Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River.
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River. Three groups of samples, A, B and C. Every group has 3 replicates.
Project description:Cadmium is one of several heavy metals present in contaminated soils. Apparently, it has no biological role but can produce DNA damage, overexpression of stress response proteins and misfolded proteins, amongst other deleterial effects. Acidithiobacillus ferrooxidans is an acidophilic bacterium capable of resisting very high concentrations of heavy metals such as cadmium. This is important for industrial bioleaching processes where Cd+2 concentrations can be in the range of 5-100 mM. Cadmium resistance mechanisms in these microorganisms have not been fully characterized. A. ferrooxidans ATCC 53993 contains genes coding for possible metal resistance determinants such as efflux systems belonging to three families: P-type ATPases, RND transporters and cation diffusion facilitators (CDF). In addition, it has some extra copies of these genes in its exclusive genomic island (GI). Several of these putative genes were characterized in the present report by determining their transcriptional expression profiles and functionality. Moreover, a global quantitative proteomic analysis was carried out to further explore new cadmium resistance determinants in this biomining acidophile. Changes in iron oxidation pathways, upregulation of transport proteins (P-type ATPases and CDFs) and changes in ribosomal protein levels were seen. Finally, increased concentrations of exclusive putative cadmium ATPases present in strain ATCC 53993 GI and other non-identified proteins such as Lferr_0210, which forms part of a possible operon, could explain its greater resistance to cadmium compared to other acidophiles such as A. ferrooxidans ATCC 23270.
Project description:Background: Heavy metal cadmium (Cd) is a common environmental pollutant in soils, which has an negative impacts on crop growth and development. At present, cadmium has become a major soil and water heavy metal pollutant, which not only causes permanent and irreversible health problems for humans, but also causes a significant reduction in crop yields. Results: This study examined the chemical forms of Cd in the roots of two wheat varieties (M1019 and Xinong20) by continuous extraction and analyzed differences in distribution characteristics of Cd in the root cell wall, cytoplasm, and organelles by elemental content determination and subcellular separation. Furthermore, we conducted proteomics analysis of the roots of the two varieties under Cd pollution using mass spectrometry quantitative proteomics techniques. A total of 11,651 proteins were identified, of which 10,532 proteins contained quantitative information. In addition, the differentially expressed proteins in the two varieties were related to DNA replication and repair, protein metabolism, and the glutathione metabolism pathway. Conclusion: The results of this study improve our understanding of the mechanism of plant responses to Cd stress.
Project description:High Arctic soils have low nutrient availability, low moisture content and very low temperatures and, as such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the microbiology involved in this process is likely to be crucial to understand and optimize the factors most influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments, located at Alert (ex situ approach) and Eureka (in situ approach), in the Canadian high Arctic. Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of bacteria found in cold environments and hydrocarbon degradation genes as well as reverse-transcriptase real-time PCR targeting key functional genes. Results indicated a large difference between sampling sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases and polyaromatic hydrocarbon ring-hydroxylating-dioxygenases were observed one month after the bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year). Such discrepancies are likely caused by differences in bioremediation treatments (i.e. ex situ vs. in situ), weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring of polar bacteria and their associated functions during bioremediation. 38 soil samples from two high arctic locations that were contaminated-treated, contaminated or not contaminated followed for up to 4 years
Project description:High Arctic soils have low nutrient availability, low moisture content and very low temperatures and, as such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the microbiology involved in this process is likely to be crucial to understand and optimize the factors most influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments, located at Alert (ex situ approach) and Eureka (in situ approach), in the Canadian high Arctic. Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of bacteria found in cold environments and hydrocarbon degradation genes as well as reverse-transcriptase real-time PCR targeting key functional genes. Results indicated a large difference between sampling sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases and polyaromatic hydrocarbon ring-hydroxylating-dioxygenases were observed one month after the bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year). Such discrepancies are likely caused by differences in bioremediation treatments (i.e. ex situ vs. in situ), weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring of polar bacteria and their associated functions during bioremediation. 38 soil samples from two high arctic locations that were contaminated-treated, contaminated or not contaminated followed for up to 4 years
Project description:Comparison of hexachlorocyclohexane (HCH) contaminated soils from Spain with a community-specific microarray. These results are being submitted for publication and represent the first use of microarrays for analysis of soil DNA and the first community-specific microarray design. Keywords: other
Project description:From the result of comparative the gene expression analyses of human hepatoma cell line, HepG2 following exposures of three heavy metals; arsenic, cadmium and nickel and three carcinogens; N-dimethylnitrosoamine (DMN), 12-O-tetradecanoylphorbol-13-acetate (TPA) and tetrachloroethylene (TCE), 31-55% of the genes altered by As, Cd and Ni exposure were overlapped with those by three model carcinogen exposures in our experiments. In particular, three heavy metals shared certain characteristics with TPA and TCE in remarkable up-regulations of the genes associated with progression of cell cycle, which might play a central role in heavy metal carcinogenesis. In addition, this characteristic of gene expressions alteration was counteracted by intracellular accumulation of vitamine C in As-exposed cells but not in Cd- and Ni-exposed cells. These results suggest that the cell proliferative responses are caused by reactive oxygen species mainly in As exposure, while other mechanisms would be involved in these responses in Cd and Ni exposures. Experiment Overall Design: In this study, we examined the gene expression alteration in human hepatoma cell line, HepG2 following exposures of three heavy metals; arsenic, cadmium and nickel and three carcinogens; N-dimethylnitrosoamine (DMN), 12-O-tetradecanoylphorbol-13-acetate (TPA) and tetrachloroethylene (TCE) using DNA microarray with 8795 human genes. Furthermore, we also performed the DNA microarray analyses for the heavy metal exposed-cells that were loaded with vitamine C beforehand to examine the effects of antioxidant molecule to heavy metal exposures.