Ultrastructure des spermatozoïdes mûrs de trois Bucephalidae (Prosorhynchus longisaccatus, Rhipidocotyle khalili et Bucephalus margaritae) et implications phylogénétiques.

International audienceWe describe here the mature spermatozoa of three species of bucephalids, namely Bucephalus margar-itae, Rhipidocotyle khalili and Prosorhynchus longisaccatus. This study provides the first ultrastructural data on the genera Bucephalus and Rhipidocotyle and enabled us to confirm the model of the mature spermatozoon in the Bucephalinae. The spermatozoon exhibits two axonemes with the 9 + ''1'' pattern of the Trepaxonemata, one of which is very short, lateral expansion, external ornamentation of the plasma membrane located in the anterior extremity of the spermatozoon and associated with cortical microtubules, spine-like bodies, a mitochondrion, and a nucleus. The maximum number of cortical microtubules is located in the anterior part of the spermatozoon. However, more studies are needed to elucidate if spine-like bodies are present in all the Bucephalinae or not. In the Prosorhynchinae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the ax-oneme lengths and the arrangement of the spine-like bodies. The posterior extremity of the spermatozoon in the Bucephalinae exhibits only the nucleus, but prosorhynchines have microtubules.Dans cette étude, nous décrivons les spermatozoïdes mûrs de trois espèces de bucephalidés, à savoir Bucephalus margaritae, Rhipidocotyle khalili et Prosorhynchus longisaccatus. Ces premières données ultrastructurales pour les genres Bucephalus et Rhipidocotyle nous ont permis de confirmer le modèle du spermatozoïde chez les Bucephalinae. Le spermatozoïde comprend deux axonèmes de type 9 + ‘‘1’’ des Trepaxonemata, l’un d’entre eux étant très court, une expansion latérale, une ornementation externe de la membrane plasmique située au niveau de l’extrémité antérieure du spermatozoïde et associée avec des microtubules corticaux, des corps en forme d’épines, une mitochondrie et un noyau. Le nombremaximum de microtubules corticaux est situé dans la partie antérieure du spermatozoïde. Toutefois, des études supplémentaires seraient nécessaires pour vérifier si les corps en forme d’épines sont présents chez tous les Bucephalinae. Chez les Prosorhynchinae, le spermatozoïde mûr présente une structure similaire. Quelques différences sont toutefois observées, notamment au niveau de la longueur des axonèmes et de la disposition des corps en forme d’épines. L’extrémité postérieure du spermatozoïde chez les Bucephalidae est caractérisée par la présence du noyau seul, alors que les Prosorhynchinae ont des microtubules

Toxoplasmosis and Chagas disease : report of severe cases of troops in French Guiana and review on foodborne mode of transmission in Amazonia

In contrast with the usual clinical feature of toxoplasmosis, a cosmopolitan disease, severe cases with visceral disorders have been reported in non-immunocompromised adult patients, particularly in French Guiana. Most of the cases seem to result from the consumption of undercooked game meat or ingestion of non-filtered surface water. In Amazonia, a sylvatic cycle of toxoplasmosis involves large felids as definitive hosts and numerous mammals and birds as intermediate hosts. Atypical strains of Toxoplasma gondii, characterized by increased virulence, are involved in these complex cycles. Although Chagas disease, caused by another protozoan parasite, Trypanosoma cruzi, has been known for a long time, a new foodborne mode of transmission to man seems to emerge. Several outbreaks have been reported, mainly in Brasil, resulting from the contamination of food items by infected Triatominae or their dejections. When food or water are taken from the natural environment, measures have to be implemented in order to prevent these serious diseases.Contrastant avec la toxoplasmose habituelle, maladie cosmopolite, des formes sévères avec atteinte viscérale sont apparues chez des patients adultes non immunodéprimés, notamment en Guyane française. La consommation de viande de gibier mal cuite ou l'ingestion d'eau de surface non filtrée semblent être à l'origine de la plupart des cas. En Amazonie, un cycle sylvestre de la toxoplasmose s'établit entre les grands félidés hôtes définitifs et de nombreux mammifères et oiseaux, hôtes intermédiaires. Dans ces cycles complexes, circulent des souches atypiques de Toxoplasma gondii, caractérisées par une virulence accrue. Bien que la maladie de Chagas, provoquée par un autre protozoaire, Trypanosoma cruzi, soit connue de longue date, le mode de transmission à l'homme par la voie alimentaire semble émerger. Plusieurs foyers sont rapportés, surtout au Brésil, résultant de la contamination de denrées par des Triatominae infectées ou leurs déjections. Lorsque des ressources en aliments ou en eau sont prélevées dans le milieu naturel, des mesures sont à appliquer pour prévenir l'apparition de ces maladies graves

First spermatological study in the Atractotrematidae (Digenea, Haploporoidea): the case of Atractotrema sigani, intestinal parasite of Siganus lineatus

The ultrastructural organization of the mature spermatozoon of the digenean Atractotrema sigani(from Siganus lineatus off New Caledonia) was investigated by transmission electron microscopy. The male gamete of A. sigani exhibits the general morphology described in digeneans with the presence of two axonemes of different lengths showing the 9 + '1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies and granules of glycogen. However, the mature spermatozoon of A. sigani has some specific characters such as the morphology of its anterior region and the submembranous electron-dense material. Although similar structures have been reported in some digenean species, the presence of a submembranous electron-dense material describing a complete ring is reported here for the first time in the mature spermatozoon of A. sigani. In addition, sperm characteristics are compared between the Haploporoidea and their supposed close superfamilies, and possible phylogenetic implications of these findings for the Digenea are discussed

The abcc6a Gene Expression Is Required for Normal Zebrafish Development

Pseudoxanthoma elasticum (PXE) is caused by mutations in the ABCC6 gene, which encodes a putative efflux transporter, ABCC6. The zebrafish (Danio rerio) has two ABCC6-related sequences. To study the function of abcc6 during zebrafish development, the mRNA expression levels were measured using RT-PCR and in situ hybridization. The abcc6a showed a relatively high level of expression at 5 days post-fertilization (d.p.f.) and the expression was specific to the Kupffer's vesicles. The abcc6b expression was evident at 6hours post-fertilization (h.p.f.) and remained high up to 8 d.p.f., corresponding to embryonic kidney proximal tubules. Morpholinos were designed to both genes to prevent pre-mRNA splicing and block translation. Injection of the abcc6a morpholinos into 1–4 cell zebrafish embryos decreased gene expression by 54–81%, and induced a phenotype, pericardial edema and curled tail associated with death at around 8 d.p.f. Microinjecting zebrafish embryos with full-length mouse Abcc6 mRNA together with the morpholino completely rescued this phenotype. No phenotypic changes were observed when the abcc6b gene morpholino was injected into embryos with knock-down efficiency of 100%. These results suggest that abcc6a is an essential gene for normal zebrafish development and provide insight into the function of ABCC6, the gene mutated in PXE

West Nile Virus in Horses, sub-Saharan Africa

To evaluate the presence and extension of West Nile virus where French soldiers are stationed in Africa, specific antibody prevalence was determined by using ELISA and Western blot. Among 245 horses living in close proximity to the soldiers, seroprevalence was particularly high in Chad (97%) and Senegal (92%)

Are vertebrates reservoir hosts for rickettsia?

Rickettsiae sensu stricto are the bacteria from the genus Rickettsia. Many of them are responsible for human arthropod-borne (fleas, lice, ticks, mites) diseases. One hundred years after having detected rats as reservoirs of Rickettsia typhi, it is important to assemble the current knowledge on the role of vertebrates in the rickettsial epidemiology. For the agent of Mediterranean spotted fever, R. conorii, dogs are thought to be an intermittent reservoir. R. rickettsii, the agent of Rocky Mountain spotted fever, is capable of infecting dogs, although, in this case they are most likely accidental hosts ; wild animals are the more probable reservoirs. R. felis is the cause of emerging spotted fever in humans ; studies showed that opossums in the USA may be its reservoir. Finally, hematophagous arthropods are considered to be the principal vectors and reservoirs for rickettsiae, although vertebrates may be secondary reservoirs in particular ecosystems that favour the persistence of rickettsiae and in which humans may become accidentally infected.Les rickettsies, sensu stricto, sont des bactéries du genre Rickettsia. Elles sont responsables de maladies humaines transmises par des arthropodes (puces, poux, tiques, acariens). Cent ans après la mise en évidence de l’agent du typhus (Rickettsia typhi) ayant comme réservoir le rat, il est important de faire un point des connaissances concernant le rôle des vertébrés dans le cycle des rickettsies. Pour R. conorii, agent de la fièvre boutonneuse méditerranéenne, le chien est considéré comme un réservoir intermittent. R. rickettsii, agent de la fièvre pourprée des montagnes rocheuses, infecte le chien qui joue plus un rôle de sentinelle que de réservoir, celui-ci étant dévolu à des animaux sauvages. Parmi les rickettsioses émergentes, la fièvre boutonneuse à puces due à R. felis fait l’objet d’études en particulier aux États-Unis où l’opossum est suspecté d’être un réservoir. En plus des arthropodes hématophages vecteurs et réservoirs principaux, les vertébrés constituent bien des réservoirs secondaires dans des écosystèmes donnés qui permettent la persistance des rickettsies et dans lesquels l’homme peut s’infecter accidentellement

Association of CD99 short and long forms with MHC class I, MHC class II and tetraspanin CD81 and recruitment into immunological synapses

<p>Abstract</p> <p>Background</p> <p>CD99, a leukocyte surface glycoprotein, is broadly expressed in many cell types. On the cell surface, CD99 is expressed as two distinct isoforms, a long form and a short form. CD99 has been demonstrated to play a key role in several biological processes, including the regulation of T cell activation. However, the molecular mechanisms by which CD99 participates in such processes are unclear. As CD99 contains a short cytoplasmic tail, it is unlikely that CD99 itself takes part in its multi-functions. Association of CD99 with other membrane proteins has been suggested to be necessary for exerting its functions.</p> <p>Results</p> <p>In this study, we analyzed the association of CD99 with other cell surface molecules involved in T cell activation. We demonstrate the association of MHC class I, MHC class II and tetraspanin CD81 with CD99 molecules on the cell surface. Association of CD99 with its partners was observed for both isoforms. In addition, we determined that CD99 is a lipid raft-associated membrane protein and is recruited into the immunologic synapse during T cell activation. The implication of CD99 on T cell activation was investigated. Inhibition of anti-CD3 induced T cell proliferation by an anti-CD99 monoclonal antibody was observed.</p> <p>Conclusions</p> <p>We provide evidence that CD99 directly interact and form the complex with the MHC class I and II, and tetraspanin CD81, and is functionally linked to the formation of the immunologic synapse. Upon T cell activation, CD99 engagement can inhibit T cell proliferation. We speculate that the CD99-MHC-CD81 complex is a tetraspanin web that plays an important role in T cell activation.</p

Measurement Report: Firework Impacts on Air Quality in Metro Manila, Philippines, during the 2019 New Year Revelry

Fireworks degrade air quality, reduce visibility, alter atmospheric chemistry, and cause short-term adverse health effects. However, there have not been any comprehensive physicochemical and optical measurements of fireworks and their associated impacts in a Southeast Asia megacity, where fireworks are a regular part of the culture. Size-resolved particulate matter (PM) measurements were made before, during, and after New Year 2019 at the Manila Observatory in Quezon City, Philippines, as part of the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex). A high-spectral-resolution lidar (HSRL) recorded a substantial increase in backscattered signal associated with high aerosol loading ∼440 m above the surface during the peak of firework activities around 00:00 (local time). This was accompanied by PM2.5 concentrations peaking at 383.9 µg m−3. During the firework event, water-soluble ions and elements, which affect particle formation, growth, and fate, were mostly in the submicrometer diameter range. Total (\u3e0.056 µm) water-soluble bulk particle mass concentrations were enriched by 5.7 times during the fireworks relative to the background (i.e., average of before and after the firework). The water-soluble mass fraction of PM2.5 increased by 18.5 % above that of background values. This corresponded to increased volume fractions of inorganics which increased bulk particle hygroscopicity, kappa (κ), from 0.11 (background) to 0.18 (fireworks). Potassium and non-sea-salt (nss) SO42- role= presentation style= box-sizing: border-box; border-radius: 0px; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3e2−4 contributed the most (70.9 %) to the water-soluble mass, with their mass size distributions shifting from a smaller to a larger submicrometer mode during the firework event. On the other hand, mass size distributions for NO3- role= presentation style= box-sizing: border-box; border-radius: 0px; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3e−3, Cl−, and Mg2+ (21.1 % mass contribution) shifted from a supermicrometer mode to a submicrometer mode. Being both uninfluenced by secondary aerosol formation and constituents of firework materials, a subset of species were identified as the best firework tracer species (Cu, Ba, Sr, K+, Al, and Pb). Although these species (excluding K+) only contributed 2.1 % of the total mass concentration of water-soluble ions and elements, they exhibited the highest enrichments (6.1 to 65.2) during the fireworks. Surface microscopy analysis confirmed the presence of potassium/chloride-rich cubic particles along with capsule-shaped particles in firework samples. The results of this study highlight how firework emissions change the physicochemical and optical properties of water-soluble particles (e.g., mass size distribution, composition, hygroscopicity, and aerosol backscatter), which subsequently alters the background aerosol\u27s respirability, influence on surroundings, ability to uptake gases, and viability as cloud condensation nuclei (CCN)

Coxiella burnetii Infection in Livestock, Pets, Wildlife, and Ticks in Latin America and the Caribbean: a Comprehensive Review of the Literature

Purpose of the Review Q fever , a bacterial zoonosis caused by Coxiella burnetii, is reported very heterogeneously in humans in Latin America. The objective of this study was to review the data on Coxiella burnetii Infection in animals in Latin America and the Caribbean. Recent Findings A comprehensive literature review was carried out in the 47 countries and territories of Latin America on various search engines and grouped into four groups: livestock, pets, wildlife, and ticks. Summary Thus, 113 studies were selected between 1950 and 2022. Among the 47 countries, only 25 (53%) had at least one publication related to C. burnetii infection in animals. The most productive country was Brazil (N = 51), followed by French Guiana (N = 21), and Colombia (N = 16). Studies in livestock from 20 countries have shown widely varying country-to-country rates of seroprevalence, ranging from 0 to 67%. Some studies from seven countries, especially French Guiana and Brazil, found antibodies and sometimes positive PCR in dogs and cats, generally in the context of investigations around human clustered cases. Knowledge remained fragmented about infection in wildlife from only five countries (Chile, Colombia, Brazil, French Guiana, and Uruguay). C. burnetii infection was identified by PCR in Chiroptera (7 species), Rodentia (6 species), Suina (2 species), Xenartha (1 species), Cingulata (1 species), and Perissodactyla (1 species). Studies on Coxiella sp. in ticks have been performed in 11 countries, mostly in Brazil, and mainly found Coxiella-like endosymbionts. Thus, data on C. burnetii infection in animals are sparse and incomplete in Latin America and the Caribbean, and more research is warranted