Biology subjects

Beye, M.

Publications and source records attributed to Beye, M..

4 recordsLinked to original sources

bioRxiv2026

Sarrella massiliensis gen. nov. sp. nov., a new gut genus isolated from the stool of a healthy donor

Strain Marseille-QA0792 (=CSUR QA0792, CECT 31199) was isolated from the feces of a healthy person using the culturomics method. The fecal sample originated from leftover material collected for a fecal microbiota transplantation (FMT) procedure, obtained during a routine screening in accordance with the guidelines of the French National Agency for Medicines and Health Products Safety (ANSM). This strain is Gram-stain-negative, rod-shaped, non-motile, and non-spore-forming. It is strictly anaerobic, with optimal growth at 37{degrees}C. Strain Marseille-QA0792 presented its highest 16S rRNA identity, 96.2%, with ''Merdibacter massiliensis'' strain Marseille-P3254 (not validly published) (accession number LT598590) and ANI similarity of 75.0% with the same species. Among validly published species, strain Marseille-QA0792 showed its highest 16S rRNA gene sequence similarity (91.5%) with Faecalicoccus acidiformans strain 37-2a (accession number HQ452864), whereas all computed average nucleotide identity (ANI) values were below 75%. Genome sequencing revealed a genome size of 2.67 Mb and a G+C content of 50.01%. This species is classified within the Erysipelotrichaceae family in the Bacillota phylum. Thus, we isolated for the first time a novel genus named Sarrella massiliensis gen. nov., sp. nov., strain Marseille-QA0792. This discovery highlights the importance of continuing culturomics efforts to explore the human microbiome.

microbiology↗

bioRxiv2026

Methyltransferases in Candidate Phyla Radiation: A Weapon or a Simple Shield?

The Candidate Phyla Radiation (CPR) consists of microorganisms with highly reduced genomes and limited metabolic capabilities, including the inability to synthesize nucleotides and amino acids. Previous studies revealed an unexpected abundance of antimicrobial resistance-related genes in CPR genomes, with methyltransferases (MTs) accounting for up to 47.34% of detected resistance determinants. Here, we investigated the distribution, diversity, and potential functions of MTs across 12,552 CPR genomes, focusing on their roles in antimicrobial resistance and restriction-modification (R-M) systems. Sequence similarity searches were performed using BLASTp, followed by domain validation with the NCBI Conserved Domain Database (CDD). Putative restriction endonucleases (REs) associated with these systems were also identified and analyzed. We detected 20,232 resistance-associated MTs, 7,391 hsdM-like MTs, and 4,737 REs, revealing a high prevalence of putatively functional MTs relative to REs across CPR genomes. Functional CPR MTs and REs displayed extensive sequence divergence from known bacterial homologs and exhibited greater domain diversity and functional complexity than their bacterial counterparts. Selected high-confidence MT candidates were heterologously expressed in Escherichia coli BL21 and characterized using BIOLOG phenotypic assays and antimicrobial susceptibility testing. Transformed strains showed enhanced utilization of methyl pyruvate as a carbon source, whereas no significant antimicrobial resistance phenotype was detected. Collectively, these findings suggest that CPR-encoded MTs are primarily associated with R-M systems, supporting defense against foreign DNA and facilitating nucleotide scavenging rather than direct antimicrobial resistance. This study provides new insights into the adaptive strategies of CPR bacteria and the multifunctional roles of MTs in metabolically streamlined microorganisms. ImportanceCandidate Phyla Radiation (CPR) microorganisms represent a major fraction of Earths microbial diversity, yet their biology remains poorly understood. We show that CPR genomes contain large numbers of methyltransferases and associated restriction enzymes, suggesting the existence of a specialized DNA-processing system. Because CPR organisms have highly reduced metabolic capabilities, this system may help them recover valuable nucleotides from external DNA while simultaneously protecting their genomes from foreign genetic material. We also found that CPR enzymes are highly distinct from those described in other bacteria and display remarkable functional diversity, highlighting the unique evolutionary trajectories of these microorganisms. By providing the first large-scale characterization of these enzymes in CPR, our study offers new insights into how these widespread microbes survive, acquire resources, and interact with their environment, expanding our understanding of microbial diversity and adaptation.

genomics↗

bioRxiv2022

Multisite imaging of neural activity using a genetically encoded calcium sensor in the honey bee Apis mellifera

Understanding of the neural bases for complex behaviors in Hymenoptera insect species has been limited by a lack of tools that allow measuring neuronal activity simultaneously in different brain regions. Here, we developed the first pan-neuronal genetic driver in a Hymenopteran model organism, the honey bee, and expressed the calcium indicator GCaMP6f under the control of the honey bee synapsin promoter. We show that GCaMP6f is widely expressed in the honey bee brain, allowing to record neural activity from multiple brain regions. To assess the power of this tool, we focused on the olfactory system, recording simultaneous responses from the antennal lobe, and from the more poorly investigated lateral horn and mushroom body calyces. Neural responses to 16 distinct odorants demonstrate that odorant quality (chemical structure) and quantity are faithfully encoded in the honey bee antennal lobe. In contrast, odor coding in the lateral horn departs from this simple physico-chemical coding, supporting the role of this structure in coding the biological value of odorants. We further demonstrate robust neural responses to several bee pheromone odorants, key drivers of social behavior, in the lateral horn. Combined, these brain recordings represent the first use of a neurogenetic tool for recording large-scale neural activity in a eusocial insect, and will be of utility in assessing the neural underpinnings of olfactory and other sensory modalities and of social behaviors and cognitive abilities.

neuroscience↗

bioRxiv2020

CRISPR/Cas9 mediated mutations as a new tool for studying taste in honeybees

BackgroundHoneybees rely on nectar as their main source of carbohydrates [1]. Sucrose, glucose and fructose are the main components of plant nectars [2] [3]. Intriguingly, honeybees express only three putative sugar receptors (AmGr1, AmGr2 and AmGr3) [4], which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized [5] [6]. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. ResultsWe show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioural change and serve to characterize the function of taste receptors in vivo. ConclusionCRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterisation in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=166 HEIGHT=200 SRC="FIGDIR/small/009696v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1100f07org.highwire.dtl.DTLVardef@14ac138org.highwire.dtl.DTLVardef@d37468org.highwire.dtl.DTLVardef@7f6abb_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 0C_FLOATNO C_FIG

genetics↗