Intensity of infection with intracellular Eimeria spp. and pinworms is reduced in hybrid mice compared to parental subspecies

Genetic diversity in animal immune systems is usually beneficial. In hybrid recombinants, this is less clear, as the immune system could also be impacted by genetic conflicts. In the European house mouse hybrid zone, the long‐standing impression that hybrid mice are more highly parasitized and less fit than parentals persists despite the findings of recent studies. Working across a novel transect, we assessed infections by intracellular protozoans, Eimeria spp., and infections by extracellular macroparasites, pinworms. For Eimeria, we found lower intensities in hybrid hosts than in parental mice but no evidence of lowered probability of infection or increased mortality in the centre of the hybrid zone. This means ecological factors are very unlikely to be responsible for the reduced load of infected hybrids. Focusing on parasite intensity (load in infected hosts), we also corroborated reduced pinworm loads reported for hybrid mice in previous studies. We conclude that intensity of diverse parasites, including the previously unstudied Eimeria, is reduced in hybrid mice compared to parental subspecies. We suggest caution in extrapolating this to differences in hybrid host fitness in the absence of, for example, evidence for a link between parasitemia and health.Peer Reviewe

Shrews (Mammalia, Eulipotyphla) from a biodiversity hotspot, Mount Nimba (West Africa), with a field identification key to species

In this study, we collected 226 shrew specimens originating from 16 localities on the Guinean and Liberian sides of Mount Nimba. We surveyed all major vegetation zones from 400 to 1600 m above sea level (asl), including forest and savannah habitats. We recorded 11 species, whose identifications were confirmed by genetic analyses and classical morphometrics. Furthermore, we provide cytogenetic data for five of these species. The shrew community at Mount Nimba is composed of a mix of both savannah- and forest-dependent species, which is related to the peculiar position of Mount Nimba situated at the transition between lowland rainforest to the south and Guinean woodlands to the north. We recorded 11 species of shrews in syntopy in lowland rainforest, seven in edaphic savannah and mountain forest, and five in high-altitude savannah at 1600 m asl. Based on morphometric analyses, we show that these syntopic species separate along a size axis, allowing species to occupy different ecological niches, which we speculate allows them to access different food resources. We also highlight that Crocidura theresae Heim de Balsac, 1968 from Mount Nimba has a different karyotype from that described in Côte d’Ivoire. Finally, we develop a novel identification key for shrews from Mount Nimba using external characters and standard body measurements, allowing it to be used in the field on live specimens. In total 12 shrew species are now known from Mount Nimba, which highlights its exceptional position as a tropical African biodiversity hotspot.https://sciencepress.mnhn.fr/en/periodiques/zoosystemadm2022Mammal Research InstituteZoology and Entomolog

Negative relationships between cellular immune response, Mhc class II heterozygosity and secondary sexual trait in the montane water vole

Heterogeneities in immune responsiveness may affect key epidemiological parameters and the dynamics of pathogens. The roles of immunogenetics in these variations remain poorly explored. We analysed the influence of Major histocompatibility complex (Mhc) genes and epigamic traits on the response to phytohaemagglutinin in males from cyclic populations of the montane water vole (Arvicola scherman). Besides, we tested the relevance of lateral scent glands as honest signals of male quality. Our results did not corroborate neither the hypotheses of genome-wide heterozygosity-fitness correlation nor the Mhc heterozygote advantage. We found a negative relationship between Mhc hetetozygosity and response to phytohaemagglutinin, mediated by a specific Mhc homozygous genotype. Our results therefore support the hypothesis of the Arte-Dqa-05 homozygous genotype being a ‘good’ Mhc variant in terms of immunogenetic quality. The development of the scent glands seems to be an honest signal for mate choice as it is negatively correlated with helminth load. The ‘good gene’ hypothesis was not validated as Arte-Dqa-05 homozygous males did not exhibit larger glands. Besides, the negative relationship observed between the size of these glands and the response to phytohaemagglutinin, mainly for Mhc homozygotes, corroborates the immunocompetence handicap hypothesis. The Mhc variants associated with larger glands remain yet to be determined

Annual (2023) taxonomic update of RNA-directed RNA polymerase-encoding negative-sense RNA viruses (realm Riboviria: kingdom Orthornavirae: phylum Negarnaviricota)

55 Pág.In April 2023, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by one new family, 14 new genera, and 140 new species. Two genera and 538 species were renamed. One species was moved, and four were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.This work was supported in part through the Laulima Government Solutions, LLC, prime contract with the U.S. National Institute of Allergy and Infec tious Diseases (NIAID) under Contract No. HHSN272201800013C. J.H.K. performed this work as an employee of Tunnell Government Services (TGS), a subcontractor of Laulima Government Solutions, LLC, under Contract No. HHSN272201800013C. U.J.B. was supported by the Division of Intramural Resarch, NIAID. This work was also funded in part by Contract No. HSHQDC15-C-00064 awarded by DHS S and T for the management and operation of The National Biodefense Analysis and Countermeasures Centre, a federally funded research and development centre operated by the Battelle National Biodefense Institute (V.W.); and NIH contract HHSN272201000040I/HHSN27200004/D04 and grant R24AI120942 (N.V., R.B.T.). S.S. acknowl edges support from the Mississippi Agricultural and Forestry Experiment Station (MAFES), USDA-ARS project 58-6066-9-033 and the National Institute of Food and Agriculture, U.S. Department of Agriculture, Hatch Project, under Accession Number 1021494. The funders had no role in the design of the study; in the collection, analysis, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of the Army, the U.S. Department of Defence, the U.S. Department of Health and Human Services, including the Centres for Disease Control and Prevention, the U.S. Department of Homeland Security (DHS) Science and Technology Directorate (S and T), or of the institutions and companies affiliated with the authors. In no event shall any of these entities have any responsibility or liability for any use, misuse, inability to use, or reliance upon the information contained herein. The U.S. departments do not endorse any products or commercial services mentioned in this publication. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S.Government retains a non-exclusive, paid up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. Government purposes.Peer reviewe

Understanding Flooding Phenomena in Mini-Channel of Proton Exchane Membrane Fuel Cells

International audienceProper management of the water produced in the Proton Exchange Membrane Fuel Cell (PEMFC) is necessary to improve the system performance and lifetime. Indeed, the accumulation of liquid water in the GDL (Gas Diffusion Layer) or in the gas supply channels can reduce the supply of reactants to the active layer. The development of PEMFCs with more compact cells, with thinner channels and reaching higher current densities will make this system even more sensitive to flooding. On the contrary, the absence of humidification in a cell will cause a decrease in the proton conductivity of the ionomers and a degradation of the materials.In order to improve the predictability of the flooding of PEMFCs, and to better understand the liquid water transport phenomena in the cell, a channel-rib pore network model is under development. It relies on previous work done at CEA-LITEN and CNRS/IMFT[1], [2]. This model has been validated against experimental data, as shown in Figure 1. It will eventually allow predicting the behaviour of the system locally as a function of the local operating conditions and local properties of the gas diffusion layer. This model, once coupled to a second model developed at the scale of a cell, which accounts for heterogeneities between inlet and outlet of the cell [3], will allow a more efficient prediction of water distribution in the cell and especially the occurrence of flooding. This coupling is necessary since even though the cell model has already shown good agreement with experimental data for some operating conditions as seen in Figure 2, it still needs more accuracy in other cases, for example at higher current density (Figure 3).A first step towards the objective of a coupled model is to obtain for given operating conditions effective transport parameters at the rib-channel scale, which can be used as inputs to the cell model. A simple transport model to represent the transport of species in the GDL is Fick's law, which allows to consider a binary mixture (vapour and oxygen in our case) whose species would only be subject to diffusion. However, there is a pressure gradient across the GDL, imposed by the difference between the flow of O2 consumed and the flow of water vapour produced. Of course, this gradient can be assumed small outside of flooding conditions. However, in the case where the GDL is highly saturated with water, the pressure gradient within the GDL can increase. The convective fluxes due to the pressure gradient will then be higher. Therefore, the gas transport within the GDL will be studied mainly by two models: a binary diffusion model based on Fick's law, and a diffusion/convection model based on Young and Todd's model[4]. They will be compared to define if a simple and low computational time consuming model can be sufficient for our study or not

Understanding Flooding Phenomena in Mini-Channel of Proton Exchane Membrane Fuel Cells

International audienceProper management of the water produced in the Proton Exchange Membrane Fuel Cell (PEMFC) is necessary to improve the system performance and lifetime. Indeed, the accumulation of liquid water in the GDL (Gas Diffusion Layer) or in the gas supply channels can reduce the supply of reactants to the active layer. The development of PEMFCs with more compact cells, with thinner channels and reaching higher current densities will make this system even more sensitive to flooding. On the contrary, the absence of humidification in a cell will cause a decrease in the proton conductivity of the ionomers and a degradation of the materials.In order to improve the predictability of the flooding of PEMFCs, and to better understand the liquid water transport phenomena in the cell, a channel-rib pore network model is under development. It relies on previous work done at CEA-LITEN and CNRS/IMFT[1], [2]. This model has been validated against experimental data, as shown in Figure 1. It will eventually allow predicting the behaviour of the system locally as a function of the local operating conditions and local properties of the gas diffusion layer. This model, once coupled to a second model developed at the scale of a cell, which accounts for heterogeneities between inlet and outlet of the cell [3], will allow a more efficient prediction of water distribution in the cell and especially the occurrence of flooding. This coupling is necessary since even though the cell model has already shown good agreement with experimental data for some operating conditions as seen in Figure 2, it still needs more accuracy in other cases, for example at higher current density (Figure 3).A first step towards the objective of a coupled model is to obtain for given operating conditions effective transport parameters at the rib-channel scale, which can be used as inputs to the cell model. A simple transport model to represent the transport of species in the GDL is Fick's law, which allows to consider a binary mixture (vapour and oxygen in our case) whose species would only be subject to diffusion. However, there is a pressure gradient across the GDL, imposed by the difference between the flow of O2 consumed and the flow of water vapour produced. Of course, this gradient can be assumed small outside of flooding conditions. However, in the case where the GDL is highly saturated with water, the pressure gradient within the GDL can increase. The convective fluxes due to the pressure gradient will then be higher. Therefore, the gas transport within the GDL will be studied mainly by two models: a binary diffusion model based on Fick's law, and a diffusion/convection model based on Young and Todd's model[4]. They will be compared to define if a simple and low computational time consuming model can be sufficient for our study or not

STRUCTURE parameter settings

Parameter settings used in the software STRUCTURE, to infer population genetic structure of Mastomys natalensis based on microsatellite genotypes

MrBayes input files

Input files for the software MrBayes of arenavirus partial L, NP and GPC sequences, containing the used alignments and parameter settings to infer the phylogenetic trees displayed in the manuscript