Biology subjects

Mathe-Hubert, H.

Publications and source records attributed to Mathe-Hubert, H..

5 recordsLinked to original sources

bioRxiv2023

Hospital and urban wastewaters shape the structure and active resistome of environmental biofilms

BackgroundDemonstration of the transfer, dynamics, and regulation of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in a complex environmental matrix is yet experimentally challenging, with many essential open questions such as how and where transfer and dissemination of ARGs happens in nature. The extent and conditions of MGEs transfer that carry ARGs is still largely unexplored in natural environments and microbial communities. Biofilms are structures that include high density multi-species bacterial communities embedded in self-produced extracellular polymeric substances (EPS) constituting a matrix that facilitates gene transfer and where bacteria exhibit high tolerance to stress and to antibiotics. In this study we implemented a sampling and analysis approach that allows phenotypic and genomic analyses of in situ and reconstituted in vitro hospital and urban wastewater (WW) biofilms. To assess the potential of hospital and urban WW biofilms to efficiently disseminate ARGs in the WW system, we explored the EPS within the biofilm matrix and assessed the expression of the resistome (ARGs) and mobilome (MGEs) by metatranscriptomics. ResultsWe first showed that a) the composition of EPS differs depending on their growth environment (in situ and in vitro) and their sampling origin (hospital vs urban WW) and that b) a low amount of ciprofloxacin impacted the composition of the EPS. Next, the metatranscriptomic approach showed that a) expression of ARGs and MGEs increase upon adding a low amount of ciprofloxacin for biofilms from hospital WW but not for those from urban WW and b) that expression of specific plasmids that carry individual or multiple ARGs varies depending on the WW origins of the biofilms. When the same plasmids were expressed in both, urban and hospital WW biofilms, they carried and expressed different ARGs. ConclusionWe show that hospital and urban wastewaters shape the structure and active resistome of environmental biofilms, and we confirmed that hospital WW is an important hot spot for the dissemination and selection of AMR. The different responses to antibiotic pressure in hospital vs urban biofilms, coupled with differences in biofilm structure helps delineate distinct characteristics of hospital and urban WW biofilms highlighting the relationships between the resistome and its expression in environmental biofilms and their surrounding ecosystems.

microbiology↗

bioRxiv2022

Evolution of bacterial persistence to antibiotics during a 50,000-generation experiment in an antibiotic-free environment.

Failure of antibiotic therapies causes > 700,000 deaths yearly and involves both bacterial resistance and persistence. Persistence results in the relapse of infections by producing a tiny fraction of pathogen survivors that stay dormant during antibiotic exposure. From an evolutionary perspective, persistence is either a bet-hedging strategy that helps to cope with stochastically changing environments or an unavoidable minimal rate of cellular errors that lock the cells in a low activity state. Here, we analyzed the evolution of persistence over 50,000 bacterial generations in a stable environment by improving a published method that estimates the number of persister cells based on the growth of the reviving population. Our results challenged our understanding of the factors underlying persistence evolution. In one case, we observed a substantial decrease in persistence proportion, suggesting that the naturally observed persistence level is not an unavoidable minimal rate of cellular errors. However, although there was no obvious environmental stochasticity, in 11 of the 12 investigated populations, the persistence level was maintained during 50,000 bacterial generations.

evolutionary biology↗

bioRxiv2020

Parasitic success and venom composition evolve upon specialization of parasitoid wasps to different host species

AO_SCPLOWBSTRACTC_SCPLOWFemale endoparasitoid wasps usually inject venom into hosts to suppress their immune response and ensure offspring development. However, the parasitoids ability to evolve towards increased success on a given host simultaneously with the evolution of the composition of its venom has never been demonstrated. Here, we designed an experimental evolution to address this question. We crossed two parasitoid lines of Leptopilina boulardi differing both in parasitic success on different Drosophila hosts and venom composition. F2 descendants were reared on three different Drosophila species for nine generations. We tested for evolution of parasitic success over the generations and for the capacity of parasitoids selected on a given host to succeed on another host. We also tested whether the venom composition - based on a statistical analysis of the variation in intensity of the venom protein bands on SDS-PAGE 1D - evolved in response to different host species. Results showed a specialization of the parasitoids on their selection host and a rapid and differential evolution of the venom composition according to the host. Overall, data suggest a high potential for parasitoids to adapt to a new host, which may have important consequences in the field as well in the context of biological control.

evolutionary biology↗

bioRxiv2019

Rapid and differential evolution of the venom composition of a parasitoid wasp depending on the host strain

Parasitoid wasps rely primarily on venom to suppress the immune response and regulate the physiology of their host. Intraspecific variability of venom protein composition has been documented in some species, but its evolutionary potential is poorly understood. We performed an experimental evolution initiated with crosses of two lines of Leptopilina boulardi of different venom composition to generate variability and create new combinations of venom factors. The offspring were maintained for 10 generations on two strains of Drosophila melanogaster differing in resistance / susceptibility to the parasitoid lines. The venom composition of individuals was characterized by a semi-automatic analysis of 1D SDS-PAGE protein profiles whose accuracy was checked by Western blot analysis of well-characterized venom proteins. Results evidenced a rapid and differential evolution of the venom composition on both hosts and showed that the proteins beneficial on one host can be costly on the other. Overall, we demonstrated the capacity of rapid evolution of the venom composition in parasitoid wasps, important regulators of arthropod populations, suggesting a potential for adaptation to new hosts. Our approach also proved relevant in identifying, among the diversity of venom proteins, those possibly involved in parasitism success and whose role deserves to be deepened.\n\nKey ContributionThe venom protein composition of parasitoid wasps can evolve rapidly and differently depending on the host strain. Studying this evolution can help identify new venom proteins possibly involved in parasitism success on a given host.

evolutionary biology↗

bioRxiv2018

Non-random associations of maternally transmitted symbionts in insects: The roles of drift versus co-transmission and selection

Virtually all higher organisms form holobionts with associated microbiota. To understand the biology of holobionts we need to know how species assemble and interact. Controlled experiments are suited to study interactions between particular symbionts, but they can only inform about a tiny portion of the diversity within each species. Alternatively, interactions can be inferred from associations among symbionts in the field that are more or less frequent than expected under random assortment. However, random assortment may not be a valid null hypothesis for maternally transmitted symbionts in finite populations, where drift alone can result in associations. Here we report results from a European field survey of endosymbionts in the pea aphid (Acyrthosiphon pisum), and we develop a model to study the effect of drift on symbiont associations under different population sizes, considering varying rates of horizontal and maternal transmission. The model showed that even though horizontal transmissions and maternal transmission failures tend to randomise symbiont associations, drift can induce significant departures from random assortment, at least in moderate-sized populations. Based on these results, we carefully interpret our field survey and we re-visit the association between Spiroplasma and Wolbachia in Drosophila neotestacea reported by Jaenike et al. (2010). For this and for several significant associations between symbionts in European pea aphids we conclude that under reasonable assumptions of effective population size, they are indeed likely to be maintained by biased co-transmission or selection. Our study shows that formulating appropriate null expectations can strengthen the biological inference from co-occurrence patterns in the field.

ecology↗