Assessing the Potential Ecological Impacts of Perfluorinated Chemicals (PFCs) in the liver and testis of male largemouth bass (Micropterus salmoides) in Minnesota Lakes

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. Seven or Eight biological replicates performed per lake; 5 lakes examined. (i) Expression profiles of male liver compared. Upper Prior Lake (reference) compared to Medicine Lake. (ii) Expression profiles of male testis compared. Upper Prior Lake (reference) compared to Medicine Lake. (iii) Expression profiles of male testis compared. Steiger Lake (reference) compared to Lake Calhoun and Twin Lake. (iv) Expression profiles of male liver compared. Steiger Lake (reference) compared to Lake Calhoun and Twin Lake.