What is it about?
The dragon lizard has sex chromosomes (ZZ male and ZW female), and there is a good candidate for the gene that turns on maleness. This gene (called a1) is involved in sex in mammals and all other vertebrates. But how does it work? Tthere are identical copies on the Z and the W chromosomes, but they are read very differently; the Z copy makes standard messenger RNA that is translated into a useable protein. However, the W copy makes many different mRNAs that are translated into truncated versions of the protein that could act as inhibitors, producing females. We propose that the copy on the W chromosome is read incorrectly because it is in an altered conformation - kinky sex personified.
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Why is it important?
We propose a new way of determining if an animal is born male or female. Although it looks like sex is determined by the presence, or the dosage of a gene on the sex chromosomes, it is controlled, not by sequence differences, but epigenetically by the conformation of the W chromosome. The W is characterised by a high content of repetitive sequence, which we suggest causes the W to adopt an altered, kinky, configuration.
Perspectives
Evolution has so many different ways of doing the same thing, namely directing development into a male or female pathway. Some animals do it by the presence or absence of a gene (like the SRY gene on the mammalian Y). Others do it by differences in dosage of a gene on the Z chromosome; for instance you need two copies of a gene DMRT! on the Z chromosome to be male in birds. Here's another quite different way.
Jennifer Graves
La Trobe University
Read the Original
This page is a summary of: Sex-specific splicing of Z- and W-borne
nr5a1
alleles suggests sex determination is controlled by chromosome conformation, Proceedings of the National Academy of Sciences, January 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2116475119.
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