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When two species hybridize, the two parental genomes are brought together and some alleles might interact for the first time. To the date, the extent of the transcriptomic changes in first hybrid generations, along with their functional outcome constitute an important knowledge gap especially in non-model organisms. Here we explored the molecular and functional outcomes of hybridization in first-generation hybrid between the blood fluke parasitesS. haematobiumandS. bovis. To this aim we fist assembled a hybrid reference transcriptome allowing us to measure gene expression in both parental species and hybrids to further described and quantified the profiles of gene expression encountered in hybrids. We identified large-scale gene expression remodeling since up to 55% of genes were differentially expressed in hybrids compared to at least one of the parental species. We further showed that intermediate level of expression in hybrids compared to parental species was the most prevalent expression profile (38% of genes) in agreement withS. haematobium x S. bovishigh genomic compatibility and limited divergence. Also, among the differentially expressed genes of each of the identified profiles (intermediate, under-, over-expressed, or matching the expression of one of the parental species), only a few biological processes were found enriched without patterns being consistent through crosses and sexes. Our findings suggest that hybrid heterosis could be due to change in expression of a large portion of random genes which affect various biological processes.Author SummaryWhen two species manage to produce a viable offspring, due to different parental genetic material, new allelic interactions might arise. We do not know much about how genes are expressed in such hybrids compared to their parental species and especially for non-model species. Here we gene expressions in first generation hybrids of two blood flukes’ parasitesSchistosoma haematobiumandS. bovis.We quantified and categorized gene differentially expressed in first generation hybrids. We showed that more than half the genes of the hybrids were differentially expressed compared to at least one of their parental species, hence showing major gene expression remodeling occurring during hybridization. However, the most common hybrid expression pattern was intermediate level of expression compared to parental species and various but no specific biological processes were associated with hybrids differentially expressed genes. We hypothesized that becauseS. haematobiumandS. bovisremain very compatible, when hybridizing many non-specific genes can have their expression level remodeled hence impacting the overall molecular machinery of the offspring while still sustaining highly operational hybrids.

Contrary to the majority of other Trematoda

Background As a major threat to the oyster industry, Pacific Oyster Mortality Syndrome (POMS) is a polymicrobial disease affecting the main oyster species farmed across the world. POMS affects oyster juveniles and became panzootic this last decade, but POMS resistance in some oyster genotypes has emerged. While we know some genetic loci associated with resistance, the underlying mechanisms remained uncharacterized. So, we developed a comparative transcriptomic approach using basal gene expression profiles between different oyster biparental families with contrasted phenotypes when confronted to POMS (resistant or susceptible). Results We showed that POMS resistant oysters show differential expression of genes involved in stress responses, protein modifications, maintenance of DNA integrity and repair, and immune and antiviral pathways. We found similarities and clear differences among different molecular pathways in the different resistant families. These results suggest that the resistance process is polygenic and partially varies according to the oyster genotype. Conclusions We found differences in basal expression levels of genes related to TLR-NFκB, JAK-STAT and STING-RLR pathways. These differences could explain the best antiviral response, as well as the robustness of resistant oysters when confronted to POMS. As some of these genes represent valuable candidates for selective breeding, we propose future studies should further examine their function.

Species usually develop reproductive isolation mechanisms allowing them to avoid interbreeding. These preventive barriers can act before reproduction, “pre-zygotic barriers”, or after reproduction, “post-zygotic barriers”. Pre-zygotic barriers prevent unfavourable mating, while post-zygotic barriers determine the viability and selective success of the hybrid offspring. Hybridization in parasites and the underlying reproductive isolation mechanisms maintaining their genetic integrity have been overlooked. Using an integrated approach this work aims to quantify the relative importance of pre-zygotic barriers in Schistosoma haematobium x S. bovis crosses. These two co-endemic species cause schistosomiasis, one of the major debilitating parasitic diseases worldwide, and can hybridize naturally. Using mate choice experiments we first tested if a specific mate recognition system exists between both species. Second, using RNA-sequencing we analysed differential gene expression between homo- and hetero-specific pairing in male and female adult parasites. We show that homo- and hetero-specific pairing occurs randomly between these two species, and few genes in both sexes are affected by hetero-specific pairing. This suggests that i) mate choice is not a reproductive isolating factor, and that ii) no pre-zygotic barrier except spatial isolation “by the final vertebrate host” seems to limit interbreeding between these two species. Interestingly, among the few genes affected by the pairing status of the worms, some can be related to pathways affected during male and female interactions and may also present interesting candidates for species isolation mechanisms and hybridization in schistosome parasites., Author summary Understanding how species maintain their genetic integrity is a central question in evolutionary biology. While isolation mechanisms are well documented in free-living organisms, it is currently not the case for parasite species. Yet, occurrence of parasite hybrids is a critical global health concern since these hybrids are expected to be more harmful than parental species. We addressed the question of reproductive isolation mechanisms in parasitic species by conducting an integrative experimental study (from mate choice to gene expression) on two schistosome species (Schistosoma haematobium and S. bovis) that parasitize human and cattle, respectively. Importantly, their hybrid progeny has been involved in recent outbreaks, including outbreaks outside of endemic areas. We showed that rather than having a homo-specific mate choice, S. haematobium and S. bovis mate randomly. Also, male and female worms only express a few genes differentially when involved in a hetero-specific pair compared to a homo-specific pair. We consequently suggest that these two schistosome species lack strong reproduction isolation mechanisms, except those imposed by specificity to the final host species. Our results raise the concern that in the absence of post-zygotic barriers in sympatric zones hybridization might be more common than previously thought if these two species are able to encounter each other.

Hybridization is a fascinating evolutionary phenomenon that raises the question of how species maintain their integrity. Inter-species hybridization occurs between certain Schistosoma species that can cause important public health and veterinary issues. In particular hybrids between Schistosoma haematobium and S. bovis associated with humans and animals respectively are frequently identified in Africa. Recent genomic evidence indicates that some S. haematobium populations show signatures of genomic introgression from S. bovis. Here, we conducted a genomic comparative study and investigated the genomic relationships between S. haematobium, S. bovis and their hybrids using 19 isolates originating from a wide geographical range over Africa, including samples initially classified as S. haematobium (n = 11), S. bovis (n = 6) and S. haematobium x S. bovis hybrids (n = 2). Based on a whole genomic sequencing approach, we developed 56,181 SNPs that allowed a clear differentiation of S. bovis isolates from a genomic cluster including all S. haematobium isolates and a natural S. haematobium-bovis hybrid. All the isolates from the S. haematobium cluster except the isolate from Madagascar harbored signatures of genomic introgression from S. bovis. Isolates from Corsica, Mali and Egypt harbored the S. bovis-like Invadolysin gene, an introgressed tract that has been previously detected in some introgressed S. haematobium populations from Niger. Together our results highlight the fact that introgression from S. bovis is widespread across S. haematobium and that the observed introgression is unidirectional., Author summary Hybridization is a fascinating evolutionary phenomenon that raises the question of how species maintain their integrity. Inter-species hybridization occurs between certain Schistosoma species that can cause important public health and veterinary issues. In particular hybrids between Schistosoma haematobium and S. bovis associated with humans and animals respectively are frequently identified in Africa. Recent genomic evidence indicates that some S. haematobium populations show signatures of genomic introgression from S. bovis. Here we conducted a comparative genomic study to assess the genomic diversity within S. haematobium and S. bovis species and genetic differentation at the genome scale between these two sister species over the African continent. We also investigated traces of possible ancient introgression from one species to another. We found that S. haematobium display low genetic diversity compared to S. bovis. We also found that most S. haematobium samples harbor signature of past introgression with S. bovis at some genomic positions. Our results strongly suggest that introgression occurred long time ago and that such introgression is unidirectional from S. bovis within S. haematobium. Such introgresssion event(s) result in diverging patterns of genomic introgression across S. haematobium lineages.

version 2; peer review: 2 approved; International audience; We describe here a protocol for the generation of sequence-ready libraries for population epigenomics studies, and the analysis of alignment results. We show that the protocol can be used to monitor chromatin structure changes in populations when exposed to environmental cues. The protocol is a streamlined version of the Assay for transposase accessible chromatin with high-throughput sequencing (ATAC-seq) that provides a positive display of accessible, presumably euchromatic regions. The protocol is straightforward and can be used with small individuals such as daphnia and schistosome worms, and probably many other biological samples of comparable size (~10,000 cells), and it requires little molecular biology handling expertise.

International audience; To assess the effect of anthropogenic activities on ecosystems, it is of prime importance to develop new tools enabling a rapid characterization of ecological communities. Freshwater ecosystems are particularly impacted and threatened by human activities and need thorough attention to preserve their biodiversity and the ecological services they provide. Studying such ecosystems is generally difficult because the associated organisms are hard to sample and to monitor. We present a ready-to-use environmental metabarcoding protocol to characterize and monitor the freshwater gastropods communities from water samples. The efficiency of this new tool was compared to a classical malacological survey at 19 sampled sites from 10 distinct rivers distributed over Corsica Island (France). From a single water sample, our eDNA monitoring tool provided a faithful characterization of the local malacofauna compared to the results obtained from the classical malacological survey, with 97.1% of species detection confirmed by both methods. The present tool successfully detected the 11 freshwater snail species previously reported in Corsica by malacological survey but was limited at the genus level for some species. Moreover, our malacological survey allowed an update of the local distribution of a wide diversity of freshwater snails including invasive species (i.e. Potamopyrgus antipodarum and Physa acuta) as well as snail hosts of pathogens of medical and veterinary importance (i.e. Bulinus truncatus and Galba truncatula). These results strengthened a previous hypothesis of an eventual competitive interaction between B. truncatus and P. antipodarum that could limit the endemization of the uro-genital bilharziasis in Corsica

Phenotypic plasticity is an important feature of biological systems that is likely to play a major role in the future adaptation of organisms to the ongoing global changes. It may allow an organism to produce alternative phenotypes in responses to environmental cues. Modifications in the phenotype can be reversible but are sometimes enduring and can even span over generations. The notion of phenotypic plasticity was conceptualized in the early 20thcentury by Richard Woltereck. He introduced the idea that the combined relations of a phenotypic character and all environmental gradients that influence on it can be defined as “norm of reaction”. Norms of reaction are specific to species and to lineages within species, and they are heritable. He postulated that reaction norms can progressively be shifted over generations depending on the environmental conditions. One of his biological models was the water-fleedaphnia. Woltereck proposed that enduring phenotypic modifications and gene mutations could have similar adaptive effects, and he postulated that their molecular bases would be different. Mutations occurred in genes, while enduring modifications were based on something he called theMatrix. He suggested that this matrix (i) was associated with the chromosomes, (ii) that it was heritable, (iii) it changed during development of the organisms, and (iv) that changes of the matrix could be simple chemical substitutions of an unknown, but probably polymeric molecule. We reasoned that the chromatin has all postulated features of this matrix and revisited Woltereck’s classical experiments withdaphnia. We developed a robust and rapid ATAC-seq technique that allows for analyzing chromatin of individual daphnia and show here (i) that this technique can be used with minimal expertise in molecular biology, and (ii) we used it to identify open chromatin structure in daphnia exposed to different environmental cues. Our result indicates that chromatin structure changes consistently in daphnia upon this exposure confirming Woltereck’s classical postulate.

While population genetics of Schistosoma haematobium have been investigated in West Africa, only scant data are available from Côte d’Ivoire. The purpose of this study was to analyze both genetic variability and genetic structure among S. haematobium populations and to quantify the frequency of S. haematobium × S. bovis hybrids in school-aged children in different parts of Côte d’Ivoire. Urine samples were subjected to a filtration method and examined microscopically for Schistosoma eggs in four sites in the western and southern parts of Côte d’Ivoire. A total of 2692 miracidia were collected individually and stored on Whatman® FTA cards. Of these, 2561 miracidia were successfully genotyped for species and hybrid identification using rapid diagnostic multiplex mitochondrial cox1 PCR and PCR Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of the nuclear ITS2 region. From 2164 miracidia, 1966 (90.9%) were successfully genotyped using at least 10 nuclear microsatellite loci to investigate genetic diversity and population structure. Significant differences were found between sites in all genetic diversity indices and genotypic differentiation was observed between the site in the West and the three sites in the East. Analysis at the infrapopulation level revealed clustering of parasite genotypes within individual children, particularly in Duekoué (West) and Sikensi (East). Of the six possible cox1-ITS2 genetic profiles obtained from miracidia, S. bovis cox1 × S. haematobium ITS2 (42.0%) was the most commonly observed in the populations. We identified only 15 miracidia (0.7%) with an S. bovis cox1 × S. bovis ITS2 genotype. Our study provides new insights into the population genetics of S. haematobium and S. haematobium × S. bovis hybrids in humans in Côte d’Ivoire and we advocate for researching hybrid schistosomes in animals such as rodents and cattle in Côte d’Ivoire., Alors que la génétique des populations de Schistosoma haematobium a été étudiée en Afrique de l’Ouest, seules quelques données sont disponibles pour la Côte d’Ivoire. Le but de cette étude était d’analyser à la fois la variabilité génétique et la structure génétique des populations de S. haematobium et de quantifier la fréquence des hybrides S. haematobium × S. bovis chez les enfants d’âge scolaire dans différentes régions de la Côte d’Ivoire. Des échantillons d’urine ont été soumis à une méthode de filtration et examinés au microscope pour les œufs de Schistosoma dans quatre sites de l’ouest et du sud de la Côte d’Ivoire. Au total, 2 692 miracidia ont été collectés individuellement et stockés sur des cartes Whatman® FTA. Parmi ceux-ci, 2 561 miracidia ont été génotypés avec succès pour l’identification des espèces et des hybrides à l’aide de la PCR multiplex de diagnostic rapide du cox1 mitochondrial et d’une analyse du polymorphisme de longueur des fragments de restriction de PCR (PCR-RFLP) de la région ITS2 de l’ADN nucléaire. Sur 2 164 miracidia, 1 966 (90,9 %) ont été génotypés avec succès en utilisant au moins 10 loci microsatellites nucléaires pour étudier la diversité génétique et la structure de la population. Des différences significatives ont été trouvées entre les sites dans tous les indices de diversité génétique et une différenciation génotypique a été observée entre le site de l’Ouest et les trois sites de l’Est. L’analyse au niveau de l’infrapopulation a révélé un regroupement des génotypes de parasites au sein de chaque enfant, en particulier à Duekoué (Ouest) et Sikensi (Est). Parmi les six profils génétiques cox1-ITS2 possibles obtenus à partir de miracidia, S. bovis cox1 × S. haematobium ITS2 (42,0 %) était le plus fréquemment observé dans les populations. Nous avons identifié seulement 15 miracidia (0,7 %) avec un génotype S. bovis cox1 × S. bovis ITS2. Notre étude apporte de nouvelles connaissances sur la génétique des populations de S. haematobium et des hybrides S. haematobium × S. bovis chez l’homme en Côte d’Ivoire et nous plaidons pour la recherche de schistosomes hybrides chez les animaux (rongeurs et bovins) en Côte d’Ivoire.

Under ongoing climate changes, the development of large‐scale monitoring tools for assessing the risk of disease emergence constitutes an urging challenge. This is particularly the case for snail‐borne diseases such as the urogenital bilharziasis that emerged in Corsica and threat European countries. The expansion of this tropical disease mainly relies on the local presence of competent snail hosts such as Bulinus truncatus. Unfortunately, very little is known about the actual repartition of freshwater snails worldwide which makes new emergences difficult to predict. In this study, we developed two ready‐to‐use environmental DNA‐based methods for assessing the distribution of B. truncatus from water samples collected in the field. We used two approaches, a quantitative PCR (qPCR) and a droplet digital PCR (ddPCR) approach. We successfully detected B. truncatus in natural environments where the snail was previously visually reported. Our environmental DNA diagnostic methods showed a high sensitivity (≈60 DNA copy per mL of filtered water) and a high specificity to B. truncatus. Results obtained in qPCR and ddPCR were very similar. This study demonstrates that environmental DNA diagnostics tools enable a sensitive large‐scale monitoring of snail‐borne diseases hence allowing the delimitation of areas potentially threatened by urogenital schistosomiasis.

Schistosomiasis is a neglected tropical disease, though it is highly prevalent in many parts of sub-Saharan Africa. While Schistosoma haematobium-bovis hybrids have been reported in West Africa, no data about Schistosoma hybrids in humans are available from Côte d'Ivoire. This study aimed to identify and quantify S. haematobium-bovis hybrids among schoolchildren in four localities of Côte d'Ivoire. Urine samples were collected and examined by filtration to detect Schistosoma eggs. Eggs were hatched and 503 miracidia were individually collected and stored on Whatman(®) FTA cards for molecular analysis. Individual miracidia were molecularly characterized by analysis of mitochondrial cox1 and nuclear internal transcribed spacer 2 (ITS 2) DNA regions. A mitochondrial cox1-based diagnostic polymerase chain reaction was performed on 459 miracidia, with 239 (52.1%) exhibiting the typical band for S. haematobium and 220 (47.9%) the S. bovis band. The cox1 and ITS 2 amplicons were Sanger sequenced from 40 randomly selected miracidia to confirm species and hybrids status. Among the 33 cox1 sequences analysed, we identified 15 S. haematobium sequences (45.5%) belonging to seven haplotypes and 18 S. bovis sequences (54.5%) belonging to 12 haplotypes. Of 40 ITS 2 sequences analysed, 31 (77.5%) were assigned to pure S. haematobium, four (10.0%) to pure S. bovis and five (12.5%) to S. haematobium-bovis hybrids. Our findings suggest that S. haematobium-bovis hybrids are common in Côte d'Ivoire. Hence, intense prospection of domestic and wild animals is warranted to determine whether zoonotic transmission occurs.

Schistosomiasis is a neglected tropical disease, though it is highly prevalent in many parts of sub-Saharan Africa. While Schistosoma haematobium-bovis hybrids have been reported in West Africa, no data about Schistosoma hybrids in humans are available from Côte d'Ivoire. This study aimed to identify and quantify S. haematobium-bovis hybrids among schoolchildren in four localities of Côte d'Ivoire. Urine samples were collected and examined by filtration to detect Schistosoma eggs. Eggs were hatched and 503 miracidia were individually collected and stored on Whatman® FTA cards for molecular analysis. Individual miracidia were molecularly characterized by analysis of mitochondrial cox1 and nuclear internal transcribed spacer 2 (ITS 2) DNA regions. A mitochondrial cox1-based diagnostic polymerase chain reaction was performed on 459 miracidia, with 239 (52.1%) exhibiting the typical band for S. haematobium and 220 (47.9%) the S. bovis band. The cox1 and ITS 2 amplicons were Sanger sequenced from 40 randomly selected miracidia to confirm species and hybrids status. Among the 33 cox1 sequences analysed, we identified 15 S. haematobium sequences (45.5%) belonging to seven haplotypes and 18 S. bovis sequences (54.5%) belonging to 12 haplotypes. Of 40 ITS 2 sequences analysed, 31 (77.5%) were assigned to pure S. haematobium, four (10.0%) to pure S. bovis and five (12.5%) to S. haematobium-bovis hybrids. Our findings suggest that S. haematobium-bovis hybrids are common in Côte d'Ivoire. Hence, intense prospection of domestic and wild animals is warranted to determine whether zoonotic transmission occurs.

15 páginas, 3 figuras y 2 tablas., Environmental and anthropogenic changes are expected to promote emergence and spread of pathogens worldwide. Since 2013, human urogenital schistosomiasis is established in Corsica island (France). Schistosomiasis is a parasitic disease affecting both humans and animals. The parasite involved in the Corsican outbreak is a hybrid form between Schistosoma haematobium, a human parasite, and Schistosoma bovis, a livestock parasite. S. bovis has been detected in Corsican livestock few decades ago raising the questions whether hybridization occurred in Corsica and if animals could behave as a reservoir for the recently established parasite lineage. The latter hypothesis has huge epidemiological outcomes since the emergence of a zoonotic lineage of schistosomes would be considerably harder to control and eradicate the disease locally and definitively needs to be verified. In this study we combined a sero-epidemiological survey on ruminants and a rodent trapping campaign to check whether schistosomes could shift on vertebrate hosts other than humans. A total of 3,519 domesticated animals (1,147 cattle; 671 goats and 1,701 sheep) from 160 farms established in 14 municipalities were sampled. From these 3,519 screened animals, 17 were found to be serologically positive but were ultimately considered as false positive after complementary analyses. Additionally, our 7-day extensive rodent trapping (i.e. 1,949 traps placed) resulted in the capture of a total of 34 rats (Rattus rattus) and 4 mice (Mus musculus). Despite the low number of rodents captured, molecular diagnostic tests showed that two of them have been found to be infected by schistosomes. Given the low abundance of rodents and the low parasitic prevalence and intensity among rodents, it is unlikely that neither rats nor ruminants play a significant role in the maintenance of schistosomiasis outbreak in Corsica. Finally, the most likely hypothesis is that local people initially infected in 2013 re-contaminated the river during subsequent summers, however we cannot definitively rule out the possibility of an animal species acting as reservoir host., JB received a grant from the ANSES (Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail) (https://www.anses.fr/fr). This study is set within the framework of the "Laboratoire d’Excellence (LABEX)" TULIP (ANR-10-LABX-41).

Selective pressures between hosts and their parasites can result in reciprocal evolution or adaptation of specific life history traits. Local adaptation of resident hosts and parasites should lead to increase parasite infectivity/virulence (higher compatibility) when infecting hosts from the same location (in sympatry) than from a foreign location (in allopatry). Analysis of geographic variations in compatibility phenotypes is the most common proxy used to infer local adaptation. However, in some cases, allopatric host-parasite systems demonstrate similar or greater compatibility than in sympatry. In such cases, the potential for local adaptation remains unclear. Here, we study the interaction between Schistosoma and its vector snail Biomphalaria in which such discrepancy in local versus foreign compatibility phenotype has been reported. Herein, we aim at bridging this gap of knowledge by comparing life history traits (immune cellular response, host mortality, and parasite growth) and molecular responses in highly compatible sympatric and allopatric Schistosoma/Biomphalaria interactions originating from different geographic localities (Brazil, Venezuela and Burundi). We found that despite displaying similar prevalence phenotypes, sympatric schistosomes triggered a rapid immune suppression (dual-RNAseq analyses) in the snails within 24h post infection, whereas infection by allopatric schistosomes (regardless of the species) was associated with immune cell proliferation and triggered a non-specific generalized immune response after 96h. We observed that, sympatric schistosomes grow more rapidly. Finally, we identify miRNAs differentially expressed by Schistosoma mansoni that target host immune genes and could be responsible for hijacking the host immune response during the sympatric interaction. We show that despite having similar prevalence phenotypes, sympatric and allopatric snail-Schistosoma interactions displayed strong differences in their immunobiological molecular dialogue. Understanding the mechanisms allowing parasites to adapt rapidly and efficiently to new hosts is critical to control disease emergence and risks of Schistosomiasis outbreaks., Author summary Schistosomiasis, the second most widespread human parasitic disease after malaria, is caused by helminth parasites of the genus Schistosoma. More than 200 million people in 74 countries suffer from the pathological, and societal consequences of this disease. To complete its life cycle, the parasite requires an intermediate host, a freshwater snail of the genus Biomphalaria for its transmission. Given the limited options for treating Schistosoma mansoni infections in humans, much research has focused on developing methods to control transmission by its intermediate snail host. Biomphalaria glabrata. Comparative studies have shown that infection of the snail triggers complex cellular and humoral immune responses resulting in significant variations in parasite infectivity and snail susceptibility, known as the so-called polymorphism of compatibility. However, studies have mostly focused on characterizing the immunobiological mechanisms in sympatric interactions. Herein we used a combination of molecular and phenotypic approaches to compare the effect of infection in various sympatric and allopatric evolutionary contexts, allowing us to better understand the mechanisms of host-parasite local adaptation. Learning more about the immunobiological interactions between B. glabrata and S. mansoni could have important socioeconomic and public health impacts by changing the way we attempt to eradicate parasitic diseases and prevent or control schistosomiasis in the field.

International audience; Schistosomiasis is frequently detected in persons entering Europe. In 2017, we detected a Schistosoma mansoni-Schistosoma haematobium hybrid parasite infection in a migrant boy from Côte d'Ivoire entering France. Because such parasites might be established in Europe, as illustrated by an outbreak on Corsica Island, vectors of these parasites should be investigated.

Table S1. Details of the schistosomes from different cows that were molecularly characterized using the nuclear ITS and mitochondrial cox1 markers. (DOCX 13 kb)

Figure S2. Mitochondrial cox1 maximum likelihood tree based of the S. bovis samples. The code for each sample corresponds to the sampling site-the animal number-the sex of the schistosome (M or F) and the parasite number. (DOCX 21 kb)

Figure S1. ΔK-values calculated by Evanno’s method detecting K = 2 and K = 4 subpopulations as the most genetically probable within the 14 loci analyzed. (DOCX 32 kb)

International audience; The grey partridge Perdix perdix is an important gamebird in Europe. Its numbers have decreased dramatically during the XXth century and releases are commonly undertaken for the conservation of the populations and/or hunting purposes in Western Europe. However, this practice that generally involves birds from commercial farms raises several concerns, among which a potential hybridization between farmed and wild individuals. Herein, based on microsatellite markers, we characterize the genetic patterns of farmed birds in view of wild birds of the two French subspecies (P. p. armoricana in centralnorthern France and P. p. hispaniensis in the Pyrenees). Hence, we estimate the risk of genetic introgression between wild and farmed birds. Our results highlight a genetic divergence between both subspecies-in accordance with the known evolutionary history of the grey partridge during the Quaternary. In central-northern France, a slight but significant difference in the genetic signature between wild and farmed partridges is detected. This difference however does not seem prone to alter the gene pool of wild birds if farmed birds are released in the wild and reproduce. On the contrary, in the Pyrenees, the large and significant genetic difference between wild and farmed birds represents a real risk of genetic introgression. This threat should be taken into account in population management.

Background Schistosomiasis is neglected tropical parasitic disease affecting both humans and animals. Due to the human health impact, population genetic studies have focused on the three main human-infecting schistosome species: Schistosoma mansoni, S. haematobium and S. japonicum. Here we present novel data on the population genetic structure of Schistosoma bovis, a highly widespread and prevalent schistosome infecting ruminants, and therefore of veterinary importance. Methods Adult S. bovis were sampled in the two main abattoirs of Cameroon (Yaoundé and Douala). Twenty-two cows originating from four distinct localities were sampled and a total of 218 parasites were recovered. All parasites were genotyped using a panel of 14 microsatellite markers and a sub-sample of 91 parasites were sequenced and characterized with the mitochondrial (cox1) and nuclear (ITS) genetic markers. Results No significant difference in allelic richness, heterozygosity, nucleotide diversity and haplotype diversity was observed between the populations. Additionally, no strong genetic structure was observed at the country scale. Our data also show that S. bovis is more polymorphic than its sister species, S. haematobium, and that the haplotype diversity is similar to that of S. mansoni while the nucleotide diversity does not significantly differ from that of S. haematobium. The resulting negative Tajima’s D* and Fu and Li’s D* indices could be a signature of population demographic expansion. No S. haematobium/S. bovis hybrids were observed in our populations, thus all samples were considered as pure S. bovis. Conclusions This study provides novel insights into genetic diversity and population genetic structure of S. bovis. No strong genetic structure was observed at the country scale but some genetic indices could be associated as a signature of population demographic expansion. Electronic supplementary material The online version of this article (10.1186/s13071-019-3307-0) contains supplementary material, which is available to authorized users.

Schistosomes cause schistosomiasis, the world’s second most important parasitic disease after malaria. A peculiar feature of schistosomes is their ability to produce viable and fertile hybrids. Originally only present in the tropics, schistosomiasis is now also endemic in Europe. Based on two genetic markers the European species had been identified as a hybrid between the ruminant-infective Schistosoma bovis and the human-infective Schistosoma haematobium.Here we describe for the first time the genomic composition of the European schistosome hybrid (77% of S. haematobium and 23% of S. bovis origins), its morphometric parameters and its compatibility with the European vector snail and intermediate host Compatibility is a key parameter for the parasites life cycle progression. We also show that egg morphology (a classical diagnostic parameter) does not allow for differential diagnosis while genetic tests do so. Additionally, we performed genome assembly improvement and annotation of S. bovis, the parental species for which no satisfactory genome assembly was available.For the first time since the discovery of hybrid schistosomes, these results reveal at the whole genomic level a complex admixture of parental genomes highlighting (i) the high permeability of schistosomes to other species’ alleles, and (ii) the importance of hybrid formation for pushing species boundaries not only conceptionally but also geographically.

International audience; Indoplanorbis exustus is a freshwater snail known as the intermediate host of various trematode parasites, including different species of the genus Schistosoma. Although its genetic diversity is well described in Asia, the phylogenetic diversity of strains from Africa and Guadeloupe (French West Indies) and their relationship to Asian and SouthEast Asian strains remain unknown. To tackle this issue, we sampled individuals from Africa and Guadeloupe, and we computed phylogenetic reconstructions using five molecular markers: partial sequences of two mitochondrial genes, cox1 and 16S, and three nuclear markers, ITS1, ITS2 (Internal Transcribed Spacer 1 and 2) and 5.8S. Our results suggest that strains in Africa and Guadeloupe come from Asia and that they all belong to a single clade that is widespread around the globe.

International audience; Schistosomiasis due to Schistosoma haematobium is a widespread disease usually affecting the urinary tract associated with hematuria and kidney disorders. Neurological damage is rarely reported and symptoms are nonspecific and may suggest brain tumors such as glioma. We describe the first double ectopic haematobium schistosomiasis case involving the brain and intestine.

International audience; Hyalomma scupense (Acari, Ixodidae) is a common tick species found in several areas in North Africa, Asia and South Europe and an efficient natural vector of bovine tropical theileriosis (Theileria annulata), a livestock disease with an important economic impact. For one year, 1938 ticks were collected on cattle in several Corsican slaughterhouses; 168 of them were morphologically identified as H. scupense. This result was confirmed by genetic identification using sequences of mitochondrial cytochrome c oxidase subunit I (COI) and ribosomal internal transcribed spacer 2 (ITS2) genes. The presence of 2 different stages (adults and nymphs), collected in various areas of the island, indicates that a population of H. scupense is established in Corsica. However, bovine tropical theileriosis has not been diagnosed on the island so far.

International audience; The Dmrt (Double sex/Male-abnormal-3 Related Transcription factor) genes have been intensively studied because they represent major transcription factors in the pathways governing sex determination and differentiation. These genes have been identified in animal groups ranging from cnidarians to mammals, and some of the genes functionally studied. Here, we propose to analyze (i) the presence/absence of various Dmrt gene groups in the different taxa across the animal kingdom; (ii) the relative expression levels of the Dmrt genes in each sex; (iii) the specific spatial (by organ) and temporal (by developmental stage) variations in gene expression. This review considers non-mammalian animals at all levels of study (i.e. no particular importance is given to animal models), and using all types of sexual strategy (hermaphroditic or gonochoric) and means of sex determination (i.e. genetic or environmental). To conclude this global comparison, we offer an analysis of the DM domains conserved among the different DMRT proteins, and propose a general sex-specific pattern for each member of the Dmrt gene family

Seven cases of urogenital schistosomiasis occurred in Corsica in 2015 and 2016. The episodes were related to exposure to the same river and involved the same parasite strain as an outbreak with 106 cases in summer 2013. The connection calls for further investigations on the presence of an animal reservoir and the survival of infested snails during winter. However, recontamination of the river from previously infected bathers remains the most likely hypothesis. Since 2015, seven cases of urogenital schistosomiasis reported exposure to the Cavu river in southern Corsica. They had no history of contact to fresh water in endemic areas. Here, we describe the cases indicating persistent schistosomal transmission linked to this river since 2013. To date, no contamination has been related to an exposure in 2017, but cases might arise in the coming months considering the long parasitic cycle in humans. Therefore, physicians in France and elsewhere should test possible clinical cases, regardless of the year of exposure to the Cavu river.