Project description:In the present study, we used NGST to characterize mRNA-seq of control-, moderate hypoxia-treated and severe hypoxia-treated Micropterus salmoides livers to elucidate the molecular mechanisms of hypoxia adaptation. This is the first report on integrated analysis of the tissue specific and temporal changes in gene expression in largemouth bass (Micropterus salmoides) exposed to hypoxia could reveal mechanisms of hypoxia adaptation. We provide a good case study with which to analyse mRNA expression and profile non-model fish species using NGST.
Project description:Intensive aquaculture and environmental changes will inevitably lead to hypoxic stress for largemouth bass (Micropterus salmoides). To better understand the hypoxia responds mechanisms of largemouth bass, we compared the miRNA profile in liver under different environmental DO to determine which miRNAs are most affected during hypoxia. A total of 266 miRNAs were identified, and 84 miRNAs were differentially expressed compared with in control group. GO and KEGG analysis indicated that the miRNAs may play important roles in environment information processing. Specifically, we considered the VEGF signaling pathway, Phosphatidylinositol signaling system and MAPK signaling pathway, the results show that, the 13 miRNAs (miR-15b-5p, miR-30a-3p, miR-133a-3p, miR-19d-5p, miR-1288-3p, miR456, miR-96-5p, miR-23a-3p, miR-23b, miR-214, miR-24, miR-20a-3p and miR-2188-5p) involved in these three pathways are significantly down-regulated during hypoxia stress. And 12 target genes of these miRNAs were showed a higher degree of expression. We found the obvious negative correlation between miRNA and their target mRNAs, providing several miRNA-mRNA interaction networks in largemouth bass in response to hypoxia. Although relatively little information is currently available concerning the biological function of miRNAs identified to date, we strongly suggest that miRNAs play an important role in modulating gene expression involved in the physiological response to hypoxic stress in the fish liver.
Project description:We sequenced mRNA from 9 liver samples of juvenile largemouth bass (Micropterus salmoides) taken from different lead concentration exposure treatment fish and control fish to investigate the transcriptome and comparative expression profiles of largemouth bass liver undergoing lead exposure.
Project description:Cadmium is a natural element that can accumulate to toxic levels in the environment leading to detrimental effects in animals and humans including kidney, liver and lung injuries. Using a transcriptomics approach, genes and cellular pathways affected by a low dose of cadmium were investigated. Adult largemouth bass were intraperitoneally injected with 20 µg/kg of cadmium chloride and microarray analyses were conducted in the liver and testis 48 hours after injection. Transcriptomics profiles identified in response to cadmium treatment were tissue-specific with the most differential expression changes found in the liver tissues, which also contained much higher levels of cadmium than the testes. Acute exposure to a low dose of cadmium induced oxidative stress response and oxidative damage pathways in the liver. The mRNA levels of antioxidants such as catalase increased and numerous transcripts related to DNA damage and DNA repair were significantly altered. Hepatic mRNA levels of metallothionein, a proposed marker of cadmium exposure, showed a small insignificant increase after 48 hours exposure. Carbohydrate metabolic pathways were also disrupted in cadmium-exposed fish with hepatic transcripts such as UDP-glucose pyrophosphorylase 2 and sorbitol dehydrogenase highly induced. Both tissues exhibited a disruption of steroid signalling pathways. In the testis, estrogen receptor beta and transcripts linked to cholesterol metabolism were suppressed. On the contrary, genes involved in cholesterol metabolism were highly increased in the liver including genes encoding for the rate limiting steroidogenic acute regulatory protein and the catalytic enzyme 7-dehydrocholesterol reductase. Integration of the transcriptomics data using functional enrichment analyses revealed a number of enriched gene networks associated with previously reported adverse outcomes of cadmium exposure such as liver toxicity and impaired reproduction. Adult largemouth bass (n=4 per treatment) were ip injected with a single dose of cadmium chloride (20 ug/kg) or a saline solution. After 48 hours, liver and testis were excised and differential gene expression profiles were examined.
Project description: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.