Obscurin is required for ankyrinB-dependent dystrophin localization and sarcolemma integrity

Obscurin is a large myofibrillar protein that contains several interacting modules, one of which mediates binding to muscle-specific ankyrins. Interaction between obscurin and the muscle-specific ankyrin sAnk1.5 regulates the organization of the sarcoplasmic reticulum in striated muscles. Additional muscle-specific ankyrin isoforms, ankB and ankG, are localized at the subsarcolemma level, at which they contribute to the organization of dystrophin and β-dystroglycan at costameres. In this paper, we report that in mice deficient for obscurin, ankB was displaced from its localization at the M band, whereas localization of ankG at the Z disk was not affected. In obscurin KO mice, localization at costameres of dystrophin, but not of β-dystroglycan, was altered, and the subsarcolemma microtubule cytoskeleton was disrupted. In addition, these mutant mice displayed marked sarcolemmal fragility and reduced muscle exercise tolerance. Altogether, the results support a model in which obscurin, by targeting ankB at the M band, contributes to the organization of subsarcolemma microtubules, localization of dystrophin at costameres, and maintenance of sarcolemmal integrity.     

Oligodendrocyte ablation affects the coordinated interaction between granule and Purkinje neurons during cerebellum development

Oligodendrocytes (OLs) are the glial cells of the central nervous system (CNS) classically known to be devoted to the formation of myelin sheaths around most axons of the vertebrate brain. We have addressed the role of these cells during cerebellar development, by ablating OLs in vivo. Previous analyses had indicated that OL ablation during the first six postnatal days results into a striking cerebellar phenotype, whose major features are a strong reduction of granule neurons and aberrant Purkinje cells development. These two cell types are highly interconnected during cerebellar development through the production of molecules that help their proliferation, differentiation and maintenance. In this article, we present data showing that OL ablation has major effects on the physiology of Purkinje (PC) and granule cells (GC). In particular, OL ablation results into a reduction of sonic hedgehog (Shh), Brain Derived Neurotrophic Factor (BDNF), and Reelin (Rln) expression. These results indicate that absence of OLs profoundly alters the normal cerebellar developmental program.     

Evidence for glycosylation on a DNA-binding protein of <Emphasis Type="Italic">Salmonella enterica</Emphasis>

Background  

All organisms living under aerobic atmosphere have powerful mechanisms that confer their macromolecules protection against oxygen reactive species. Microorganisms have developed biomolecule-protecting systems in response to starvation and/or oxidative stress, such as DNA biocrystallization with Dps (DNA-binding protein from starved cells). Dps is a protein that is produced in large amounts when the bacterial cell faces harm, which results in DNA protection. In this work, we evaluated the glycosylation in the Dps extracted from Salmonella enterica serovar Typhimurium. This Dps was purified from the crude extract as an 18-kDa protein, by means of affinity chromatography on an immobilized jacalin column.     

Effects of high-fat diet exposure during fetal life on type 2 diabetes development in the progeny

Nutrition during fetal life is a critical factor contributing to diabetes development in adulthood. The aim of our study was to verify: 1) whether a high-fat (HF) diet in young adult mice induces alterations in beta-cell mass, proliferation, neogenesis, and apoptosis, as well as insulin sensitivity and secretion; 2) whether these alterations may be reversible after HF diet suspension; 3) the effects in a first (F1) and second generation (F2) of mice without direct exposure to a HF diet after birth. Type 2 diabetes developed in adult mice on a HF diet, in F1 mice that were HF diet-exposed during fetal or neonatal life, and in F2 mice whose mothers were HF diet-exposed during their fetal life. beta-cell mass, replication, and neogenesis were high in HF diet-exposed mice and decreased after diet suspension. beta-cell mass and replication remained high in F1 mice and decreased in F2 mice whose mothers were exposed to a HF diet. beta-cell neogenesis was present in adult mice on a HF diet and in F1 mice that were HF diet-exposed during fetal and/or neonatal life. We conclude that a HF diet during fetal life, particularly if combined with the same insult during the suckling period, can induce the type 2 diabetes phenotype, which can be directly transmitted to the progeny even in the absence of additional dietary insults.     

Growth inhibition by glucose oxidase system of enterotoxic Escherichia coli and Salmonella derby: in vitro studies

The antibacterial effect of different glucose oxidase (GOX)/glucose combinations was studied on two food-poisoning organisms, enterotoxic Escherichia coli PM 015 and Salmonella derby BP 177. Growth of E. coli in nutrient broth (NB) was clearly inhibited by 4.0 mg/ml glucose after 24 h when combined with 2.0 U/ml GOX and after 48 h when combined with 0.5 or 1.0 U/ml GOX. Salmonella derby was more resistant than E. coli, but showed clear growth inhibition only after 48 h when inoculated in tubes where 2 mg glucose/ml and 2 U GOX/ml (or 4 mg glucose/ml and 1 U GOX/ml) were combined. In order to understand if the enzyme effect on microbial growth can be attributed to hydrogen peroxide or to pH decrease as a result of the production of gluconic acid, catalase (CAT) was added to GOX/glucose system. Since CAT decomposes H₂O₂ to H₂O and O₂, the antibacterial effect was ascribed to a pH decrease as a result of gluconic acid in the system.     

Complement-mediated in vitro bactericidal activity of monoclonal antibodies reactive with outer-surface-protein OspB of Borrelia burgdorferi

Murine monoclonal antibodies (mAbs) were obtained against the outer-surface-protein OspA and OspB and against the 41-kDa flagellar antigen of Borrelia burgdorferi. The specificity of mAb was determined by the Western blotting technique and the surface association of the antigens was inferred by immunofluorescence of living bacteria. In an in vitro assay in the presence of complement, two mAbs reactive with the Ospa were able to kill borreliae, whereas several mAbs reactive with the OspA as well as with the 41-kDa flagellar protein were not.     

In a human lymphomyeloid progenitor cell line (KG-1) HIV-1 gp120 binds to chemokine-receptors CXC-R4 and CCR5, only in the presence of CD4.

A CD34+ human hematopoietic progenitor cell lines, KG-1, became susceptible to HIV-1 infection in the presence of a concurrent infection by human herpesvirus-6 (HHV-6). We have now analyzed the possible mechanism(s) underlying this phenomenon, in the light of the recent demonstration that at least two members of the chemokine receptor family, CXCR4 (LESTR/fusin) and CCR5 molecules, are the HIV-1-specific co-receptors, necessary, together with the high affinity receptor CD4, for the entry into target cells of HIV-1. Cytofluorimetric analysis demonstrated that in KG-1 cells, after HHV-6 infection, more than 40% of cell population became CD4 positive and only in KG-1 cells expressing the CD4+ phenotype, the exposure to r-gp120 masks a significant amount, not only of CD4, but also of both CXCR4 and CCR5 chemokine receptors. In fact, only when pre-infected by HHV-6, KG-1 cells, after exposure to r-gp120, exhibit a significant reduction in the percentage of CXCR4 or CCR5-positive cells.