Induction of gonad maturation and spawning is an important step in artificial propagation of shrimp, but our understanding of the molecular regulatory mechanism underlying shrimp ovary development and maturation is still very limited.
Using high-throughput sequencing platform, we analyzed the transcriptomes of five reproduction-related organs, including the eyestalk ganglion, brain, thoracic ganglion, hepatopancreas and ovary, from the Pacific white shrimp Litopenaeus vannamei at various stages of ovary development. A total of 48,722 unique transcripts (or unigenes) were assembled (N50=2,463 bp and average length=1,244 bp). Through Blast comparison with sequences in major databases, 18,661 unigenes were annotated. 2,974-11,999 genes were detected as differentially expressed at different ovarian stages, and 7 groups of genes were significantly enriched. By weighted gene co-expression network analysis (WGCNA), 14 distinct gene expression modules were identified. GO and KEGG analysis showed that these genes were involved in many important biological processes and pathways. In particular, genes related to CHH family neuropeptides, ecdysone signaling pathway, juvenile hormone signaling pathway, insulin signaling pathway, PI3K-Akt signaling pathway and TGF-β signaling pathway showed tissue-specific expression patterns (Fig. 1), suggesting their crucial roles in different tissues and at different development stages. Some candidate genes, including juvenile hormone pathway genes, were further investigated and their regulatory effects on vitellogenesis and ovarian growth were preliminarily confirmed.
Taken together, our study revealed the dynamic transcriptomic changes of several neuroendocrine organs during ovary maturation of L. vannamei, laying a foundation for further elucidation of the molecular regulatory network underpinning ovary development and maturation of shrimp.