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:Largemouth bass is one of the most important freshwater aquaculture species in China. However, the mechanisms underlying the development of skeleton in the fish are unclear. High-throughput RNA-Seq was used to analyze the transcriptome of largemouth bass skeleton between high-phospholipids and low-phospholipids groups. Thirty individuals each from 3 high-phospholipids families and 3 low-phospholipids families were used to reduce inaccuracies. The results indicated that 255 up-regulated and 329 down-regulated genes were identified in the differentially expressed genes (DEGs). GO and KEGG enrichment analyses revealed the DEGs were involved in the MAPK signaling pathway, phosphatidylinositol signaling system, glycosphingolipid biosynthesis-lacto and neolacto series and fatty acid degradation. Twist2 and Daam1, genes related to osteoblast development, were up-regulated in high-phospholipids group. BGLAP, gene associated with the skeletal development and osteohormatology, was also up-regulated in high-phospholipids group. PCOLCE b, a gene related to the development of gristle, was up-regulated in high-phospholipids group. Higher expression of SCPP1 and SCPP7 in high-phospholipids group was associated with tooth and bone development. The trend changes in the above genes all indicate that the lack of phospholipids may affect the skeletal development through the above genes, increasing malformations. In summary, these results provide valuable information about the reduction of deformity rates in largemouth bass and contribute to our understanding of the molecular mechanisms and regulative pathways regulating skeletal growth in teleosts.
Project description:Female largemouth bass were injected with 10mg/kg dieldrin and sacrificed after 7 days. Hypothalami were dissected and total RNA extracted for microarray analysis. Exposure to dieldrin induces neurotoxic effects in the vertebrate CNS and disrupts reproductive processes in teleost fish. Reproductive impairment observed in fish is likely the result of multiple mechanisms of action along the hypothalamic-pituitary-gonadal axis. To better elucidate the mode of action of dieldrin in the hypothalamus, we measured neurotransmitter levels and examined the transcriptomic response of female largemouth bass (LMB) to an acute treatment of dieldrin. Female LMB were injected with either vehicle or 10 mg/kg dieldrin and sacrificed after seven days. The neurotransmitter γ-aminobutyric acid was significantly elevated by approximately 25-30% in the hypothalamus and cerebellum but there was no change in dopamine levels in the hypothalamus, telencephalon, or cerebellum. We identified 270 transcripts (p<0.001) as being differentially regulated by dieldrin. Functional enrichment analysis identified transcription, DNA repair, ubiquitin pathway, cell communication, and phosphorylation as biological processes over-represented in the microarray analysis. Pathway analysis identified DNA damage, inflammation, regeneration, and Alzheimerâs disease as major cell processes and diseases affected by dieldrin. Using multiple bioinformatics approaches, this study demonstrates that the teleostean hypothalamus is a target for dieldrin-induced neurotoxicity and provides mechanistic evidence that dieldrin activates similar cell pathways and biological processes that are involved in the etiology of human neurological disorders. Key words: ubiquitin-proteasome pathway, mutagenicity, neurodegeneration, apoptosis, DNA damage Largemouth bass injected with single i.p. with 10 mg/kg diedrin; sacrificed 7 days later, hypothalamic tissue studied
Project description:This study used an emerging analytical technology (cDNA microarrays) to assess the potential effects of PFC exposure on largemouth bass in TCMA lakes. Microarrays simultaneously measure the expression of thousands of genes in various tissues from organisms exposed to different environmental conditions. From this large data set, biomarkers (i.e., genes that are expressed in response to an exposure to known stressors) and bioindicators (e.g., suites of genes that correspond to changes in organism health) can be simultaneously measured to clarify the relationship between contaminant exposure and organism health. Based on current scientific literature, we hypothesized that gene expression patterns would be altered in fish exposed to PFCs (as compared with fish from reference lakes), and that the magnitude of these changes would correspond to the concentrations of PFCs present throughout TCMA lakes. Patterns of gene expression in largemouth bass observed across the TCMA lakes corresponded closely with PFC concentration. Concentrations of PFCs in largemouth bass varied significantly across the sampled lakes, where the lowest concentrations were found in Steiger and Upper Prior Lakes and the highest concentrations were found in Calhoun and Twin Lakes. Patterns of gene expression were most different (relative to controls) in fish with the highest PFC tissue concentrations, where fish from Twin and Calhoun Lakes were observed to have between 5437 and 5936 differentially expressed genes in liver and gonad tissues. Although gene expression patterns demonstrated a high degree of correlation with PFC concentrations, microarray data also suggest there are likely additional factors influencing gene expression patterns in largemouth bass in TCMA lakes.
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.