Structure dependent induction of CYP1A by polychlorinated biphenyls in hepatocytes of male castrated pigs

Hepatocytes cultures prepared from castrated pig hepatocytes (Great Yorkshire x Dutch Landrace), as a model for human liver, were used to study the effect of twenty polychlorinated biphenyls (PCBs) on CYP1A activity, measured as the dealkylation of either ethoxyresorufin or methoxyresorufin. The selection of the PCBs was based on their differences in physico-chemical properties. The non-ortho and mono-ortho substituted PCBs were the most potent CYP1A inducers in pig hepatocytes. In addition, several multiple-ortho substituted congeners, with five or more chlorine atoms, were inducers of CYP1A activity as well. Their relative effect potencies (REP) were proximately 10,000 times lower than the most potent congener, 3,3',4,4',5 PeCB (PCB#126). Using partial least-squares (PLS) modeling, predictions of CYP1A activity could be made for all tetra to hepta substituted congeners. Several multiple-ortho substituted PCBs, which are highly abundant in the biotic and abiotic environment, have been found to induce CYP1A activity in pig hepatocytes. Because induction of CYP1A activity is used as biomarker for Ah-receptor mediated responses, it is suggested to include these congeners in future risk assessment.     

Partition coefficients of organic chemicals derived from reversed phase thin layer chromatography: Evaluation of methods and application on phosphate esters,polychlorinated paraffins and some PCB-substitutes

The application of reversed phase high performance thin layer chromatography has been evaluated for determination of octanol-water partition coefficients (P_oct) of organic chemicals. Best correlations between log P_oct and R_M-values were obtained on a C₁₈-bonded stationary phase using acetone-water or acetonitrile-water mixtures as eluting solvent. The latter mixture is preferred in work with high pressure liquid chromatography. A number of aryl and alkyl/aryl phosphate esters, polychlorinated paraffins and chemicals suggested as PCB-substitutes were chromatographed and the corresponding log P_oct-values calculated. Values for the phosphate esters corresponded reasonably well with previously reported data while data for other, often more complex compound mixtures (eg PCB-substitutes), need further evaluation. The use of the chromatographic system for screening purposes in work on environmentally significant data of possible organic pollutants is discussed.     

Solid chemosorbent for sampling sub-ppm levels of acrolein and glutaraldehyde in air

A personal air sampling method using Amberlite XAD-2 coated with 2,4-dinitrophenylhydrazine has been developed for acrolein and glutaral dehyde. Acrolein in the 0.01 to 1.2 mg/m³ range or glutaraldehyde in the 0.03 to 3.5 mg/m³ range is easily analysed in a 5 1 air sample. Recoveries are high (80–100%), and samples stable at least for two weeks if stored in the dark until analysed.     

Synthesis of halogenated diphenyl ethers and dibenzofurans - A discussion of specific isomers available

Synthetic routes for the preparation of halogenated diphenyl ethers and dibenzofurans are reviewed, and isomers reported in the literature are listed. In addition, the routes preferred for the synthesis of specific chlorinated isomers - especially from the point of view of an unambiguous structural assignment - are discussed in detail. The route recommended for chlorinated diphenyl ethers is the coupling of biaryliodonium salts with phenols, and for chlorinated dibenzofurans the palladium acetate-promoted cyclization of diphenyl ethers. Chlorinated isomers of diphenyl ethers and dibenzofurans which are available via these routes are listed. Furthermore, the synthesis of a new octachlorodiphenyliodonium salt and its coupling with three different chlorophenols are described, and the cyclization of an octachlorodiphenyl ether to octachlorodibenzofuran is shown.     

Sampling of epichlorohydrin and ethylene chlorohydrin in workroom air using Amberlite XAD-7 resin

Activated charcoal, Amberlite XAD-2 and Amberlite XAD-7 were evaluated for the adsorption of epichlorohydrin and ethylene chlorohydrin from air followed by desorption with solvent. Ethylene chlorohydrin was found to be unstable on activated charcoal in the presence of carbon disulfide. Recoveries from XAD-2 were low, and XAD-7 was found to be the best adsorbent for the sampling of these compounds from air.     

Looking on the bright side: females prefer coloration indicative of male size and condition in the sexually dichromatic spadefoot toad, <Emphasis Type="Italic">Scaphiopus couchii</Emphasis>

Females across many taxa commonly use multiple or complex traits to choose mates. However, the functional significance of multiple or complex signals remains controversial and largely unknown. Different elements of multiple or complex signals may convey independent pieces of information about different aspects of a prospective mate (the “multiple messages” hypothesis). Alternatively, multiple or complex signals could provide redundant information about the same aspect of a prospective mate (the “redundant” or “back-up” signal hypothesis). We investigated these alternatives using spadefoot toads, Scaphiopus couchii. Spadefoot toads primarily use calls to attract their mates, but males also exhibit sexually dimorphic coloration. We investigated whether male coloration is indicative of male size, condition, or infection status by a socially transmitted monogenean flatworm. We found that male coloration and dorsal patterning predicts male size and condition but not infection status. Moreover, when we presented females with a choice between a bright male model and a dark male model, we found that females preferred the bright model. Because aspects of males’ calls are also associated with male size and condition, we conclude that coloration is a potentially redundant indicator of male phenotype. We suggest that coloration could enhance mate choice in conjunction with male calling behavior by providing females with a long distance cue that could enable them to identify prospective mates in a noisy chorus environment where the discrimination of individual calls is often difficult. Generally, such redundant signals may facilitate mate choice by enhancing the quality and accuracy of information females receive regarding prospective mates.