14 research outputs found
Comportement de butinage de l'abeille domestique et des abeilles sauvages dans des vergers de pommiers en Belgique
International audienc
Rhodium-Catalyzed and Zinc(II)-Triflate-Promoted Asymmetric Hydrogenation of Tetrasubstituted α,β-Unsaturated Ketones
The asymmetric hydrogenation of tetrasubstituted α,β-unsaturated ketones has been accomplished using an in situ formed rhodium-Josiphos catalyst. The reaction is enhanced by addition of catalytic zinc(II) triflate, which significantly improves turnover frequency while suppressing epimerization of the products
Parasitization of a wild and reared population of the solitary bee Osmia cornuta
A nest-trapping (NT) and a releasing and rearing (RR) campaign were performed in two similar areas of Tuscany (Italy), towards nest inducing and reproduction of Osmia cornuta Latr. For the NT campaign, artificial nests built with reed segments (Arundo donax L.) (reed nests) and grooved hardboard plates were used. The latter type was termed Artificial Assembled Trap Nest (AATN). The RR campaign utilized the same nest types and a reared O. cornuta population, with 100 cocoons having a sex-ratio of 2:1 (female:male). Nests were removed from fields during the first week of August, placed in mesh bags and kept in the laboratory at room temperature up to the month of October, when each nest was opened in order to analyse its content. Results showed that in both investigated areas, the wild and reared population were parasitized by the bombylid dipteran Anthrax anthrax Schrank. A. anthrax parasitization of O. cornuta was found to be greater in assembled (AATN) compared to reed nests. Highest prevalence of parasitization was found in the innermost portion of the tunnel, where Osmia cocoons usually contains females. Additional damage is cocoon crashing, caused by A. anthrax armed pupae as it forces its way out of the tunnel. Both O. cornuta population (reared and wild) resulted parasitized by A. anthrax specimens. In October, when broodnests were opened, exuviae of newly emerged specimens, armed pupae and mature diapausing A. anthrax Schrank larvae were, in some cases, found inside together, suggesting that the life cycle of this dipteran is parsivoltine
Development of an Enantioselective Hydrogenation Based Synthesis of a Glucokinase Activator
This article describes the development and optimization
of chemical
reactions and subsequent multikilogram preparation of the glucokinase
activator (<i>R</i>)-<b>1</b> to fund clinical evaluation
as a potential therapeutic for type II diabetes. The major process
developments presented here are a Wittig olefination isomerization
based synthesis of an <i>E</i>-acrylic acid, an optimized
enantioselective hydrogenation of the <i>E</i>-acrylic acid,
and a challenging final amide coupling
XSip1 neuralizing activity involves the co-repressor CtBP and occurs through BMP dependent and independent mechanisms.
The DNA-binding transcription factor Smad-interacting protein-1 (Sip1) (also named Zfhx1b/ZEB2) plays essential roles in vertebrate embryogenesis. In Xenopus, XSip1 is essential at the gastrula stage for neural tissue formation, but the precise molecular mechanisms that underlie this process have not been fully identified yet. Here we show that XSip1 functions as a transcriptional repressor during neural induction. We observed that constitutive activation of BMP signaling prevents neural induction by XSip1 but not the inhibition of several epidermal genes. We provide evidence that XSip1 binds directly to the BMP4 proximal promoter and modulates its activity. Finally, by deletion and mutational analysis, we show that XSip1 possesses multiple repression domains and that CtBPs contribute to its repression activity. Consistent with this, interference with XCtBP function reduced XSip1 neuralizing activity. These results suggest that Sip1 acts in neural tissue formation through direct repression of BMP4 but that BMP-independent mechanisms are involved as well. Our data also provide the first demonstration of the importance of CtBP binding in Sip1 transcriptional activity in vivo.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe