Y Chromosome Retains Key Genes for Fertility

Study Dispels Theories of Y Chromosome’s Demise:

Stripped-Down Chromosome Retains Key Genes for Fertility

Stripped-Down Chromosome Retains Key Genes for Fertility

 

“Y chromosome has lost 90 percent of genes that once shared with the X chromosome, and some scientists have speculated that the Y chromosome will disappear in less than 5 million years ,” said evolutionary biologist Melissa A. Wilson Sayres a Miller Postdoctoral Fellow in the Department of Integrative Biology , University of California, Berkeley, and lead author of the new analysis .

Some mammals have lost their Y chromosome, although they still have men and women and reproduce normally . Researchers reported some shuffling genes in mice to create Y- less males could produce normal offspring , leading some analysts to wonder if the chromosome is superfluous.

“Our study shows that genes that have remained , and those who migrated from X to Y , that are important , and human and will stay for a long time,” he said.

Wilson Sayres and coauthor Rasmus Nielsen, in PLoS Genetics that patterns of variation in the Y chromosome among the 16 men are consistent with the selection naturally acts to maintain gene content there, many of which have been shown to play a role in male fertility. Insignificant size of the Y chromosome – which contains 27 unique genes in front of thousands of people in the other chromosomes – is a sign that is lean and stripped to essentials.

“The results are quite impressive. They show that because there is a lot of natural selection working on the Y chromosome , which has to be much more depending on the chromosome of people previously thought,” Nielsen said.

Variations in the Y chromosomes are used to track human populations moved around the world, and according to Nielsen , the new research will help improve estimates of the evolutionary history of humans.

” Melissa has shown that this strong negative selection – natural selection to eliminate deleterious genes – tends to make us think the dates are older than they are , which gives very different estimates of the history of our ancestors,” Nielsen said.  And it has degraded over the past 200 million

Before about 200 million years ago when mammals were relatively new to the Earth, the first versions of the sex chromosomes, X and Y, were like other pairs of chromosomes in each generation , they swapped a pair of genes for the children were a mix of genes from their parents. Fertilized eggs obtained two proto -X became females and eggs with a proto -X and proto -Y became men.

But for some reason , said Wilson Sayres , the gene that triggers the cascade of events that result in male characteristics became fixed on the Y chromosome and attracted other gene specific , such as those that control the development of the testes men , sperm and semen. Many of them proved to be harmful to women , so that the X and Y stopped exchanging genes and the two chromosomes began to evolve separately.

“Now the X and Y do not exchange DNA over most of its length , which means that Y can not be efficiently fix errors , so degraded over time,” he said. “In XX females , the X still has a partner to exchange with and correct mistakes , so we think the X has also degraded . ”

Wilson Sayres was fascinated by the strange story of the sex chromosomes , and in particular , the lack of genetic variation worldwide in the Y chromosome compared to the range observed in the DNA in the non-sex chromosomes. This variation , although used to trace human history, was poorly characterized in whole chromosome Y. .

” Y chromosomes are more similar to each other than we expect ,” said Wilson Sayres . “There has been some debate about whether this is because there are fewer men who contribute to the next generation , or whether natural selection acts to eliminate variation . ”

Did genes contribute fewer males the Y chromosome ?

UC Berkeley researchers showed that if fewer males were the only cause of low variability , mean that less than 1 in 4 men throughout history had happened in his chromosome each generation. Variations in other human chromosomes , including the X chromosome, making it an unlikely scenario . Instead, showed low variation will be explained by intense natural selection , ie , a strong evolutionary pressure to weed out the bad mutations that eventually cut the chromosome to its essential elements.

” We show that a model of purifying selection acting on the Y chromosome to eliminate harmful mutations , in combination with a moderate reduction in the number of men who are going into their chromosomes and may explain low Y diversity , ” said Wilson Sayres .

The researchers also found that 27 genes on the Y chromosome – 17 humans retained after 200 million years , and 10 genes more recently acquired but little known – are likely to be affected by natural selection . Most new gene, called ampliconic genes are present in multiple copies in the chromosome and the loss of one or more copies has been related to male infertility.

“These ampliconic regions that we have not really understood until now are obviously very important and probably should be researched and studied for fertility ,” he said .

Wilson Sayres was able to accurately measure the variable Y for first comparing the variation in the chromosome of a person with the variation in other 22 pairs of the person (called autosomes ) , the X chromosome and the mitochondrial DNA. She used data from the entire genome of 16 men whose DNA was sequenced by the company based in Mountain View , Complete Genomics Inc. , which is the most accurate of the Y chromosome sequences. The company was recently acquired by BGI , the Genome Institute of Bejing .

Comparative studies of populations of the variation in the Y chromosome are in their infancy , said, noting that more than 36 mammalian genomes sequenced to date, the full Y chromosomes are only available for three. Most human genomes sequenced + 1000 no longer have sufficiently accurate coverage And to make this type of comparison among individuals, but advances in technology to better characterize facilitate future DNA analysis of the Y chromosome , said.

South Africa “World Rape Capital”

Despite A Decline South Africa Still Remains The “World Rape Capital”:

Despite A Decline South Africa Still Remains The "World Rape Capital"

Despite A Decline South Africa Still Remains The “World Rape Capital”

South Africa’s National Freedom Party (NFP) has said the sexual offense statistics in the country were still very high despite a small decline observed. “We note that while sex-related crimes… decreased by just more than one percent, these crimes still remain very high as compared to global figures and South Africa remains the rape capital of the world,” News24 quoted NFP president Zanele KaMagwaza-Msibi, as saying. KaMagwaza-Msibi welcomed an overall decrease in crime reflected in the latest statistics released by Police Minister Nathi Mthethwa on Thursday, and she added sexual crimes were not always reported. “We call on the government to provide safe shelters for the elderly and orphans, especially in rural areas, as these sections of our population are the most vulnerable to sexual crimes,” KaMagwaza-Msibi said.

Woman discovers husband was her FATHER

Ohio woman discovers that her husband was her FATHER:

Woman discovers husband was her FATHER

Woman discovers husband was her FATHER

An Ohio woman is finally speaking out about the pain she suffered after discovering that the man she married also fathered her. Valerie Spruill of Doylestown learned of her husband’s identity six years after he passed away in 1998 thanks to an uncle who eventually came forward with the truth. She says she is now going public with her past in the hopes that it will inspire those going through a rough time. “I want this to be more of an inspirational story,” the 60-year-old told the newspaper. “If I’ve come through this, anyone can come through anything through the help of the Lord.” Valerie’s mother and father, Percy Spruill, first started seeing each other when he was 15. It remains unclear how many children they had together, though Valerie says she is aware of six brothers. Valerie’s grandmother began taking care of her when she was 3-months-old, but it wasn’t until age 9 that Valerie discovered the first of many secrets her family had kept from her. She learned that the man she believed was her father was actually her grandfather. She also realized that a woman who said she was a family friend actually was her mother. The story “needs to be told, because children need to know where they come from,” she said. “And I know it hurts, because I have been devastated by this.” Her mother, Christine, was a “night lady” before she died in 1984, Valerie said. Christine testified in the infamous 1980s corruption trial of Summit County Probate Judge James Barbuto, who was later convicted of sex charges. In 2004, Valerie confirmed that her late husband was her father with the help of a DNA test. Valerie said she can’t say for certain whether Percy was aware of the extent of their relationship, though she believes he did know and was simply too afraid to tell her. She is still seeing a therapist to come to terms with the difficult revelation. She has also sought medical treatment for a series of serious medical problems that she believes stem from the stress she endured in the years after the discovery. Valerie says she hopes her decision to go public will help her find more siblings. “My biggest goal is to find them and let ’em know that [their mother] loved them, no matter what,” she said. “And [to say], ‘Thank God she gave you away like she did me, so you could have a beautiful life.'”

 

Woman falsely claimed rape Jailed!

Woman who falsely claimed she was raped by three men because she regretted having sex with them jailed for two years

Woman who falsely claimed she was raped by three men because she regretted having sex with them jailed for two years

Woman who falsely claimed she was raped by three men because she regretted having sex with them jailed for two years

A woman who cried rape because she regretted having sex with three men at a drunken orgy has been jailed for two years for her ‘wicked’ lies. Rosie Dodd, 20, had been out drinking when she met the men, aged 25, 23, and 21, and started groping one of them on a bus on the way home. She had sex with them one after the other, but after telling a friend she felt ‘dirty’ she lied to police that she had been raped. The men, two of them students, then suffered a ‘nightmare’ involving intimate examinations and being locked up in cells. But after police became  concerned about inconsistencies in Dodd’s account, she admitted the encounters had been consensual. Last night she was put behind bars. On a social networking website, she has left displayed numerous photographs of herself with a string of men, apparently taken as trophies of her conquests. Jailing Dodd at Nottingham crown court, Judge John Milmo told her: ‘None of these three lads had seen the inside of a police station before. ‘They may well have been wrongly convicted if these charges had gone to trial. It was ten days before police managed to talk to you – and you admitted your allegations had been completely untrue. I am told, from your perspective, it was easier to tell lies rather than tell the truth. ‘I have no idea why you decided to make these wicked allegations.’ Dodd went out drinking in Nottingham city centre in June, downing eight vodkas and ending up in a casino. There she met one of her numerous ex-boyfriends and through him met the trio. She and the three men took a bus to a house in the Clifton area of the city, and  during the journey she began groping one of them. In the house she willingly had sex with all three. But afterwards she texted a friend saying that she felt ‘dirty’. With that in mind she claimed to police that all three of her partners had raped her. The men, who have not been named, were arrested on suspicion of rape and spent a total of 50 hours in custody before being released on bail. After further enquiries police grew suspicious and, when challenged, Dodd admitted she had consensual sex with the men and made up the claims because she felt regret at sleeping with them. But police said Dodd, of Nottingham, who is listed as in a relationship on a social media site, showed no remorse. She was charged with perverting the course of justice and pleaded guilty at a previous hearing. The court heard that one of her victims had recently graduated from university – but what should have been a time for celebration became a ‘nightmare’. Another victim, who was  also a student, said a medical investigation he was forced to go through was ‘awful’, and told of his embarrassment at having to detail the consensual sex he had had. One of the men said he feared his plans to work with children in America would be wrecked by the episode, although police claimed any trace of the investigation would be wiped from their files. None of the men had any criminal record.