An international research collaboration among researchers at the University of Queensland, Osaka University, and Tokushima University. has found that the Y-chromosome gene that makes mice male is made up of two different DNA parts, not one, as scientists had previously assumed. UQ's Institute of Molecular Biosciences Emeritus Professor Peter Koopman, PhD, said the critical DNA fragment had been hidden from researchers for more than 30 years. "Expression of the Y chromosomal gene Sry (sex-determining region Y) is required for male development in mammals and since its discovery in 1990 has been considered a one-piece gene," Dr. Koopman said. "Sry turns out to have a cryptic second part, which nobody suspected was there, that is essential for determining the sex of male mice. We have called the two-piece gene Sry-T." The scientists tested their theory and found that male mice (XY) lacking in Sry-T developed as female, while female mice (XX) carrying a Sry-T transgene developed as male. The success rate for the experiments was almost 100 per cent. The results were reported in the October 2, 2020 issue of Science. The article is titled “The Mouse Sry Locus Harbors a Cryptic Exon That Is Essential for Male Sex Determination.” Dr. Koopman said the discovery would change how basic biology and evolution is taught around the world. "For the last 30 years, we've been trying to figure out how this works," he said. "Sry is a master switch gene because it flicks the switch for male development, it gets the ball rolling for a whole series of genetic events that result in a baby being born as a male instead of female. This new piece of the gene is absolutely essential for its function; without that piece, the gene simply doesn't work.
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