Wolbachia Age-Sex-Specific Density in Aedes albopictus: A Host Evolutionary Response to Cytoplasmic Incompatibility?

Wolbachia bacteria have invaded many arthropod species by inducing Cytoplasmic Incompatibility (CI). These symbionts represent fascinating objects of study for evolutionary biologists, but also powerful potential biocontrol agents. Here, we assess the density dynamics of Wolbachia infections in males and females of the mosquito Aedes albopitcus, an important vector of human pathogens, and interpret the results within an evolutionary framework.Wolbachia densities were measured in natural populations and in age controlled mosquitoes using quantitative PCR. We show that the density dynamics of the wAlbA Wolbachia strain infecting Aedes albopictus drastically differ between males and females, with a very rapid decay of infection in males only.Theory predicts that Wolbachia and its hosts should cooperate to improve the transmission of infection to offspring, because only infected eggs are protected from the effects of CI. However, incompatible matings effectively lower the fertility of infected males, so that selection acting on the host genome should tend to reduce the expression of CI in males, for example, by reducing infection density in males before sexual maturation. The rapid decay of one Wolbachia infection in Aedes albopictus males, but not in females, is consistent with this prediction. We suggest that the commonly observed reduction in CI intensity with male age reflects a similar evolutionary process. Our results also highlight the importance of monitoring infection density dynamics in both males and females to assess the efficiency of Wolbachia-based control strategies

Malaria risk in Corsica, former hot spot of malaria in France

Background: The prevalence of Plasmodium falciparum and Plasmodium vivax malaria was very high in Corsica just before the Second World War. The last outbreak was in 1972 and the most recent indigenous case was in 2006. Results: Analysis of historical data shows that anopheline vectors were abundant. Recent surveys demonstrated that potential vectors are still present in Corsica, despite the likely disappearance of Anopheles sacharovi. Moreover, P. falciparum can develop experimentally into these mosquitoes, notably Anopheles labranchiae, which is locally abundant, and parasites are regularly introduced into the island. Discussion, Conclusions: The presence of vectors, the introduction of parasites and the conducive climate raise questions about the possibility of malaria re-emerging and becoming re-established in Corsica. Analysis of historic and current parasitological and entomological data shows that the current theoretical risk of indigenous cases or malaria foci is negligible, particularly since there is very little contact between humans and Anopheles mosquitoes, Plasmodium carriers are reliably treated and there is a widespread vector control on the island

Evaluation of intersectoral collaborations : "Relevailles" and intersectoral collaborations. Brief Report.

HIGHLIGHTS • In 3 of the 4 cases, the key actor in the collaborative network was the OCF coordinator/liaison officer. • All the networks were vulnerable to the departure of a key actor. • Collaborative networks did not include any perinatal assistants. • 35 of the 37 HSSE actors involved in collaborative networks belonged to a local community services centre (CLSC), even when there was a birthing hospital or birthing centre in the HSSE. • Five determinants contributed to or constrained intersectoral collaborations between OCFs and HSSEs. • Sufficiency of resources, knowledge of the partner organization, and complementarity/flexibility in the delivery of services were determinants of collaborations. • Six modes of OCF/HSSE collaboration were identified. • There are few formal mechanisms for collaboration between organizations. • Disagreements/misunderstandings on the mechanisms for sharing information about families occurred between organizations and even within organizations. • Some parents perceived links between OCFs and CLSCs as falling into two modes of collaboration, namely 1) activating the request/recourse to partner organization services and 2) coordinating the services provided to families

Genetic and phenotypic variation of the malaria vector Anopheles atroparvus in southern Europe

<p>Abstract</p> <p>Background</p> <p>There is a growing concern that global climate change will affect the potential for pathogen transmission by insect species that are vectors of human diseases. One of these species is the former European malaria vector, <it>Anopheles atroparvus</it>. Levels of population differentiation of <it>An. atroparvus </it>from southern Europe were characterized as a first attempt to elucidate patterns of population structure of this former malaria vector. Results are discussed in light of a hypothetical situation of re-establishment of malaria transmission.</p> <p>Methods</p> <p>Genetic and phenotypic variation was analysed in nine mosquito samples collected from five European countries, using eight microsatellite loci and geometric morphometrics on 21 wing landmarks.</p> <p>Results</p> <p>Levels of genetic diversity were comparable to those reported for tropical malaria vectors. Low levels of genetic (0.004 <<it>F</it>_{<it>ST </it>}<0.086) and phenotypic differentiation were detected among <it>An. atroparvus </it>populations spanning over 3,000 km distance. Genetic differentiation (0.202 <<it>F</it>_{<it>ST </it>}<0.299) was higher between the sibling species <it>An. atroparvus </it>and <it>Anopheles maculipennis </it>s.s. Differentiation between sibling species was not so evident at the phenotype level.</p> <p>Conclusions</p> <p>Levels of population differentiation within <it>An. atroparvus </it>were low and not correlated with geographic distance or with putative physical barriers to gene flow (Alps and Pyrenées). While these results may suggest considerable levels of gene flow, other explanations such as the effect of historical population perturbations can also be hypothesized.</p

Life on Arginine for Mycoplasma hominis: Clues from Its Minimal Genome and Comparison with Other Human Urogenital Mycoplasmas

Mycoplasma hominis is an opportunistic human mycoplasma. Two other pathogenic human species, M. genitalium and Ureaplasma parvum, reside within the same natural niche as M. hominis: the urogenital tract. These three species have overlapping, but distinct, pathogenic roles. They have minimal genomes and, thus, reduced metabolic capabilities characterized by distinct energy-generating pathways. Analysis of the M. hominis PG21 genome sequence revealed that it is the second smallest genome among self-replicating free living organisms (665,445 bp, 537 coding sequences (CDSs)). Five clusters of genes were predicted to have undergone horizontal gene transfer (HGT) between M. hominis and the phylogenetically distant U. parvum species. We reconstructed M. hominis metabolic pathways from the predicted genes, with particular emphasis on energy-generating pathways. The Embden–Meyerhoff–Parnas pathway was incomplete, with a single enzyme absent. We identified the three proteins constituting the arginine dihydrolase pathway. This pathway was found essential to promote growth in vivo. The predicted presence of dimethylarginine dimethylaminohydrolase suggested that arginine catabolism is more complex than initially described. This enzyme may have been acquired by HGT from non-mollicute bacteria. Comparison of the three minimal mollicute genomes showed that 247 CDSs were common to all three genomes, whereas 220 CDSs were specific to M. hominis, 172 CDSs were specific to M. genitalium, and 280 CDSs were specific to U. parvum. Within these species-specific genes, two major sets of genes could be identified: one including genes involved in various energy-generating pathways, depending on the energy source used (glucose, urea, or arginine) and another involved in cytadherence and virulence. Therefore, a minimal mycoplasma cell, not including cytadherence and virulence-related genes, could be envisaged containing a core genome (247 genes), plus a set of genes required for providing energy. For M. hominis, this set would include 247+9 genes, resulting in a theoretical minimal genome of 256 genes

Recently introduced Aedes albopictus in Corsica is competent to Chikungunya virus and in a lesser extent to dengue virus

International audienceAedes albopictus has been established in Europe for some decades rendering temperate countries vulnerable to tropical diseases. The Italian chikungunya (CHIK) outbreak in the summer of 2007 demonstrated that indigenous transmission of CHIK was possible in Europe. To estimate the risk of a CHIK outbreak in Corsica, we assessed the vector competence of A. albopictus established in the island since 2006 towards a CHIK variant (E1-A226V). A dengue serotype 2 virus was also tested. Experimental infections showed that A. albopictus was highly competent to CHIK virus (disseminated infection rates ranging from 75% to 100%) and to a lesser extent, to dengue virus (12.5-68.8%). Moreover, A. albopictus ensured a high level of viral replication and was able to transmit the virus as early as 2 days after ingestion of infected blood with around 1,000 viral RNA available in salivary glands. The risk for a local transmission of CHIK is thus likely in Corsica, if other parameters determining the vector capacity of A. albopictus are suitable.Aedes albopictus ha estado establecido en Europa durante algunas décadas convirtiendo a países con climas templados en vulnerables frente a enfermedades tropicales. El brote de chikungunya (CHIK) italiano durante el verano del 2007, demostró que la trasmisión indígena de CHIK era posible en Europa. Para estimar el riesgo de un brote de CHIK en Córcega, hemos evaluado la competencia del vector Ae. albopictus estabecido en la isla desde el 2006 frente a una variante CHIK (E1-A226V). También se evaluó el serotipo 2 del virus del dengue. La infección experimental mostró que Ae. albopictus era altamente competente para el virus CHIK (tasas de infección diseminada entre el 75% y 100%) y en menor grado al virus del dengue (12.5% a 68.8%). Más aún, Ae. albopictus aseguró un alto nivel de replicación viral y fue capaz de transmitir el virus de forma temprana, dos días tras la ingestión de sangre infectada, con alrededor de 1,000 copias de ARN viral disponibles en las glándulas salivares. El riesgo de transmisión local de CHIK es por lo tanto posible en Córcega, si se cumplen otros parámetros que determinan la capacidad vectorial de Ae. albopictus.Aedes albopictus a été introduit en Europe depuis quelques décennies, rendant les pays tempérés vulnérables aux maladies tropicales. L’épidémie de chikungunya italien (CHIK) au cours de l’été 2007 a démontré que la transmission indigène du CHIK était possible en Europe. Afin d’estimer le risque d’une épidémie de CHIK en Corse, nous avons évalué la compétence du vecteur Ae. albopictusétabli dans l’île depuis 2006 pour une variante de CHIK (E1-A226V). Un sérotype 2 du virus de la dengue a également été testé. Des infections expérimentales ont montré que Ae. albopictusétait très compétent pour le virus CHIK (taux d’infection disséminée allant de 75%à 100%) et dans une moindre mesure, pour le virus de la dengue (12,5%à 68,8%). En outre, Ae. albopictus assurait un niveau élevé de réplication virale et était en mesure de transmettre le virus au plus tôt, deux jours après l’ingestion de sang infecté avec environ 1000 ARN viraux dans les glandes salivaires. Le risque d’une transmission locale du CHIK est donc probable en Corse, si d’autres paramètres déterminant la capacité du vecteur Ae. albopictus sont convenables

Exploring the medical cannabis prescribing behaviors of French general practitioners

International audienc

Exploring the medical cannabis prescribing behaviors of French general practitioners

International audienc

Exploring the medical cannabis prescribing behaviors of French general practitioners

International audienc