Metabolism of cinnamic, p-coumaric, and ferulic acids by Streptomyces setonii

Streptomyces setonii strain 75Vi2 was grown at 45 degrees C in liquid media containing yeast extract and trans-cinnamic acid, p-coumaric acid, ferulic acid, or vanillin. Gas chromatography, thin-layer chromatography, and mass spectrometry showed that cinnamic acid was catabolized via benzaldehyde, benzoic acid, and catechol; p-coumaric acid was catabolized via p-hydroxybenzaldehyde, p-hydroxybenzoic acid, and protocatechuic acid; ferulic acid was catabolized via vanillin, vanillic acid, and protocatechuic acid. When vanillin was used as the initial growth substrate, it was catabolized via vanillic acid, guaiacol, and catechol. The inducible ring-cleavage dioxygenases catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase were detected with an oxygen electrode in cell-free extracts of cultures grown in media with aromatic growth substrates and yeast extract.     

Sample preparation and high-resolution separation of mycotoxins possessing carboxyl groups

The chromatographic analysis of carboxyl-containing mycotoxins, such as fumonisin B₁, ochratoxin A, and citrinin, presents a continual challenge. Toxins must first be extracted from foods or tissues and then cleaned up before chromatographic separation and detection. Liquid–liquid extraction efficiencies for some carboxylic mycotoxins are marginal for spiked samples and uncertain for incurred residues. Immunoaffinity columns may be useful for concentrating mycotoxins from samples before chromatography. In almost every case, more than one analytical method must be used to confirm the identification of the mycotoxin. The fumonisins are especially troublesome to analyze because they are relatively insoluble in organic solvents, they are not separated easily by gas chromatography, and they do not respond to the usual absorbance or fluorescence detectors used in liquid chromatography. Fluorescence derivatization and electrospray liquid chromatography–mass spectrometry have now made it possible to detect trace levels of mycotoxins. The purity of mycotoxin standards for toxicological studies can be determined by liquid chromatography with either an evaporative light scattering detector or electrospray mass spectrometer. New developments in capillary electrophoresis, nonporous microsphere liquid chromatography, and detection methods for low-volatility compounds show promise for improving the analysis of mycotoxins in the future.     

The fate of paternal mitochondrial DNA in developing female mussels,Mytilus edulis: implications for the mechanism of doubly uniparental inheritance of mitochondrial DNA.

Species of the marine mussel family Mytilidae have two types of mitochondrial DNA: one that is transmitted from the mother to both female and male offspring (the F type) and one that is transmitted from the father to sons only (the M type). By using pair matings that produce only female offspring or a mixture of female and male offspring and a pair of oligonucleotide primers that amplify part of the COIII gene of the M but not the F mitochondrial genome, we demonstrate that both male and female embryos receive M mtDNA through the sperm and that within 24 hr after fertilization the M mtDNA is eliminated or is drastically reduced in female embryos but maintained in male embryos. These observations are important for understanding the relationship between mtDNA transmission and sex determination in species with doubly uniparental inheritance of mitochondrial DNA.     

Teratogenicity of three substituted 4-biphenyls in the rat as a result of the chemical breakdown and possible metabolism of a thromboxane A2-receptor blocker

AH23848 is a potent thromboxane A2-receptor blocker inhibiting platelet aggregation in vitro and in vivo. Oral administration to pregnant rats during days 7-16 of pregnancy, at doses of 0, 10, 45, or 200 mg/kg twice daily, resulted in dose-related maternal, embryonic, and fetal toxicity. The most notable observation was herniation of the diaphragm occurring in 1.5 and 100.0% of fetuses at the 45 and 200 mg/kg doses, respectively, when examined at term. A further study at 150 mg/kg twice daily during days 7-16, 7-11, or 12-16 of pregnancy revealed incidences of diaphragmatic hernia up to 42%. Herniation varied from small areas of eventration of membranous diaphragm to fetuses with apparent total absence of the diaphragm. The positions of the hernias in the diaphragm, following dosing over varying periods of organogenesis, reflected the chronology of diaphragm formation in the rat. The teratology of AH23848 was unrelated to its thromboxane A2-receptor blocker properties but was related to a chemical breakdown product, 4-biphenylmethanol. Some substituted biphenyl compounds appear to be specific teratogens in the rat, with their effects targeted at the developing diaphragm. A possible mechanism of herniation is the interference with muscularisation of the membranous diaphragm, resulting in weakness and perforation.