humans, these cats often are sterile because of the imbalance in sex chromosomes. Some male calico or tortoiseshell cats may be chimeras, which result from the fusion in early development of two (fraternal twin) embryos with different color genotypes. Others are mosaics, in which the XXY condition arises after conception and the cat is a mixture of cells with different numbers of X chromosomes.

In the folklore of many cultures, cats of the tortoiseshell coloration are believed to bring good luck.[15] Dating back to Celtic times, tortoiseshell cats have been perceived to bring good fortune into their homes. Even today, the Irish and Scottish believe stray tortoiseshell cats bring them luck.[16] In the United States, tortoiseshells are sometimes referred to as money cats.[17]

One study found that tortoiseshell owners frequently believe their cats have increased attitude ("tortitude");[18] however, little scientific evidence supports this.[19] According to celebrity cat expert Jackson Galaxy, tortoiseshell cats tend to have a much more distinct personality.[20]

See the rest here:
Tortoiseshell cat - Wikipedia

Binary thought suppresses identity – The Daily Evergreen

WSU forms ask non-inclusive race and gender questions, even though these answers are not important to the evaluation of the form.

While our country has become increasingly more accepting of individuality, there are still many instances where our society is failing to adequately represent minorities.

For example, the WSU Junior Writing Portfolios (JWP) cover sheet asks students to specify their gender as either male or female, giving no option for individuals who do not identify as one or the other.

Freshman mechanical engineering major Nicklaus McHendry said that they have had difficulties with how to identify themself for others.

Ive been out as a non-binary person for many years, McHendry said. At this point (it is exhausting to see) a question with a binary male or female box on a form that I dont particularly feel I need to be asked that on.

So, why is WSU asking questions such as these on forms where specifying something such as gender or race isnt necessary? For the JWP, WSU just wants a representation of a students writing ability.

I dont feel that my gender or anyone elses should be specified on a form that doesnt have anything to do with it, McHendry said.

The director of writing assessments, Xyanthe Neider, wrote in an email that students can mark the gender that they feel most adequately represents them or they can leave the question blank.

We understand that gender is much more fluid beyond the binary male/female designators and we revisit this regularly, Neider wrote.

However, there is no indication on the form to suggest that specifying ones gender is optional.

Consequently, attempting to answer this question has left many students confused and frustrated while they ponder which of the two boxes most correctly identifies them.

Its hard not to be upset, McHendry said. In order to get through the day and not spend every waking moment of my life being bothered, angry and upset ... I try to focus on things that are more important.

If they want to ask about gender, they should add the option to write it in on the JWP form, which would make certain minority students feel more accepted.

In addition to the JWP, the WSU online application for admission requires students to report their gender as either male or female. The application also asks students to report their race.

Many universities across the country consider ethnicity and gender in the admission process, which unfairly puts some students at a disadvantage and gives others the upper hand.

According to ballotpedia.org, Washington is one of eight states that currently bans public universities from considering race in admissions, a policy known as Affirmative Action.

WSU does not discriminate on the basis of race, sex, sexual orientation, gender identity/expression (or) religion, the Office for Equal Opportunity states on its website.

It is completely inappropriate to ask students to specify certain personal demographics when those responses have absolutely nothing to do with the reason the form is completed.

So, if WSU is not allowed to consider race during the application process, then why are they asking students to specify it on their application?

Emily Hogan is a freshman genetics and cell biology major from Harrington, Delaware. She can be contacted at 335-2290 or byopinion@dailyevergreen.com. The opinions expressed in this column are not necessarily those of the staff of The Daily Evergreen or those of The Office of Student Media.

Read the original:
Binary thought suppresses identity - The Daily Evergreen

The 44 Chromosome Man | Understanding Genetics

In a recent article, a doctor in China has identified a man who has 44 chromosomes instead of the usual 46. Except for his different number of chromosomes, this man is perfectly normal in every measurable way.

His chromosomes are arranged in a stable way that could be passed on if he met a nice girl who had 44 chromosomes too. And this would certainly be possible in the future given his family history.

But why doesn't he have any problems? A loss of one let alone two chromosomes is almost always fatal because so many essential genes are lost.

In this case, he has fewer chromosomes but is actually missing very few genes. Instead, he has two chromosomes stuck to two other chromosomes. More specifically, both his chromosome 14's are stuck to his chromosome 15's.

So he has almost all the same genes as any other person. He just has them packaged a bit differently.

This is an important finding because it tells us about a key genetic event in human prehistory. All the evidence points to humans, like their relatives the chimpanzees, having 48 chromosomes a million or so years ago. Nowadays most humans have 46.

What happened to this 44 chromosome man shows one way that the first step in this sort of change might have happened in our past. Scientists could certainly predict something like this. But now there is proof that it can actually happen.

Note added in Proof: Here are some older papers that I missed that have very similar findings:

And the current one:

Case Report: Potential Speciation in Humans Involving Robertsonian Translocations.

His Story

So how did this man end up with 44 chromosomes? It is a story of close relatives having children together. And a chromosomal rearrangement called a balanced translocation.

A balanced translocation is when one chromosome sticks to another. Because no genes are lost in this process, it usually doesn't have any effect. Until these folks try to have kids that is.

Usually around 2/3 of pregnancies involving one person with a balanced translocation will end in miscarriage. This has to do with how chromosomes separate when eggs and sperm are made. This process is called meiosis.

Remember, humans (and most other living things) have two copies of each chromosome. So they have two copies of chromosome 1, two copies of chromosome 2, etc. Only one chromosome from each pair gets put into any one sperm or egg. That way, when the sperm fertilizes the egg, the fetus has the right number of chromosomes.

This is where the problem starts for people with a balanced translocation. They have one unpaired chromosome and a pair with an extra chromosome. Here is what can happen in this situation:

The top row represents two potential parents. The parent on the right has a balanced translocation. There are two possible ways for the fused chromosome to line up.

In the figure, only two chromosomes are shown. Numbers 14 and 15 were chosen because these are the two that are fused in the 44 chromosome man.

The parent with the balanced translocation can make 4 different kinds of sperm or egg (the second row). As the figure shows, when the eggs and sperm combine, 1/2 of the time the fetus ends up with an extra or missing chromosome. Unless this chromosome is the X, Y or number 21, the usual result is miscarriage or being born with severe problems.

In this case it would almost certainly result in miscarriage. In fact, the 44 chromosome man's family has a long history of miscarriages and spontaneous abortions.

To get two of the same balanced translocations, both parents need to have the same balanced translocation. This is incredibly rare. Except when the parents are related.

In this case, both parents are first cousins and they share the same translocation. When these parents try to have kids, they run into the same kinds of problems that can happen with one balanced translocation. Except that the problems are doubled. This makes for the many possibilities outlined below:

This very complicated table shows the 36 possible outcomes when two parents with the same balanced translocation attempt to have a child.

In this representation, the father's possible sperm are shown on the top and the mother's eggs on the side. Each pregnancy has only an 8 in 36 chance for success. And 1 out of 36 would have two of the same balanced translocation (the circled possibility).

Theoretically the 44 chromosome man should have fewer problems having children than his parents did. As this figure shows, there are no unpaired chromosomes when he and a woman with 46 chromosomes have children. But all of their kids would have a balanced translocation:

So this is how he came to have 44 chromosomes. This might also be how humans started on the road to 46 chromosomes a million or so years ago.

See the article here:
The 44 Chromosome Man | Understanding Genetics

Sex – Wikipedia

Organisms of many species are specialized into male and female varieties, each known as a sex,[1] with some falling in between being intersex. Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent. Gametes can be identical in form and function (known as isogamy), but in many cases an asymmetry has evolved such that two sex-specific types of gametes (heterogametes) exist (known as anisogamy).

Among humans and other mammals, males typically carry XY chromosomes, whereas females typically carry XX chromosomes, which are a part of the XY sex-determination system. Other animals have a sex-determination system as well, such as the ZW sex-determination system in birds, and the X0 sex-determination system in insects.

The gametes produced by an organism are determined by its sex: males produce male gametes (spermatozoa, or sperm, in animals; pollen in plants) while females produce female gametes (ova, or egg cells); individual organisms which produce both male and female gametes are termed hermaphroditic. Frequently, physical differences are associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience. For instance, mate choice and sexual selection can accelerate the evolution of physical differences between the sexes.

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One of the basic properties of life is reproduction, the capacity to generate new individuals, and sex is an aspect of this process. Life has evolved from simple stages to more complex ones, and so have the reproduction mechanisms. Initially the reproduction was a replicating process that consists in producing new individuals that contain the same genetic information as the original or parent individual. This mode of reproduction is called asexual, and it is still used by many species, particularly unicellular, but it is also very common in multicellular organisms.[2] In sexual reproduction, the genetic material of the offspring comes from two different individuals. As sexual reproduction developed by way of a long process of evolution, intermediates exist. Bacteria, for instance, reproduce asexually, but undergo a process by which a part of the genetic material of an individual (donor) is transferred to an other (recipient).[3]

Disregarding intermediates, the basic distinction between asexual and sexual reproduction is the way in which the genetic material is processed. Typically, prior to an asexual division, a cell duplicates its genetic information content, and then divides. This process of cell division is called mitosis. In sexual reproduction, there are special kinds of cells that divide without prior duplication of its genetic material, in a process named meiosis. The resulting cells are called gametes, and contain only half the genetic material of the parent cells. These gametes are the cells that are prepared for the sexual reproduction of the organism.[4] Sex comprises the arrangements that enable sexual reproduction, and has evolved alongside the reproduction system, starting with similar gametes (isogamy) and progressing to systems that have different gamete types, such as those involving a large female gamete (ovum) and a small male gamete (sperm).[5]

In complex organisms, the sex organs are the parts that are involved in the production and exchange of gametes in sexual reproduction. Many species, particularly animals, have sexual specialization, and their populations are divided into male and female individuals. Conversely, there are also species in which there is no sexual specialization, and the same individuals both contain masculine and feminine reproductive organs, and they are called hermaphrodites. This is very frequent in plants.[6]

Sexual reproduction first probably evolved about a billion years ago within ancestral single-celled eukaryotes.[7] The reason for the evolution of sex, and the reason(s) it has survived to the present, are still matters of debate. Some of the many plausible theories include: that sex creates variation among offspring, sex helps in the spread of advantageous traits, that sex helps in the removal of disadvantageous traits, and that sex facilitates repair of germ-line DNA.

Sexual reproduction is a process specific to eukaryotes, organisms whose cells contain a nucleus and mitochondria. In addition to animals, plants, and fungi, other eukaryotes (e.g. the malaria parasite) also engage in sexual reproduction. Some bacteria use conjugation to transfer genetic material between cells; while not the same as sexual reproduction, this also results in the mixture of genetic traits.

The defining characteristic of sexual reproduction in eukaryotes is the difference between the gametes and the binary nature of fertilization. Multiplicity of gamete types within a species would still be considered a form of sexual reproduction. However, no third gamete is known in multicellular animals.[8][9][10]

While the evolution of sex dates to the prokaryote or early eukaryote stage,[11] the origin of chromosomal sex determination may have been fairly early in eukaryotes (see Evolution of anisogamy). The ZW sex-determination system is shared by birds, some fish and some crustaceans. XY sex determination is used by most mammals,[12] but also some insects,[13] and plants (Silene latifolia).[14]X0 sex-determination is found in certain insects.

No genes are shared between the avian ZW and mammal XY chromosomes,[15] and from a comparison between chicken and human, the Z chromosome appeared similar to the autosomal chromosome 9 in human, rather than X or Y, suggesting that the ZW and XY sex-determination systems do not share an origin, but that the sex chromosomes are derived from autosomal chromosomes of the common ancestor of birds and mammals. A paper from 2004 compared the chicken Z chromosome with platypus X chromosomes and suggested that the two systems are related.[16]

Sexual reproduction in eukaryotes is a process whereby organisms form offspring that combine genetic traits from both parents. Chromosomes are passed on from one generation to the next in this process. Each cell in the offspring has half the chromosomes of the mother and half of the father.[17] Genetic traits are contained within the deoxyribonucleic acid (DNA) of chromosomesby combining one of each type of chromosomes from each parent, an organism is formed containing a doubled set of chromosomes. This double-chromosome stage is called "diploid", while the single-chromosome stage is "haploid". Diploid organisms can, in turn, form haploid cells (gametes) that randomly contain one of each of the chromosome pairs, via meiosis.[18] Meiosis also involves a stage of chromosomal crossover, in which regions of DNA are exchanged between matched types of chromosomes, to form a new pair of mixed chromosomes. Crossing over and fertilization (the recombining of single sets of chromosomes to make a new diploid) result in the new organism containing a different set of genetic traits from either parent.

In many organisms, the haploid stage has been reduced to just gametes specialized to recombine and form a new diploid organism; in others, the gametes are capable of undergoing cell division to produce multicellular haploid organisms. In either case, gametes may be externally similar, particularly in size (isogamy), or may have evolved an asymmetry such that the gametes are different in size and other aspects (anisogamy).[19] By convention, the larger gamete (called an ovum, or egg cell) is considered female, while the smaller gamete (called a spermatozoon, or sperm cell) is considered male. An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. An individual that produces both types of gametes is a hermaphrodite; in some cases hermaphrodites are able to self-fertilize and produce offspring on their own, without a second organism.[20]

Most sexually reproducing animals spend their lives as diploid organisms, with the haploid stage reduced to single cell gametes.[21] The gametes of animals have male and female formsspermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism.

The male gamete, a spermatozoon (produced within a testicle), is a small cell containing a single long flagellum which propels it.[22] Spermatozoa are extremely reduced cells, lacking many cellular components that would be necessary for embryonic development. They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization.

Female gametes are egg cells (produced within ovaries), large immobile cells that contain the nutrients and cellular components necessary for a developing embryo.[23] Egg cells are often associated with other cells which support the development of the embryo, forming an egg. In mammals, the fertilized embryo instead develops within the female, receiving nutrition directly from its mother.

Animals are usually mobile and seek out a partner of the opposite sex for mating. Animals which live in the water can mate using external fertilization, where the eggs and sperm are released into and combine within the surrounding water.[24] Most animals that live outside of water, however, must transfer sperm from male to female to achieve internal fertilization.

In most birds, both excretion and reproduction is done through a single posterior opening, called the cloacamale and female birds touch cloaca to transfer sperm, a process called "cloacal kissing".[25] In many other terrestrial animals, males use specialized sex organs to assist the transport of spermthese male sex organs are called intromittent organs. In humans and other mammals this male organ is the penis, which enters the female reproductive tract (called the vagina) to achieve inseminationa process called sexual intercourse. The penis contains a tube through which semen (a fluid containing sperm) travels. In female mammals the vagina connects with the uterus, an organ which directly supports the development of a fertilized embryo within (a process called gestation).

Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination, for example, is used by some insect species to inseminate females through a wound in the abdominal cavitya process detrimental to the female's health.

Like animals, plants have developed specialized male and female gametes.[26] Within seed plants, male gametes are contained within hard coats, forming pollen. The female gametes of plants are contained within ovules; once fertilized by pollen these form seeds which, like eggs, contain the nutrients necessary for the development of the embryonic plant.

Female (left) and male (right) cones are the sex organs of pines and other conifers.

Many plants have flowers and these are the sexual organs of those plants. Flowers are usually hermaphroditic, producing both male and female gametes. The female parts, in the center of a flower, are the pistils, each unit consisting of a carpel, a style and a stigma. One or more of these reproductive units may be merged to form a single compound pistil. Within the carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: these consist of long filaments arranged between the pistil and the petals that produce pollen in anthers at their tips. When a pollen grain lands upon the stigma on top of a carpel's style, it germinates to produce a pollen tube that grows down through the tissues of the style into the carpel, where it delivers male gamete nuclei to fertilize an ovule that eventually develops into a seed.

In pines and other conifers the sex organs are conifer cones and have male and female forms. The more familiar female cones are typically more durable, containing ovules within them. Male cones are smaller and produce pollen which is transported by wind to land in female cones. As with flowers, seeds form within the female cone after pollination.

Because plants are immobile, they depend upon passive methods for transporting pollen grains to other plants. Many plants, including conifers and grasses, produce lightweight pollen which is carried by wind to neighboring plants. Other plants have heavier, sticky pollen that is specialized for transportation by insects. The plants attract these insects or larger animals such as humming birds and bats with nectar-containing flowers. These animals transport the pollen as they move to other flowers, which also contain female reproductive organs, resulting in pollination.

Most fungi reproduce sexually, having both a haploid and diploid stage in their life cycles. These fungi are typically isogamous, lacking male and female specialization: haploid fungi grow into contact with each other and then fuse their cells. In some of these cases the fusion is asymmetric, and the cell which donates only a nucleus (and not accompanying cellular material) could arguably be considered "male".[27]

Some fungi, including baker's yeast, have mating types that create a duality similar to male and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type.[28]

Fungi produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid sporesthe height of the mushroom aids the dispersal of these sexually produced offspring.

The most basic sexual system is one in which all organisms are hermaphrodites, producing both male and female gametes[citation needed] this is true of some animals (e.g. snails) and the majority of flowering plants.[29] In many cases, however, specialization of sex has evolved such that some organisms produce only male or only female gametes. The biological cause for an organism developing into one sex or the other is called sex determination.

In the majority of species with sex specialization, organisms are either male (producing only male gametes) or female (producing only female gametes). Exceptions are commonfor example, the roundworm C. elegans has an hermaphrodite and a male sex (a system called androdioecy).

Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects.

In genetic sex-determination systems, an organism's sex is determined by the genome it inherits. Genetic sex-determination usually depends on asymmetrically inherited sex chromosomes which carry genetic features that influence development; sex may be determined either by the presence of a sex chromosome or by how many the organism has. Genetic sex-determination, because it is determined by chromosome assortment, usually results in a 1:1 ratio of male and female offspring.

Humans and other mammals have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. The "default sex," in the absence of a Y chromosome, is female-like. Thus, XX mammals are female and XY are male. In humans, biological sex is determined by five factors present at birth: the presence or absence of a Y chromosome (which alone determines the individual's genetic sex), the type of gonads, the sex hormones, the internal reproductive anatomy (such as the uterus in females), and the external genitalia.[30]

XY sex determination is found in other organisms, including the common fruit fly and some plants.[29] In some cases, including in the fruit fly, it is the number of X chromosomes that determines sex rather than the presence of a Y chromosome (see below).

In birds, which have a ZW sex-determination system, the opposite is true: the W chromosome carries factors responsible for female development, and default development is male.[31] In this case ZZ individuals are male and ZW are female. The majority of butterflies and moths also have a ZW sex-determination system. In both XY and ZW sex determination systems, the sex chromosome carrying the critical factors is often significantly smaller, carrying little more than the genes necessary for triggering the development of a given sex.[32]

Many insects use a sex determination system based on the number of sex chromosomes. This is called X0 sex-determinationthe 0 indicates the absence of the sex chromosome. All other chromosomes in these organisms are diploid, but organisms may inherit one or two X chromosomes. In field crickets, for example, insects with a single X chromosome develop as male, while those with two develop as female.[33] In the nematode C. elegans most worms are self-fertilizing XX hermaphrodites, but occasionally abnormalities in chromosome inheritance regularly give rise to individuals with only one X chromosomethese X0 individuals are fertile males (and half their offspring are male).[34]

Other insects, including honey bees and ants, use a haplodiploid sex-determination system.[35] In this case diploid individuals are generally female, and haploid individuals (which develop from unfertilized eggs) are male. This sex-determination system results in highly biased sex ratios, as the sex of offspring is determined by fertilization rather than the assortment of chromosomes during meiosis.

For many species, sex is not determined by inherited traits, but instead by environmental factors experienced during development or later in life. Many reptiles have temperature-dependent sex determination: the temperature embryos experience during their development determines the sex of the organism. In some turtles, for example, males are produced at lower incubation temperatures than females; this difference in critical temperatures can be as little as 12C.

Many fish change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism. In clownfish, smaller fish are male, and the dominant and largest fish in a group becomes female. In many wrasses the opposite is truemost fish are initially female and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male.

In some ferns the default sex is hermaphrodite, but ferns which grow in soil that has previously supported hermaphrodites are influenced by residual hormones to instead develop as male.[36]

Many animals and some plants have differences between the male and female sexes in size and appearance, a phenomenon called sexual dimorphism. Sex differences in humans include, generally, a larger size and more body hair in men; women have breasts, wider hips, and a higher body fat percentage. In other species, the differences may be more extreme, such as differences in coloration or bodyweight.

Sexual dimorphisms in animals are often associated with sexual selection the competition between individuals of one sex to mate with the opposite sex.[37] Antlers in male deer, for example, are used in combat between males to win reproductive access to female deer. In many cases the male of a species is larger than the female. Mammal species with extreme sexual size dimorphism tend to have highly polygynous mating systemspresumably due to selection for success in competition with other malessuch as the elephant seals. Other examples demonstrate that it is the preference of females that drive sexual dimorphism, such as in the case of the stalk-eyed fly.[38]

Other animals, including most insects and many fish, have larger females. This may be associated with the cost of producing egg cells, which requires more nutrition than producing spermlarger females are able to produce more eggs.[39] For example, female southern black widow spiders are typically twice as long as the males.[40] Occasionally this dimorphism is extreme, with males reduced to living as parasites dependent on the female, such as in the anglerfish. Some plant species also exhibit dimorphism in which the females are significantly larger than the males, such as in the moss Dicranum[41] and the liverwort Sphaerocarpos.[42] There is some evidence that, in these genera, the dimorphism may be tied to a sex chromosome,[42][43] or to chemical signalling from females.[44]

In birds, males often have a more colourful appearance and may have features (like the long tail of male peacocks) that would seem to put the organism at a disadvantage (e.g. bright colors would seem to make a bird more visible to predators). One proposed explanation for this is the handicap principle.[45] This hypothesis says that, by demonstrating he can survive with such handicaps, the male is advertising his genetic fitness to femalestraits that will benefit daughters as well, who will not be encumbered with such handicaps.

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