Fast atom bombardment mass spectrometry and tandem mass spectrometry in antibiotics: identification of nucleoside antitumor antibiotic toyocamycin in fermentation broth

The presence of the nucleoside antitumor antibiotic toyocamycin in the fermentation broth was determined by a combination of negative and positive ion fast atom bombardment (FAB) mass spectrometry, high resolution FAB mass spectrometry and mass-analysed ion kinetic energy spectrometry (MIKES). A reasonable limit of detection for toyocamycin in the whole broth was obtained by combining the specificity of mass spectrometry/mass spectrometry (also called tandem mass spectrometry) to FAB. The role played by the fermentation matrix upon the production and the observation of characteristic ions by FAB using xenon atoms was examined. High-performance liquid chromatography (HPLC) and FAB mass spectrometry were used to monitor toyocamycin at all stages of strain development, fermentation and recovery.     

A rationale for the prophylactic use of monophosphoryl lipid A in sepsis and septic shock.

Monophosphoryl lipid A (MLA), a substructure of bacterial lipopolysaccharide (LPS), is being developed as a prophylactic for sepsis and septic shock. In the present study it was shown that MLA induced a rapid accumulation of IFN-gamma in mice that correlated with an in vivo priming of macrophages. Primed macrophages could be induced in vitro to synthesize nitric oxide, a key mediator of macrophage cytotoxicity. Due to its rapid clearance, MLA was not present in circulation at the time when IFN-gamma accumulated, suggesting that MLA could not synergize with IFN-gamma to systemically activate macrophages in vivo. MLA treatment tolerized mice against the IFN-gamma response--ie., treatment of mice with MLA on day 1 blocked LPS from inducing IFN-gamma on days 2-4. The significance of these results in relation to MLA's ability to enhance non-specific resistance and block LPS lethality in animals is discussed.     

Repetitive, genome-specific probes in wheat (Triticum aestivum L. em Thell) amplified with minisatellite core sequences

The detection and analysis of DNA polymorphisms in crops is an essential component of marker-assisted selection and cultivar identification in plant breeding. We have explored the direct amplification of minisatellite DNA by PCR (DAMD-PCR) as a means for generating DNA probes that are useful for detecting DNA polymorphisms and DNA fingerprinting in wheat. This technique was facilitated by high-stringency PCR with known plant and animal minisatellite core sequences as primers on wheat genomic DNA. The products of DAMD-PCR from Triticum aestivum, T. durum, T. monococcum, T. speltoides and T. tauschii showed a high degree of polymorphism and the various genomes could be identified. Cloning of the DAMD-PCR products and subsequent Southern hybridization frequently revealed polymorphic probes showing a good degree of genome specificity. In addition, polymorphic, single locus, and moderately dispersed PCR products were cloned that may have a potential for DNA fingerprinting. Our experiments were limited primarily to diploid wheats and the results indicated that DAMD-PCR may isolate genome-specific probes from wild diploid wheat species that could be used to monitor genome introgression into hexaploid wheat.This paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the USDA or the University of Missouri. Contribution from the University of Missouri, the Agricultural Experimental Station and U.S. Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, journal series No. 12523     

Isolation,characterization, and genetic analysis ofAspergillus nidulans mutants resistant to the antifungal compound LY214352

We have isolated and characterized six chemically induced mutants of the filamentous fungusAspergillus nidulans that are resistant to the experimental fungicide 8-chloro-4-(2-chloro-4-fluoro-phenoxy)quinoline (LY214352). The mutants are 13- to 430-fold more resistant to LY214352 than the parental strain, and one of the mutant strains requires LY214352 for maximal growth. The resistance trait is governed by a single dominant or partially dominant gene in each mutant, and it is likely that all of the mutations are allelic. The LY214352-resistant mutants were not cross-resistant to other compounds that inhibit the growth ofA. nidulans. The implications of these findings on the potential for development of resistance to LY214352 are discussed.