Collaborative studies for the establishment of reference substances for the microbiological assay of antibiotics.

Collaborative studies were initiated by the European Directorate for the Quality of Medicines (EDQM) to assign potency values for candidate European Pharmacopoeia Chemical Reference Substances (Ph. Eur. CRSs) used for the microbiological assay of antibiotics. The candidates were assayed against their respective International Standard (IS), using the methods by diffusion or turbidimetry. Potencies were assigned to all the antibiotics concerned, which were adopted by the European Pharmacopoeia Commission.

Short-range genetic structure of Drosophila melanogaster populations in an Afrotropical urban area and its significance.

Alcohol dehydrogenase (Adh) (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) gene frequencies and ethanol tolerance in Drosophila melanogaster are known to exhibit long-range latitudinal variations on different continents; this has led to the argument that the clines are adaptive. Accordingly, tropical populations are characterized both by a low frequency of Adh-F and by a low ethanol tolerance. In the urban area of Brazzaville (Congo) under an equatorial African climate, an original genetic structure of local populations has been found: Adh-F frequency varies from 3% to 90% when countryside and brewery populations are compared. This variation is accompanied by an increase of ethanol tolerance (from 6% to 13% alcohol). Such differences, which have remained stable for the past 3 years, were observed between collection sites less than 1 km apart. Two other enzyme loci exhibited a correlated variation with Adh-F--i.e., an increase of the S allele of glycerol-3-phosphate dehydrogenase (NAD+) (sn-glycerol-3-phosphate:NAD+ 2-oxidoreductase, EC 1.1.1.8) and of the F allele of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49). Such observations suggest very strong selective pressures exerted by environmental ethanol that oppose the gene flow due to adult dispersal between contiguous habitats. A functional relationship between the polymorphisms of the three enzyme loci seems likely, and a metabolic interaction involving NAD and NADP cofactors is proposed.

[Influence of reduced pterine and juvenile hormone on the pigmentation of the phasms Carausius morosus (author's transl)]. / Influence des ptérines réduites et de l'hormone juvénile sur la pigmentation du phasme Carausius morosus

Tetrahydrofolic acid and dimethyltetrahydropterine, FH4 and DMH4P, have an antagonist action. FH4 darkens the phasms. DMH4P and the tryptophane have an inhibitrice influence on the melanisation, probably by the increase of the synthesis or the release of serotonin, in the hypoderm. For the adult phasm remaining ivory, xanthopterin must be added in the treatment. The addition of diapausing chrysalids pieridae extract (containing juvenile hormone JH) and treated by FH4, in the treatment precedent, transmits the pgimentary effect at the first generation, which presents a strong percentage of dark or ivory phasms.