Immunoglobulin classes in aquatic mammals. Characterization by serologic cross-reactivity, molecular size and binding of human free secretory component.

On the basis of serologic cross-reactivity, three immunoglobulin classes homologous to human IgG, IgM and IgA were identified in two species of acquatic mammal representing the orders Cetacea (dolphin) and Pinnipedea (sea lion). Molecular size was estimated by sucrose density gradient ultracentrifugation and Sephadex G-200 chromatography, indicating a 7S IgG, 19S IgM and heterogeneous serum IgA. Human secretory component was readily bound to the IgM of both species and to an apparently lesser extent to the larger molecular size populations of IgA. No binding was observed with IgG. Several antisera specific for human γ-chains gave a single precipitin line with the sea lion IgG but when made to react with dolphin serum produced two lines, suggesting the presence of two different subclasses of IgG in this species.

Mutations in the cdc10 start gene of Schizosaccharomyces pombe implicate the region of homology between cdc10 and SWI6 as important for p85cdc10 function.

The cdc10 gene of the fission yeast Schizosaccharomyces pombe is required for traverse of start and commitment to the mitotic cell division cycle rather than other fates. The product of the gene, p85cdc10, is a component of a factor that is thought to be involved in regulating the transcription of genes that are required for DNA synthesis. In order to define regions of the p85cdc10 protein that are important for its function a fine structure genetic map of the cdc10 gene was derived and the sequences of 13 cdc10ts mutants determined. The 13 mutants tested define eight alleles. Eleven of the mutants are located in the region that contains the two copies of the cdc10/SWI6 repeat motif, implicating it as important for p85cdc10 function.

Relations entre le poids la fécondité des reines de fourmis récemment accouplées et leur mode de fondation

Schématiquement on distingue chez les fourmis deux modes principaux de fondation des nouvelles sociétés: la fondation indépendante et la fondation dépendante. Ces deux stratégies entraînent des particularités biologiques importantes. On a étudié dans le présent travail les conséquences du type de fondation sur la fécondité des jeunes reines. Chez les reines monogynes des espèces à fondation indépendante (Camponotus ligniperda, Camponotus herculeanus, Lasius niger), on observe une fécondité d'abord très faible puis qui augmente ensuite régulièrement avec le temps. Chez les reines polygynes des espèces à fondation dépendante (Plagiolepis pygmaea, Iridomyrmex humilis), la fécondité atteint pratiquement son niveau maximal dans les semaines qui suivent l'accouplement. Ces différences dans le niveau de l'activité ovarienne sont confrontées à l'espérance de vie des femelles. ll apparaît que les espèces monogynes à fondation indépendante ont une durée de vie de plusieurs années; leur fécondité ne s'exprimera pleinement qu'au bout de plusieurs saisons d'activité. A l'inverse, les reines polygynes à fondation dépendante ont une vie bien plus courte; elles compensent ce handicap par une ponte qui atteint son niveau maximal dès la fondation.

PIDD orchestrates translesion DNA synthesis in response to UV irradiation.

PIDD has been implicated in survival and apoptotic pathways in response to DNA damage, and a role for PIDD was recently identified in non-homologous end-joining (NHEJ) repair induced by γ-irradiation. Here, we present an interaction of PIDD with PCNA, first identified in a proteomics screen. PCNA has essential functions in DNA replication and repair following UV irradiation. Translesion synthesis (TLS) is a process that prevents UV irradiation-induced replication blockage and is characterized by PCNA monoubiquitination and interaction with the TLS polymerase eta (polη). Both of these processes are inhibited by p21. We report that PIDD modulates p21-PCNA dissociation, and promotes PCNA monoubiquitination and interaction with polη in response to UV irradiation. Furthermore, PIDD deficiency leads to a defect in TLS that is associated, both in vitro and in vivo, with cellular sensitization to UV-induced apoptosis. Thus, PIDD performs key functions upon UV irradiation, including TLS, NHEJ, NF-κB activation and cell death.

Role of the stress sigma factor RpoS in GacA/RsmA-controlled secondary metabolism and resistance to oxidative stress in Pseudomonas fluorescens CHA0.

In Pseudomonas fluorescens biocontrol strain CHA0, the two-component system GacS/GacA positively controls the synthesis of extracellular products such as hydrogen cyanide, protease, and 2,4-diacetylphloroglucinol, by upregulating the transcription of small regulatory RNAs which relieve RsmA-mediated translational repression of target genes. The expression of the stress sigma factor sigmaS (RpoS) was controlled positively by GacA and negatively by RsmA. By comparison with the wild-type CHA0, both a gacS and an rpoS null mutant were more sensitive to H2O2 in stationary phase. Overexpression of rpoS or of rsmZ, encoding a small RNA antagonistic to RsmA, restored peroxide resistance to a gacS mutant. By contrast, the rpoS mutant showed a slight increase in the expression of the hcnA (HCN synthase subunit) gene and of the aprA (major exoprotease) gene, whereas overexpression of sigmaS strongly reduced the expression of these genes. These results suggest that in strain CHA0, regulation of exoproduct synthesis does not involve sigmaS as an intermediate in the Gac/Rsm signal transduction pathway whereas sigmaS participates in Gac/Rsm-mediated resistance to oxidative stress.

Synthesis and characterization of a new class of anti-angiogenic agents based on ruthenium clusters.

New triruthenium-carbonyl clusters derivatized with glucose-modified bicyclophosphite ligands have been synthesized. These compounds were found to have cytostatic and cytotoxic activity and depending on the number of bicyclophosphite ligands, and could be tuned for either anti-cancer or specific anti-angiogenic activity. While some compounds had a broad cellular toxicity profile in several cell types others showed endothelial cell specific dose-dependent anti-proliferative and anti-migratory efficacy. A profound inhibition of angiogenesis was also observed in the in vivo chicken chorioallantoic membrane (CAM) model, and consequently, these new compounds have considerable potential in drug design, e.g. for the treatment of cancer.

Analyse des cannabinoïdes par spectrométrie de masse en mode tandem = Analysis of cannabinoids by tandem mass spectrometry

Depuis quelques années, la spectrométrie de masse en tandem (MS/MS) ne cesse de gagner du terrain comme méthode d'analyse en toxicologie forensique, notamment pour le dosage des cannabinoïdes. Couplée à la chromatographie liquide (LC) ou gazeuse (GC), elle permet l'identification fiable et le dosage rapide du THC, de son précurseur acide, et de ses principaux métabolites, y compris les glucuronides. Au cours de ces dix dernières années, un nombre significatif de publications sont parues sur ce sujet. L'objectif de cet article est de passer en revue les analyses par spectrométrie de masse en tandem des cannabinoïdes dans diverses matrices biologiques. In recent years, tandem mass spectrometry (MS/MS) is gaining ground as a reference method of analysis in clinical and forensic toxicology, especially for the determination of cannabinoids. Coupled to liquid chromatography (LC) or gas chromatography (GC), it allows the definitive identification and rapid determination of THC, its acid precursor, and its major metabolites, including the glucuronides. During the past decade, several methods of analysis of cannabinoids in different matrices have appeared on this subject. The aim of this paper is to review the analysis of cannabinoids by tandem mass spectrometry methods in various biological matrices