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Biology subjects

Bellanger, M.

Publications and source records attributed to Bellanger, M..

2 recordsLinked to original sources

Resolving and Quantifying Viral-Like Particles via Blind Deconvolution

Viruses represent the most numerous biological entities on Earth; but the direct quantification of viruses within ecosystems reminds an ongoing challenge. The classical method of epifluorescence microscopy (EFM) reminds the gold standard measurement of viral-like particles (VLPs) within ecosystems. Quantifying VLPs in epifluorescence microscopy is burdened by ongoing challenges that include manual human counting, an absence of accurate morphological sizing, and the a range of viral sizes (20-300 nm) falling below the diffraction limit of light microscopy. Here, a proof-of-concept computer vision framework for the automated enumeration and sizing of viral-like particles is presented, known as EpiVirQuant. A novel tunable pointspread function is introduced which allows for a dynamic blind deconvolution. Final enumeration by EpiVirQuant was directly compared to manual human counting which yielded 18% more VLPs identified. EpiVirQuant quantified average VLP size of 179.5 nm, which is consistent with median size of VLPs in nature of of _160 nm. Runtime ranged from 60-80 seconds-perimage depending on parameter selection. This provides a viable proof-of-concept cost-effective solution for the enumeration and large-scale morphological analysis of VLPs.

bioinformatics↗

NFixDB (Nitrogen Fixation DataBase) - A Comprehensive Integrated Database for Robust 'Omics Analysis of Diazotrophs

Biological nitrogen fixation is a fundamental biogeochemical process that transforms that provides fixed biologically available nitrogen by diazotrophic microbes. Diazotrophs anaerobically fix nitrogen using the nitrogenase enzyme which has three different gene clusters: 1) molybdenum nitrogenase (nifDHK) is the most abundant, followed by its alternatives 2) vanadium nitrogenase (vnfDHK), and 3) iron nitrogenase (anfDHK). Multiple databases have been constructed as resources for diazotrophic omics analysis; however, an integrated database based on whole genome references does not exist. Here, we present NFixDB (Nitrogen Fixation DataBase), a comprehensive integrated whole genome based database for diazotrophs, which includes all nitrogenases (nifDHK, vnfDHK, anfDHK) and nitrogenase-like enzymes (e.g., nflDH) linked to ribosomal operons (16S-5.8S-23S). NFixDB was computed using Hidden Markov Models (HMMs) against the entire whole genome based Genome Taxonomy Database (GTDB R214), providing searchable reference HMMs for all nitrogenase and nitrogenase-like genes, complete ribosomal operons, both GTDB and NCBI/RefSeq taxonomy, and an SQL database for querying matches. We compared NFixDB to nifH databases from Buckley, Zehr, Mise, and FunGene finding extensive evidence of nifH, in addition to vnfH and nflH. NFixDB contains more than 4,000 verified nifHDK sequences contained on 50 unique phyla of bacteria and archaea. NFixDB offers the first comprehensive nitrogenase database available to researchers.

bioinformatics↗