Project description:Environmental contamination from heavy metals poses a global concern for the marine environment, as heavy metals are passed up the food chain and persist in the environment long after the pollution source is contained. Cnidarians, dating back to 700 million years ago, play an important role in shaping marine ecosystems, but environmental pollution profoundly affects their vitality. Among the cnidarians, the sea anemone Nematostella vectensis is an advantageous model for addressing questions in molecular ecology and toxicology as it tolerates extreme environments and its genome has been published. Here we employed a transcriptome-wide RNA-Seq approach to analyze N.vectensis molecular defense mechanisms against four heavy metals: Hg, Cu, Cd and Zn. Altogether, more than 5000 transcripts showed significant changes in gene expression, with Hg having the greatest impact on up-regulating transcripts, followed by Cu, Cd and Zn. We identified, for the first time, co-up-regulation of immediate-early transcription factors such as Egr1, AP1 and NF-κB. Time-course analysis of these genes revealed their early expression as rapidly as one hour after exposure to heavy metals, suggesting that they may complement or substitute for the roles of the metal mediating Mtf1 transcripton factor. We further characterized regulation of a large array of stress-response gene families including Hsp, ABC, CYP members and phytochelatin synthase that may regulate synthesis of the metal-binding phytochelatins instead of the methallothioneins that are absent from Cnidaria genome. This study provides mechanistic insight into heavy-metal toxicity in N.vectensis and sheds light on ancestral stress adaptations. 4 metals were tested in triplicates in comparison to control (4 replicates)
Project description:Environmental contamination from heavy metals poses a global concern for the marine environment, as heavy metals are passed up the food chain and persist in the environment long after the pollution source is contained. Cnidarians, dating back to 700 million years ago, play an important role in shaping marine ecosystems, but environmental pollution profoundly affects their vitality. Among the cnidarians, the sea anemone Nematostella vectensis is an advantageous model for addressing questions in molecular ecology and toxicology as it tolerates extreme environments and its genome has been published. Here we employed a transcriptome-wide RNA-Seq approach to analyze N.vectensis molecular defense mechanisms against four heavy metals: Hg, Cu, Cd and Zn. Altogether, more than 5000 transcripts showed significant changes in gene expression, with Hg having the greatest impact on up-regulating transcripts, followed by Cu, Cd and Zn. We identified, for the first time, co-up-regulation of immediate-early transcription factors such as Egr1, AP1 and NF-κB. Time-course analysis of these genes revealed their early expression as rapidly as one hour after exposure to heavy metals, suggesting that they may complement or substitute for the roles of the metal mediating Mtf1 transcripton factor. We further characterized regulation of a large array of stress-response gene families including Hsp, ABC, CYP members and phytochelatin synthase that may regulate synthesis of the metal-binding phytochelatins instead of the methallothioneins that are absent from Cnidaria genome. This study provides mechanistic insight into heavy-metal toxicity in N.vectensis and sheds light on ancestral stress adaptations.
Project description:We hypothesize that microarray-based analysis of Lycopersicon esculentum is a sensitive tool for the early detection of potential toxicity of heavy metals, as well as an effective tool for identifying the heavy metal-specific genes. To test the hypothesis, the Agilent whole-genome cDNA microarrays were used to assess the effects of heavy metal on L. esculentum at relatively low concentrations (1/10 LC50 of heavy metals). Results showed that the characteristic gene expression profiles induced by Cd, Cr, Hg and Pb were not only distinct from the control but also distinct from one another, demonstrating the feasibility of discriminating between the effects of these four heavy metals present at relatively low concentrations. Moreover, heavy metal-specific genes were identified by microarray analysis. These findings support the above hypothesis.
Project description:For environmental safety, the high concentration of heavy metals in the soil should be removed. Cadmium (Cd), one of the heavy metals polluting the soil while its concentration exceeds 3.4 mg/kg in soil. Potential use of cotton for remediating heavy Cd-polluted soils is available while its molecular mechanisms of Cd tolerance remains unclear in cotton. In this study, transcriptome analysis was used to identify the Cd tolerance genes and their potential mechanism in cotton. Finally 4,627 differentially expressed genes (DEGs) in the root, 3,022 DEGs in the stem and 3,854 DEGs in leaves were identified through RNA-Seq analysis, respectively. These genes contained heavy metal transporter genes (ABC, CDF, HMA, etc.), annexin genes, heat shock genes (HSP) amongst others. Gene ontology (GO) analysis showed that the DEGs were mainly involved in the oxidation-reduction process and metal ion binding. The DEGs mainly enriched in two pathways, the influenza A and the pyruvate pathway. GhHMAD5 protein, containing a heavy-metal domain, was identified in the pathway to transport or to detoxify the heavy ion. GhHMAD5-overexpressed plants of Arabidopsis thaliana showed the longer roots compared with the control. Meanwhile, GhHMAD5-silenced cotton plants showed more sensitive to Cd stress compared with the control. The results indicated that GhHMAD5 gene is remarkably involved in Cd tolerance, which gives us a preliminary understanding of Cd tolerance mechanisms in upland cotton. Overall, this study provides valuable information for the use of cotton to remediate the soil polluted with heavy metals.
Project description:Marine cyanobacteria are thought to be the most sensitive of the phytoplankton groups to copper toxicity, yet little is known of the transcriptional response of marine Synechococcus to copper shock. Global transcriptional response to two levels of copper shock was assayed in both a coastal and an open ocean strain of marine Synechococcus using whole genome expression microarrays. Both strains showed an osmoregulatory-like response, perhaps as a result of increasing membrane permeability. This could have implications for marine carbon cycling if copper shock leads to dissolved organic carbon leakage in Synechococcus. The two strains additionally showed a reduction in photosynthetic gene transcripts. Contrastingly, the open ocean strain showed a typical stress response whereas the coastal strain exhibited a more specific oxidative or heavy metal type response. In addition, the coastal strain activated more regulatory elements and transporters, many of which are not conserved in other marine Synechococcus strains and may have been acquired by horizontal gene transfer. Thus, tolerance to copper shock in some marine Synechococcus may in part be a result of an increased ability to sense and respond in a more specialized manner.
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance Two-condition experiments. Comparing samples after induction with heavy metals versus non-induced samples. Biological duplicate or triplicate. Each array contains 3 or 4 technical replicates.
Project description:Cupriavidus metallidurans CH34 is a metal resistant beta-proteobacterium. The genome of this bacterium contain many genes involved in heavy metal resistance. Gene expression of C. metallidurans was studied after the addition of of Zn(II), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II) or Co(II). Keywords: Heavy metal stress response