Virginia Edgcomb - Academia.edu (original) (raw)

Papers by Virginia Edgcomb

De Gruyter eBooks, Mar 14, 2014

Frontiers in Microbiology

Communications Earth & Environment

In Guaymas Basin, organic-rich hydrothermal sediments produce complex hydrocarbon mixtures includ... more In Guaymas Basin, organic-rich hydrothermal sediments produce complex hydrocarbon mixtures including saturated, aromatic and alkylated aromatic compounds. We examined sediments from push cores from Guyamas sites with distinct temperature and geochemistry profiles to gain a better understanding on abiotic and biological hydrocarbon alteration. Here we provide evidence for biodegradation of hopanoids, producing saturated hydrocarbons like drimane and homodrimane as intermediate products. These sesquiterpene by-products are present throughout cooler sediments, but their relative abundance is drastically reduced within hotter hydrothermal sediments, likely due to hydrothermal mobilization. Within the sterane pool we detect a trend toward aromatization of steroidal compounds within hotter sediments. The changes in hopane and sterane biomarker composition at different sites reflect temperature-related differences in geochemical and microbial hydrocarbon alterations. In contrast to traditi...

PLOS ONE

The flanking regions of Guaymas Basin, a young marginal rift basin located in the Gulf of Califor... more The flanking regions of Guaymas Basin, a young marginal rift basin located in the Gulf of California, are covered with thick sediment layers that are hydrothermally altered due to magmatic intrusions. To explore environmental controls on microbial community structure in this complex environment, we analyzed site- and depth-related patterns of microbial community composition (bacteria, archaea, and fungi) in hydrothermally influenced sediments with different thermal conditions, geochemical regimes, and extent of microbial mats. We compared communities in hot hydrothermal sediments (75-100°C at ~40 cm depth) covered by orange-pigmented Beggiatoaceae mats in the Cathedral Hill area, temperate sediments (25-30°C at ~40 cm depth) covered by yellow sulfur precipitates and filamentous sulfur oxidizers at the Aceto Balsamico location, hot sediments (>115°C at ~40 cm depth) with orange-pigmented mats surrounded by yellow and white mats at the Marker 14 location, and background, non-hydrot...

Here we present the 647 viral populations (clustered at 95% ID over 80% of the sequence) larger t... more Here we present the 647 viral populations (clustered at 95% ID over 80% of the sequence) larger than 5kb from the Cariaco Basin and an additional 101 viral populations from the Tara Oceans GOV2.0 dataset which were also identified in Cariaco Basin via read recruitment.

Environmental Microbiology, 2022

Developing transfection protocols for marine protists is an emerging field that will allow the fu... more Developing transfection protocols for marine protists is an emerging field that will allow the functional characterization of protist genes and their roles in organism responses to the environment. We developed a CRISPR/Cas9 editing protocol for Bodo saltans, a free-living kinetoplastid with tolerance to both marine and freshwater conditions, and a close non-parasitic relative of trypanosomatids. Our results show that SaCas9/sgRNA ribonucleoprotein (RNP) complex-mediated disruption of the paraflagellar rod 2 gene (BsPFR2) was achieved using electroporation-mediated transfection. The use of CRISPR/Cas9 genome editing can increase the efficiency of targeted homologous recombination when a repair DNA template is provided. Based on sequence analysis, two mechanisms for repairing double-strand breaks (DSB) in B. saltans are active; homologous directed repair (HDR) utilizing an exogenous DNA template that carries an antibiotic resistance gene, and non-homologous end joining (NHEJ). However, HDR was only achieved when a single (vs. multiple) SaCas9 RNP complex was provided. Further, the biallelic knockout of BsPFR2 was detrimental for the cell, highlighting its essential role for cell survival because it facilitates the movement of food particles into the cytostome. Our Cas9/sgRNA RNP complex protocol provides a new tool for assessing gene functions in B. saltans, and perhaps similar protists with polycistronic transcription. This article is protected by copyright. All rights reserved.

Porewater nutrient, sulfide, and sulfate (NH4+, NO2-, NO3-, PO43-, SiO42-, Cl-, S2-, SO24-) conce... more Porewater nutrient, sulfide, and sulfate (NH4+, NO2-, NO3-, PO43-, SiO42-, Cl-, S2-, SO24-) concentrations in Alvin pushcore samples collected from Guaymas Basin hydrothermal vents during R/V Atlantis cruise AT42-05 in November 2018. This dataset was obtained at the Max-Planck-Institute for Marine Microbiology in Bremen, Germany.

Porewater sulfate and sulfide concentrations in Alvin pushcore samples collected from Guaymas Bas... more Porewater sulfate and sulfide concentrations in Alvin pushcore samples collected from Guaymas Basin hydrothermal vents during R/V Atlantis cruise AT42-05 in November 2018. This dataset was obtained at the University of North Carolina Chapel Hill.

Frontiers in Microbiology, 2022

Oxygen-depleted water columns (ODWCs) host a diverse community of eukaryotic protists that change... more Oxygen-depleted water columns (ODWCs) host a diverse community of eukaryotic protists that change dramatically in composition over the oxic-anoxic gradient. In the permanently anoxic Cariaco Basin, peaks in eukaryotic diversity occurred in layers where dark microbial activity (chemoautotrophy and heterotrophy) were highest, suggesting a link between prokaryotic activity and trophic associations with protists. Using 18S rRNA gene sequencing, parasites and especially the obligate parasitic clade, Syndiniales, appear to be particularly abundant, suggesting parasitism is an important, but overlooked interaction in ODWC food webs. Syndiniales were also associated with certain prokaryotic groups that are often found in ODWCs, including Marinimicrobia and Marine Group II archaea, evocative of feedbacks between parasitic infection events, release of organic matter, and prokaryotic assimilative activity. In a network analysis that included all three domains of life, bacterial and archaeal ta...

Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorgani... more Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists. Although estimates for the number of fungal species on the planet range from 1.5 to over 5 million, likely fewer than 10% of fungi have been identified so far. To date, a relatively small percentage of described species are associated with marine environments, with 1,100 species retrieved exclusively from the marine environment. Nevertheless, fungi have been found in nearly every marine habitat explored, from the surface of the ocean to kilometers below ocean sediments. Fungi are hypothesized to contribute to phytoplankton population cycles and the biological carbon pump and are active in the chemistry of marine sediments. Many fungi have been identified as commensals or pathogens of marine animals (e.g., corals and sponges), plants, and algae. Despite their varied roles, remarkably little is known about the diversity of this major branch of eu...

FEMS Microbiology Ecology, 2021

Relatively little is known about the diversity of fungi in deep-sea, hydrothermal sediments. Less... more Relatively little is known about the diversity of fungi in deep-sea, hydrothermal sediments. Less thoroughly explored environments are likely untapped reservoirs of unique biodiversity with the potential to augment our current arsenal of microbial compounds with biomedical and/or industrial applications. In this study, we applied traditional culture-based methods to examine a subset of the morphological and phylogenetic diversity of filamentous fungi and yeasts present in 11 hydrothermally influenced sediment samples collected from eight sites on the seafloor of Guaymas Basin, Mexico. A total of 12 unique isolates affiliating with Ascomycota and Basidiomycota were obtained and taxonomically identified on the basis of morphological features and analyses of marker genes including actin, β-tubulin, small subunit ribosomal DNA (18S rRNA), internal transcribed spacer (ITS) and large subunit ribosomal DNA (26S rRNA) D1/D2 domain sequences (depending on taxon). A total of 11 isolates posse...

Biological and Chemical Oceanography Data Management Office, 2019

Dataset: Hydrothermal vent porewater nutrients: NO3+NO2, NH4, and PO4Porewater nutrient concentra... more Dataset: Hydrothermal vent porewater nutrients: NO3+NO2, NH4, and PO4Porewater nutrient concentrations from pushcore samples collected at two locations in the Guaymas Basin hydrothermal vents region during Alvin dives on RV/Atlantis cruise AT42-05, Nov. 2018. NO3+NO2, NH4, and PO4 concentrations at different depths within the cores are reported. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/773129NSF Division of Ocean Sciences (NSF OCE) OCE-182990

Proceedings of the National Academy of Sciences, 2002

Molecular microbial ecology studies have revealed remarkable prokaryotic diversity in extreme hyd... more Molecular microbial ecology studies have revealed remarkable prokaryotic diversity in extreme hydrothermal marine environments. There are no comparable reports of culture-independent surveys of eukaryotic life in warm, anoxic marine sediments. By using sequence comparisons of PCR-amplified small subunit ribosomal RNAs, we characterized eukaryotic diversity in hydrothermal vent environments of Guaymas Basin in the Gulf of California. Many sequences from these anoxic sediments and the overlaying seawater represent previously uncharacterized protists, including early branching eukaryotic lineages or extended diversity within described taxa. At least two mechanisms, with overlapping consequences, account for the eukaryotic community structure of this environment. The adaptation to anoxic environments is evidenced by specific affinity of environmental sequences to aerotolerant anaerobic species in molecular trees. This pattern is superimposed against a background of widely distributed ae...

BMC Microbiology, 2013

BackgroundDeep hypersaline anoxic basins (DHABs) are isolated habitats at the bottom of the easte... more BackgroundDeep hypersaline anoxic basins (DHABs) are isolated habitats at the bottom of the eastern Mediterranean Sea, which originate from the ancient dissolution of Messinian evaporites. The different basins have recruited their original biota from the same source, but their geological evolution eventually constituted sharp environmental barriers, restricting genetic exchange between the individual basins. Therefore, DHABs are unique model systems to assess the effect of geological events and environmental conditions on the evolution and diversification of protistan plankton. Here, we examine evidence for isolated evolution of unicellular eukaryote protistan plankton communities driven by geological separation and environmental selection. We specifically focused on ciliated protists as a major component of protistan DHAB plankton by pyrosequencing the hypervariable V4 fragment of the small subunit ribosomal RNA. Geospatial distributions and responses of marine ciliates to differen...