Biology subjects

Boisseau, M.

Publications and source records attributed to Boisseau, M..

3 recordsLinked to original sources

bioRxiv2022

Spatial scale influences taxon conservation in the eukaryotic virome of a mosquito

Our knowledge on the diversity of eukaryotic viruses has recently undergone a massive expansion. This diversity could influence host physiology through yet unknown phenomena of potential interest to the fields of health and food production. However, the assembly processes in eukaryotic viromes of terrestrial animals remain elusive. This situation hinders hypothesis-driven tests of virome influence on host physiology. Here, we explore virome assembly at different spatial scales in the eukaryotic virome of the mosquito Culex pipiens. This mosquito is a vector of human pathogens worldwide. Several new aspects of virome assembly were unveiled through a sampling involving five countries in Africa and Europe and large sample sizes. A group of viruses was conserved in C. pipiens populations in all countries. This core group represented a relatively large and diverse fraction of the virome. However, core viruses were not shared by all host individuals in a given country, and their infection rates fluctuated between countries and years. Moreover, the distribution of co-infections in individual mosquitoes suggested random co-occurrence of certain core viruses. We also observed differences in the virome depending on geography, with viromes tending to cluster depending on the continent. Thus, our results unveil that taxon conservation in a eukaryotic virome changes with spatial scale. Thus, predictions on virome assembly seem possible at a large geographical scale in C. pipiens. IMPORTANCEThe study of the eukaryotic virome of mosquitoes is an emerging research field. Beyond its fundamental interest, this field could lead to the development of control tools against the transmission of mosquito-borne human pathogens. However, we yet know little on the assembly patterns in the eukaryotic viromes of mosquitoes, as well as of terrestrial animals in general. This situation hampers the design of hypothesis-driven studies on the influence of the virome on pathogen transmission. Here, we have analyzed virome assembly in the mosquito vector Culex pipiens within and between countries in Africa and Europe. Our results show that integrating contrasted spatial scales allows to identify deterministic patterns in virome assembly. Such patterns can guide future studies of virome influence on mosquito physiology.

ecology↗

bioRxiv2022

Evaluation of the nemabiome approach for the study of equine strongylid communities

Basic knowledge on the biology and epidemiology of equine strongylid species remains insufficient although it would contribute to the design of better parasite control strategies. Nemabiome is a convenient tool to quantify and to identify species in bulk samples that could overcome the hurdle that cyathostomin morphological identification represents. To date, this approach has relied on the internal transcribed spacer 2 (ITS-2) of the ribosomal RNA cistron and its predictive performance and associated biases both remain unaddressed. This study aimed to bridge this knowledge gap using cyathostomin mock communities and comparing performances of the ITS-2 and a cytochrome c oxidase subunit I (COI) barcode newly developed in this study. The effects of bioinformatic parameters were investigated to determine the best analytical pipelines. Subsequently, barcode predictive abilities were compared across various mock community compositions. The replicability of the approach and the amplification biases of each barcode were estimated. Results were also compared between various types of biological samples, i.e. eggs, infective larvae or adults. Overall, the proposed COI barcode was suboptimal relative to the ITS-2 rDNA region, because of PCR amplification biases, a reduced sensitivity and higher divergence from the expected community composition. Metabarcoding yielded consistent community composition across the three sample types, although infective larvae may remain the most tractable in the field. Additional strategies to improve the COI barcode performances are discussed. These results underscore the critical need of mock communities for metabarcoding purposes.

ecology↗

bioRxiv2021

Species turnover between age groups of horses and positive network of co-occurrences define the structure of horse strongylid communities: a meta-analysis

Grazing horses are infected by a wide range of strongylid species mostly located in the large intestine. Despite their impact on equine health and the emergence of drug resistant isolates, the phenology of these nematodes has been poorly characterized and the rules structuring their assembly as a community are not understood. Here, we compiled data on 46 equine strongylid species collected worldwide at the regional or horse scales (upon deworming or after necropsy) to analyse their richness, diversity and associated factors of variation. Worldwide, twelve species from the Cylicocyclus (n = 4), Cylicostephanus (n = 3), Coronocyclus (n = 2) and Cyathostomum (n = 2) genera were found in at least 75% of sites. Geoclimatic conditions had a limited effect on strongylid communities, but reduced species richness was found under the temperate European area. The recovery method did not affect species richness and differences on the temporal and sampling effort scales between studies applying either methods underpinned heterogeneous variances in community diversity. At the horse level, rarefaction curves correlated poorly to parasite egg excretion, suggesting little contribution of community diversity to this trait. Using a diversity partitioning approach, we found that within-host diversity represented half of overall diversity underscoring the importance of host density and environmental contamination to the diversity of strongylid communities. While this is expected to erase diversity across communities, species turnover between age classes was the second most important contributor to overall diversity (23.9%). This was associated with a network of positive co-occurrences between the four most prevalent genera that we resolved at the anatomical niche level. Altogether this pattern of {beta}-diversity maintenance across age classes combined with positive co-occurrences may be grounded by priority effects between major species. Our findings set the first assembly rules of equine strongylid communities.

ecology↗