Gene co-expression networks drive and predict reproductive effects in Daphnia in response to environmental disturbances
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ABSTRACT: ncreasing effects of anthropogenic stressors and those of natural origin on aquatic ecosystems have intensified the need for predictive and functional models of their effects. Here, we use gene expression patterns in combination with weighted gene co-expression networks and generalized additive models to predict effects on reproduction in the aquatic microcrustacean Daphnia. We developed models to predict effects on reproduction upon exposure to different cyanobacteria, different insecticides and binary mixtures of cyanobacteria and insecticides. Models developed specifically for groups of stressors (e.g. either cyanobacteria or insecticides) performed better than general models developed on all data. Furthermore, models developed using in silico generated mixture gene expression profiles from single stressor data were able to better predict effects on reproduction compared to models derived from the mixture exposures themselves. Our results highlight the potential of gene expression data to quantify effects of complex exposures at higher level organismal effects without prior mechanistic knowledge or complex exposure data.
Project description:The oceans are now all affected by human activities. The study of the impact of pollution on the health status of exploited marine populations is essential to better understand the direct constraints that stress generates on growth, reproduction, immune system and, ultimately, on the reproductive success of animals. Interactions between different stressors can generate non-additive effects ("cocktail effects"), which makes experimental models under controlled conditions based on only one or a few "stressors" insufficient. Thus, quantitative proteomics was used to analyse liver proteome of wild gilt-head sea bream evolving in the Mediterranean Sea (coastal area) with contrasting levels of organic and inorganic contamination. The prospects of researching biomarkers of health status that can be used as indicators of the status of a population or an ecosystem are of major interest for the monitoring and management of natural environments, hence promoting the conservation and management of marine species.
Project description:The oceans are now all affected by human activities. The study of the impact of pollution on the health status of exploited marine populations is essential to better understand the direct constraints that stress generates on growth, reproduction, immune system and, ultimately, on the reproductive success of animals. Interactions between different stressors can generate non-additive effects ("cocktail effects"), which makes experimental models under controlled conditions based on only one or a few "stressors" insufficient. Thus, quantitative proteomics was used to analyse muscle proteome of wild European pilchards evolving in the Mediterranean Sea with contrasting levels of organic and inorganic contamination. The prospects of researching biomarkers of health status that can be used as indicators of the status of a population or an ecosystem are of major interest for the monitoring and management of natural environments, hence promoting the conservation and management of marine species.
Project description:The oceans are now all affected by human activities. The study of the impact of pollution on the health status of exploited marine populations is essential to better understand the direct constraints that stress generates on growth, reproduction, immune system and, ultimately, on the reproductive success of animals. Interactions between different stressors can generate non-additive effects ("cocktail effects"), which makes experimental models under controlled conditions based on only one or a few "stressors" insufficient. Thus, quantitative proteomics was used to analyse muscle proteome of wild gilt-head sea bream evolving in the Mediterranean Sea (coastal area) with contrasting levels of organic and inorganic contamination. The prospects of researching biomarkers of health status that can be used as indicators of the status of a population or an ecosystem are of major interest for the monitoring and management of natural environments, hence promoting the conservation and management of marine species.
Project description:The oceans are now all affected by human activities. The study of the impact of pollution on the health status of exploited marine populations is essential to better understand the direct constraints that stress generates on growth, reproduction, immune system and, ultimately, on the reproductive success of animals. Interactions between different stressors can generate non-additive effects ("cocktail effects"), which makes experimental models under controlled conditions based on only one or a few "stressors" insufficient. Thus, quantitative proteomics was used to analyse liver proteome of wild European pilchards evolving in the Mediterranean Sea with contrasting levels of organic and inorganic contamination. The prospects of researching biomarkers of health status that can be used as indicators of the status of a population or an ecosystem are of major interest for the monitoring and management of natural environments, hence promoting the conservation and management of marine species.
Project description:Standard bioassays allow hazard assessment at the population level, but much remains to be learned about the molecular level response of organisms to stressors. The main aim of this study was the development of a DNA microarray for Enchytraeus albidus, a common soil worm species. Further, this microarray was tested using worms exposed to Cu, phenmedipham, and different soil types. Hybridization onto the developed microarray revealed several genes with homology to known sequences. Genes of interest were confirmed through real-time polymerase chain reaction. It was possible to discriminate between natural and chemical stressors and chemical concentrations. Gene responses were detected under conditions known to have effects in the reproduction of individuals. It was confirmed that the integration of different endpoints improves the assessment process and enhances the understanding of the modes of action of stressors. The chemical stress–induced genes were related to factors such as immune response, stress response, metabolic processes, and/or signal transduction. The present study represents the first step of a gene-level study in the ecologically relevant and standard test species E. albidus. It demonstrates the usefulness of cDNA normalization in the production of cDNA libraries of ecotoxicological standard organisms that are not genome models like E. albidus.
Project description:Gene expression changes and polymorphisms were investigated in genetically related mosquito lines maintained for 30 generations under four different selection regimes. All mosquito line derived from the same parental line (Anopheles gambiae Tiassale line from Ivory coast). Selection regimes were as follows: i) no selection pressure (Control line), ii) selection at each generation at larval stage with a mixture of insecticides used against agricultural pests (Ins line); iii) selection at each generation at larval stage with a mixture of herbicides and fungicides used on crops (Herb line), iv) selection at each generation at larval stage with a mixture of both insecticides and non-insecticide compounds (compounds ii + iii, Mix line). The transcriptome of each line was sequenced using RNA-seq with four replicates per condition.
Project description:There is still a lot of contradiction on whether metal ions are solely responsible for the observed the toxicity of ZnO and CuO nanoparticles to aquatic species. While most tests have studied nanoparticle effects at organismal levels (e.g. mortality, reproduction), effects at suborganismal levels may clarify the role of metal ions, nanoparticles and nanoparticle aggregates. In this study, the effect of ZnO, CuO nanoparticles and zinc, copper salts was tested on the gene expression levels in Daphnia magna. D. magna was exposed during 96 hours to 10% immobilization concentrations of all chemicals, after which daphnids were sampled for a differential gene expression analysis using microarray. When comparing the nanoparticle exposed daphnids (ZnO or CuO) to the metal salt exposed daphnids (zinc or copper salt), the microarray results showed no significantly differentially expressed genes. These results indicate that the toxicity of the tested ZnO and CuO nanoparticles to D. magna caused is solely caused by toxic metal ions. 4 replicate exposures of ZnO nanoparticles, ZnCl2, Blank (for Zn); 4 replicate exposures of CuO nanoparticles, CuCl2.2H2O, Blank (for Cu); Individual reference design with swapped dyes for zinc (e.g. ZnO-REFZn; REFZn-bl) and copper exposure (e.g. CuO-REFCu; REFCu-bl); Zinc reference sample is a mixture of equal aliquots of ZnO nanoparticle, ZnCl2 and blank; Copper reference sample is a mixture of equal aliquots of CuO nanoparticle, CuCl2.2H2O and blank
Project description:There is still a lot of contradiction on whether metal ions are solely responsible for the observed the toxicity of ZnO and CuO nanoparticles to aquatic species. While most tests have studied nanoparticle effects at organismal levels (e.g. mortality, reproduction), effects at suborganismal levels may clarify the role of metal ions, nanoparticles and nanoparticle aggregates. In this study, the effect of ZnO, CuO nanoparticles and zinc, copper salts was tested on the gene expression levels in Daphnia magna. D. magna was exposed during 96 hours to 10% immobilization concentrations of all chemicals, after which daphnids were sampled for a differential gene expression analysis using microarray. When comparing the nanoparticle exposed daphnids (ZnO or CuO) to the metal salt exposed daphnids (zinc or copper salt), the microarray results showed no significantly differentially expressed genes. These results indicate that the toxicity of the tested ZnO and CuO nanoparticles to D. magna caused is solely caused by toxic metal ions. 4 replicate exposures of ZnO nanoparticles, ZnCl2, Blank (for Zn); 4 replicate exposures of CuO nanoparticles, CuCl2.2H2O, Blank (for Cu); Individual reference design with swapped dyes for zinc (e.g. ZnO-REFZn; REFZn-bl) and copper exposure (e.g. CuO-REFCu; REFCu-bl); Zinc reference sample is a mixture of equal aliquots of ZnO nanoparticle, ZnCl2 and blank; Copper reference sample is a mixture of equal aliquots of CuO nanoparticle, CuCl2.2H2O and blank
Project description:Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants still present in aquatic environments despite their total or partial ban. Previously, we observed that an environmentally realistic mixture of these compounds affects energy balance, growth, and reproduction in exposed zebrafish (F0), and behavior in their unexposed offspring (F1-F4). In the present work, we performed lipidomic and transcriptomic analyses on brains of zebrafish (F0-F2) from exposed and control lineages to identify molecular changes that could explain the observed phenotypes. The use of both technologies highlighted that F0 zebrafish displayed impaired mitochondrial function and lipid metabolism dysregulation (depletion in triacylglycerols and phospholipids) which can explain disruption of energy homeostasis. A subset of the dysregulated biological pathways (Gene Ontology and Reactome databases) related to energetic metabolism and neurotransmission were inherited in F2. In addition, there were increasing effects on epigenetic pathways from the F0 to the F2 generation. Altogether, we show that the effects of an environmental exposure to PCBs and PBDEs on energetic metabolism as well as neurotransmission extend over 2 generations of zebrafish, possibly due to transgenerational epigenetic inheritance.
Project description:The mechanisms of acclimating to a nitrogen-fluctuating environment are necessary for the survival of aquatic cyanobacteria in their natural habitats, but our understanding is still far from complete. Here, the synthesis of phycobiliprotein is confirmed to be much earlier than that of photosystem components during recovery from nitrogen chlorosis and an unknown protein Ssr1698 is discovered to be involved in this synthetic process. The unknown protein is further identified as a c-type heme oxygenase (cHO) in tetrapyrrole biosynthetic pathway and catalyzes the opening of heme ring to form biliverdin IXα, which is required for phycobilin production and ensuing phycobiliprotein synthesis. In addition, the cHO-dependent phycobiliprotein is found to be vital for the growth of cyanobacterial cells during chlorosis and regreening through its nitrogen-storage and light-harvesting functions, respectively. Collectively, the cHO expressed preferentially during recovery from nitrogen chlorosis is identified in photosynthetic organisms and the dual function of this enzyme-dependent phycobiliprotein is proposed to be an important mechanism for acclimation of aquatic cyanobacteria to a nitrogen-fluctuating environment.