Project description:Quantitative RNA sequencing (RNA-seq) and the complementary phenotypic assays were implemented to investigate the transcriptional responses of Chromohalobacter salexigens to osmotic and heat stress. These conditions trigger the synthesis of ectoine and hydroxyectoine, two compatible solutes of biotechnological interest. Our findings revealed that both stresses make a significant impact on C. salexigens global physiology. Apart from compatible solute metabolism, the most relevant adaptation mechanisms were related to “oxidative- and protein-folding- stress responses”, “modulation of respiratory chain and related components”, and “ion homeostasis”. A general salt-dependent induction of genes related to the metabolism of ectoines, as well as repression of ectoine degradation genes by temperature, was observed. Different oxidative stress response mechanisms, secondary or primary, were induced at low and high salinity respectively, and repressed by temperature. A higher sensitivity to H2O2 was observed at high salinity, regardless of temperature. Low salinity induced genes involved in “protein-folding-stress response”, suggesting disturbance of protein homeostasis. Transcriptional shift of genes encoding three types of respiratory NADH dehydrogenases, ATP synthase, quinone pool, Na+/H+ antiporters, and sodium-solute symporters, was observed depending on salinity and temperature, suggesting modulation of the components of the respiratory chain and additional systems involved in the generation of H+ and/or Na+ gradients. Remarkably, the Na+ intracellular content remained constant regardless of salinity and temperature. Disturbance of Na+- and H+-gradients with specific ionophores suggested that both gradients influence ectoine production, but with differences depending on the solute, salinity, and temperature conditions. Flagellum genes were strongly induced by salinity, and further induced by temperature. However, salt-induced cell motility was reduced at high temperature, possibly caused by an alteration of Na+ permeability by temperature, as dependence of motility on Na+-gradient was observed. The transcriptional induction of genes related to the synthesis and transport of siderophores correlated with a higher siderophore production and intracellular iron content only at low salinity. In addition, compared to low salinity external iron increased hydroxyectoine accumulation by 20% at high salinity, but reduced the intracellular content of ectoines by 50% at high salinity plus high temperature. These findings support the relevance of iron homeostasis for osmoadaptation, thermoadaptation and accumulation of ectoines, in C. salexigens
Project description:To understand the sensitivity of larval lice to changing environmental parameters we applied a 38K oligo microarray and characterized transcriptome responses after 24 hour exposures to reduced salinity (30-10 parts per thousand (ppt)) or varied temperature (16-4ºC). To further characterize the effects of salinity, we profiled expression changes over a range of seawater with single increment differences (30-25 ppt).
Project description:In the marine environment, macroalgae face changing environmental conditions and some species are known for their high capacity to adapt to the new factors of their ecological niche. Some macroalgal metabolites play diverse ecological functions and belong to the adaptive traits of such species. Because algal metabolites are involved in many processes that shape marine biodiversity, understanding their sources of variation and regulation is therefore of utmost relevance. This work aims at exploring the possible sources of metabolic variations with time and space of four common algal species from the genus Lobophora (Dictyotales, Phaeophyceae) in the New Caledonian lagoon using a UHPLC-HRMS metabolomic fingerprinting approach. While inter-specific differences dominated, a high variability of the metabolome was noticed for each species when changing their natural habitats and types of substrates. Fatty acids derivatives and polyolefins were identified as chemomarkers of these changing conditions. The four seaweeds metabolome also displayed monthly variations over the 13-months survey and a significant correlation was made with sea surface temperature and salinity. This study highlights a relative plasticity for the metabolome of Lobophora species.
Project description:To understand the sensitivity of larval lice to changing environmental parameters we applied a 38K oligo microarray and characterized transcriptome responses after 24 hour exposures to reduced salinity (30-10 parts per thousand (ppt)) or varied temperature (16-4M-BM-:C). To further characterize the effects of salinity, we profiled expression changes over a range of seawater with single increment differences (30-25 ppt). Three separate projects. Low resolution salinity (aka wide range or LR_SAL) contains 2 duplicate experiments, each with pools of lice (~500 copepodid lice per beaker; n=3 beakers per condition), incubated for 24 hr at 10M-BM-:C diluted to 30, 25, 20, or 10 parts per thousand (ppt). Temperature study conducted as above, but with a constant salinity of 30 ppt and changed temperature of 4, 10, or 16M-BM-:C. High resolution salinity conducted as above, but with no experiment replication, but with biological repication of n=6 beakers per condition, and with a range of 25, 26, 27, 28, 29, 30 ppt salinity. Please note that each experiment was normalized separately.
Project description:Freshwater salinization is an escalating global environmental issue that threatens freshwater biodiversity, including fish populations. This study aims to uncover the molecular basis of salinity physiological responses in a non-native minnow species (Phoxinus septimaniae x P. dragarum) exposed to saline effluents from potash mines in the Llobregat River, Barcelona, Spain. Employing high-throughput mRNA sequencing and differential gene expression analyses, brain, gills, and liver tissues collected from fish at two stations (upstream and downstream of saline effluent discharge) were examined. Salinization markedly influenced global gene expression profiles, with the brain exhibiting the most differentially expressed genes, emphasizing its unique sensitivity to salinity fluctuations. Pathway analyses revealed the expected enrichment of ion transport and osmoregulation pathways across all tissues. Furthermore, tissue-specific pathways associated with stress, reproduction, growth, immune responses, methylation, and neurological development were identified in the context of salinization. Rigorous validation of RNA-seq data through quantitative PCR (qPCR) underscored the robustness and consistency of our findings across platforms. This investigation unveils intricate molecular mechanisms steering salinity physiological response in non-native minnows confronting diverse environmental stressors. This comprehensive analysis sheds light on the underlying genetic and physiological mechanisms governing fish physiological response in salinity-stressed environments, offering essential knowledge for the conservation and management of freshwater ecosystems facing salinization.
Project description:Local adaptation is often a product of environmental variations in geographical space and has implications for biodiversity conservation. We investigated the role of latitudinal heterogeneity in climate on the organization of genetic and phenotypic variation in the dominant coastal tree Avicennia schaueriana. In a common garden experiment, samples from an equatorial region, with pronounced seasonality in precipitation, accumulated less biomass, and showed lower stomatal conductance and transpiration, narrower xylem vessels, smaller leaves and higher reflectance of long wavelengths by the stem epidermis than samples from a subtropical region, with seasonality in temperature and no dry season. Transcriptomic differences identified between trees sampled under field conditions at equatorial and subtropical sites, were enriched in functional categories such as responses to temperature, solar radiation, water deficit, photosynthesis and cell wall biosynthesis. Remarkably, the diversity based on genome-wide SNPs revealed a north-south genetic structure and signatures of selection were identified for loci associated with photosynthesis, anthocyanin accumulation and the responses to osmotic and hypoxia stresses. Our results suggest the existence of divergence in key resource-use characteristics, likely driven by seasonality in water deficit and solar radiation. These findings provide a basis for conservation plans and for predicting coastal plants responses to climate change.
Project description:Colwellia psychrerythraea is a marine psychrophilic bacterium known for its remarkable ability to maintain activity during long-term exposure to extreme subzero temperatures and correspondingly high salinities in sea ice. These microorganisms must have simultaneous adaptations to high salinity and low temperature to survive, be metabolically active, or grow in the ice. Here we report results obtained through an experimental design that allowed us to monitor culturability, activity, and proteomic signatures of Colwellia psychrerythraea strain 34H (Cp34H) to subzero temperature, salinity, and nutrient availability by performing long-term incubations in eight different conditions. Shotgun proteomics revealed novel metabolic strategies used to maintain culturability in response to each independent experimental variable, particularly in pathways regulating carbon, nitrogen, and fatty acid metabolism. For the first time, statistical analysis of differential abundances of proteins uniquely identified in these isolated conditions provide metabolism-specific protein biosignatures indicative of growth or survival in either increased salinity, decreased temperature, or nutrient limitation. Additionally, to aid in the search for extant life on other icy worlds, analysis of detected short peptides enriched and retained in -10oC incubations for four months identified over 400 potential biosignatures that could indicate the presence of terrestrial-like cold-active or halophilic metabolisms on other icy worlds.
Project description:In Sparus aurata, seasonal temperature variations outside the normal thermal range, may trigger physiological responses leading to pathologies and death. In the present study two groups of wild sea bream were exposed for 21 days to two temperature regimes: 16 ± 0.3 °C (control group) and 6.8 ± 0.3 °C (cold-exposed group). Samples were collected during the acute phase (0, 6 and 24 hours after temperature drop) and upon chronic exposure (21 days).
Project description:This project is aiming to examine the molecular response of the blue mussel (Mytilus edulis) to increased air temperatures and reduced salinity under laboratory conditions. There are 5 treatment groups (n=5), with group A representing the control (salinity 23percent salinity and temperature 5 degree celsius), group B ( 23percent salinity 30 degree celsius), group C (23percent salinity 33 degree celsius), group D (15percent salinity 5 degree celsius), group E (15percent salinity 30 degree celsius), group F (15percent salinity33 degree celsius), group G (5percent salinity 5 degree celsius).