Project description:The aim of this study is to obtain a systems level understanding of the interactions between Dehalococcoides and corrinoid-supplying microorganisms by analyzing community structures and functional compositions, activities and dynamics in trichloroethene (TCE)-dechlorinating enrichments. Metagenomes and metatranscriptomes of the dechlorinating enrichments with and without exogenous cobalamin were compared. Seven draft genomes were binned from the metagenomes. At an early stage (2 d), more transcripts of genes in the Veillonellaceae bin-genome were detected in the metatranscriptome of the enrichment with exogenous cobalamin compared to the one without cobalamin addition. Among these genes, sporulation-related genes exhibited the highest differential expression when cobalamin was not added, suggesting a possible release route of corrinoids from corrinoid-producers. Other differentially expressed genes include those involved in energy conservation and nutrient transport (including cobalt transport). The most highly expressed corrinoid de novo biosynthesis pathway was also assigned to the Veillonellaceae bin-genome. Targeted qPCR analyses confirmed higher transcript abundances of those corrinoid biosynthesis genes in the enrichment without exogenous cobalamin. Furthermore, Dehalococcoides' corrinoid salvaging and modification pathway was upregulated in response to the cobalamin stress. This study provides important insights into the microbial interactions and roles of members of dechlorinating communities under cobalamin-limited conditions.
Project description:In low rainfall regions soils are naturally conditioned with frequent co-occurrence of salinity and alkalinity. Plant salinity responses both at physiological and molecular level have been extensively researched. However, effects of the combined treatment of alkaline salinity that could greatly reduce plant growth and the mechanisms responsible for tolerance remain indeterminate. In Brassica juncea, large reductions in biomass and increased leaf Na+ concentration under alkaline salinity indicates that the combined treatment had greater negative effect than salinity on both growth and the physiological responses of the plant. To determine molecular mechanisms potentially controlling adaptive tolerance responses to salinity and alkaline salinity, the moderately tolerant genotype NDR 8501 was further investigated using microarray analysis. The transcripts of treated leaf tissues verses those of the untreated control sample were analysed after prolonged stress of four weeks. In total, 528 salinity responsive and 1245 alkaline salinity responsive genes were indentified and only 101 genes were expressed jointly in either of the two treatments. Transcription of 37% more genes involved in response to alkaline salinity than salinity alone, which suggests the increased impact and severity of the combined stress on the plant, indicating the transcription of a far greater number of genes likely involved in mitigation and damage control. Transcription of KUP2 and KUP7 genes involved in potassium homeostasis under salinity alone and NHX1 and ENH1 genes for ion (K+ and Na+) homeostasis under alkaline salinity, clearly demonstrated that different genes and genetic pathways are involved in response to each stress. They further provide supporting evidence for the physiological responses that occur in the plant, with massive reprogramming of the transcriptome leading to partial ion exclusion, shuttling and compartmentation.
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals.
Project description:Populations that tolerate extreme environmental conditions with frequent fluctuations can give valuable insights into physiological limits and adaptation. In some estuarine and marine ecosystems, organisms must adapt to extreme and fluctuating salinities, but not much is known how varying salinities impact local adaptation across a wide geographic range. We used eight geographically and genetically divergent populations of the intertidal copepod Tigriopus californicus to test if northern populations have greater tolerance to low salinity stresses, as they experience greater precipitation and less evaporation. We used a common garden experiment approach and exposed all populations to acute low (1, 3ppt) and high (110, 130ppt) salinities for 24 hours, and a fluctuation between baseline salinity and moderate low (7ppt) and high (80ppt) salinities over 49 hours. We also performed RNA-sequencing at several time points during the fluctuation between baseline and 7ppt to understand the molecular basis of divergence between two populations with differing physiological responses. We present these novel findings: 1) acute low salinity conditions caused more deaths than high salinity, 2) molecular processes that elevate proline levels increased in 7ppt, which contrasts with other T. californicus studies that mainly associated accumulation of proline with hyperosmotic stress. We also find that 3) tolerance to a salinity fluctuation did not follow a latitudinal trend, but was instead governed by a complex interplay of factors including population and the duration of salinity stress. This highlights the importance of including a wider variety of environmental conditions in empirical studies to understand local adaptation.
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals. Microbial community structure was determined using PhyoChio (G3)
Project description:In low rainfall regions soils are naturally conditioned with frequent co-occurrence of salinity and alkalinity. Plant salinity responses both at physiological and molecular level have been extensively researched. However, effects of the combined treatment of alkaline salinity that could greatly reduce plant growth and the mechanisms responsible for tolerance remain indeterminate. In Brassica juncea, large reductions in biomass and increased leaf Na+ concentration under alkaline salinity indicates that the combined treatment had greater negative effect than salinity on both growth and the physiological responses of the plant. To determine molecular mechanisms potentially controlling adaptive tolerance responses to salinity and alkaline salinity, the moderately tolerant genotype NDR 8501 was further investigated using microarray analysis. The transcripts of treated leaf tissues verses those of the untreated control sample were analysed after prolonged stress of four weeks. In total, 528 salinity responsive and 1245 alkaline salinity responsive genes were indentified and only 101 genes were expressed jointly in either of the two treatments. Transcription of 37% more genes involved in response to alkaline salinity than salinity alone, which suggests the increased impact and severity of the combined stress on the plant, indicating the transcription of a far greater number of genes likely involved in mitigation and damage control. Transcription of KUP2 and KUP7 genes involved in potassium homeostasis under salinity alone and NHX1 and ENH1 genes for ion (K+ and Na+) homeostasis under alkaline salinity, clearly demonstrated that different genes and genetic pathways are involved in response to each stress. They further provide supporting evidence for the physiological responses that occur in the plant, with massive reprogramming of the transcriptome leading to partial ion exclusion, shuttling and compartmentation. Salinity and alkaline salinity induced gene expression in Brassica juncea leaf was measured at 4 weeks of prolonged treatment of 50 mM NaCl alone and combined with 2.5 mM HCO3- versus non-stressed control. A single experiment was conducted using Brassica juncea genotype NDR 8501 at a single time point (fours weeks after treatment) with three replications per treatment.