The SRY gene is widely considered as the gene for determining sexual identity. See for instance this page about the role of the SRY gene in determining sexual identity. Also, see this page:
By its structure, the SRY gene is a 1,0 kb one exon gene located just centromeric to the pseudoautosomal region of Yp functioning as the dominant inducer of testis development. This gene comprises a single exon that encodes a 203- amino acid protein. The middle third of the protein represents the HMG (high-mobility group) domain specifically binging to a target nucleotide sequence 5’-AACAAAG-3’ characterising it as a transcription regualtor protein. Although its function is not entirely known, this gene is obviously the first initiator of male sexual differentiation 13, 19, 37, 42.
However, a UCLA team led by Eric Vilain has discovered differences in genetic expression that happen before the SRY gene becomes active during development. It is possible that male-female brain differences start developing before SRY starts changing genitals development:
"But in a study of mice, a team at the University of California, Los Angeles, has now found that males and females show differences in the expression of no fewer than 50 genes well before SRY switches on," according to the magazine.
Eric Vilain, the head of the UCLA team, said three of the genes are dominant in females and four in males, but they still need to determine whether the genes influence brain sexuality in mice and whether the same thing occurs in humans.
You can find the same article here.
Eric Vilain's home page at UCLA provides some more details about his lab's work:
Sex determination orients development toward sexually dimorphic individuals, male or female. In mammals, male sex determination is triggered by a primary signal, encoded by the testis determining factor SRY, localized on the Y chromosome. Subsequently, a complex network of genes, most of them still unknown, is regulated and leads to male sexual differentiation. We have discovered new molecular and cellular mechanisms of sex determination during fetal development. In particular, we have provided strong evidence supporting SRY as the testis determining gene, and identified regulatory mechanisms of transcription of DAX1, another sex determining gene. We have also recently identified human WNT-4, a signalling molecule responsible, when duplicated, for XY sex reversal in mammals. A new concept is now emerging: normal sexual development is highly dependent on strict gene dosage at all major steps of the sex determination pathway.
One possibility this opens up is the ability to separately control genital and brain sexual differentiation. Some day there will be people who have male minds in female bodies and vice versa. They will be more like the opposite sex in their thinking than is the case with homosexuals.
|Share |||Randall Parker, 2002 October 19 02:14 PM Brain Development|