Esterase polymorphism and sensitivity to dursban organophosphorus insecticide in Culex pipiens pipiens populations

Esterase polymorphism and Dursban (O,O-dimethyl-2-pyridylphosphorothioate) sensitivity have been investigated in 12 natural populations and three laboratory strains of Culex pipiens pipiens. This mosquito has two esterase loci, Est-1 and Est-2, which were shown to code esterases of the B group (aliesterases) but not cholinesterases. No correlation between Est-1 polymorphism and Dursban sensitivity was found, but the increase of the Est-2(0.64) allele in the populations less sensitive to Dursban was highly significant (r = -0.9850 for 6 df).     

Etude ultrastructurale d'images de fonte holocrine dans la cortico-surrenale

Conclusion La présence d'un phénomène dégénératif dans les couches profondes de la cortico-surrénale de 12 animaux normaux donne à penser qu'il existe dans cette glande un mécanisme physiologique de fonte holocrine. Cette idée est appuyée sur des images de passage de débris cellulaires dans la lumière des vaisseaux. L'influence qui détermine de telles modifications des cellules glandulaires reste à préciser. Ce sera l'objet d'une étude expérimentale en cours d'exécution.     

Improving the pharmacokinetic properties of biologics by fusion to an anti-HSA shark VNAR domain

Advances in recombinant antibody technology and protein engineering have provided the opportunity to reduce antibodies to their smallest binding domain components and have concomitantly driven the requirement for devising strategies to increase serum half-life to optimise drug exposure, thereby increasing therapeutic efficacy. In this study, we adopted an immunization route to raise picomolar affinity shark immunoglobulin new antigen receptors (IgNARs) to target human serum albumin (HSA). From our model shark species, Squalus acanthias, a phage display library encompassing the variable binding domain of IgNAR (VNAR) was constructed, screened against target, and positive clones were characterized for affinity and specificity. N-terminal and C-terminal molecular fusions of our lead hit in complex with a naïve VNAR domain were expressed, purified and exhibited the retention of high affinity binding to HSA, but also cross-selectivity to mouse, rat and monkey serum albumin both in vitro and in vivo. Furthermore, the naïve VNAR had enhanced pharmacokinetic (PK) characteristics in both N- and C-terminal orientations and when tested as a three domain construct with naïve VNAR flanking the HSA binding domain at both the N and C termini. Molecules derived from this platform technology also demonstrated the potential for clinical utility by being available via the subcutaneous route of delivery. This study thus demonstrates the first in vivo functional efficacy of a VNAR binding domain with the ability to enhance PK properties and support delivery of multifunctional therapies.     

Grazing insects reduce algal biomass in a neotropical stream

The Darwinulidae are the only surviving post-Palaeozoic darwinulocopine family of an extensive radiation that reached its maximum in the Permian. Whereas at least some Palaeozoic darwinulids are known from sexual populations, the surviving lineages after the end-Permian mass extinction have abandoned sex since 200 million years ago. This makes the extant family Darwinulidae one of the few putative ancient asexual groups. Only about 30 species in 5 genera are presently known. The phylogeny of these taxa is here analysed using both morphological characters and molecular data. Twelve characters on valve morphology and 17 characters pertaining to appendages are used to construct the most parsimonious (unrooted) cladogram of 12 species in 5 genera. DNA sequences of one nuclear (ITS1) and a mitochondrial (COI) gene of 6 species in 5 genera are used to construct rooted maximum parsimony trees. Both molecular and morphological trees show a high degree of congruence, indicating that Alicenula and Vestalenula mostly cluster closely together, while Penthesilenula and Microdarwinula constitute a robust group. The position of the monospecific genus Darwinulais more variable, but is mostly closer to the two former genera. Congeneric species always cluster together in the morphological cladograms, and these results thus confirm that the five genera recognised by Rossetti & Martens (1998) are good phyletic units. An approximate molecular clock (calibrated with fossil data) indicates that the extant darwinulids share a common ancestor, which lived at least 100 million years ago.     

DNA strand breaking capacity of acrylamide and glycidamide in mammalian cells

We compared the DNA damaging potency of acrylamide (AA) and its metabolite glycidamide (GA) in the comet assay in cell systems differing with respect to species origin and cytochrome P450-depended monooxygenase (CYP2E1) expression (V79, Caco-2, primary rat hepatocytes). Only after 24 h incubation in the highest concentration of AA (6 mM) a slight but significant increase in DNA damage was observed in V79 and Caco-2 cells. In primary rat hepatocytes, however, expressing substantial amounts of CYP2E1, no induction of DNA strand breaks was found. At the end of the incubation time period (24 h), still 67 ± 19% of the CYP2E1 protein was detected by Western blotting. Direct treatment with GA resulted in a significant increase in DNA damage in V79 cells and primary rat hepatocytes at concentrations ≥100 μM (24 h). Caco-2 cells were found to be less sensitive, exhibiting an increase in DNA strand breaks at concentrations ≥300 μM GA. These data confirm the higher genotoxic potential of GA compared to AA but also indicate that high expression of CYP2E1 per se is not necessarily associated with increased genotoxicity of AA. We, therefore, investigated whether the intracellular glutathione (GSH) level might be a critical determinant for the genotoxicity of AA in cells with different CYP2E1 status. Depletion of intracellular GSH by DL-buthionine-[S,R]-sulfoxime (BSO) in rat hepatocytes and V79 cells resulted in a significant induction of DNA strand breaks after incubation with 1 mM AA. However, at higher concentrations (≥1.25 mM) a strong increase in cytotoxicity, resulting in a severe loss of viability, was observed. In summary, the DNA strand breaking effect of AA appeared not to be directly correlated with the CYP2E1 status of the cells. Depletion of GSH is associated with an increase in AA genotoxicity but seems also to lead to a substantial enhancement of cytotoxicity.