The proliferating cell nuclear antigen gene (pcna) plays a key role in ovarian development in the ridgetail white prawn, Exopalaemon carinicauda

Abstract

Abstract The ridgetail white prawn, Exopalaemon carinicauda, has advantages in its rapid growth and strong environmental adaptability, and it is a good species for the biological research of crustaceans. To explore the function of the pcna gene in the ovarian development of crustaceans, we cloned the pcna (Ec-pcna) from E. carinicauda. The open reading frame of the pcna is 786 bp, and it encodes a total of 261 aa. A PCNA/RFC (replication factor C) domain exists at 208–254 aa, and according to a phylogenetic analysis, the amino acid sequence of Ec-pcna has the highest similarity with the pcna gene from Litopenaeus vannamei, and it is clustered into one branch with L. vannamei and Penaeus monodon. The results of qRT-PCR showed that the expression of pcna was highest in the ovarian tissue of E. carinicauda, and it was significantly higher than that of other tissues (p < 0.05). In addition, the expression level gradually increased in Stages I-III of ovarian development, with the expression level in Stage III being significantly higher compared to the other stages (p < 0.05). The protein overexpression analysis showed that the overexpression of the PCNA protein was due to an overexpression of cell cycle-related genes cdk2 and cyclin A, and accelerated ovarian development. Immunohistochemical results showed that pcna played an important role in the accumulation of exogenous nutrients. Moreover, the RNAi results showed that knocking down the expression of the pcna gene can significantly reduce the expression of the gene Vg, related to vitelline, indicating that pcna has a regulatory effect on the expression of Vg. Based on the results of flow cytometry, we speculate that the decreasing of vg expression level in the ovary may be caused by the inhibition of follicular cell polyploidization.This study showed that pcna plays an important role in the proliferation of ovarian cells and the accumulation of exogenous nutrients in E. carinicauda.