Discovery of the indicator role of period 2 in yellow catfish (Pelteobagrus fulvidraco) food intake during early life development stages

ABSTRACT

The early development stages of fish are a highly ordered and tightly regulated, involving many circadian rhythm-related gene and protein processes. Nonetheless, there are few reports on the effects of circadian clock genes on the early development stages of fish. We studied Pelteobagrus fulvidraco Period 2 (Pf-Per 2) gene structures and expression patterns during the early life stages of development, including the fertilized embryo, yolk absorption, preliminary food, rotifer breeding, and mixed food stages. cDNA of Pf-Per 2 is 4593 bp in length, with 357 bp 5ʹ-untranslated region (5ʹUTR), 216 bp 3ʹUTR. The 4020 bp open reading frame consists of 1339 encoded amino acids. By multiple sequence alignment and phylogenetic analysis, the sequence was found to demonstrate high similarity to humans, rodents, microorganisms, and other fish species. Expression patterns of mRNA transcripts showed existence of rhythmic oscillations in the yellow catfish during the early development phase. The higher expression level of Per 2 is obviously present in the early embryonic development stage; the continuous downward trend of Per 2 was observed in the embryonic development and yolk nutrition absorption stages; additionally, the expression of Per 2 mRNA was significantly increased during individual development, rotifer breeding, and mixed food stages. Moreover, immunohistochemistry studies revealed strongest immune-labeled positive signals of Per 2 proteins mainly located in the cytoplasm of the olfactory bulb cell. Our findings reveal Pf-Per 2 serves important functions and may be useful as an indicator of P. fulvidraco early life development and initial food intake process stages.

KEYWORDS:

• Yellow catfish Fish
• circadian clock genes
• period 2
• fish developmental stages
• initial Feeding

Acknowledgements

This project was funded by the basic scientific research special project in Chinese Academy of Fishery Sciences (2017HY-ZD0104), Open project from Conservation and Utilization of Fishes resources in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province (NJSYKF-001) and the National Infrastructure of Fishery Germplasm Resources (2019DKA3047003).

Competing Interests

The authors declare that they have no competing interests.