Rhône-Poulenc

About: Rhône-Poulenc is a based out in . It is known for research contribution in the topics: Alkyl & Catalysis. The organization has 8909 authors who have published 8934 publications receiving 182241 citations. The organization is also known as: Rhone-Poulenc.

Polymer-entrapped rhizobium as an inoculant for legumes

Abstract: Field and cylinder experiments conducted in France and in Senegal showed that polyacrylamide, previously proposed as an entrapping gel for preparing Rhizobium inoculants, could be replaced by alginate (AER inoculant) or a mixture of xanthan and carob gum (XER inoculant). Semi-dried or dried AER and XER were used successfully provided that their storage time was less than 90 days. In soil inoculation trails, no marked differences were observed among semi-dried XER, dried AER, and dried XER. A number of seed inoculation experiments indicated that dried XER significantly outranked AER. Seeds preinoculated by up to 48 days with XER yielded plants which were comparable in nodulation and growth parameters to those derived from plant receiving peat inoculation at the time of planting.

Behaviour of fipronil in soil under Sahelian Plain field conditions

Abstract: The behaviour of fipronil, a phenylpyrazole insecticide used for locust control, was studied under sub-Saharan conditions in soils of the Niamey region of Niger. A formulation of fipronil (Adonis®) was applied to uncultivated soils at Banizoumbou and Saguia. Soil was sampled at 0–10, 10–20 and 20–30 cm depths for up to two months after treatment. Residues were analysed by gas chromatography using electron capture and mass detectors. For both soils, a rapid initial decrease of fipronil was observed, with rapid formation for the most part of a photodegradate. Three other metabolites of fipronil were also detected throughout the study. These metabolites displayed different dissipation kinetics. Fipronil and its metabolites did not move beyond 10 cm depth, except for the amide, which is not considered a toxicologically significant metabolite. © 1998 SCI.

Purification of the two-enzyme system catalyzing the oxidation of the D-proline residue of pristinamycin IIB during the last step of pristinamycin IIA biosynthesis.

Abstract: High levels of conversion of 14C-labelled pristinamycin IIB (PIIB) to pristinamycin IIA (PIIA) were obtained in vivo in Streptomyces pristinaespiralis and in some other streptogramin A producers. This established that PIIB was an intermediate on the pathway to PIIA. In addition, in vitro studies with cell-free protein preparations demonstrated that the oxidation of PIIB to PIIA is a complex process requiring NADH, riboflavin 5'-phosphate (FMN), and molecular oxygen. Two enzymes were shown to be necessary to catalyze this reaction. Both were purified to homogeneity from S. pristinaespiralis by a coupled enzyme assay based on the formation of PIIA and by requiring addition of the complementing enzyme. One enzyme was purified about 3,000-fold by a procedure including a decisive affinity chromatography step on FMN-agarose. It was shown to be a NADH:FMN oxidoreductase (E.C. 1.6.8.1.) (hereafter called FMN reductase), providing reduced FMN (FMNH2) to the more abundant second enzyme. The latter was purified only 160-fold and was called PIIA synthase. Our data strongly suggest that this enzyme catalyzes a transient hydroxylation of PIIB by molecular oxygen immediately followed by a dehydration leading to PIIA. The native PIIA synthase consists of two different subunits with Mrs of around 50,000 and 35,000, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while the FMN reductase seems to be a monomer with a Mr of around 28,000 and containing one molecule of tightly bound FMN. Stepwise Edman degradation of the entire polypeptides or some of their trypsin-digested fragments provided amino acid sequences for the two isolated proteins.