HAYAMA, Japan, Dec. 23 (UPI) — The sex of many crocodilian and turtle species is determined by how hot or cold it is as young incubate in their eggs.
For American alligators, the temperature split occurs in the low thirties. Thirty degrees Fahrenheit and below, eggs hatch females. Thirty-three degrees and above, eggs hatch males.
Scientists already knew all of this.
What they didn’t know was the biological mechanism that made it so. New research, however, has identified a key protein in the process of temperature-dependent sex determination. The thermosensor protein is called TRPV4.
A team of researchers from the United States and Japan located TRPV4 residing within the maturing alligator gonad inside the egg. Lab tests showed that when temperatures approach the mid 30s, TRPV4 releases a calcium ion influx to induce cell signaling — cell signalling that precipitates the development of male features.
Researchers were also able to identify specific male genes signaled by TRPV4, including genes that encode anti-Mullerian hormone and SOX9.
“Reptiles can be difficult to study at times, but we were delighted to obtain such an interesting result and elucidate part of the alligator TSD mechanism,” researcher Ryohei Yatsu, a PhD student at the Graduate University for Advanced Studies in Japan, or SOKENDAI, said in a press release. “We still have much to research, but we are interested in how our results relate with other TSD species diversity and evolution.”
The new research was published this week in the journal Scientific Reports.
“Organisms that have adopted TSD systems may be more susceptible to the risks of environmental change, such as global warming,” added Taisen Iguchi, a professor at SOKENDAI. “In future, we would like to know how an unstable environmental factor such as incubation temperature was able to establish itself as a sex determination factor.”
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