The Immune Cellular Effectors of Terrestrial Isopod Armadillidium vulgare: Meeting with Their Invaders, Wolbachia

Most of crustacean immune responses are well described for the aquatic forms whereas almost nothing is known for the isopods that evolved a terrestrial lifestyle. The latter are also infected at a high prevalence with Wolbachia, an endosymbiotic bacterium which affects the host immune system, possibly to improve its transmission. In contrast with insect models, the isopod Armadillidium vulgare is known to harbor Wolbachia inside the haemocytes.In A. vulgare we characterized three haemocyte types (TEM, flow cytometry): the hyaline and semi-granular haemocytes were phagocytes, while semi-granular and granular haemocytes performed encapsulation. They were produced in the haematopoietic organs, from central stem cells, maturing as they moved toward the edge (TEM). In infected individuals, live Wolbachia (FISH) colonized 38% of the haemocytes but with low, variable densities (6.45±0.46 Wolbachia on average). So far they were not found in hyaline haemocytes (TEM). The haematopoietic organs contained 7.6±0.7×10(3)Wolbachia, both in stem cells and differentiating cells (FISH). While infected and uninfected one-year-old individuals had the same haemocyte density, in infected animals the proportion of granular haemocytes in particular decreased by one third (flow cytometry, Pearson's test = 12 822.98, df = 2, p<0.001).The characteristics of the isopod immune system fell within the range of those known from aquatic crustaceans. The colonization of the haemocytes by Wolbachia seemed to stand from the haematopoietic organs, which may act as a reservoir to discharge Wolbachia in the haemolymph, a known route for horizontal transfer. Wolbachia infection did not affect the haemocyte density, but the quantity of granular haemocytes decreased by one third. This may account for the reduced prophenoloxidase activity observed previously in these animals

Einstein, l'autre regard

Conçu dans le cadre de l'exposition " Einstein ,l'autre regard " ( Bruxelles ,Tour et Taxis ,de décembre 2005 au 1er mai 2006 ) ,ce dossier pédagogique comporte plusieurs leçons et articles sur Albert Einstein ,la physique et l'exposition .Il a notamment pour objectif de permettre aux professeurs de diverses disciplines ( sciences ,mathématique ,histoire ,morale ,sciences sociales ,) de préparer des cours portant sur l'homme Einstein ,son époque, ses découvertes et son impact .On y trouvera ,entre autres ,des chapitres consacrés aux relations entre Einstein et la Belgique ,à la physique au 19ème siècle et au temps d'Einstein ,à la naissance de la mécanique quantique ,à la relativité restreinte ,à la relativité générale et au Big bang .Le dossier est le fruit d'une collaboration entre plusieurs professeurs d'université ( des scientifiques de ULB et de la VUB ) ,des pédagogues et des enseignants du secondaire .info:eu-repo/semantics/publishedAuteur Collectif de scientifiques VUB et ULB TEMPORA S.A.Editeur scientifique asbl e=mc23 DE GREVE Jean-Pierre TYTGAT MichelValidateur Université libre de Bruxelles VU

Feminization of the Isopod Cylisticus convexus after Transinfection of the wVulC Wolbachia Strain of Armadillidium vulgare.

Reproductive parasites such as Wolbachia are able to manipulate the reproduction of their hosts by inducing parthenogenesis, male-killing, cytoplasmic incompatibility or feminization of genetic males. Despite extensive studies, no underlying molecular mechanism has been described to date. The goal of this study was to establish a system with a single Wolbachia strain that feminizes two different isopod species to enable comparative analyses aimed at elucidating the genetic basis of feminization. It was previously suggested that Wolbachia wVulC, which naturally induces feminization in Armadillidium vulgare, induces the development of female secondary sexual characters in transinfected Cylisticus convexus adult males. However, this does not demonstrate that wVulC induces feminization in C. convexus since feminization is the conversion of genetic males into functional females that occurs during development. Nevertheless, it suggests that C. convexus may represent a feminization model suitable for further development. Knowledge about C. convexus sexual differentiation is also essential for comparative analyses, as feminization is thought to take place just before or during sexual differentiation. Consequently, we first described gonad morphological differentiation of C. convexus and compared it with that of A. vulgare. Then, wVulC was injected into male and female C. convexus adult individuals. The feminizing effect was demonstrated by the combined appearance of female secondary sexual characters in transinfected adult males, as well as the presence of intersexes and female biases in progenies in which wVulC was vertically transmitted from transinfected mothers. The establishment of a new model of feminization of a Wolbachia strain in a heterologous host constitutes a useful tool towards the understanding of the molecular mechanism of feminization

Savene® (dexrazoxane) use in clinical practice

Introduction Anthracycline extravasation (ACEV) is a rare but potentially devastating event which can result in severe injuries including ulceration and necrosis, slow-healing lesions, serious joint damage and permanent disfigurement. It can delay further scheduled chemotherapy and affect cancer treatment outcome. Savene (R) (dexrazoxane) is the only approved antidote for ACEV in Europe (Totect (R) in the USA) and is administered by intravenous infusion. Its efficacy has been demonstrated in clinical trials with biopsy-verified ACEV with a 98% success rate (no need for surgical debridement) allowing for immediate continuation of chemotherapy in 71% of patients. Adverse events, mainly haematological toxicity, were rapidly reversible. The objective of the study was to assess, in clinical practice, the efficacy and safety profile of Savene (R) for ACEV in different Belgian hospitals. Patients and methods A survey of Savene (R) use was conducted in Belgium from 2007 to 2010 by using a questionnaire sent to 44 hospitals. Main results Data were obtained for 41 cancer patients, 68% (28/41) had ACEV from central venous catheters. Surgical debridement due to ACEV could be avoided in 26 out of 28 extravasations from a central venous access and in 95% (39/41) of the total population treated with Savene (R). Planned chemotherapy was maintained in 73% (30/41) of patients. Eight adverse events were reported in four patients treated with Savene (R), six events were assessed to be of common toxicity criteria grades 1-2 (nausea, leucopenia and arm pain) and two events (neutropenia and pancytopenia) were assessed to be grade 3. Conclusion These data are comparable with the data from previous clinical trials and confirm the efficacy and safety profile of Savene (R) in clinical practice for the treatment of anthracycline extravasation, including extravasations from central venous catheters

Signs of Neutralization in a Redundant Gene Involved in Homologous Recombination in Wolbachia Endosymbionts

International audienceGenomic reduction in bacterial endosymbionts occurs through large genomic deletions and long-term accumulation of mutations. The latter process involves successive steps including gene neutralization, pseudogenization, and gradual erosion until complete loss. Although many examples of pseudogenes at various levels of degradation have been reported, neutralization cases are scarce because of the transient nature of the process. Gene neutralization may occur due to relaxation of selection in nonessential genes, for example, those involved in redundant functions. Here, we report an example of gene neutralization in the homologous recombination (HR) pathway of Wolbachia, a bacterial endosymbiont of arthropods and nematodes. The HR pathway is often depleted in endosymbiont genomes, but it is apparently intact in some Wolbachia strains. Analysis of 12 major HR genes showed that they have been globally under strong purifying selection during the evolution of Wolbachia strains hosted by arthropods, supporting the evolutionary importance of the HR pathway for these Wolbachia genomes. However, we detected signs of recent neutralization of the ruvA gene in a subset of Wolbachia strains, which might be related to an ancestral, clade-specific amino acid change that impaired DNA-binding activity. Strikingly, RuvA is part of the RuvAB complex involved in branch migration, whose function overlaps with the RecG helicase. Although ruvA is experiencing neutralization, recG is under strong purifying selection. Thus, our high phylogenetic resolution suggests that we identified a rare example of targeted neutralization of a gene involved in a redundant function in an endosymbiont genome

Gonad intersexual morphology of progenies produced by transinfected <i>C</i>. <i>convexus</i> females.

<p>Observed with binocular magnifiers in adult progenies (50X) (a-c) and by light microscopy during sexual differentiation (100X: d; 200X: e-g) at stage 3 (e), stage 5 (d,f) and stage 6 (g). HAG = hypertrophied androgenic gland, AG = androgenic gland, Oo = oocyte, SV = seminal vesicle, T = testis, vd = <i>vas deverens</i>, Ov = oviduct.</p

Gonad morphology of transinfected adult <i>C</i>. <i>convexus</i> males observed with binocular magnifiers (50X).

<p>(a) With magnification of the hypertrophied androgenic glands (b) and a genital aperture on the ventral face (indicated with a white arrow, at c). As a control, gonad morphology of Ringer-injected <i>C</i>. <i>convexus</i> males (d) with magnification of a normal androgenic gland (e) and the absence of genital apertures (highlighted by a white circle, at f). T = testis, SV = seminal vesicle, HAG = hypertrophied androgenic gland, vd = <i>vas deferens</i>, AG = androgenic gland.</p

Investigating the Molecular Genetic Basis of Cytoplasmic Sex Determination Caused by Wolbachia Endosymbionts in Terrestrial Isopods

In animals, sexual differences between males and females are usually determined by sex chromosomes. Alternatively, sex may also be determined by vertically transmitted intracellular microbial endosymbionts. The best known cytoplasmic sex manipulative endosymbiont is Wolbachia which can, for instance, feminize genetic males into phenotypic females in the terrestrial isopod Armadillidium vulgare. However, the molecular genetic basis of cytoplasmic sex determination is unknown. To identify candidate genes of feminization induced by Wolbachia strain wVulC from A. vulgare, we sequenced the genome of Wolbachia strain wCon from Cylisticus convexus, the most closely related known Wolbachia strain to wVulC that does not induce feminization, and compared it to the wVulC genome. Then, we performed gene expression profiling of the 216 resulting wVulC candidate genes throughout host developmental stages in A. vulgare and the heterologous host C. convexus. We identified a set of 35 feminization candidate genes showing differential expression during host sexual development. Interestingly, 27 of the 35 genes are present in the f element, which is a piece of a feminizing Wolbachia genome horizontally transferred into the nuclear genome of A. vulgare and involved in female sex determination. Assuming that the molecular genetic basis of feminization by Wolbachia and the f element is the same, the 27 genes are candidates for acting as master sex determination genes in A. vulgare females carrying the f element

Sexual differentiation timing in <i>A. vulgare</i> and in <i>C. convexus</i>.

<p>Gonad status is indicated above the stage number. <i>C</i>. <i>convexus</i> sexual differentiation begins one stage earlier than that of <i>A</i>. <i>vulgare</i> and lasts for the same number of stages.</p