Where Did The Y Chromosome Come From?

By tracing the evolution of genes on the Y chromosome, scientists hope to understand how genes control sex determination.

AsianScientist (May 5, 2014) – Scientists are a step closer to discovering what determines the sex of Australia’s iconic platypus and echidna, after an international study unravelled new genes contained on mammalian Y chromosomes.

The findings of the study have been published in the journal Nature.

Dr. Paul Waters, an author of the study from the School of Biotechnology and Biomolecular Sciences at the University of New South Wales, says that the X and Y chromosomes started their existence as normal autosomes (non-sex chromosomes) harboring the same genes.

“As the Y chromosome evolved, it withered away, losing most of the 1000 genes that are found on today’s X chromosomes. The preserved genes were then recruited into male-specific functions,” he says.

Despite its importance for sex determination, gene content and evolution of the Y chromosome has long been a mystery in most mammals, particularly in monotremes (the platypus and echidna).

“The most important aspect of this work for us was to identify more genes on platypus Y chromosomes to reveal new leads about potential sex determining genes in these animals,” says Deborah Toledo-Flores, a PhD student at the University of Adelaide and co-author of the study.

“The next step will be to discover which gene on the Y chromosomes determines sex in the platypus and echidna,” she says.

The study saw researchers analyze billions of genetic sequences from 15 mammal species and revealed, for the first time, new gene repertoires for all major mammal groups, tracing the evolution of the Y chromosome in unprecedented detail.

The article can be found at: Cortez et al. (2014) Origins and Functional Evolution of Y Chromosomes Across Mammals.

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Source: University of Adelaide; Photo: Can H./Flickr/CC.

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