Project description:Background: Ocean temperatures are projected to increase over the coming century, with dramatic consequences for the marine biosphere. Diatoms are important contributors to marine primary production and the ocean carbon cycle, yet the molecular mechanisms that regulate their acclimation and adaptation to temperature are poorly understood. Method: Here we use a transcriptomic approach to identify the molecular mechanisms associated with temperature acclimation and adaptation in closely related colder- and warmer-adapted diatom species. Results: We find contrasting patterns of differential expression at sub- and supra-optimal temperatures across the two species, which may be due to adaptive changes in baseline expression. Frontloaded and divested pathways indicate protein processing machinery, membrane structure, and the balance between temperature-independent photosynthesis and temperature-dependent metabolism are key elements of adaptation to temperature changes. Conclusions: Our findings suggest that transcriptional frontloading and divestment may provide a framework to interpret diatom acclimation and adaptation to temperature and success under future warming.
Project description:Chemical analysis of the compounds present in sediment, although informative, often is not indicative of the downstream biological effects that these contaminants exert on resident aquatic organisms. More direct molecular methods are needed to determine if marine life is affected by exposure to sediments. In this study, we used an aquatic multispecies microarray and q-PCR to investigate the effects on gene expression in juvenile sea bream (Sparus aurata) of two contaminated sediments defined as sediment 1 and 2 respectively, from marine areas in Northern Italy.
Project description:In the present study, we were interested in gene expression changes in the pectoralis muscle of juvenile king penguins during the transition from terrestrial to marine life. Strictly terrestrial during their first year after hatching, king penguin chicks must then depart to sea to reach nutritional emancipation and pectoralis muscle is largely involved in penguin adaptation to the marine environment. To compare these transcriptomic profiles, we realized heterologous hybridization on Affymetrix GeneChip Chicken Genome Arrays, as the chicken is the closest model species for which microarrays are available. The development of a new algorithm, MaxRS, allow us to determine differentially expressed genes implicated in energetic metabolism or involved in cellular defense against reactive oxygen species and associated injuries. We compared muscle sample biopsy from 4 penguin juveniles captured just before they undergone their first immersion to cold water (named NI for Never Immersed) and 3 penguin juveniles that had completly accomplished their acclimation to marine life (named SA for Sea Acclimated).
Project description:In the present study, we were interested in gene expression changes in the pectoralis muscle of juvenile king penguins during the transition from terrestrial to marine life. Strictly terrestrial during their first year after hatching, king penguin chicks must then depart to sea to reach nutritional emancipation and pectoralis muscle is largely involved in penguin adaptation to the marine environment. To compare these transcriptomic profiles, we realized heterologous hybridization on Affymetrix GeneChip Chicken Genome Arrays, as the chicken is the closest model species for which microarrays are available. The development of a new algorithm, MaxRS, allow us to determine differentially expressed genes implicated in energetic metabolism or involved in cellular defense against reactive oxygen species and associated injuries.
Project description:Background: Marine phytoplankton are responsible for 50% of the CO2 that is fixed annually worldwide and contribute massively to other biogeochemical cycles in the oceans. Diatoms and coccolithophores play a significant role as the base of the marine food web and they sequester carbon due to their ability to form blooms and to biomineralise. To discover the presence and regulation of short non-coding RNAs (sRNAs) in these two important phytoplankton groups, we sequenced short RNA transcriptomes of two diatom species (Thalassiosira pseudonana, Fragilariopsis cylindrus) and validated them by Northern blots along with the coccolithophore Emiliania huxleyi. Results: Despite an exhaustive search, we did not find canonical miRNAs in diatoms. The most prominent classes of sRNAs in diatoms were repeat-associated sRNAs and tRNA-derived sRNAs. The latter were also present in E. huxleyi. tRNA-derived sRNAs in diatoms were induced under important environmental stress conditions (iron and silicate limitation, oxidative stress, alkaline pH), and they were very abundant especially in the polar diatom F. cylindrus (20.7% of all sRNAs) even under optimal growth conditions. Conclusions: This study provides first experimental evidence for the existence of short non-coding RNAs in marine microalgae. Our data suggest that canonical miRNAs are absent from diatoms. However, the group of tRNA-derived sRNAs seems to be very prominent in diatoms and coccolithophores and may be used for acclimation to environmental conditions.
Project description:In the present study, we were interested in gene expression changes in the pectoralis muscle of juvenile king penguins during the transition from terrestrial to marine life. Strictly terrestrial during their first year after hatching, king penguin chicks must then depart to sea to reach nutritional emancipation and pectoralis muscle is largely involved in penguin adaptation to the marine environment. To compare these transcriptomic profiles, we realized heterologous hybridization on Affymetrix GeneChip Chicken Genome Arrays, as the chicken is the closest model species for which microarrays are available. The development of a new algorithm, MaxRS, allow us to determine differentially expressed genes implicated in energetic metabolism or involved in cellular defense against reactive oxygen species and associated injuries. Data from NI and SA penguin juveniles are already on GEO n°GSE17725
Project description:Background: Marine phytoplankton are responsible for 50% of the CO2 that is fixed annually worldwide and contribute massively to other biogeochemical cycles in the oceans. Diatoms and coccolithophores play a significant role as the base of the marine food web and they sequester carbon due to their ability to form blooms and to biomineralise. To discover the presence and regulation of short non-coding RNAs (sRNAs) in these two important phytoplankton groups, we sequenced short RNA transcriptomes of two diatom species (Thalassiosira pseudonana, Fragilariopsis cylindrus) and validated them by Northern blots along with the coccolithophore Emiliania huxleyi. Results: Despite an exhaustive search, we did not find canonical miRNAs in diatoms. The most prominent classes of sRNAs in diatoms were repeat-associated sRNAs and tRNA-derived sRNAs. The latter were also present in E. huxleyi. tRNA-derived sRNAs in diatoms were induced under important environmental stress conditions (iron and silicate limitation, oxidative stress, alkaline pH), and they were very abundant especially in the polar diatom F. cylindrus (20.7% of all sRNAs) even under optimal growth conditions. Conclusions: This study provides first experimental evidence for the existence of short non-coding RNAs in marine microalgae. Our data suggest that canonical miRNAs are absent from diatoms. However, the group of tRNA-derived sRNAs seems to be very prominent in diatoms and coccolithophores and may be used for acclimation to environmental conditions. RNA-seq study of sRNA populations in two species of diatoms using Illumina GAII high-throughput sequencing
Project description:Ocean global warming affects the distribution, life history and physiology of marine life. Extreme events, like marine heatwaves, are increasing in frequency and intensity. During sensitive developmental windows of fish, the consequences may be long-lasting and mediated by epigenetic mechanisms. Here, we used adult European sea bass as a model to study the effects of a marine heatwave during development. We measured DNA methylation and gene expression in four tissues (brain, muscle, liver and testis) and detected differentially methylated regions (DMRs). Six genes were differentially expressed and contained DMRs three years after exposure to increased temperature, indicating direct phenotypic consequences and representing persistent changes. Interestingly, nine genes contained DMRs around the same genomic regions across tissues, therefore consisting of common footprints of developmental temperature in environmentally responsive loci. These loci are, to our knowledge, the first metastable epialleles (MEs) described in fish. MEs may serve as biomarkers to infer past life history events linked with persistent consequences. These results highlight the importance of subtle phenotypic changes mediated by epigenetics to extreme weather events during sensitive life stages. Also, to our knowledge, it is the first time the molecular effects of a marine heatwave during the lifetime of individuals are assessed. MEs could be used in surveillance programs aimed at determining the footprints of climate change on marine life. Our study paves the way for the identification of conserved MEs that respond equally to environmental perturbations across species. Conserved MEs would constitute a tool of assessment of global change effects in marine life at a large scale.