Hormones and Sex-Specific Transcription Factors Jointly Control Yolk Protein Synthesis in Musca domestica

In the housefly Musca domestica, synthesis of yolk proteins (YPs) depends on the level of circulating ecdysteroid hormones. In female houseflies, the ecdysterone concentration in the hemolymph oscillates and, at high levels, is followed by expression of YP. In male houseflies, the ecdysterone titre is constantly low and no YP is produced. In some strains, which are mutant in key components of the sex-determining pathway, males express YP even though their ecdysterone titre is not significantly elevated. However, we find that these males express a substantial amount of the female variant of the Musca doublesex homologue, Md-dsx. The dsx gene is known to sex-specifically control transcription of yp genes in the fat body of Drosophila melanogaster. Our data suggest that Md-dsx also contributes to the regulation of YP expression in the housefly by modulating the responsiveness of YP-producing cells to hormonal stimuli

Analysis of Chemical Warfare Agents at the NC Laboratory Spiez

The group for chemical analysis and verification at the NC Laboratory Spiez engages in the analysis of chemical warfare agents and related compounds in the frame of international chemical disarmament. Its area of work and instrumentation are described together with the analysis of a sample taken in Iraq after the Gulf War

Identification of acidic degradation products of chemical warfare agents by methylation with trimethylsilyldiazomethane and gas chromatography-mass spectrometry

Sensitive and reliable analysis of alkylphosphonic acids (APAs) and 2-(N,N-dialkylamino)ethanesulfonic acids (SAs), the degradation products of chemical warfare agents (CWAs), is one of the most important tasks for verification of the Chemical Weapons Convention (CWC). Unambiguous identification of these chemicals is required in a variety of environmental matrices, including soil and water. These acids with low volatility are very polar, and efficient and reliable methylation methods for their derivatization are needed for analysis with gas chromatography-mass spectrometry (GC-MS). In this study, the derivatization conditions for trimethylsilyldiazomethane (TMSDAM) methylation were optimized for rapid GC-MS screening. Optimized methylation of APAs and SAs with TMSDAM was compared with methylation with diazomethane. The TMSDAM methylation of SAs and benzilic acid was further compared with silylation with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide. The significance and necessity of cation exchange prior to derivatization and analysis were tested on samples with a high inorganic background. A recommendation to use the method for methylation of water samples and aqueous extracts using TMSDAM is given. The robustness of the method was illustrated by the successful identification of APAs and SAs in aqueous samples from proficiency tests organized by the Organisation for the Prohibition of Chemical Weapons.Peer reviewe