Comparative Transcriptome Analysis Reveals the Effect of Aurantiochytrium sp. on Gonadal Development in Zebrafish

SIMPLE SUMMARY: Aurantiochytrium sp. has received much attention as a potential resource for large-scale production of omega-3 fatty acids. In this project, we fed zebrafish through feed supplementation for 56 days and found that Aurantiochytrium sp. extracts improved the gonadal index of zebrafish. Moreover, it promoted oocyte maturation in an ex vivo environment. ABSTRACT: Aurantiochytrium sp. has received much attention as a potential resource for mass production of omega-3 fatty acids, which contribute to improved growth and reproduction in aquatic animals. In this study, we evaluated the gonadal index changes in zebrafish supplemented with 1–3% Aurantiochytrium sp. crude extract (TE) and the effects of ex vivo environmental Aurantiochytrium sp. on oocytes. 1% TE group showed significant improvement in the gonadal index, and both in vitro incubation and intraperitoneal injection promoted the maturation of zebrafish oocytes. In contrast, the transcriptome revealed 576 genes that were differentially expressed between the 1% TE group and the control group, including 456 up-regulated genes and 120 down-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway analysis of differentially expressed genes indicated that Aurantiochytrium sp. potentially affects pathways such as lipid metabolism, immune regulation, and oocyte development in zebrafish. The results of this study enriched the knowledge of Aurantiochytrium sp. in regulating gonadal development in zebrafish and provided a theoretical basis for its application in aquaculture.