Project description:This SuperSeries is composed of the following subset Series: GSE38738: High contaminant loads in Lake Apopka mesocosms affect the ovarian transcriptome in largemouth bass [April] GSE38773: High contaminant loads in Lake Apopka mesocosms affect the ovarian transcriptome in largemouth bass [January] Refer to individual Series
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: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: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