Biology subjects

Burguet, P.

Publications and source records attributed to Burguet, P..

4 recordsLinked to original sources

bioRxiv2023

Responses of the hyper-diverse community of canopy-dwelling Hymenoptera to oak decline

O_LIForest decline and dieback are growing phenomena worldwide, resulting in severe, large-scale degradation of the canopy. This can profoundly alter the provision of trophic resources and microhabitats for canopy-dwelling arthropods. C_LIO_LIIn 2019, we assessed the effect of oak decline on the community of canopy-dwelling Hymenoptera. We selected 21 oak stands, and 42 plots, located in three forests in France, presenting contrasting levels of decline. Insects were sampled at the canopy level with green multi-funnel and flight-interception traps. C_LIO_LIWe collected a particularly diverse community of 19,289 insect individuals belonging to 918 taxa, ten larval trophic guilds and five nesting guilds. C_LIO_LIOak decline had no effect on the abundance or richness of the overall community, but significantly reshaped the community assemblages. Decline had contrasting effects depending on the taxa and guilds considered. Specialist parasitoids were more abundant at intermediate levels of decline severity while generalists were negatively affected. Taxa depending on ground-related resources and microhabitats were promoted. Saproxylic taxa were more abundant while xylophagous insects were negatively impacted. C_LIO_LIReduced leaf area index promoted several guilds, and the diversity of the overall community. While an increasing tree mortality rate enhanced the abundance and diversity of deadwood resources, it had negative impacts on several Hymenoptera guilds. Our results suggest that micro-environmental changes at the ground-level due to canopy decline have major cascading effects on the communities of canopy-dwelling Hymenoptera. C_LIO_LIOur study highlights the relevance of studying Hymenoptera communities to investigate the outcomes of disturbances on forest biodiversity. C_LI

ecology↗

bioRxiv2023

The fate of bacterial secondary metabolites in the rhizosphere: Streptomyces degrades and feeds on cyclic lipopeptides produced by competitors

Cyclic lipopeptides are key bioactive secondary metabolites produced by some plant beneficial rhizobacteria such as Pseudomonas and Bacillus. They exhibit antimicrobial properties, promote induced systemic resistance in plants and support key developmental traits including motility, biofilm formation and root colonization. However, our knowledge about the fate of lipopeptides once released in the environment and especially upon contact with neighboring rhizobacteria remains limited. Here, we investigated the enzymatic degradation of Bacillus and Pseudomonas cyclic lipopeptides by Streptomyces venezuelae. We observed that Streptomyces is able to degrade the three lipopeptides surfactin, iturin and fengycin upon confrontation with of B. velezensis in vitro and in planta according to specific mechanisms. S. venezuelae was also able to degrade the structurally diverse sessilin, tolaasin, orfamide, xantholisin and putisolvin-type lipopeptides produced by Pseudomonas, indicating that this trait is likely engage in the interaction with various competitors.Furthermore, the degradation of CLPs is associated with the release of free amino and fatty acids and was found to enhance Streptomyces growth, indicating a possible nutritional utilization. Thereby, this work stresses on how the enzymatic arsenal of S. venezuelae may contribute to its adaptation to BSMs-driven interactions with microbial competitors. The ability of Streptomyces to degrade exogenous lipopeptides and feed on them adds a new facet to the implications of the degradation of those compounds by Streptomyces, where linearization of surfactin was previously reported as a detoxification mechanism. Additionally, we hypothesize that lipopeptide-producing rhizobacteria and their biocontrol potential are impacted by the degradation of their lipopeptides as observed with the polarized motility of B. velezensis, avoiding the confrontation zone with Streptomyces and the loss of antifungal properties of degraded iturin. This work illustrates how CLPs, once released in the environment, may rapidly be remodeled or degraded by members of the bacterial community, with potential impacts on CLP-producing rhizobacteria and the biocontrol products derived from them.

microbiology↗

bioRxiv2023

Exploring the phytobeneficial and biocontrol capacities of endophytic bacteria isolated from hybrid vanilla pods

Few studies have been conducted on endophytic bacteria of vanilla. In this study, 58 bacterial strains were isolated from two hybrid vanilla plants from Madagascar, Manitra ampotony and Tsy taitra. They were genetically characterised and divided into four distinct phylotypes. A selection of twelve strains corresponding to the identified genetic diversity were tested in vitro for four phytobeneficial capacities: phosphate solubilisation, free nitrogen fixation, phytohormone and siderophore production. They were also evaluated in vitro for their ability to biocontrol the growth of the vanilla pathogenic fungi, Fusarium oxysporum f. sp. radicis vanillae and Cholletotrichum orchidophilum. Bacteria belonging to three different phyla were found to be highly competent in each of the phytobeneficial capacities tested. Bacteria belonging to the phylum related to Bacillus siamensis showed the best capacity to inhibit fungal growth making them good candidates for controlling fungal diseases of vanilla. This competence was highlighted with spectral imaging showing the production of lipopeptides by the bacterial strains confronted with the pathogenic fungi of vanilla.

microbiology↗

bioRxiv2020

Cell-derived hexameric β-amyloid: a novel insight into composition, self-assembly and nucleating properties

A key hallmark of Alzheimers disease (AD) is the extracellular deposition of amyloid plaques composed primarily of the amyloidogenic amyloid-{beta} (A{beta}) peptide. The A{beta} peptide is a product of sequential cleavage of the Amyloid Precursor Protein (APP), the first step of which gives rise to a C-terminal Fragment (C99). Cleavage of C99 by {gamma}-secretase activity releases A{beta} of several lengths and the A{beta}42 isoform in particular has been identified as being neurotoxic. The misfolding of A{beta} leads to subsequent amyloid fibril formation by nucleated polymerisation. This requires an initial and critical nucleus for self-assembly. Here, we identify and characterise the composition and self-assembly properties of cell-derived hexameric A{beta}42 and show its nucleating properties which are dependent on the A{beta} monomer availability. Identification of nucleating assemblies that contribute to self-assembly in this way may serve as therapeutic targets to prevent the formation of toxic oligomers.

biochemistry↗