Turtle Sex Secrets: How Temperature and Genes Team Up

In the world of turtles, the sex of a baby turtle isn't just about chromosomes. It's also about temperature. This is called temperature-dependent sex determination. Scientists have been curious about how this works for a long time. They knew that something called alternative splicing might play a role. But they weren't sure how. Recently, researchers made a big discovery. They found a special protein in turtles called RBM20. This protein is active in the early stages of turtle embryo development. It's found in the gonads, which are the organs that will become either male or female. The amount of RBM20 changes depending on the temperature. This happens before the gonads even start to develop into male or female organs. Here's where it gets interesting. When scientists reduced the amount of RBM20 in turtle embryos at a male-producing temperature, the turtles developed as females instead. On the other hand, when they increased the amount of RBM20 at a female-producing temperature, the turtles developed as males. This shows that RBM20 is a big deal in determining the sex of turtles. But how does RBM20 do this? It turns out that RBM20 controls the splicing of another gene called WT1. Splicing is like editing a movie. It's a process where the body cuts and pastes different parts of a gene to make different versions of a protein. RBM20 makes sure that the right version of WT1 is made at the right temperature. This version is called +KTS. It's crucial for male development in turtles. The scientists also found that the +KTS version of WT1 is both necessary and enough to make a turtle male. This means that RBM20 is like a switch. It turns on the male pathway by controlling the splicing of WT1. This is a big deal because it shows a direct link between alternative splicing and sex determination in vertebrates. This discovery is important because it helps us understand how sex is determined in animals. It's not just about chromosomes. It's also about temperature and genes working together. This could have big implications for understanding sex determination in other animals, including humans.