Transcriptomic analysis of Procambarus clarkii ovary at two development stages

【Objective】The main metabolic pathways and specific expression genes related to the ovarian development of Procambarus clarkii were screened through transcriptome sequencing analysis,which provided theoretical basis for revealing the molecular mechanism of the ovarian development of P. clarkii.【Method】 The ovarian tissue samples of P.clarkii developed to stage Ⅲ or stage Ⅳ were collected for histological observation by paraffin embedding method. At the same time,RNA was extracted to construct a cDNA library,and the transcriptome was sequenced through Illumina NovaSeq 6000 to screen out differentially expressed genes(DEGs). Then GO function annotation analysis and KEGG metabolic pathway enrichment analysis were performed,and the accuracy of transcriptome data was verified through realtime fluorescence quantitative PCR.【Result】The ovary indexes of P.clarkii at stage Ⅲ and stage Ⅳ were 0.22% and 2.70%,respectively,and the corresponding egg cells were dominated by the oocytes at the big growth period and mature period respectively. The transcriptome sequencing obtained 49716560 and 44573146 clean reads respectively,and the matching rate between clean reads of each sample and the reference genome sequence of P.clarkii exceeded 92.00%. A total of 1508 DEGs(762 DEGs were up-regulated and 746 DEGs were down-regulated)were screened from the ovarian tissues of P.clarkii at stage Ⅲ and stage Ⅳ,and GO function annotation analysis showed that DEGs were mainly annotated in the items of membrane transport,binding,catalytic activity and cell growth. KEGG metabolic pathway enrichment analysis showed that up-regulated DEGs were enriched in 247 metabolic pathways,mainly including lysosome,antigen processing and presentation,pancreatic secretion,sphingomyelin metabolism,PI3K-Akt signaling pathway,and downregulated DEGs were enriched in 270 metabolic pathways,mainly including systemic lupus erythematosus,lysosome, TGF-â signaling pathway,and GnRH signaling pathway. Ten conservative genes related to the ovarian development of P.clarkii were screened, namely H2A, S3a, IR93a, FOXL, nanos, RPB1, piwi, insulin, sclla and serine genes.【Conclusion】 During the development of P.clarkii ovary from stage Ⅲ to stage Ⅳ,pathways of antigen processing and presentation, PI3K-Akt signaling pathway,lysosome,sphingomyelin metabolism and TGF-â coordinately cooperate to promote ovarian development. The 10 conservative genes related to the ovarian development of P.clarkii,H2A,S3a,IR93a,FOXL,nanos, RPB1,piwi,insulin,scylla and serine,are highly expressed in the ovarian tissues of P.clarkii at stage Ⅲ and stage Ⅳ, suggesting that they are involved in regulating the accumulation of yolk substances and oocyte maturation during ovarian development.