Genetic variation and population structure of the carpet shell clam <Emphasis Type="Italic">Ruditapes decussatus</Emphasis> along the Tunisian coast inferred from mtDNA and ITS1 sequence analysis

Surveys of allozyme polymorphisms in the carpet shell clam Ruditapes decussatus have revealed sharp genetic differentiation of populations. Analysis of population structure in this species has now been extended to include nuclear and mitochondrial genes. A partial sequence of a mitochondrial COI gene and of the internal transcribed spacer region (ITS-1) were used to study haplotype distribution, the pattern of gene flow, and population genetic structure of R. decussatus. The samples were collected from twelve populations from the eastern and western Mediterranean coasts of Tunisia, one from Concarneau and one from Thau. A total of twenty and twenty-one haplotypes were detected in the examined COI and ITS1 regions respectively. The study revealed higher levels of genetic diversity for ITS1 compared to COI. The analysis of haplotype frequency distribution and molecular variation indicated that the majority of the genetic variation was distributed within populations (93% and 86% for COI and ITS1 respectively). No significant differentiation was found among eastern and western groups on either side of the Siculo-Tunisian strait. However, distinct and significant clinal changes in haplotypes frequencies between eastern and western samples were found at the most frequent COI haplotype and at three out of five major ITS1 haplotypes. These results suggest the relative importance of historical processes and contemporary hydrodynamic features on the observed patterns of genetic structure.     

Silymarin, a natural antioxidant, protects cerebral cortex against manganese-induced neurotoxicity in adult rats

Manganese (Mn) is an essential element for biological systems, nevertheless occupational exposure to high levels of Mn can lead to neurodegenerative disorders, characterized by serious oxidative and neurotoxic effects with similarities to Parkinson’s disease. The aim of this study was to investigate the potential effects of silymarin (SIL), an antioxidant flavonoid, against manganese chloride induced neurotoxicity both in vivo (cerebral cortex of rats) and in vitro (Neuro2a cells). Twenty-eight male Wistar rats were randomly divided into four groups: the first group (C) received vehicle solution (i.p.) served as controls. The second group (Mn) received orally manganese chloride (20 mg/ml). The third group (Mn + SIL) received both Mn and SIL. The fourth group (SIL) received only SIL (100 mg/kg/day, i.p.). Animals exposed to Manganese chloride showed a significant increase in TBARS, NO, AOPP and PCO levels in cerebral cortex. These changes were accompanied by a decrease of enzymatic (SOD, CAT, GPx) and non-enzymatic (GSH, NpSH, Vit C) antioxidants. Co-administration of silymarin to Mn-treated rats significantly improved antioxidant enzyme activities and attenuated oxidative damages observed in brain tissue. The potential effect of SIL to prevent Mn induced neurotoxicity was also reflected by the microscopic study, indicative of its neuroprotective effects. We concluded that silymarin possesses neuroprotective potential, thus validating its use in alleviating manganese-induced neurodegenerative effects.     

Human articular chondrocytes express ChemR23 and chemerin; ChemR23 promotes inflammatory signalling upon binding the ligand chemerin<Superscript>21-157</Superscript>

Introduction  

Chemerin is a chemotactic peptide which directs leukocytes expressing the chemokine-like receptor ChemR23 towards sites of inflammation. ChemR23 is a G protein-coupled receptor which binds several different ligands, and it is also expressed by other cell types such as adipocytes. In addition to chemotaxis, recent reports suggest that ChemR23 is capable of mediating either inflammatory or anti-inflammatory effects, depending on the type of ligand it binds. In the present study, we aimed to clarify whether human chondrocytes express ChemR23 and chemerin, and whether chemerin/ChemR23 signalling could affect secretion of inflammatory mediators.     

Immune recovery after allogeneic stem cell transplantation: study of 19 patients

The aim of this study was to access average delays for novogeneration of myeloid and lymphoid cells after allogeneic bone marrow transplantation (BMT) outcome and factors affecting this organization. A prospective analysis over 2 years (01/01/07 to 31/12/08) enrolling 19 children treated with allogeneic intrafamilial bone marrow transplantation. Indications for bone marrow transplantation were: aplastic anemia (3 cases), bemoglobinopathies (9 cases), myelodysplastic syndrome (1 case) and primary immunodeficiency (6 cases). Different conditioning regiments were used according to the indication. The study of immune reconstitution was based on the quantitative determination of immunoglobulin and lymphocyte subpopulation. These tests were routinely requested to 1 month, 2 months, 3 months, 6 months, 9 months and 12 months. The average time of engraftment was 18 days (12-24). A rate of CD4+T lymphocytes>200/mm3 was provided within an average of 2,5 months (1-7). The average time to obtain CD8+T lymphocytes>200/mm3 was 2 months (1-5). The humoral immune reconstitution was made within an average of 2 months (1-4). A report of CD4+/CD8+T lymphocytes>I was obtained within 10 months and a half (1-24). Univaried analysis showed a correlation between the bone marrow sex matched and the faster reorganization of CD8+T cells (p=0.042). A quantity of CD34+>6 10(6)/kg was significantly associated with the recapture of a formula lymphocyte CD4+/CD8+T>1 (p=0.03) Immune recovery post bone marrow transplantation in children begins with myeloid lineage then lymphoid B then lymphoid T The inversion of the report CD4+/CD8+T lymphocytes, seems to be influenced by the high contain of CD34+cells in the graft as well as the type of conditioning.     

Effect of vertebrate and invertebrate kairomones on the life history of Daphnia magna Straus (Crustacea: Branchiopoda)

The history of selection of Daphnia magna populations living in North African temporary ponds may differ from populations inhabiting permanent ponds. Laboratory experiments were conducted to examine the effect of fish Gambusia holbrooki and invertebrate Notonecta glauca kairomones on the life history traits of the freshwater Cladocera Daphnia magna Straus. With fish kairomones, Daphnia reproduced early and had a significantly smaller size at first reproduction (SFR) and a smaller size of neonates compared to control. In contrast, daphnids reared in water treated with Notonecta glauca had no effect on the age at first reproduction but females were also smaller and produced smaller neonates.     

Prednisolone-Loaded PLGA Microspheres. <Emphasis Type="BoldItalic">In Vitro</Emphasis> Characterization and <Emphasis Type="BoldItalic">In Vivo</Emphasis> Application in Adjuvant-Induced Arthritis in Mice

This study aimed at preparation of a sustained-release steroidal treatment for chronic inflammatory conditions, such as rheumatoid arthritis. To achieve such a goal, biodegradable poly-lactide-co-glycolide prednisolone-loaded microspheres were prepared using o/w emulsion solvent evaporation method. Formulation parameters were adjusted so as to optimize the microsphere characteristics. The prepared microspheres exhibited smooth and intact surfaces, with average size range not exceeding 65 μm. The encapsulation efficiency percent of most microsphere formulations fell within the range of 25–68%. Drug release from these microspheres took place over 4 weeks, with near-to-zero-order patterns. Two successful formulations were chosen for the treatment of unilateral arthritis, induced in mice using Freund's complete adjuvant (FCA). Inflammatory signs of adjuvant arthritis included severe swelling of the FCA-injected limbs, in addition to many histopathological lesions. These included inflammatory cell infiltration, synovial hyperplasia, cartilage, and bone erosion. Parenteral administration of the selected formulae dramatically reduced the swelling of the FCA-injected limbs. In addition, histological examination revealed that the microsphere treatment protocol efficiently protected cartilages and bones of mice, injected with FCA initial and booster doses, from erosion. These results could not be achieved by a single prednisolone dose of 5 mg/kg.     

Identification of trkH,Encoding a Potassium Uptake Protein Required for Francisella tularensis Systemic Dissemination in Mice

Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularaemia. During its infectious cycle, F. tularensis is not only exposed to the intracellular environment of macrophages but also resides transiently in extracellular compartments, in particular during its systemic dissemination. The screening of a bank of F. tularensis LVS transposon insertion mutants on chemically defined medium (CDM) led us to identify a gene, designated trkH, encoding a homolog of the potassium uptake permease TrkH. Inactivation of trkH impaired bacterial growth in CDM. Normal growth of the mutant was only restored when CDM was supplemented with potassium at high concentration. Strikingly, although not required for intracellular survival in cell culture models, TrkH appeared to be essential for bacterial virulence in the mouse. In vivo kinetics of bacterial dissemination revealed a severe defect of multiplication of the trkH mutant in the blood of infected animals. The trkH mutant also showed impaired growth in blood ex vivo. Genome sequence analyses suggest that the Trk system constitutes the unique functional active potassium transporter in both tularensis and holarctica subspecies. Hence, the impaired survival of the trkH mutant in vivo is likely to be due to its inability to survive in the low potassium environment (1–5 mM range) of the blood. This work unravels thus the importance of potassium acquisition in the extracellular phase of the F. tularensis infectious cycle. More generally, potassium could constitute an important mineral nutrient involved in other diseases linked to systemic dissemination of bacterial pathogens.     

Potential of yeasts as biocontrol agents of soil-borne fungal plant pathogens and as plant growth promoters

Among soil microorganisms, yeasts have received little attention as biocontrol agents of soil-borne fungal plant pathogens in comparison to bacterial, actinomycetes, and filamentous fungal antagonists. The mechanisms of action of potential antagonism by yeasts in relation to soil-borne fungal plant pathogens are expected to be similar to those involved with pathogens of aerial parts of the plant, including leaves and fruits. Several taxa of yeasts have been recorded as endophytes in plants, with a small proportion recorded to promote plant growth. The ability of certain taxa of yeasts to multiply rapidly, to produce antibiotics and cell wall-degrading enzymes, to induce resistance of host tissues, and to produce plant growth regulators indicates the potential to exploit them as biocontrol agents and plant growth promoters. More than ten genera of yeasts have been used to control postharvest diseases, especially of fruits. Suppression of classes of fungal pathogens of fruits and foliage that are similar to those associated with soil-borne fungal root pathogens, strongly suggests that yeasts also have potential for the biological control of diseases caused by soil-borne fungal plant pathogens, as is evident in reports of certain yeasts in suppressing some soil-borne fungal plant pathogens. This review explores the potential of soil yeasts to suppress a wider range of soil-borne fungal plant pathogens and to promote plant growth.     

Notes on Soil Ciliates (Protozoa, Ciliophora) from The Netherlands, with Description of Keronopsis schminkei nov. spec. and Apobryophyllum schmidingeri nov. spec

Fifty-six ciliate taxa, including three new species, were found in two soil samples from the Hoge Veluwe National Park in The Netherlands. A literature search showed that The Netherlands, Belgium and Denmark are terra incognita with respect to soil ciliates: only about 100 species have been recorded. Likely, a much greater number, including many undescribed species, can be found on more detailed investigations. Two of the three new species are described in detail. Keronopsis schminkei nov. spec. differs from the congeners by the nuclear apparatus and cirral pattern. Keronopsis wetzeli?Wenzel, 1953 is neotypified with the Austrian population described by Berger and Foissner (1987). Apobryophyllum schmidingeri differs from the congeners by body shape, the macronucleus pattern (many nodules), the arrangement of the extrusomes, and various morphometric features. Scanning electron micrographs and protargol preparations of Enchelys polynucleata confirm earlier transmission electron microscopic data on the occurrence of oralized somatic monokinetids and the lack of a circumoral kinety. Extrusome length and morphology of the resting cysts are rather different in various populations of E. polynucleata, indicating high genetic diversity (subspecies?).