Turtle Sex Secrets: How Temperature and Genes Team Up

In the fascinating world of turtles, the sex of a baby turtle isn't solely determined by chromosomes. Instead, it's influenced by temperature—a phenomenon known as temperature-dependent sex determination.

The Mystery of Alternative Splicing

Scientists have long been intrigued by how this process works. They suspected that alternative splicing might play a crucial role, but the details remained unclear.

A Groundbreaking Discovery

Recently, researchers made a significant breakthrough. They identified a special protein in turtles called RBM20, which is active during the early stages of embryo development. This protein is found in the gonads, the organs that will eventually develop into either male or female structures.

The amount of RBM20 varies depending on the temperature, even before the gonads begin to differentiate into male or female organs.

The Switch That Changes Sex

Here's where it gets truly interesting:

• When scientists reduced RBM20 levels in embryos at a male-producing temperature, the turtles developed as females.
• Conversely, when they increased RBM20 levels at a female-producing temperature, the turtles developed as males.

This demonstrates that RBM20 is a key player in determining the sex of turtles.

How RBM20 Works: The Role of WT1

RBM20 controls the splicing of another gene called WT1. Splicing is akin to editing a movie—it involves cutting and pasting different parts of a gene to create various protein versions. RBM20 ensures that the correct version of WT1, known as +KTS, is produced at the right temperature. This version is essential for male development in turtles.

The +KTS Version: Necessary and Sufficient for Maleness

The scientists discovered that the +KTS version of WT1 is both necessary and sufficient to make a turtle male. This means RBM20 acts like a switch, turning on the male development pathway by regulating WT1 splicing.

Implications for Sex Determination in Vertebrates

This discovery is groundbreaking because it establishes a direct link between alternative splicing and sex determination in vertebrates. It highlights that sex determination is not just about chromosomes but also about temperature and gene interaction.

This research could have far-reaching implications for understanding sex determination in other animals, including humans.