# Genomic Features and Tissue Expression Profiles of the Tyrosinase Gene Family in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

## TL;DR

This study explores the TYR gene family in Chinese soft-shelled turtles to understand how these genes influence body color, which is important for aquaculture.

## Contribution

The study identifies and characterizes three TYR genes in Pelodiscus sinensis and links their expression to body color variation.

## Key findings

- Three TYR genes (TYR, TYRP1, DCT) were identified and found to have conserved domains and similar physicochemical properties.
- TYR and DCT genes showed high expression in the eyes, while TYR and TYRP1 were more active in dark-colored skin.
- Phylogenetic and collinearity analysis confirmed high conservation of these genes in P. sinensis.

## Abstract

In farmed animals, body color is not only an ecological trait but also an important trait that influences the commercial value of the animals. Melanin plays an important role in the formation of body color in animals, while the tyrosinase (TYR) gene family is a group of key enzymes that regulate melanogenesis. The Chinese soft-shelled turtle (Pelodiscus sinensis) is one of the most important reptiles in freshwater aquaculture. However, the potential role of the TYR gene family in the body color formation of P. sinensis remains unclear. This study aimed to investigate the expression and conservation of the TYR gene family in relation to body color variation in P. sinensis. Three core members of this gene family were identified from the P. sinensis genome. Following identification, the genomic features were analyzed. They shared similar physicochemical properties and conserved domains. Chromosome mapping showed that the three genes of P. sinensis were all located on the autosomes, while phylogenetic and collinearity analysis suggested that the protein functions of the three genes in the studied species were highly conserved. Amino acid sequence alignment indicated high conservation among the three TYR gene family proteins (TYR, TYRP1, and DCT) in multiple critical regions, particularly in their hydrophobic N-/C-terminal regions and cysteine/histidine-rich conserved domains. The qRT-PCR revealed that the TYR and DCT genes were highly expressed in the eyes of individuals with different body colors. The expression levels of TYR and TYRP1 genes in the skin were significantly higher in dark-colored individuals than in light-colored ones (p < 0.05). These results will lay the groundwork for functional studies and breeding programs targeting color traits in aquaculture.