NADPH-dependent extracellular superoxide production is vital to photophysiology in the marine diatom Thalassiosira oceanica

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Diaz, J. M., Plummer, S., Hansel, C. M., Andeer, P. F., Saito, M. A., & McIlvin, M. R. NADPH-dependent extracellular superoxide production is vital to photophysiology in the marine diatom Thalassiosira oceanica. Proceedings of the National Academy of Sciences of the United States of America, 116 (33), (2019): 16448-16453, doi: 10.1073/pnas.1821233116.Reactive oxygen species (ROS) like superoxide drive rapid transformations of carbon and metals in aquatic systems and play dynamic roles in biological health, signaling, and defense across a diversity of cell types. In phytoplankton, however, the ecophysiological role(s) of extracellular superoxide production has remained elusive. Here, the mechanism and function of extracellular superoxide production by the marine diatom Thalassiosira oceanica are described. Extracellular superoxide production in T. oceanica exudates was coupled to the oxidation of NADPH. A putative NADPH-oxidizing flavoenzyme with predicted transmembrane domains and high sequence similarity to glutathione reductase (GR) was implicated in this process. GR was also linked to extracellular superoxide production by whole cells via quenching by the flavoenzyme inhibitor diphenylene iodonium (DPI) and oxidized glutathione, the preferred electron acceptor of GR. Extracellular superoxide production followed a typical photosynthesis-irradiance curve and increased by 30% above the saturation irradiance of photosynthesis, while DPI significantly impaired the efficiency of photosystem II under a wide range of light levels. Together, these results suggest that extracellular superoxide production is a byproduct of a transplasma membrane electron transport system that serves to balance the cellular redox state through the recycling of photosynthetic NADPH. This photoprotective function may be widespread, consistent with the presence of putative homologs to T. oceanica GR in other representative marine phytoplankton and ocean metagenomes. Given predicted climate-driven shifts in global surface ocean light regimes and phytoplankton community-level photoacclimation, these results provide implications for future ocean redox balance, ecological functioning, and coupled biogeochemical transformations of carbon and metals.This work was supported by a postdoctoral fellowship from the Ford Foundation (to J.M.D.), the National Science Foundation (NSF) under grants OCE 1225801 (to J.M.D.) and OCE 1246174 (to C.M.H.), a Junior Faculty Seed Grant from the University of Georgia Research Foundation (to J.M.D.), and a National Science Foundation Graduate Research Fellowship (to S.P.). The FIRe was purchased through a NSF equipment improvement grant (1624593).The authors thank Melissa Soule for assistance with LC/MS/MS analysis of peptide samples

Determination of Geochemical Bio-Signatures in Mars-Like Basaltic Environments

Bio-signatures play a central role in determining whether life existed on early Mars. Using a terrestrial basalt as a compositional analog for the martian surface, we applied a combination of experimental microbiology and thermochemical modeling techniques to identify potential geochemical bio-signatures for life on early Mars. Laboratory experiments were used to determine the short-term effects of biota on the dissolution of terrestrial basalt, and the formation of secondary alteration minerals. The chemoorganoheterotrophic bacterium, Burkholderia sp. strain B_33, was grown in a minimal growth medium with and without terrestrial basalt as the sole nutrient source. No growth was detected in the absence of the basalt. In the presence of basalt, during exponential growth, the pH decreased rapidly from pH 7.0 to 3.6 and then gradually increased to a steady-state of equilibrium of between 6.8 and 7.1. Microbial growth coincided with an increase in key elements in the growth medium (Si, K, Ca, Mg, and Fe). Experimental results were compared with theoretical thermochemical modeling to predict growth of secondary alteration minerals, which can be used as bio-signatures, over a geological timescale. We thermochemically modeled the dissolution of the basalt (in the absence of biota) in very dilute brine at 25°C, 1 bar; the pH was buffered by the mineral dissolution and precipitation reactions. Preliminary results suggested that at the water to rock ratio of 1 × 107, zeolite, hematite, chlorite, kaolinite, and apatite formed abiotically. The biotic weathering processes were modeled by varying the pH conditions within the model to adjust for biologic influence. The results suggested that, for a basaltic system, the microbially-mediated dissolution of basalt would result in “simpler” secondary alteration, consisting of Fe-hydroxide and kaolinite, under conditions where the abiotic system would also form chlorite. The results from this study demonstrate that, by using laboratory-based experiments and thermochemical modeling, it is possible to identify secondary alteration minerals that could potentially be used to distinguish between abiotic and biotic weathering processes on early Mars. This work will contribute to the interpretation of data from past, present, and future life detection missions to Mars

Expression in grasses of multiple transgenes for degradation of munitions compounds on live fire training ranges

The deposition of toxic munitions compounds, such as hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX), on soils around targets in live-fire training ranges is an important source of groundwater contamination. Plants take up RDX but do not significantly degrade it. Reported here is the transformation of two perennial grass species, switchgrass (Panicum virgatum) and creeping bentgrass (Agrostis stolonifera), with the genes for degradation of RDX. These species possess a number of agronomic traits making them well equipped for the uptake and removal of RDX from root zone leachates. Transformation vectors were constructed with xplA and xplB, which confer the ability to degrade RDX, and nfsI, which encodes a nitroreductase for the detoxification of the co-contaminating explosive 2, 4, 6-trinitrotoluene (TNT). The vectors were transformed into the grass species using Agrobacterium tumefaciens infection. All transformed grass lines showing high transgene expression levels removed significantly more RDX from hydroponic solutions and retained significantly less RDX in their leaf tissues than wild-type plants. Soil columns planted with the best-performing switchgrass line were able to prevent leaching of RDX through a 0.5-m root zone. These plants represent a promising plant biotechnology to sustainably remove RDX from training range soil, thus preventing contamination of groundwater

Long-read metagenomics of soil communities reveals phylum-specific secondary metabolite dynamics

Microbial biosynthetic gene clusters (BGCs) encoding secondary metabolites are thought to impact a plethora of biologically mediated environmental processes, yet their discovery and functional characterization in natural microbiomes remains challenging. Here we describe deep long-read sequencing and assembly of metagenomes from biological soil crusts, a group of soil communities that are rich in BGCs. Taking advantage of the unusually long assemblies produced by this approach, we recovered nearly 3,000 BGCs for analysis, including 712 full-length BGCs. Functional exploration through metatranscriptome analysis of a 3-day wetting experiment uncovered phylum-specific BGC expression upon activation from dormancy, elucidating distinct roles and complex phylogenetic and temporal dynamics in wetting processes. For example, a pronounced increase in BGC transcription occurs at night primarily in cyanobacteria, implicating BGCs in nutrient scavenging roles and niche competition. Taken together, our results demonstrate that long-read metagenomic sequencing combined with metatranscriptomic analysis provides a direct view into the functional dynamics of BGCs in environmental processes and suggests a central role of secondary metabolites in maintaining phylogenetically conserved niches within biocrusts.Supplementary Data 1 : Description: Raw metagenome and metatranscriptome statistics.Supplementary Data 2 : Description: Assembly statistics of short- and long-read metagenomes as well as metatranscriptomes.Supplementary Data 3 : Description: Each biosynthetic gene cluster identified from the assembled metagenomes in this study.Supplementary Data 4 : Description: Each biosynthetic gene cluster identified in the metatranscriptomic assemblies.Supplementary Data 5 : Description: The genes used to calculate transcription of biosynthetic gene clusters and core bacterial genes.Supplementary Data 6 : Description: DESeq2 analysis of significantly transcribed genes between day and night-time transcription.Supplementary Data 7 : Description: Transcriptional scores for cation-related genes.Supplementary Data 8 : Description: Average abundance pattern for each phylum through time.Supplementary Data 9 : Description: Taxonomic composition of metagenomes and metatranscriptomes using fulllength 16S rRNA.Supplementary Data 10 : Description: Normalized sequence data showing scores of transcription at each time point with BGC type and Phylum shownThis work was partially supported by funds provided by the Office of Science Early Career Research Program Office of Biological and Environmental Research, of the U.S. Department of Energy and by the U.S. Department of Energy Joint Genome Institute, a DOE Office of Science User Facility, supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 to Lawrence Berkeley National Laboratory. We also wish to acknowledge Simon Roux, Emiley Eloe-Fadrosh and Eoin Brodie for their constructive feedback.https://www.nature.com/commsbioam2022BiochemistryGeneticsMicrobiology and Plant Patholog

Täckningsanalys och visualisering i klinisk exomsekvensering

Motivation: The advent of clinical exome sequencing will require new tools to handlecoverage data and making it relevant to clinicians. That means genes over targets, smartsoftware over BED-files, and full stack, automated solutions from BAM-files to genetic testreport. Fresh ideas can also provide new insights into the factors that cause certain regionsof the exome to receive poor coverage.Results: A novel coverage analysis tool for analyzing clinical exome sequencing data has beendeveloped. Named Chanjo, it’s capable of converting between different elements such astargets and exons, supports custom annotations, and provides powerful statistics andplotting options. A coverage investigation using Chanjo linked both extreme GC content andlow sequence complexity to poor coverage. High bait density was shown to increasereliability of exome capture but not improve coverage of regions that had already proventricky. To improve coverage of especially very G+C rich regions, developing new ways toamplify rather than enrich DNA will likely make the biggest difference

Documentation of the one man show of sculpture

Includes photographs of exhibition.The following work is presented in partial fulfillment of the requirements for the Master of Fine Arts degree at Northern Illinois University. The work was produced between June, 1974 and September, 1975. It was presented in exhibition from October 5, 1975 through October 11, 1975 in the Graduate Gallery of the Visual Arts Building, Northern Illinois University, DeKalb, Illinois.M.F.A. (Master of Fine Arts

Rhætoromanische Elementargrammatik mit besonderer Berücksichtigung des ladinischen Dialekts im Unterengadin /

Mode of access: Internet

MIP v3.0.0

Mutation Identification Pipeline. Read the latest documentation