# Molecular Characterization and Expression Patterns of Sox3 and Sox30 Genes and Response to Exogenous Hormones in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

## TL;DR

This study explores how the Sox3 and Sox30 genes are expressed in Chinese soft-shelled turtles and how they respond to hormones, shedding light on their roles in sex differentiation.

## Contribution

The study provides new insights into the molecular roles of Sox3 and Sox30 in sex differentiation and gonadal development in Chinese soft-shelled turtles.

## Key findings

- Sox3 shows female-biased expression in multiple tissues, while Sox30 is male-biased.
- Exogenous hormones like E2 and MT significantly alter the expression of Sox3 and Sox30 in embryos.
- Sox3 may be involved in ovarian development, and Sox30 in testicular maturation.

## Abstract

Background/Objectives: The Sox transcription factor family is critical for gonadal development and sex differentiation in animals, yet its roles in chelonians, particularly in the Chinese soft-shelled turtle (Pelodiscus sinensis), have rarely been investigated. Methods: This study cloned and analyzed the cDNA sequences of Sox3 and Sox30 genes from P. sinensis, examining their amino acid sequences and structural properties. Real-time quantitative PCR (RT-qPCR) was used to assess the expression of these two genes in different adult tissues and at various stages of embryonic gonadal development. Additionally, the effects of exogenous hormones (17β-estradiol, E2 and 17α-Methyltestosterone, MT) on the expression of Sox3 and Sox30 were also investigated. Results: The results indicated that Sox3 showed significantly elevated expression in female gonads, kidney, brain, liver, lung, spleen, and muscle relative to male counterparts, displaying a female-biased expression pattern. In contrast, Sox30 showed a male-biased pattern, with higher expression in male gonads, spleen, muscle, brain, and liver than in females, showing expression. Both genes were expressed at low levels. Exogenous hormone treatments revealed that MT significantly downregulated Sox3 expression in female embryos, whereas E2 significantly enhanced Sox3 expression in male embryos. Furthermore, MT treatment significantly upregulated Sox30 expression in female embryos, and E2 treatment also significantly increased Sox30 expression in male embryos. Conclusions: These findings suggest that Sox3 and Sox30 play crucial roles in the gonadal development of P. sinensis, with Sox3 potentially involved in ovarian development and Sox30 in testicular maturation. Both genes are regulated by exogenous hormones, highlighting their importance in sex differentiation and gonadal development. This study provides valuable theoretical insights for further exploration of the molecular mechanisms of sex regulation in reptiles.