ABSTRACT: Consumer-resource interactions are a central issue in evolutionary and community ecology because they play important roles in selection and population regulation. Most consumers encounter resource variation at multiple scales, and respond through phenotypic plasticity in the short term or evolutionary divergence in the long term. The key traits for these responses may influence resource acquisition, assimilation and/or allocation. To identify candidate genes, we experimentally assayed genome-wide gene expression in pond and lake Daphnia ecotypes exposed to alternate resource environments. One was a simple, high-quality laboratory diet, Ankistrodesmus falcatus. The other was the complex natural seston from a large lake. In temporary ponds, Daphnia generally experience high-quality, abundant resources, whereas lakes provide low-quality, seasonally shifting resources that are chronically limiting. For both ecotypes, we used replicate clones drawn from a number of separate populations. We compared gene expression in whole Daphnia pulex that had been raised in the lab for 10 days, and then exposed to alternate resource environments for 24 hours. One resource environment was a 24 hour continuation of the lab resource, a satiating level of Ankistrodesmus falcatus. The alternate environment was the natural seston present in the epilimnion of Lake Murray, South Carolina. Two ecotypes were analyzed, one adapted to large lakes, and one adapted to temporary ponds. For each ecotype, eight replicate clones were used. Clones of the lake ecotype were isolated from eight independent lakes, clones of the pond ecotype were isolated from six different ponds. The total number of arrays is 16 (8 replicate clones x 2 ecotypes) x 2 resource environments). Total RNA was extracted from eight whole organisms pooled together. Pools were then converted to cDNA and labelled with a single round of amplification. For array hybridizations, samples from the two resource environments were paired for each clone, and dyes were swapped across clones.
Project description:Consumer-resource interactions are a central issue in evolutionary and community ecology because they play important roles in selection and population regulation. Most consumers encounter resource variation at multiple scales, and respond through phenotypic plasticity in the short term or evolutionary divergence in the long term. The key traits for these responses may influence resource acquisition, assimilation and/or allocation. To identify candidate genes, we experimentally assayed genome-wide gene expression in pond and lake Daphnia ecotypes exposed to alternate resource environments. One was a simple, high-quality laboratory diet, Ankistrodesmus falcatus. The other was the complex natural seston from a large lake. In temporary ponds, Daphnia generally experience high-quality, abundant resources, whereas lakes provide low-quality, seasonally shifting resources that are chronically limiting. For both ecotypes, we used replicate clones drawn from a number of separate populations. Overall design: We compared gene expression in whole Daphnia pulex that had been raised in the lab for 10 days, and then exposed to alternate resource environments for 24 hours. One resource environment was a 24 hour continuation of the lab resource, a satiating level of Ankistrodesmus falcatus. The alternate environment was the natural seston present in the epilimnion of Lake Murray, South Carolina. Two ecotypes were analyzed, one adapted to large lakes, and one adapted to temporary ponds. For each ecotype, eight replicate clones were used. Clones of the lake ecotype were isolated from eight independent lakes, clones of the pond ecotype were isolated from six different ponds. The total number of arrays is 16 (8 replicate clones x 2 ecotypes) x 2 resource environments). Total RNA was extracted from eight whole organisms pooled together. Pools were then converted to cDNA and labelled with a single round of amplification. For array hybridizations, samples from the two resource environments were paired for each clone, and dyes were swapped across clones.
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. Overall design: 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.
Project description:This data is a case study done in the context of developing methods for assessing the taxonomic composition of microbial communities using metaproteomics. For this study with analyzed phototrophic biomats from two Soda Lakes in the Canadian Rocky Mountains using metaproteomics. For protein identification we generated a metagenome from which we predicted and annotated the protein sequences used to analyze the metaproteomes. The database is available in this PRIDE submission. Lake1 refers to Goodenough Lake (GEM, 51°19'47.64"N 121°38'28.90"W) and Lake2 referes to Last Chance Lake (LCM, 51°19'39.3" N 121°37'59.3"W).
Project description:The consistent cold temperatures and large amount of precipitation in the Olympic and Cascade ranges of Washington State are thought to increase atmospheric deposition of contaminants in these high elevation locations. Total mercury and 28 organochlorine compounds were measured in composite, whole fish samples collected from 14 remote lakes in the Olympic, Mt. Rainer, and North Cascades National Parks. Mercury was detected in fish from all lakes sampled and ranged in concentration from 17 to 262 ug/kg wet weight. Only two organochlorines, total polychlorinated biphenyls (tPCB) and dichlorodiphenyldichloroethylene (DDE), were detected in fish tissues (concentrations <25 ug/kg wet weight). No organochlorines were detected in sediments (MRL ≈1-5 ug/kg), while median total and methyl mercury in sediments were 30.4 and 0.34 ug/kg (dry weight), respectively. Using a targeted rainbow trout cDNA microarray with known genes, we detected significant differences in liver transcriptional responses, including metabolic, endocrine, and immune-related genes, in fish collected from a contaminated lake compared to a lake with a lower contaminant load. Overall, our results suggest that local urban areas are contributing to the observed contaminant patterns, while the transcriptional changes point to a biological response associated with exposure to these contaminants in fish. Specifically, the gene expression pattern leads us to hypothesize a role for mercury in disrupting the metabolic and reproductive pathways in fish from high elevation lakes in western Washington. Keywords: High altitude lakes, mercury, salmonids, organochlorines Overall design: Overall, 5 independent samples from Wilcox lake and 3 independent samples from Skymo lake were used for microarray. All the 8 samples were cross hybridized using reference RNA obtained from Rainbow trout liver samples. Dye-swapping was also followed.
Project description:Understanding how maternal effects evolve requires a mechanistic understanding of how mothers influence the development of their offspring in different environments and over time, and how offspring respond to these effects, if at all. Here, we used functional genomics and a manipulation of mother and offspring food environments to assess to what extent the transcriptome of 3rd instar offspring is attributable to parental environment, offspring environment, or both in two Daphnia pulex clones isolated from the same natural population. Both clones demonstrated differential transcription in 3rd instar offspring in response to food availability, but the genes involved varied between clones. Maternal food environment had no effect on the transcriptome of offspring for either clone, irrespective of whether maternal and offspring environments were matched or mismatched. We discuss possible explanations for this finding and compare our results with those of similar studies using other systems.
Project description:Our main objectives wereto investigate the molecular mechanisms involved in metal toxicity and detoxification in the field using juvenile yellow perch subjected to differents levels of this metal exposure. Recent local adaptation to pollution has been evidenced in several organisms inhabiting environments heavily contaminated by metals. Nevertheless, the molecular mechanisms underlying adaptation to high metal concentrations are poorly understood, especially in fishes. Yellow perch (Perca flavescens) populations from lakes in the mining area of Rouyn-Noranda (QC, Canada) have been faced with metal contamination for about 90 years. Here, we examine gene transcription patterns of fish reciprocally transplanted between a reference and a metal-contaminated lake and also fish caged in their native lake. After four weeks, 111 genes were differentially transcribed in metal-naïve fish transferred to the metal-contaminated lake, revealing a plastic response to metal exposure. Genes involved in the citric cycle and beta-oxidation pathways were under-transcribed, suggesting a potential strategy to mitigate the effects of metal stress by reducing energy turnover. However, metal-contaminated fish transplanted to the reference lake did not show any transcriptomic response, indicating a reduced plastic response capability to sudden reduction in metal concentrations. Moreover, the transcription of other genes, especially ones involved in energy metabolism, was affected by caging. Overall, our results highlight environmental stress response mechanisms in yellow perch at the transcriptomic level and support a rapid adaptive response to metal exposure through genetic assimilation. Comparison between fish Op and Op→Op using a pairwise design corresponding to the cage experiment in the reference lake Opasatica (Op), comparison between fish Du and Du→Du using a pairwise design corresponding to the cage experiment in the metal contaminated lake Dufault (Du), comparison between fish from reference lake transplanted to the metal contaminated lake (Op→Du) and fish from reference lake caged in their own lake (Op→Op) using pairwise design corresponding to the experiment of metal contamination, comparison between fish from metal contaminated lake transplanted to the reference lake (Du→Op) and fish from the metal contaminated lake caged in their own lake (Du→Du) using pairwise design corresponding to the depuration experiment.
Project description:Despite the progress achieved in elucidating the ecological mechanisms of adaptive radiation, there has been little focus on documenting the extent of adaptive differentiation in physiological functions during this process. Moreover, a thorough understanding of the genomic basis underlying phenotypic adaptive divergence is still in its infancy. One important evolutionary process for which causal genetic mechanisms are largely unknown pertains to life-history trade-offs. We analysed patterns of gene transcription in liver tissue of sympatric dwarf and normal whitefish from two natural lakes, as well as from populations reared in controlled environments, using a 16 006-gene cDNA microarray in order to: (i) document the extent of physiological adaptive divergence between sympatric dwarf and normal species pairs, and (ii) explore the molecular mechanisms of differential life history trade-offs between growth and survival potentially involved in their adaptive divergence. In the two natural lakes, 6.45% of significantly transcribed genes showed regulation either in parallel fashion (2.39%) or in different directions (4.06%). Among genes showing parallelism in regulation patterns, we observed a higher proportion of over-expressed genes in dwarf relative to normal whitefish (70.6%). Patterns observed in controlled conditions were also generally congruent with those observed in natural populations. Dwarf whitefish consistently showed significant over-expression of genes potentially associated with survival through enhanced activity (energy metabolism, iron homeostasis, lipid metabolism, detoxification), whereas more genes associated with growth (protein synthesis, cell cycle, cell growth) were generally down-regulated in dwarf relative to normal whitefish. Overall, parallelism in patterns of gene transcription, as well as patterns of interindividual variation across controlled and natural environments, provide strong indirect evidence for the role of selection in the evolution of differential regulation of genes involving a vast array of potentially adaptive physiological processes between dwarf and normal whitefish. Our results also provide a first mechanistic, genomic basis for the observed trade-off in life-history traits distinguishing dwarf and normal whitefish species pairs, wherein enhanced survival via more active swimming, necessary for increased foraging and predator avoidance, engages energetic costs that translate into slower growth rate and reduced fecundity in dwarf relative to normal whitefish. Overall design: Direct comparison of Dwarf vs Normal ecotypes. Samples comes from two natural environments (two different lakes) and one controled environement.
Project description:In this study we use nimblegen high-density arrays to examine gene expression regulation in a common-garden experiment varying thermal environments. We report genome-wide patterns of gene expression in two heat tolerant southern and two heat-sensitive northern clones of Daphnia pulex exposed to either optimal (18°C) or substressful (28°C) temperatures. Four competitive hybridizations of heat tolerant clones BW102 (hereafter B) and KSP3 (hereafter K), and heat sensitive clones EB1 (hereafter E) and CHQ3 (hereafter C) in response to thermal stress of either 18 degrees Celcius (here after 18) or 28 degrees (hereafter 28) in a loop design where each hybridization was replicated four times with two dye-swaps nested in each set of replicates.
Project description:Previous studies examining the reproductive health of alligators in Florida lakes indicate that a variety of developmental and health impacts can be attributed to environmental quality and exposures to environmental contaminants. A number of these environmental contaminants have been shown to disrupt normal endocrine signaling. The potential that these environmental toxicants may influence epigenetic status and correlate to the health abnormalities was investigated in the current study. The red blood cell (RBC) (erythrocyte) in the alligator is nucleated so was used as an easily purified marker cell to investigate epigenetic programming. RBCs were collected from adult male alligators captured at three sites in Florida, each characterized by varying degrees of contamination. While Lake Woodruff (WO) has remained relatively pristine, Lake Apopka (AP) and Merritt Island (MI) convey exposures to different suites of contaminants. DNA was isolated and methylated DNA immunoprecipitation (MeDIP) was used to isolate methylated DNA that was then analyzed in a competitive hybridization using a genome-wide alligator tiling array for a MeDIP-Chip analysis. Pairwise comparisons of alligators from AP and MI to WO revealed alterations in the DNA methylome. The AP vs. WO comparison identified 85 differential DNA methylation regions (DMRs) with ≥3 adjacent oligonucleotide tiling array probes and 15,451 DMRs with a single oligo probe analysis. The MI vs. WO comparison identified 75 DMRs with the ≥3 oligo probe and 17,411 DMRs with the single oligo probe analysis. There was negligible overlap between the DMRs identified in AP vs. WO and MI vs. WO comparisons. In both comparisons DMRs were primarily associated with CpG deserts which are regions of low CpG density (1-2 CpG/100bp). Although the alligator genome is not fully annotated, gene associations were identified and correlated to major gene functional categories and pathways. Observations demonstrate that environmental quality is associated with epigenetic programming and status in the alligator. The epigenetic alterations may provide biomarkers to assess the environmental exposures and health impacts on these populations of alligators. Overall design: The current study was designed to investigate potential alterations in the epigenome of alligators living in contaminated and non-contaminated lakes in Florida. The experimental design involved the collection of blood samples from adult male alligators from Lake Apopka and Merritt Island National Wildlife Refuge as contaminated lakes and Lake Woodruff as a reference lake. The epigenome analysis in the RBC involved the isolation of DNA followed by a methylated DNA immunoprecipitation (MeDIP). The MeDIP was then analyzed using a genome-wide alligator tiling array chip set (Chip) to identify differential DNA methylation regions (DMRs). Comparative hybridizations between the Lake Apopka alligator samples versus Lake Woodruff alligator samples and Merritt Island National Wildlife Refuge alligator versus Lake Woodruff alligator samples were made with two independent experiments with different sets of multiple animals from each site.
Project description:Deep Lake is a hypersaline system in Antarctica (68°33’36.8S, 78°11’48.7E) that is so saline it remains liquid at –20°C (DeMaere et al 2013). The lake is dominated by haloarchaea, comprising a low-complexity community that differs greatly to warm-hot latitude hypersaline systems, is hierarchical structured, and supports a high level of intergenera gene exchange. Metaproteomics was performed on biomass that was collected in the austral summer of 2008 by sequential size fractionation (20 – 3 µm, 3 – 0.8 µm, 0.8 – 0.1 µm). The data were integrated to obtain a systems level view of the active host-virus interactions occurring in this novel aquatic Antarctic system. DeMaere MZ, Williams TJ, Allen MA, Brown MV, Gibson JA, Rich J, Lauro FM, Dyall-Smith M, Davenport KW, Woyke T, Kyrpides NC, Tringe SG, Cavicchioli R (2013) High level of intergenera gene exchange shapes the evolution of haloarchaea in an isolated Antarctic lake. Proc Natl Acad Sci USA 110: 16939-16944