Battle of the sexes

[randolph]

Battle of the sexes - one gene keeps us either male or female, scientists find
Women and men are constantly battling to suppress their masculine and feminine sides - at least biologically, claim scientists.


By Richard Alleyne, Science Correspondent
Published: 7:30AM GMT 11 Dec 2009

Researchers have found that the body is in a constant fight to remain either female or male and the suppression of just one gene could cause it to "flip" from one to the other.

The remarkable findings refute the generally held view that sex is determined at birth and is irreversible in later life.

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They could also lead to treatments for certain gender disorders in children, early menopause in women and even eventually non-surgical sex changes.

In mammals, males have XY chromosomes and females XX. The new research shows that another gene is responsible for switching women into men.

If the FOXL2 is switched on then the body grows ovaries, switched off and they are replaced by testicles.

But what really surprised the researchers is that the process continues after birth and the body remains in a constant tussle to either switch on or off the gene - even in adulthood.

"No one would have betted on this," said Professor Mathias Treier of the University of Cologne in Germany. "That's why the finding is so spectacular,"

The team found that in adult mice by turning off the FoxL2 gene, the ovary cells started to change testicular cells. This suggest the same effect could happen to humans.

"It was thought that you were born either female or male and then your body forgot about it," said Dr Robin Lovell-Badge, the co-author at Britain's Medical Research Council's National Institute of Medical Research.

"But this suggests that the battle of the sexes continues all the way through your life, "

The researchers believe that the process could be similar to that in some fish who are able switch sexes at times when there is a scarcity of either males or females.

Perhaps we can compromise with this gene and all become trannys!

[The Conquistador]

Nah. This is just me speaking but it seems like androgeny on a massive scale would kinda suck. Besides, it would take away what makes trannies so special and why I hold them dear in my heart...

I don't doubt for a second that there are genetic factors in play that influences transsexualism.

[randolph]

Biological differences between sexes 'may be determined after birth'
Some biological differences between male and female brains may be determined after birth, research suggests.


By Jon Swaine
Published: 7:32AM GMT 09 Jan 2009

The finding signals that not all sex-specific characteristics develop in the womb during pregnancy, as was previously thought.

Scientists came to the discovery by giving baby female rats treatment normally reserved by mother rats for their sons.

Mother rats typically spend more time grooming males. Previous studies have suggested this is necessary for their genitalia to develop properly.

The researchers, from the University of Wisconsin, stroked baby female rats in a similar way. They found that the number of receptors for oestrogen - the female sex hormone - in the stroked rats' brains was lower than in those not stroked, and were of similar levels to that in male rats' brains.

On inspection of the rats' DNA, they found that among stroked females, there were more chemical "caps" on the gene controlling how many oestrogen receptors would be produced.

The scientists believe that as this "capping" is often permanent, the effects of their stroking on sexual characteristics may be long-lasting or even irreversible.

Celia Moore, from the University of Massachusetts, Boston, said the finding should prompt further research into the effects on babies' brains of human mothers treating sons and daughters differently. "Sex may not be just genes and hormones," she told the New Scientist.

[randolph]

From The Telegraph UK

"Female transsexuals may have their genes to blame for feeling like they belong to the wrong sex.

By Jessica Salter
Published: 6:53AM BST 30 Jul 2008

Scientists identified a specific gene variant in female-to-male transsexuals that meant they had been exposed to higher levels of sex hormones during their early development.

Almost half the female-to-male transsexuals in the study carried the gene variant.

A team from the Medical University of Vienna, Austria, analysed DNA samples from 49 female-to-male and 102 male-to-female transsexuals, as well as

1669 non-transsexual controls.

They found that while men generally had a higher level of the gene variant, it did not affect levels of transsexuality. However 44% of female to male transsexuals carried the gene compared to 31 per cent of non-transsexual women.

Clemens Tempfer, who led the study, published in New Scientist, said the gene variant "may increase the likelihood that people will become transsexual".

He denied claims that researching biological explanations for transsexuality could lead people to find cures. However he said that if other gene variants were found then diagnosis would become easier. This would benefit transsexuals as they could start gender reassignment or hormone therapy earlier in life."