Biology subjects

Gerard, P.

Publications and source records attributed to Gerard, P..

4 recordsLinked to original sources

bioRxiv2025

Evolution of crop phenotypic spaces through domestication

O_LIWe used domestication as an in vivo replicated experiment to investigate how divergent selection has shaped the evolution of multivariate phenotypic spaces. C_LIO_LIWe measured 11 to 57 qualitative and quantitative traits in 13 species, either unique or shared between species, and established a framework for cross-species comparisons. C_LIO_LIOur results revealed significant convergence that translated into a cross-species domestication syndrome. Most species exhibited a reduction of the multivariate phenotypic space during domestication. We brought evidence that Near Infrared spectra measured on leaves reflect phenotypic evolution unrelated with domestication, enabling its use as a control for sampling effects across species. Building on this, we developed a multivariate Phenotypic Divergence Index (mPDI) to rank species by the extent of phenotypic divergence under domestication. We found a high disjunction of wild and domestic phenotypic spaces in all species. Neither the mPDI nor the relative size of wild versus domestic multivariate phenotypic spaces was influenced by the domestication timing or mating system. Lastly, we observed a progressive decoupling of trait correlations with increasing time since domestication. C_LIO_LIIn addition to introducing a new index that can be applied for cross-species comparisons, our study uncovers recurring patterns shared among species, pointing to general principles underlying plant domestication. C_LI

evolutionary biology↗

bioRxiv2025

Visualization of extracellular polymeric substances in Aspergillus niger biofilms using fluorescent-labeled lectins.

Aspergillus niger is a filamentous fungus that adheres to different substrate surfaces and form biofilms consisting of dense hyphal networks embedded in a self-produced gelatinous matrix composed of extracellular polymeric substance (EPS). The EPS mainly contains exopolysaccharides. The objective of this study was to visualize and assess the different exopolysaccharides structure in this extracellular polymeric substance using a combination of two different fluorescent-labeled lectin probes, Erythrina cristagalli (ECA) and Canavalia ensiformis (Con A). Each lectin is a unique protein that binds to specific a carbohydrate moiety and is classified based on these terminal sugars to which they are binding. Exopolysaccharides are imaged according to their distinct fluorescence color with the help of confocal laser scanning microscopy (CLSM). The biomass, average thickness, and roughness of biofilms were calculated from the Z-stack images using the computer program COMSTAT. A statistically significant difference was observed in the biomass (m3/m2), average thickness (m), and roughness of the biofilm treated with the two different lectin probes indicating the presence of a higher amount of galactose and {beta}-1,4 N-acetylgalactosamine ({beta}4GalNAc) when compared to the mannose and glucose moieties in the EPS of A.niger biofilm. The combination of two lectin-fluorescent probe method staining should help better characterization of A. niger biofilms in terms of their heterogeneity with regards to the EPS production.

microbiology↗

bioRxiv2020

Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota that Protects from Metabolic Diseases

Excess of chronic contact between microbial motifs and intestinal immune cells are known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes. The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described but how dendritic cells (DCs) participate to these changes is still poorly documented. To address this question, transgenic mice with enhanced DCs lifespan and immunogenicity (DChBcl-2 mice), are challenged with a high fat diet. Those mice display resistance to DIO and metabolic alterations. The DIO resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DChBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function which is associated with strong intestinal IgA, Th17 and T regulatory immune responses. Microbiota composition and function analyses reveal that the DChBcl-2 mice microbiota is characterized by a lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to WT mice demonstrating that maintenance of DCs tolerogenic ability sustains a microbiota able to drive DIO resistance. DCs tolerogenic function is revealed as a new potent target in metabolic diseases management.

immunology↗

bioRxiv2017

Relationships between clans and genetic kin explain cultural similarities over vast distances: the case of Yakutia

Archaeological studies sample ancient human populations one site at a time, often limited to a fraction of the regions and periods occupied by a given group. While this bias is known and discussed in the literature, few model populations span areas as large and unforgiving as the Yakuts of Eastern Siberia. We systematically surveyed 31,000 square kilometres in the Sakha Republic (Yakutia) and completed the archaeological study of 174 frozen graves, assembled between the 15th and the 19th century. We analysed genetic data (autosomal genotypes, Y-chromosome haplotypes and mitochondrial haplotypes) for all ancient subjects and confronted these to data on 190 modern subjects from the same area and the same population. Ancient familial links were identified between graves up to 1500 km apart, as well as paternal clans. We provide new insights on the origins of the contemporary Yakut population and demonstrate that cultural similarities in the past were linked to (i) the expansion of specific paternal clans, (ii) preferential marriage among the elites and (iii) funeral choices that could constitute a bias in any ancient population study.

genetics↗