Project description:Boreal toads (Anaxyrus boreas boreas) of the Southern Rocky Mountain population are declining due to the introduction of the chytrid fungus Batrachochytrium dendrobatidis (Bd). Boreal toads in Colorado are generally susceptible to Bd infection, but some Bd-tolerant populations persist in parts of the Southern Rocky Mountain and broader Eastern boreal toad population. We conducted a Bd challenge with lab-reared sibling toads from Bd-susceptible Colorado and purportedly Bd-tolerant Utah populations and report on transcriptomic responses to Bd during late infection in skin and liver tissue. Fewer immune genes were expressed in response to Bd in Colorado toads, but with greater upregulation compared to Utah toads, indicating a dysregulated immune response. Signatures of Bd-tolerance in Utah toads included more moderate upregulation in immune gene expression and a significantly enriched suite of gene functions related to innate and adaptive immune responses. Our transcriptomic results support the notion that Utah toads are tolerant to Bd, rather than resistant, carrying Bd loads similar to Colorado yet having a unique transcriptomic profile and presenting minimal clinical signs of chytridiomycosis. We conclude that closely related populations have divergent transcriptomic responses to Bd with a dysregulated immune response in Bd-susceptible toads.
2023-10-04 | GSE244617 | GEO
Project description:Mixtrophic sulfate-reducing Desulfobacterota dominate the dark carbon fixation process in marine sediments
Project description:Pelagic aggregates function as hotspots for microbial activity and biological carbon pumps for exporting OM fixed by photoautotrophs to sediments in lakes and oceans. In iron-rich (ferruginous) lakes, photoferrotrophic or chemolithoautotrophic bacteria appear to contribute to CO2 fixation by oxidizing reduced iron which leads to the formation of iron-rich pelagic aggregates called iron-snow. In acidic lakes, iron snow is colonized mainly by acidophilic iron-cycling microbes that can trigger interspecies aggregation mechanisms. However, the significance of iron oxidizers in carbon fixation, their general role in iron snow functioning, and the flow of carbon within iron snow is still unclear. Here, we combined a two-year metatranscriptome analysis with a 13CO2 metabolic labeling approach to determine general metabolic activities. Protein-based stable isotope probing (protein-SIP) was used to trace the 13CO2 incorporation in iron snow microcosms over time under both oxic and anoxic conditions. Analysis of our mRNA-derived metatranscriptome data identified four key players (Leptospirillum, Ferrovum, Acidithrix, Acidiphilium) with relative abundances (59.6%-85.7%) in iron snow encoding a variety of ecologically relevant pathways, including carbon fixation, polysaccharide biosynthesis, and flagellar-based motility. We did not detect transcriptional activity for carbon fixation from archaea or eukaryotes. The largest numbers of expressed genes (3008, 2991, 2936) matched to the genomes of our previously obtained iron snow isolates (Acidithrix sp. C25, Acidiphilium sp. C61, Acidocella sp. C78) separately. 13CO2 incorporation studies identified Leptospirillum and Ferrovum, as the main active chemolithoautotrophs under oxic conditions, and Ferrovum was the main active organism under anoxic conditions as well. Small amounts of labeled 13C (Relative isotope abundance: 1.0%-5.3%) were found in the heterotrophic Acidiphilium and Acidocella. Overall, our data show that iron oxidizers play an important role in the formation of iron minerals and CO2 fixation, but the majority of fixed C apparently did not reach other iron snow microbes. This finding suggests that most of the fixed C will be directly exported to the sediment without feeding heterotrophs in the water column in acidic ferruginous lakes.
2022-02-17 | PXD025534 | Pride
Project description:The Impact and Mechanism of Dam Construction on the Process of Carbon Dark Fixation
Project description:This study used an emerging analytical technology (cDNA microarrays) to assess the potential effects of PFC exposure on largemouth bass in TCMA lakes. Microarrays simultaneously measure the expression of thousands of genes in various tissues from organisms exposed to different environmental conditions. From this large data set, biomarkers (i.e., genes that are expressed in response to an exposure to known stressors) and bioindicators (e.g., suites of genes that correspond to changes in organism health) can be simultaneously measured to clarify the relationship between contaminant exposure and organism health. Based on current scientific literature, we hypothesized that gene expression patterns would be altered in fish exposed to PFCs (as compared with fish from reference lakes), and that the magnitude of these changes would correspond to the concentrations of PFCs present throughout TCMA lakes. Patterns of gene expression in largemouth bass observed across the TCMA lakes corresponded closely with PFC concentration. Concentrations of PFCs in largemouth bass varied significantly across the sampled lakes, where the lowest concentrations were found in Steiger and Upper Prior Lakes and the highest concentrations were found in Calhoun and Twin Lakes. Patterns of gene expression were most different (relative to controls) in fish with the highest PFC tissue concentrations, where fish from Twin and Calhoun Lakes were observed to have between 5437 and 5936 differentially expressed genes in liver and gonad tissues. Although gene expression patterns demonstrated a high degree of correlation with PFC concentrations, microarray data also suggest there are likely additional factors influencing gene expression patterns in largemouth bass in TCMA lakes.
Project description:Epigenetic variation has the potential to control environmentally dependent development and contribute to phenotypic responses to local environments. Environmental epigenetic studies of sexual organisms confirm the responsiveness of epigenetic variation, which should be even more important when genetic variation is lacking. A previous study of an asexual snail, Potamopyrgus antipodarum, demonstrated that different populations derived from a single clonal lineage differed in both shell phenotype and methylation signature when comparing lake versus river populations. Here, we examine methylation variation among lakes that differ in environmental disturbance and pollution histories. The differential DNA methylation regions (DMRs) identified among the different lake comparisons suggested a higher number of DMRs and variation between rural Lake 1 and one urban Lake 2 and between the two urban Lakes 2 and 3, but limited variation between the rural Lake 1 and urban Lake 3. DMR genomic characteristics and gene associations were investigated. Observations suggest there is no effect of geographic distance or any consistent pattern of DMRs between urban and rural lakes. Environmental factors may influence epigenetic response.