# The Characteristics and Expression of RBX1 Gene Involved in Ovarian Development of Scylla paramamosain

## TL;DR

This study identifies and analyzes the RBX1 gene in Scylla paramamosain, showing its role in ovarian development and response to hormones.

## Contribution

The study characterizes the RBX1 gene and its expression patterns in ovarian and hepatopancreatic development of Scylla paramamosain.

## Key findings

- Sp-RBX1 expression in the ovary increases significantly during oocyte maturation stages III to V.
- FSH up-regulates Sp-RBX1 in the ovary, while E2 inhibits it.
- Sp-RBX1 expression in the hepatopancreas is influenced by FSH concentration and E2.

## Abstract

Ring Box Protein-1 (RBX1) is an essential component of the Skp1-cullin-F-box protein (SCF) E3 ubiquitin ligase, which is involved in the regulation of oocyte maturation in the form of ubiquitination substrate modification. In this study, a sequence of RBX1 (Sp-RBX1) was identified and analyzed using bioinformatics methods from the transcriptome data of Scylla paramamosain. The length of Sp-RBX1 cDNA sequence was 1247 bp, consisting of a 336 bp open reading frame (ORF). Sequence analysis revealed that the protein contained a C-terminal modified RING-H2 finger domain, with two zinc binding sites and a Cullin binding site, classifying it as a member of the RBX1 superfamily. The results of real-time fluorescence quantitative PCR (RT-qPCR) showed that Sp-RBX1 expression in the ovary was low at stages I and II, then significantly increased from stage III to V (p < 0.05), which indicated that it might be closely related to the maturation of oocytes. It also peaked at stage II in the hepatopancreas, then sharply declined from stages III to V. The expression pattern might be related to the accumulation of fat in the early development of hepatopancreas. Furthermore, we characterized the expression of Sp-RBX1 induced by follicle-stimulating hormone (FSH) and estradiol (E2) hormones. The results showed that the expression in the ovary was up-regulated by FSH and significantly inhibited by E2. The expression in the hepatopancreas increased only at 0.5 µmol/L concentration of FSH, and decreased in other groups. Conversely, it was up-regulated by E2. Thus, the expression of Sp-RBX1 was influenced by FSH in a concentration-dependent manner. These findings could offer valuable insights for further research on ovarian maturation in crustaceans.