Karyotype of the Cricket, Zucchiella atlantica, with an Overview of the Chromosomes of the Subfamily Nemobiinae

Few reports have been published on cytogenetics in crickets of the subfamily Nemobiinae. Within the Neotropical region the karyotypes of only two species are known, both of them belonging to the genus Phoremia. In the present paper, chromosomes of a third Neotropical species, Zucchiella atlanticaMello 1990 (Orthoptera: Trigonidiidae), have been studied and a cytological review of other species of that subfamily is presented. Zucchiella atlantica shows 2n ♂ = 22 + XO and 2n ♀ = 22 + XX which suggests an ancestral condition within the subfamily as the diploid number in all the species previously studied ranges from 2n ♂ = 7 to 2n ♀ = 21. In Orthoptera those species with high chromosome numbers tend to show reduction in their chromosomal numbers by means of centric fusions rather than to increase chromosomal numbers, due to difficulties in the availability of new centromeres. A structural polymorphism in one chromosome of pair 5 was observed as an intra-individual variation, suggesting differential activity of the genome from cell to cell

Solvent-free chemo-enzymatic synthesis of fatty acyl-β-cyclodextrin

International audienceLipase-catalyzed transesterifications were carried out without solvent and in mild conditions on permethylated β-cyclodextrins derivatives to obtain lipidyl-cyclodextrin, a new class of amphiphilic compounds with expected auto-assembly properties. Good conversion rate, of 6I-(N-hydroxyethylsuccinamido)-6I-deoxy-2I, 3I-di-O-methyl-hexakis (2II–VII,3II–VII,6II–VII-tri-O-methyl) cyclomaltoheptaose were obtained by using lipozyme as catalyst. Critical Aggregation Concentrations of these new derivatives of amphiphilic cyclodextrins (5.10−3 and 5.10−4 M) are in favor of an auto-association behavior. Finally, NMR experiments were carried out to evaluate the self-assembly of the compounds in water. The resulting supramolecular aggregates have potential to be used as nano-carriers for drug

Enzymatic catalysis in presence of cyclodextrins

International audienceCyclodextrins are able to interact in biocatalysis reaction. Their effects as solubilizing agents, inhibitor blocking agents and chiral selectors are well documented and they also interact before the enzyme-catalyzed reaction. Indeed, they have lyo-protectant effect for enzyme in organic medium biocatalysis and they participate in the refolding of inactive enzymes to regain their active form

Structural characterization and mechanical properties of dextrin-graft-poly(butyl acrylate-co-styrene) copolymers

Dextrin/starch-graft-poly(butyl acrylate-co-styrene) copolymers have been synthesized by radical graft copolymerization and their structure and mechanical properties are reported. High molecular weight grafted chains formation is favored, leading to a low degree of substitution of starch hydroxyl groups. Wide-Angle-X-ray Scattering (WAXS) analysis indicates that all materials are amorphous and Transmission Electron Microscopy (TEM) investigations reveal a two-phase morphology. This is further confirmed by the presence of two glass transitions, one related to the starch/dextrin macromolecules and sensitive to water content, and one assigned to the grafted polymers that is composition dependent. Water uptake is controlled by dextrin/starch content but diffusivity increases with the butyl acrylate ratio. The mechanical behavior is dependent on monomer ratio, and water content. Increasing butyl acrylate ratio improves the ductility of the sample while materials become brittle as soon as styrene ratio is predominant in the grafted chains. While no effect of molecular weight of starch substrate on structure and thermal behavior is evidenced, dextrin-based materials are slightly more ductile than starchbased ones. The interest of using dextrin instead of starch is further highlighted by a lower viscosity of the reactive medium, together with an improved processability, as structural materials can be obtained over a wider range of composition than with native starch