Effects of in utero exposure to 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107) on developmental landmarks, steroid hormone levels, and female estrous cyclicity in rats

Previous studies have revealed that one of the major metabolites of PCBs detected in human blood, 4-OH-2,3,3',4',5-pentaCB (4-OH-CB107), accumulated in fetal liver, brain, and plasma and reduced maternal and fetal thyroid hormone levels after prenatal exposure to pregnant rats from gestational days (GD) 10¿16. In the present study, the effects of 4-OH-CB-107 on developmental landmarks, steroid hormone levels, and estrous cyclicity of rat offspring after in utero exposure to 4-OH-CB107 was investigated. Pregnant rats were exposed to 0, 0.5, and 5.0 mg 4-OH-CB107 per kg bw from GD 10 to GD 16. Another group of rats was exposed to Aroclor 1254 (25 mg/kg bw) to study the differences between effects caused by parent PCB congeners and the 4-OH-CB107 alone. A significant, dose-dependent prolongation of the estrous cycle was observed in 75% and 82% of female offspring exposed to 0.5 and 5.0 mg 4-OH-PCB107, respectively, compared to 64% of Aroclor 1254 (25 mg/kg) exposed offspring. The diestrous stage of the estrous cycle was prolonged, resembling a state of pseudopregnancy, which might reflect early signs of reproductive senescence. Plasma estradiol concentrations in female rat offspring were significantly increased (50%) in the proestrous stage after exposure to 5 mg 4-OH-CB107 per kg bw. No effects on estradiol levels were observed in Aroclor 1254 treated animals. These results indicate that in utero exposure to 4-OH-CB107 leads to endocrine-disrupting effects, especially in female offspring. The possible impact on neurobehavior following exposure to 4-OH-CB107 will be reported elsewher

Organohalogen production is a ubiquitous capacity among basidio-mycetes.

Several species of basidiomycetes are capable of producing de novo high concentrations of chloroaromatic metabolites. However, the extent to which basidiomycetes contribute to the natural pool of adsorbable organic halogen (AOX) found in the environment is unknown yet. The purpose of this study was to determine the ubiquity of organohalogen production among basidiomycetes and to determine maximal specific organohalogen production rates. Finally, the fate of the fungal chloroaromatic compounds in the environment was studied.A total of 191 fungal strains were tested for AOX production when grown on defined liquid medium. Approximately 50% of the strains tested and 55% of the genera tested produced AOX. Organohalogen production seemed to be a ubiquitous capacity among basidiomycetes. Many highly ecologically significant fungal species were identified among the moderate and high producers. Although it was found that the final AOX concentrations produced by Hypholoma fasciculare was strongly influenced by the substrate used, all maximal specific AOX production rates on different substrates were in the same order of magnitude. Seven new species and four new genera of basidiomycetes could be added to the list of known chlorinated anisyl metabolites (CAM) producing basidiomycetes. In degradation studies of the major fungal metabolite 3,5-dichloro-anisyl alcohol, it was found that in forest soils there seems to be ubiquitous mineralizing capacity for this chlorinated aromatic compound. It was found that Burkholderia cepacia was responsible for the fast degradation of the fungal compound in the oak forest soils

Trichlorinated phenols from Hypholoma elongatum.

Three trichlorinated phenols, 2,4,6-trichloro-3-methoxyphenol, 3,5,6-trichloro-2,4-dimethoxyphenol and 3,4,6-trichloro-2,5-dimethoxyphenol, were detected as novel metabolites in the ethyl acetate extract from the culture medium of the Basidiomycete, Hypholoma elongatum (strain WIJS94-28)

Acid-catalyzed enzymatic hydrolysis of 1-methylcyclohexene oxide

Limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene metabolism of this microorganism, catalyzes the enantioselective hydrolysis of 1-methylcyclohexene oxide. (1R,2S)-1- Methylcyclohexene oxide was the preferred substrate and it was mainly hydrolyzed to (1S,2S)-1-methylcyclohexane-1,2-diol, while (1S,2R)-1- methylcyclohexene oxide was converted more slowly and mainly yielded (1R,2R)- 1-methylcyclohexane-1,2-diol. The reaction proceeded with a high regioselectivity (C1:C2, 85:15). H218O-labelling experiments confirmed that the nucleophile was mainly incorporated at the most substituted carbon atom, suggesting that limonene-1,2-epoxide hydrolase uses an acid-catalyzed enzyme mechanism