Tissue-Specific Analysis of Alternative Splicing Events and Differential Isoform Expression in Large Yellow Croaker (Larimichthys crocea) After Cryptocaryon irritans Infection.

Abstract

The large yellow croaker (Larimichthys crocea) is one of the most important mariculture fish in China. Recently, cryptocaryonosis caused by Cryptocryon irritans infection has brought huge economic losses and threatens the healthy and sustainable development of the L. crocea industry. However, the molecular mechanism and regulation process for L. crocea resistance to C. irritans infection has not been fully researched. Alternative splicing (AS) is an important post-transcriptional regulatory mechanism that allows cells to produce transcriptional and proteomic diversity. The results of AS are tissue dependent, and the expression of tissue-specific transcription subtype genes is determined by AS and transcriptional regulation. However, studies on the tissue specificity of AS events in L. crocea following infection with C. irritans have not been performed. In this study, the L. crocea were artificially infected with C. irritans; their skin and gill were collected at 0h, 24h, 48h, 72h, and 96h post infection. After sequencing and differential expression analysis, a set of 452, 692, 934, 711, 534, and 297 differential alternative splicing(DAS) eventswere identified in 0h, 12h, 24h, 48h, 72h, and 96h post infection respectively. Furthermore, 4160differentially expressed isoforms (DEIs) and 4209 DEI genes were identified from all time point groups. GO enrichment and pathway analysis indicated that many genes of DAS and DEIs were rich in immune-related GO terms and KEGG pathways, such as the Toll and Imd signaling pathway, NOD-like receptor signaling pathway, TNF signaling pathway, and TNF signaling pathway. Among hub DEI genes, alternative splicing-related genes (cwc25, prpf8, and sf3a3), skin function-related gene (fa2h), and oxygen deprivation-related gene (hyo1) were found in DEI genes. This study provided insight into the temporal change of DAS and DEIs between skin and gill of L. crocea against C. irritans infection and revealed that these differences mightplay immune-related roles in the infection process.