Temperature-triggered sex determination gene revealed for first time

Researchers have finally determined the gene that controls sex determination in certain turtle populations.
By Joseph Scalise | Nov 07, 2018
For the first time in history scientists have isolated the gene behind temperature-controlled sex determination in turtles, a new study published in the journal Science reports.

There are many reptile species on Earth, and all of them operate in unique ways. Red eared slider turtles -- which are commonly kept as pets -- are interesting because they develop into male or female embryos depending on their egg incubation temperature. This process, while strange, is also present in crocodiles, alligators, and certain lizard species.

Even so, while scientists have long been aware of the gene's existence, they have never fully understood how it works until now.

In the new study, a group of researchers from the U.S. and China used a newly developed process to knock out the gene Kdm6b --which they believed to be responsible for sex determination in turtles -- in a group of study subjects.

"Knockouts come in several flavours," explained study co-author Blanche Capel, a researcher at from Duke University, according to BBC News. "It usually means a genetic manipulation that deletes a gene from the genome or blocks its function."

Researchers found that, once the gene became blocked, more than 80 percent of turtles that incubated at 78 degrees Fahrenheit -- the temperature that normally produces males -- became female. As a result, there is almost no doubtKdm6bis behind the switch.

These findings, which build off of earlier predictions that stated such genes only turn on at certain temperatures, are key to understanding reptile biology.

The team next plans to expand on their research by analyzing how embryos measure and react to the nest temperature while in the egg. That will likely give more insight into the process and could help scientists better understand how the gene operates in other reptilian species.

"This is the first venture down that path," said Clare Holleley, an evolutionary geneticist at the Australian National Wildlife Collection who was not a part of the study, according to Science News. "It's really quite a breakthrough."

The findings are published in the journalScience.

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