Identification and characterization of long non-coding RNAs in intestinal immune regulation of largemouth bass, Micropterus salmoides, under acute heat stress

Long noncoding RNAs (lncRNAs) are non-protein coding RNAs with a length of more than 200 bp, which play a vital regulatory role in intestinal immunity. Exposure to high temperature leads to death in many fish species, which is implicated in fish enteritis. Our study showed that fish enteritis was induced by acute heat stress. To date, which lncRNAs are participated in this process is still unclear. In the present study, based on the intestinal sequencing data of largemouth bass Micropterus salmoides, a total of 347,351,492 clean reads were generated from six cDNA libraries. Among them, 3399 novel lncRNA transcripts from 2488 lncRNA genes were identified. As expected, these lncRNAs exhibited shorter transcript lengths than protein-coding genes similar to those lncRNAs reported from other fish species. In total, 216 novel lncRNAs were differentially expressed (DE) in largemouth bass intestine (absolute log2 fold change > 2 and p-value < 0.05) and that 210 neighboring genes were cis-regulated by these DE-lncRNAs. An analysis of GO/KEGG enrichment showed that most of these cis-genes seemed to be significantly enriched in immune regulation (p < 0.05) and lncRNA MSTRG.8573 had an important role in regulating jak-stat signaling pathway during this process. Through this study, we showed a catalog of novel DE-lncRNAs involved in the occurrence of enteritis in largemouth bass under acute heat stress, which could provide some useful references by regulating lncRNAs to solve the heat stress-induced fish enteritis for further studies. Overall design: 120 healthy fish were randomly divided into two groups, and respectively maintained at two temperatures, 26? and 34?, with three parallels in each group. After 9h (determined by our pre-experiment), 9 fish samples were taken from the 26? group (control group) and 34°C group (9h_HS group) with 3 fish per parallel, respectively. As soon as the intestine samples were collected, they were quickly frozen in liquid nitrogen, and then preserved at -80? for RNA extraction.