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1.
Genes Dev ; 30(23): 2565-2570, 2016 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-27986858

RESUMO

RNA polymerase V (Pol V) long noncoding RNAs (lncRNAs) have been proposed to guide ARGONAUTE4 (AGO4) to chromatin in RNA-directed DNA methylation (RdDM) in plants. Here, we provide evidence, based on laser UV-assisted zero-length cross-linking, for functionally relevant AGO4-DNA interaction at RdDM targets. We further demonstrate that Pol V lncRNAs or the act of their transcription are required to lock Pol V holoenzyme into a stable DNA-bound state that allows AGO4 recruitment via redundant glycine-tryptophan/tryptophan-glycine AGO hook motifs present on both Pol V and its associated factor, SPT5L. We propose a model in which AGO4-DNA interaction could be responsible for the unique specificities of RdDM.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Metilação de DNA , DNA de Plantas/metabolismo , RNA de Plantas/metabolismo , Motivos de Aminoácidos/genética , Proteínas de Arabidopsis/química , Proteínas Argonautas/química , Cromatina/metabolismo , Metilação de DNA/genética , RNA Polimerases Dirigidas por DNA/química , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Inativação Gênica , Modelos Biológicos , Interferência de RNA , Transcrição Gênica/genética
2.
J Virol ; 96(14): e0060822, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35862713

RESUMO

Bats are natural reservoirs of numerous coronaviruses, including the potential ancestor of SARS-CoV-2. Knowledge concerning the interaction between coronaviruses and bat cells is sparse. We investigated the ability of primary cells from Rhinolophus and Myotis species, as well as of established and novel cell lines from Myotis myotis, Eptesicus serotinus, Tadarida brasiliensis, and Nyctalus noctula, to support SARS-CoV-2 replication. None of these cells were permissive to infection, not even the ones expressing detectable levels of angiotensin-converting enzyme 2 (ACE2), which serves as the viral receptor in many mammalian species. The resistance to infection was overcome by expression of human ACE2 (hACE2) in three cell lines, suggesting that the restriction to viral replication was due to a low expression of bat ACE2 (bACE2) or the absence of bACE2 binding in these cells. Infectious virions were produced but not released from hACE2-transduced M. myotis brain cells. E. serotinus brain cells and M. myotis nasal epithelial cells expressing hACE2 efficiently controlled viral replication, which correlated with a potent interferon response. Our data highlight the existence of species-specific and cell-specific molecular barriers to viral replication in bat cells. These novel chiropteran cellular models are valuable tools to investigate the evolutionary relationships between bats and coronaviruses. IMPORTANCE Bats are host ancestors of several viruses that cause serious disease in humans, as illustrated by the ongoing SARS-CoV-2 pandemic. Progress in investigating bat-virus interactions has been hampered by a limited number of available bat cellular models. We have generated primary cells and cell lines from several bat species that are relevant for coronavirus research. The various permissivities of the cells to SARS-CoV-2 infection offered the opportunity to uncover some species-specific molecular restrictions to viral replication. All bat cells exhibited a potent entry-dependent restriction. Once this block was overcome by overexpression of human ACE2, which serves at the viral receptor, two bat cell lines controlled well viral replication, which correlated with the inability of the virus to counteract antiviral responses. Other cells potently inhibited viral release. Our novel bat cellular models contribute to a better understanding of the molecular interplays between bat cells and viruses.


Assuntos
Quirópteros , SARS-CoV-2 , Replicação Viral , Enzima de Conversão de Angiotensina 2/genética , Animais , Quirópteros/virologia , Humanos , Receptores Virais/metabolismo , SARS-CoV-2/fisiologia , Especificidade da Espécie , Glicoproteína da Espícula de Coronavírus/metabolismo
3.
Emerg Infect Dis ; 27(4)2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33756099

RESUMO

Although essential for control strategies, knowledge about transmission cycles is limited for Venezuelan equine encephalitis complex alphaviruses (VEEVs). After testing 1,398 bats from French Guiana for alphaviruses, we identified and isolated a new strain of the encephalitogenic VEEV species Tonate virus (TONV). Bats may contribute to TONV spread in Latin America.


Assuntos
Alphavirus , Quirópteros , Vírus da Encefalite Equina Venezuelana , Encefalomielite Equina Venezuelana , Animais , Guiana Francesa , Cavalos
5.
J Virol ; 93(5)2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30541833

RESUMO

Human hepatitis B virus (HBV) is a global health problem, affecting more than 250 million people worldwide. HBV-like viruses, named orthohepadnaviruses, also naturally infect nonhuman primates, rodents, and bats, but their pathogenicity and evolutionary history are unclear. Here, we determined the evolutionary history of the HBV receptors NTCP and GPC5 over millions of years of primate, rodent, and bat evolution. We use this as a proxy to understand the pathogenicity of orthohepadnaviruses in mammalian hosts and to determine the implications for species specificity. We found that NTCP, but not GPC5, has evolved under positive selection in primates (27 species), rodents (18 species), and bats (21 species) although at distinct residues. Notably, the positively selected codons map to the HBV-binding sites in primate NTCP, suggesting past genetic "arms races" with pathogenic orthohepadnaviruses. In rodents, the positively selected codons fall outside and within the presumed HBV-binding sites, which may contribute to the restricted circulation of rodent orthohepadnaviruses. In contrast, the presumed HBV-binding motifs in bat NTCP are conserved, and none of the positively selected codons map to this region. This suggests that orthohepadnaviruses may bind to different surfaces in bat NTCP. Alternatively, the patterns may reflect adaptive changes associated with metabolism rather than pathogens. Overall, our findings further point to NTCP as a naturally occurring genetic barrier for cross-species transmissions in primates, which may contribute to the narrow host range of HBV. In contrast, this constraint seems less important in bats, which may correspond to greater orthohepadnavirus circulation and diversity.IMPORTANCE Chronic infection with hepatitis B virus (HBV) is a major cause of liver disease and cancer in humans. Mammalian HBV-like viruses are also found in nonhuman primates, rodents, and bats. As for most viruses, HBV requires a successful interaction with a host receptor for replication. Cellular receptors are thus key determinants of host susceptibility as well as specificity. One hallmark of pathogenic virus-host relationships is the reciprocal evolution of host receptor and viral envelope proteins, as a result of their antagonistic interaction over time. The dynamics of these so-called "evolutionary arms races" can leave signatures of adaptive selection, which in turn reveal the evolutionary history of the virus-host interaction as well as viral pathogenicity and the genetic determinants of species specificity. Here, we show how HBV-like viruses have shaped the evolutionary history of their mammalian host receptor, as a result of their ancient pathogenicity, and decipher the genetic determinants of cross-species transmissions.


Assuntos
Vírus da Hepatite B/patogenicidade , Hepatite B/veterinária , Especificidade de Hospedeiro/genética , Transportadores de Ânions Orgânicos Dependentes de Sódio/genética , Simportadores/genética , Proteínas do Envelope Viral/genética , Animais , Quirópteros/virologia , Evolução Molecular , Variação Genética , Hepatite B/patologia , Hepatite B/virologia , Humanos , Primatas/virologia , Roedores/virologia , Especificidade da Espécie , Internalização do Vírus
6.
PLoS Biol ; 15(2): e2001536, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28199335

RESUMO

Transposable elements (TEs) represent the single largest component of numerous eukaryotic genomes, and their activity and dispersal constitute an important force fostering evolutionary innovation. The horizontal transfer of TEs (HTT) between eukaryotic species is a common and widespread phenomenon that has had a profound impact on TE dynamics and, consequently, on the evolutionary trajectory of many species' lineages. However, the mechanisms promoting HTT remain largely unknown. In this article, we argue that network theory combined with functional ecology provides a robust conceptual framework and tools to delineate how complex interactions between diverse organisms may act in synergy to promote HTTs.


Assuntos
Elementos de DNA Transponíveis/genética , Ecossistema , Transferência Genética Horizontal/genética , Simulação por Computador , Genoma
7.
Mol Cell ; 48(1): 109-20, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-22940249

RESUMO

In Arabidopsis thaliana, the putative RNA-helicase SDE3 assists posttranscriptional-gene-silencing (PTGS) amplification by RNA-dependent-RNA-polymerase-6 (RDR6). SDE3 homologs in Drosophila, worm and human contribute to silence viruses, transposons or recently duplicated genes but the underlying mechanisms remain largely unknown. Here, we demonstrate that SDE3 is present with the PTGS effectors AGO1 and AGO2 in higher-order protein complexes owing to a specialized GW-repeat-containing C-terminal domain. We uncover an essential contribution of the RNA-helicase activity and a facilitating role for AGO binding in SDE3 action, which occurs downstream of RDR6. We show that these biochemical properties underpin dual roles for SDE3 in antiviral defense and, unexpectedly, in transposon silencing via a hitherto unanticipated pathway that correlates with DNA methylation, suggesting a continuum of action between PTGS and chromatin-level silencing. We identified endogenous SDE3 targets corresponding to nonconserved intergenic regions, transposons and recently evolved pseudogenes, unraveling striking functional convergences among plant and metazoan SDE3 pathways.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , DNA Intergênico/genética , DNA de Plantas/genética , RNA Helicases/química , RNA Helicases/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Arabidopsis/virologia , Proteínas de Arabidopsis/genética , Proteínas Argonautas/química , Proteínas Argonautas/metabolismo , Sequência Conservada , Metilação de DNA , DNA Intergênico/metabolismo , DNA de Plantas/metabolismo , Humanos , Modelos Biológicos , Dados de Sequência Molecular , Domínios e Motivos de Interação entre Proteínas , RNA Helicases/genética , Interferência de RNA , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , RNA Polimerase Dependente de RNA/metabolismo , Homologia de Sequência de Aminoácidos
8.
Mol Cell ; 48(1): 121-32, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-22940247

RESUMO

In Arabidopsis, transcriptional gene silencing (TGS) can be triggered by 24 nt small-interfering RNAs (siRNAs) through the RNA-directed DNA methylation (RdDM) pathway. By functional analysis of NERD, a GW repeat- and PHD finger-containing protein, we demonstrate that Arabidopsis harbors a second siRNA-dependent DNA methylation pathway targeting a subset of nonconserved genomic loci. The activity of the NERD-dependent pathway differs from RdDM by the fact that it relies both on silencing-related factors previously implicated only in posttranscriptional gene silencing (PTGS), including RNA-DEPENDENT RNA POLYMERASE1/6 and ARGONAUTE2, and most likely on 21 nt siRNAs. A central role for NERD in integrating RNA silencing and chromatin signals in transcriptional silencing is supported by data showing that it binds both to histone H3 and AGO2 proteins and contributes to siRNA accumulation at a NERD-targeted locus. Our results unravel the existence of a conserved chromatin-based RNA silencing pathway encompassing both PTGS and TGS components in plants.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Interferência de RNA , Motivos de Aminoácidos , Sequência de Aminoácidos , Proteínas de Arabidopsis/química , Proteínas Argonautas , Cromatina/genética , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/química , Metilação de DNA , Histonas/metabolismo , Dados de Sequência Molecular , Ligação Proteica , RNA Interferente Pequeno/genética , Proteínas de Ligação a RNA/metabolismo , RNA Polimerase Dependente de RNA/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais
9.
BMC Evol Biol ; 18(1): 175, 2018 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-30458712

RESUMO

BACKGROUND: The distinction between lineages of neotropical bats from the Pteronotus parnellii species complex has been previously made according to mitochondrial DNA, and especially morphology and acoustics, in order to separate them into two species. In these studies, either sample sizes were too low when genetic and acoustic or morphological data were gathered on the same individuals, or genetic and other data were collected on different individuals. In this study, we intensively sampled bats in 4 caves and combined all approaches in order to analyse genetic, morphologic, and acoustic divergence between these lineages that live in the same caves in French Guiana. RESULTS: A multiplex of 20 polymorphic microsatellite markers was developed using the 454-pyrosequencing technique to investigate for the first time the extent of reproductive isolation between the two lineages and the population genetic structure within lineages. We genotyped 748 individuals sampled between 2010 and 2015 at the 20 nuclear microsatellite loci and sequenced a portion of the cytochrome c oxydase I gene in a subset of these. Two distinct, non-overlapping haplogroups corresponding to cryptic species P. alitonus and P. rubiginosus were revealed, in accordance with previous findings. No spatial genetic structure between caves was detected for both species. Hybridization appeared to be quite limited (0.1-4%) using microsatellite markers whereas introgression was more common (7.5%) and asymmetric for mitochondrial DNA (mtDNA). CONCLUSIONS: The extremely low rate of hybridization could be explained by differences in life cycle phenology between species as well as morphological and acoustical distinction between sexes in one or the other species. Taken together, these results add to our growing understanding of the nature of species boundaries in Pteronotus parnelli, but deserve more in-depth studies to understand the evolutionary processes underlying asymmetric mtDNA introgression in this group of cryptic species.


Assuntos
Acústica , Quirópteros/genética , Ecossistema , Simpatria/fisiologia , Animais , Núcleo Celular/genética , Quirópteros/anatomia & histologia , Ecolocação , Guiana Francesa , Genótipo , Repetições de Microssatélites/genética , Reprodução , Especificidade da Espécie
10.
BMC Ecol ; 18(1): 60, 2018 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-30572866

RESUMO

BACKGROUND: Our picture of behavioral management of risk by prey remains fragmentary. This partly stems from a lack of studies jointly analyzing different behavioral responses developed by prey, such as habitat use and fine-scale behavior, although they are expected to complement each other. We took advantage of a simple system on the Kerguelen archipelago, made of a prey species, European rabbit Oryctolagus cuniculus, a predator, feral cat Felis catus, and a mosaic of closed and open foraging patches, allowing reliable assessment of spatio-temporal change in predation risk. We investigated the way such a change triggered individual prey decisions on where, when and how to perform routine activities. RESULTS: Rabbit presence and behavior were recorded both day and night in patches with similar foraging characteristics, but contrasted in terms of openness. Cats, individually recognizable, were more active at night and in closed patches, in line with their expected higher hunting success in those conditions. Accordingly, rabbits avoided using closed patches at night and increased their vigilance if they did. Both day and night, rabbits increased their use of closed patches as compared to open patches in windy conditions, thereby probably reducing the thermoregulatory costs expected under such harsh environmental conditions. CONCLUSIONS: Overall, our data map the landscape of fear in this study system and indicate that prey habitat use and vigilance complement each other. Solely focusing on one or the other tactic may lead to erroneous conclusions regarding the way predation risk triggers prey decisions. Finally, future studies should investigate inter-individual variability in the relative use of these different types of complementary behavioral responses to perceived risk, along with the determinants and outcomes of such tactics.


Assuntos
Gatos/fisiologia , Cadeia Alimentar , Comportamento Predatório , Coelhos/fisiologia , Animais , Ecossistema , Ilhas do Oceano Índico , Dinâmica Populacional
11.
Genes Dev ; 24(9): 904-15, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20439431

RESUMO

In plants and invertebrates, viral-derived siRNAs processed by the RNaseIII Dicer guide Argonaute (AGO) proteins as part of antiviral RNA-induced silencing complexes (RISC). As a counterdefense, viruses produce suppressor proteins (VSRs) that inhibit the host silencing machinery, but their mechanisms of action and cellular targets remain largely unknown. Here, we show that the Turnip crinckle virus (TCV) capsid, the P38 protein, acts as a homodimer, or multiples thereof, to mimic host-encoded glycine/tryptophane (GW)-containing proteins normally required for RISC assembly/function in diverse organisms. The P38 GW residues bind directly and specifically to Arabidopsis AGO1, which, in addition to its role in endogenous microRNA-mediated silencing, is identified as a major effector of TCV-derived siRNAs. Point mutations in the P38 GW residues are sufficient to abolish TCV virulence, which is restored in Arabidopsis ago1 hypomorphic mutants, uncovering both physical and genetic interactions between the two proteins. We further show how AGO1 quenching by P38 profoundly impacts the cellular availability of the four Arabidopsis Dicers, uncovering an AGO1-dependent, homeostatic network that functionally connects these factors together. The likely widespread occurrence and expected consequences of GW protein mimicry on host silencing pathways are discussed in the context of innate and adaptive immunity in plants and metazoans.


Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas do Capsídeo/metabolismo , Carmovirus/metabolismo , Homeostase/fisiologia , Interações Hospedeiro-Patógeno , Ribonuclease III/metabolismo , Sequência de Aminoácidos , Proteínas de Arabidopsis/genética , Proteínas Argonautas , Proteínas do Capsídeo/química , Proteínas de Ciclo Celular/genética , Inativação Gênica , Dados de Sequência Molecular , Mutação , Doenças das Plantas/virologia , Ligação Proteica , RNA Interferente Pequeno/metabolismo , Ribonuclease III/genética , Alinhamento de Sequência
12.
Nature ; 465(7294): 106-9, 2010 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-20410883

RESUMO

DNA methylation is an important epigenetic mark in many eukaryotes. In plants, 24-nucleotide small interfering RNAs (siRNAs) bound to the effector protein, Argonaute 4 (AGO4), can direct de novo DNA methylation by the methyltransferase DRM2 (refs 2, 4-6). Here we report a new regulator of RNA-directed DNA methylation (RdDM) in Arabidopsis: RDM1. Loss-of-function mutations in the RDM1 gene impair the accumulation of 24-nucleotide siRNAs, reduce DNA methylation, and release transcriptional gene silencing at RdDM target loci. RDM1 encodes a small protein that seems to bind single-stranded methyl DNA, and associates and co-localizes with RNA polymerase II (Pol II, also known as NRPB), AGO4 and DRM2 in the nucleus. Our results indicate that RDM1 is a component of the RdDM effector complex and may have a role in linking siRNA production with pre-existing or de novo cytosine methylation. Our results also indicate that, although RDM1 and Pol V (also known as NRPE) may function together at some RdDM target sites in the peri-nucleolar siRNA processing centre, Pol II rather than Pol V is associated with the RdDM effector complex at target sites in the nucleoplasm.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Metilação de DNA , Proteínas de Ligação a DNA/metabolismo , RNA Polimerase II/metabolismo , RNA de Plantas/metabolismo , Proteínas de Arabidopsis/genética , Proteínas Argonautas , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas , Inativação Gênica/fisiologia , Metiltransferases/metabolismo , Mutação
13.
BMC Public Health ; 16: 441, 2016 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-27230111

RESUMO

BACKGROUND: Improving knowledge about influenza transmission is crucial to upgrade surveillance network and to develop accurate predicting models to enhance public health intervention strategies. Epidemics usually occur in winter in temperate countries and during the rainy season for tropical countries, suggesting a climate impact on influenza spread. Despite a lot of studies, the role of weather on influenza spread is not yet fully understood. In the present study, we investigated this issue at two different levels. METHODS: First, we evaluated how weekly (intra-annual) incidence variations of clinical diseases could be linked to those of climatic factors. We considered that only a fraction of the human population is susceptible at the beginning of a year due to immunity acquired from previous years. Second, we focused on epidemic sizes (cumulated number of clinical reported cases) and looked at how their inter-annual and regional variations could be related to differences in the winter climatic conditions of the epidemic years over the regions. We quantified the impact of fifteen climatic variables in France using the Réseau des GROG surveillance network incidence data over eleven regions and nine years. RESULTS: At the epidemic scale, no impact of climatic factors was highlighted. At the intra-annual scale, six climatic variables had a significant impact: average temperature (5.54 ± 1.09 %), absolute humidity (5.94 ± 1.08 %), daily variation of absolute humidity (3.02 ± 1.17 %), sunshine duration (3.46 ± 1.06 %), relative humidity (4.92 ± 1.20 %) and daily variation of relative humidity (4.46 ± 1.24 %). Since in practice the impact of two highly correlated variables is very hard to disentangle, we performed a principal component analysis that revealed two groups of three highly correlated climatic variables: one including the first three highlighted climatic variables on the one hand, the other including the last three ones on the other hand. CONCLUSIONS: These results suggest that, among the six factors that appeared to be significant, only two (one per group) could in fact have a real effect on influenza spread, although it is not possible to determine which one based on a purely statistical argument. Our results support the idea of an important role of climate on the spread of influenza.


Assuntos
Surtos de Doenças , Influenza Humana/epidemiologia , Modelos Teóricos , Tempo (Meteorologia) , França/epidemiologia , Humanos , Incidência , Influenza Humana/transmissão , Influenza Humana/virologia , Estações do Ano
14.
Am J Primatol ; 77(3): 309-18, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25296992

RESUMO

The early stage of viral infection is often followed by an important increase of viral load and is generally considered to be the most at risk for pathogen transmission. Most methods quantifying the relative importance of the different stages of infection were developed for studies aimed at measuring HIV transmission in Humans. However, they cannot be transposed to animal populations in which less information is available. Here we propose a general method to quantify the importance of the early and late stages of the infection on micro-organism transmission from field studies. The method is based on a state space dynamical model parameterized using Bayesian inference. It is illustrated by a 28 years dataset in mandrills infected by Simian Immunodeficiency Virus type-1 (SIV-1) and the Simian T-Cell Lymphotropic Virus type-1 (STLV-1). For both viruses we show that transmission is predominant during the early stage of the infection (transmission ratio for SIV-1: 1.16 [0.0009; 18.15] and 9.92 [0.03; 83.8] for STLV-1). However, in terms of basic reproductive number (R0 ), which quantifies the weight of both stages in the spread of the virus, the results suggest that the epidemics of SIV-1 and STLV-1 are mainly driven by late transmissions in this population.


Assuntos
Infecções por Deltaretrovirus/transmissão , Síndrome de Imunodeficiência Adquirida dos Símios/transmissão , Vírus da Imunodeficiência Símia , Vírus Linfotrópico T Tipo 1 de Símios , Animais , Teorema de Bayes , Infecções por Deltaretrovirus/epidemiologia , Infecções por Deltaretrovirus/veterinária , Infecções por Deltaretrovirus/virologia , Transmissão de Doença Infecciosa , Feminino , Masculino , Mandrillus , Modelos Estatísticos , Síndrome de Imunodeficiência Adquirida dos Símios/epidemiologia , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Carga Viral
15.
Vet Res ; 45: 26, 2014 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-24589193

RESUMO

The role of maternal antibodies is to protect newborns against acute early infection by pathogens. This can be achieved either by preventing any infection or by allowing attenuated infections associated with activation of the immune system, the two strategies being based on different cost/benefit ratios. We carried out an epidemiological survey of myxomatosis, which is a highly lethal infectious disease, in two distant wild populations of rabbits to describe the epidemiological pattern of the disease. Detection of specific IgM and IgG enabled us to describe the pattern of immunity. We show that maternal immunity attenuates early infection of juveniles and enables activation of their immune system. This mechanism associated with steady circulation of the myxoma virus in both populations, which induces frequent reinfections of immune rabbits, leads to the maintenance of high immunity levels within populations. Thus, myxomatosis has a low impact, with most infections being asymptomatic. This work shows that infection of young rabbits protected by maternal antibodies induces attenuated disease and activates their immune system. This may play a major role in reducing the impact of a highly lethal disease when ecological conditions enable permanent circulation of the pathogen.


Assuntos
Imunidade Adaptativa , Imunidade Coletiva , Myxoma virus/fisiologia , Mixomatose Infecciosa/imunologia , Coelhos , Fatores Etários , Animais , Anticorpos Antivirais/sangue , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , França/epidemiologia , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Masculino , Mixomatose Infecciosa/epidemiologia , Mixomatose Infecciosa/virologia
16.
BMC Ecol ; 14: 6, 2014 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-24568541

RESUMO

BACKGROUND: Movements of animals have important consequences, at both the individual and population levels. Due to its important implications in the evolutionary dynamics of populations, dispersal is one of the most studied types of movement. In contrast, non-permanent extra home-range movements are often paid less attention. However, these movements may occur in response to important biological processes such as mating or predation avoidance. In addition, these forays are often preludes to permanent dispersal, because they may help individuals gain cues about their surroundings prior to settlement in a new place.In the European hare, exploration forays occur predominantly in juveniles, the time at which most hares disperse. In France, the timing of dispersal also overlaps with the hare hunting period. However, the determinants of such behaviour have not yet been studied. Herein, we investigate whether these non-permanent explorations are dispersal attempts/preludes or, in contrast, whether they are triggered by other factors such as disturbances related to hunting. RESULTS: Contrary to natal dispersal, we did not find strong male-bias in the propensity to engage in explorations. Exploration forays occurred less in juveniles than in adults and later in the season than natal dispersal. This was the case both for philopatric movements and for movements occurring after dispersal and settlement. These movements were also more likely to occur during the hare hunting period and the mating season. CONCLUSIONS: We suggest that explorations in hares are triggered by factors other than dispersal and that hares may respond to hunting disturbances. Overall, we emphasize the need to account for human-related predation risk as a factor driving space-use in harvested species.


Assuntos
Distribuição Animal , Comportamento Exploratório , Lebres/fisiologia , Animais , Feminino , França , Masculino , Modelos Estatísticos , Dinâmica Populacional
17.
HLA ; 101(1): 3-15, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36258305

RESUMO

In biomedical research, population differences are of central interest. Variations in the frequency and severity of diseases and in treatment effects among human subpopulation groups are common in many medical conditions. Unfortunately, the practices in terms of subpopulation labeling do not exhibit the level of rigor one would expect in biomedical research, especially when studying multifactorial diseases such as cancer or atherosclerosis. The reporting of population differences in clinical research is characterized by large disparities in practices, and fraught with methodological issues and inconsistencies. The actual designations such as "Black" or "Asian" refer to broad and heterogeneous groups, with a great discrepancy among countries. Moreover, the use of obsolete concepts such as "Caucasian" is unfortunate and imprecise. The use of adequate labeling to reflect the scientific hypothesis needs to be promoted. Furthermore, the use of "race/ethnicity" as a unique cause of human heterogeneity may distract from investigating other factors related to a medical condition, particularly if this label is employed as a proxy for cultural habits, diet, or environmental exposure. In addition, the wide range of opinions among researchers does not facilitate the attempts made for resolving this heterogeneity in labeling. "Race," "ethnicity," "ancestry," "geographical origin," and other similar concepts are saturated with meanings. Even if the feasibility of a global consensus on labeling seems difficult, geneticists, sociologists, anthropologists, and ethicists should help develop policies and practices for the biomedical field.


Assuntos
Pesquisa Biomédica , Grupos Populacionais , Humanos , Geografia
18.
Elife ; 122023 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-37773033

RESUMO

Deciphering the mechanism of secondary cell wall/SCW formation in plants is key to understanding their development and the molecular basis of biomass recalcitrance. Although transcriptional regulation is essential for SCW formation, little is known about the implication of post-transcriptional mechanisms in this process. Here we report that two bonafide RNA-binding proteins homologous to the animal translational regulator Musashi, MSIL2 and MSIL4, function redundantly to control SCW formation in Arabidopsis. MSIL2/4 interactomes are similar and enriched in proteins involved in mRNA binding and translational regulation. MSIL2/4 mutations alter SCW formation in the fibers, leading to a reduction in lignin deposition, and an increase of 4-O-glucuronoxylan methylation. In accordance, quantitative proteomics of stems reveal an overaccumulation of glucuronoxylan biosynthetic machinery, including GXM3, in the msil2/4 mutant stem. We showed that MSIL4 immunoprecipitates GXM mRNAs, suggesting a novel aspect of SCW regulation, linking post-transcriptional control to the regulation of SCW biosynthesis genes.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Lignina , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Processamento de Proteína Pós-Traducional , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas
19.
Microorganisms ; 11(2)2023 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-36838358

RESUMO

Although antibiotic resistance is a major issue for both human and animal health, very few studies have investigated the role of the bacterial host spectrum in its dissemination within natural ecosystems. Here, we assessed the prevalence of methicillin resistance among Staphylococcus aureus (MRSA) isolates from humans, non-human primates (NHPs), micromammals and bats in a primatology center located in southeast Gabon, and evaluated the plausibility of four main predictions regarding the acquisition of antibiotic resistance in this ecosystem. MRSA strain prevalence was much higher in exposed species (i.e., humans and NHPs which receive antibiotic treatment) than in unexposed species (micromammals and bats), and in NHP species living in enclosures than those in captivity-supporting the assumption that antibiotic pressure is a risk factor in the acquisition of MRSA that is reinforced by the irregularity of drug treatment. In the two unexposed groups of species, resistance prevalence was high in the generalist strains that infect humans or NHPs, supporting the hypothesis that MRSA strains diffuse to wild species through interspecific transmission of a generalist strain. Strikingly, the generalist strains that were not found in humans showed a higher proportion of MRSA strains than specialist strains, suggesting that generalist strains present a greater potential for the acquisition of antibiotic resistance than specialist strains. The host spectrum is thus a major component of the issue of antibiotic resistance in ecosystems where humans apply strong antibiotic pressure.

20.
PLoS Negl Trop Dis ; 17(7): e0010439, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37486923

RESUMO

Bats are important natural reservoir hosts of a diverse range of viruses that can be transmitted to humans and have been suggested to play an important role in the Zika virus (ZIKV) transmission cycle. However, the exact role of these animals as reservoirs for flaviviruses is still controversial. To further expand our understanding of the role of bats in the ZIKV transmission cycle in Latin America, we carried out an experimental infection in wild-caught Artibeus lituratus bats and sampled several free-living neotropical bats across three countries of the region. Experimental ZIKV infection was performed in wild-caught adult bats (4 females and 5 males). The most relevant findings were hemorrhages in the bladder, stomach and patagium. Significant histological findings included inflammatory infiltrate consisting of a predominance of neutrophils and lymphocytes, in addition to degeneration in the reproductive tract of males and females. This suggests that bat reproduction might be at some level affected by ZIKV. Leukopenia was also observed in some inoculated animals. Hemorrhages, genital alterations, and leukopenia are suggested to be caused by ZIKV; however, since these were wild-caught bats, we cannot exclude other agents. Detection of ZIKV by qPCR was observed at low concentrations in only two urine samples in two inoculated animals. All other animals and tissues tested were negative. Finally, no virus-neutralizing antibodies were found in any animal. To determine ZIKV infection in nature, the blood of a total of 2056 bats was sampled for ZIKV detection by qPCR. Most of the sampled individuals belonged to the genus Pteronotus sp. (23%), followed by the species Carollia sp. (17%), Anoura sp. (14%), and Molossus sp. (13.7%). No sample of any tested species was positive for ZIKV by qPCR. These results together suggest that bats are not efficient amplifiers or reservoirs of ZIKV and may not have an important role in ZIKV transmission dynamics.


Assuntos
Quirópteros , Infecção por Zika virus , Zika virus , Animais , Feminino , Masculino , Costa Rica/epidemiologia , Guiana Francesa/epidemiologia , Peru/epidemiologia , Zika virus/genética , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/veterinária , Infecção por Zika virus/diagnóstico
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