Project description:The Atlantic killifish (Fundulus heteroclitus) is an ideal model species to study physiological and toxicological adaptations to stressors. Killifish inhabiting the PCB-contaminated Superfund site in New Bedford Harbor, MA (NBH) have evolved resistance to toxicity and activation of the aryl hydrocarbon receptor (AHR) signaling pathway after exposure to PCBs and other AHR agonists. Until recently, a lack of genomic information has limited efforts to understand the molecular mechanisms underlying environmental adaptation to stressors. The advent of high throughput sequencing has facilitated an unbiased assessment of coding as well as non-coding RNAs in any species of interest. Among non-coding RNAs, microRNAs (miRNAs) are important regulators of gene expression and play crucial roles in development and physiology. The objective of this study is to catalog the miRNAs in killifish and determine their expression patterns in the embryos from contaminated (NBH) and pristine (Scorton Creek, MA (SC)) sites. Embryos from NBH and SC were collected daily from 1 to 15 days post-fertilization and RNA from pooled samples from each site was sequenced using SOLiD sequencing. We obtained 7.5 and 11 million raw reads from pooled SC and NBH samples, respectively. Analysis of the sequencing data identified 216 conserved mature miRNA sequences that are expressed during development. Using the draft killifish genome, we retrieved the miRNA precursor sequences. Based on the capacity of these putative precursor sequences to form the characteristic hairpin loop (assessed using RNAfold), we identified 197 conserved miRNA sequences in the genome.
Project description:Subspecies of the Atlantic killifish, Fundulus heteroclitus, differ in their maximum thermal tolerance. To determine whether there is a link between the heat shock response (HSR) and maximum thermal tolerance, we exposed 20ºC acclimated killifish from these subspecies to a 2hr heat shock at 34ºC and examined gene expression during heat shock and recovery using real time quantitative PCR and a heterologous cDNA microarray designed for salmonid fishes. Keywords: Expression profiling by array
Project description:Transcriptomic assessment of resistance to effects of an aryl hydrocarbon receptor (AHR) agonist in embryos of Atlantic killifish (Fundulus heteroclitus) from a marine Superfund site
Project description:The Atlantic killifish (Fundulus heteroclitus), native to estuarine areas of the Atlantic coast of the United States, has become a valuable ecotoxicological model due to its ability to acclimate to rapid environmental changes and adapt to polluted habitats. Killifish respond to rapid increases in salinity with an immediate change in gene expression, as well as long-term remodeling of the gills. Arsenic, a major environmental toxicant, was previously shown to inhibit the ability of killifish gill to respond to a rapid increase in salinity. We characterized miRNA expression in killifish gill under salinity acclimation with and without arsenic and identified a small group of highly expressed, well-conserved miRNAs as well as 16 novel miRNAs not yet identified in other organisms.
Project description:Subspecies of the Atlantic killifish, Fundulus heteroclitus, differ in their maximum thermal tolerance. To determine whether there is a link between the heat shock response (HSR) and maximum thermal tolerance, we exposed 20ºC acclimated killifish from these subspecies to a 2hr heat shock at 34ºC and examined gene expression during heat shock and recovery using real time quantitative PCR and a heterologous cDNA microarray designed for salmonid fishes. Keywords: Expression profiling by array Microarray analyses were performed on four individual fish per subspecies of killifish (northern and southern) prior to heat shock (control) and after 60 minutes of heat shock, hybridized (one slide per individual) against a common reference RNA pool composed of an equal amount of RNA from all samples in the analysis.
Project description:Killifish (Fundulus heteroclitus) inhabiting the New Bedford Harbor (NBH) Superfund Site have evolved resistance to the toxic and biochemical effects of non-ortho (dioxin-like) polychlorinated biphenyls (DL-PCBs) and other compounds that act via the aryl hydrocarbon receptor (AHR) signaling pathway. However, the majority of PCBs in NBH are ortho-substituted (non-DL) PCBs (o-PCBs), and the impacts of these o-PCBs on fish populations are not well understood. To determine whether the NBH killifish population has adapted to o-PCBs, we performed a series of experiments involving exposure to killifish embryos and adults from NBH and a reference site (Scorton Creek; SC) to 2,2’,4,4’,5,5’-hexachlorobiphenyl (PCB-153), a model o-PCB. PCB-153 was not acutely embryotoxic to developing F2 killifish embryos (SC or NBH) at concentrations up to 28 µM. RNA-seq showed that SC embryos exposed to PCB-153 (28 µM for 6 hr at 10 days post fertilization) had changes in the expression of genes involved in glucose homeostasis. However, NBH embryos were much less sensitive to these effects of PCB-153. When adult killifish from SC and NBH were exposed to PCB-153 (20 mg/kg) and sampled 3 days later for gene expression, many more genes were affected in forebrains of SC fish than in NBH fish, in a sex-specific manner. Together, these results demonstrate that NBH killifish have evolved reduced sensitivity to o-PCBs, suggesting complex adaptation to chemical mixtures at a Superfund site.
Project description:This study presents statistical analyses of gene expression in 5, 10 and 15 day post-fertilization (dpf) embryos of the teleost Fundulus heteroclitus treated with control vehicle (DMSO) or a potent non-ortho-PCB (PCB-126; 3,3’,4,4’,5-pentachlorobiphenyl). The embryos were from two populations: a clean, reference population (SC, Scorton Creek, MA USA) and a polluted Superfund population (N, New Bedford Harbor, MA USA). For each site, eggs from 8 females (~1100 total) were fertilized using minced testes from 5 males. After non-fertile eggs were culled, embryos were exposed to vehicle (DMSO; 0.1%) or PCB-126 (50 nM) in filtered seawater (salinity 25 part per thousand, 65 embros per 20 ml in glass petri dish) for 4 hr at 20º C. After exposure, the embryos were washed in filtered seawater and incubated at 20º C under a 14-h light, 10-h dark cycle. At 5-, 10-, and 15-dpf, embryos were collected as three pools of 20 embryos from each treatment group and flash frozen in liquid nitrogen and stored at -80º C until used for RNA isolation.
Project description:Gene expression was measured in the gills of saltwater (SW) acclimated Atlantic Killifish, Fundulus heteroclitus, over a time course of freshwater (FW) exposure, in which half the fish were exposed to arsenic. Fish were sampled from three populations, two from Maine, USA (ME) and one from Virginia, USA (VA)