M-phase regulation of the recruitment of mRNAs onto polysomes using the CDK1/cyclin B inhibitor aminopurvalanol

Translation under the control of the universal cell cycle regulator CDK1/cyclin B was investigated during the first cell cycle in sea urchin embryos. The CDK1/cyclin B inhibitor aminopurvalanol arrested embryos at the G2/M transition. Polysomal mRNAs were purified from control and arrested embryos, and screened for specific mRNA recruitment or release at M-phase by subtractive hybridization. The polysomal repartition of clones issued from this screen was analyzed. Three specific mRNAs were selectively recruited onto polysomes at M-phase. Conversely, two other specific mRNAs were released from polysomes. The isolation of these translationally regulated mRNAs gives now important tools for insights into the regulation of protein synthesis by the cell cycle regulator CDK1-cyclin B.     

Cellular and humoral responses to collagen-polyvinylpyrrolidone administered during short and long periods in humans

Collagen, particularly type I, and its related derivatives have been extensively employed in many areas of pharmacology. The present study was performed to determine the safety of collagen-polyvinylpyrrolidone (collagen-PVP) by in vitro and in vivo studies. Sera and peripheral blood cells from healthy donors without treatment and patients treated with collagen-PVP were evaluated. We observed that the biodrug does not stimulate lymphoproliferation or DNA damage in vitro, nor does it induce human anti-porcine type I collagen or anti-collagen-PVP antibodies in vivo. Furthermore, no hepatic or renal metabolic dysfunctions were observed when collagen-PVP was administered by intradermal or intramuscular routes in short- or long-term treatments. In conclusion, the present work shows that no cellular damage or immunological adverse effects (cellular and humoral) occurred during collagen-PVP treatment, even after more than 400 weeks of consecutive administrations.     

Characterization of non-cytoplasmic incompatibility inducing Wolbachia in two continental African populations of Drosophila simulans

Wolbachia is an endocellular bacterium infecting arthropods and nematodes. In arthropods, it invades host populations through various mechanisms, affecting host reproduction, the most common of which being cytoplasmic incompatibility (CI). CI is an embryonic mortality occurring when infected males mate with uninfected females or females infected by a different Wolbachia strain. This phenomenon is observed in Drosophila simulans, an intensively studied Wolbachia host, harbouring at least five distinct bacterial strains. In this study, we investigate various aspects of the Wolbachia infections occurring in two continental African populations of D. simulans: CI phenotype, phylogenetic position based on the wsp gene and associated mitochondrial haplotype. From the East African population (Tanzania), we show that (i) the siIII mitochondrial haplotype occurs in continental populations, which was unexpected based on the current views of D. simulans biogeography, (ii) the wKi strain (that rescues from CI while being unable to induce it) is very closely related to the CI-inducing strain wNo, (iii) wKi and wNo might not derive from a unique infection event, and (iv) wKi is likely to represent the same entity as the previously described wMa variant. In the West African population (Cameroon), the Wolbachia infection was found identical to the previously described wAu, which does not induce CI. This finding supports the view that wAu might be an ancient infection in D. simulans.     

Association of vitamin D receptor polymorphisms with osteoporosis in mexican postmenopausal women

It has been reported that Vitamin D receptor polymorphisms are associated with osteoporosis, particularly those demonstrated by the BsmI and FokI restriction enzymes. Herein we report the results of a case-control study performed in postmenopausal Mexican women. We studied 65 osteoporotic women (< or = -2.5 SD bone mineral density [BMD] of young normal females) and 57 controls (over 90% > or = -1.5 SD BMD of young normal females. Restriction enzymes BsmI and FokI were used to identify polymorphisms. Odds ratios and their 95% confidence intervals were calculated, and analysis was performed controlling for age as a covariate. The BsmI genotypes revealed a higher frequency of the bb genotype in cases than in controls, contradicting much of the literature that suggests this genotype protects females against osteoporosis. Regarding the FokI genotypes, we were unable to confirm that the FF genotype has a protective effect against osteoporosis. The inconsistencies found in the literature and the results obtained in the present work suggest to us that other genetic and nongenetic factors are involved in the occurrence of osteoporosis, confounding the results of the possible association of osteoporosis and VDR polymorphisms.     

Bacillus subtilis ResA is a thiol-disulfide oxidoreductase involved in cytochrome c synthesis

Covalent attachment of heme to apocytochromes c in bacteria occurs on the outside of the cytoplasmic membrane and requires two reduced cysteinyls at the heme binding site. A constructed ResA-deficient Bacillus subtilis strain was found to lack c-type cytochromes. Cytochrome c synthesis was restored in the mutant by: (i) in trans expression of resA; (ii) deficiency in BdbD, a thiol-disulfide oxidoreductase that catalyzes formation of an intramolecular disulfide bond in apocytochrome c after transfer of the polypeptide across the cytoplasmic membrane; or (iii) by addition of the reductant dithiothreitol to the growth medium. In vivo studies of ResA showed that it is membrane-associated with its thioredoxin-like domain on the outside of the cytoplasmic membrane. Analysis of a soluble form of the protein revealed two redox reactive cysteine residues with a midpoint potential of about -340 mV at pH 7. We conclude that ResA, probably together with another thiol-disulfide oxidoreductase, CcdA, is required for the reduction of the cysteinyls in the heme binding site of apocytochrome c.