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SUMMARYThe percentage colonization of roots by arbuscular mycorrhizal fungi was measured in the field in two crops of spring oats {Avena sativa L.) and one of maincrop potatoes {Solanum tuberosum L.), successively grown over a period of 3 yr on the long-term liming experiments at Rothamsted and Woburn. In both crops, all years, both phosphorus treatments and at both sites, percentage colonization was little affected by soil pH from over a range approximately 4-5 to 7-5. There was little effect of pH on crop yields. Up to nine species of coarse endophyte could be identified from spores (> 50 //m diameter) m plots of pH 55 and above. There were markedly fewer spores at (approximately) pH 5-5 and none in the most acid plots.

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Human and veterinary drug development addresses absorption, distribution, metabolism, elimination and toxicology (ADMET) of the Active Pharmaceutical Ingredient (API) in the target species. Metabolism is an important factor in controlling circulating plasma and target tissue API concentrations and in generating metabolites which are more easily eliminated in bile, faeces and urine. The essential purpose of xenobiotic metabolism is to convert lipid-soluble, non-polar and non-excretable chemicals into water soluble, polar molecules that are readily excreted. Xenobiotic metabolism is classified into Phase I enzymatic reactions (which add or expose reactive functional groups on xenobiotic molecules), Phase II reactions (resulting in xenobiotic conjugation with large water-soluble, polar molecules) and Phase III cellular efflux transport processes. The human–fish plasma model provides a useful approach to understanding the pharmacokinetics of APIs (e.g. diclofenac, ibuprofen and propranolol) in freshwater fish, where gill and liver metabolism of APIs have been shown to be of importance. By contrast, wildlife species with low metabolic competency may exhibit zero-order metabolic (pharmacokinetic) profiles and thus high API toxicity, as in the case of diclofenac and the dramatic decline of vulture populations across the Indian subcontinent. A similar threat looms for African Cape Griffon vultures exposed to ketoprofen and meloxicam, recent studies indicating toxicity relates to zero-order metabolism (suggesting P450 Phase I enzyme system or Phase II glucuronidation deficiencies). While all aspects of ADMET are important in toxicity evaluations, these observations demonstrate the importance of methods for predicting API comparative metabolism as a central part of environmental risk assessment.

The activity of paraoxonase in serum was found to be bimodally distributed, both in a control group and in a group of patients who had suffered myocardial infarction. Activity in the myocardial infarct group was significantly lower than in the control group. Low paraoxonase activity in serum may provide an indication of susceptibility to the development of coronary heart disease.

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The organophosphorus insecticide Malathion 60 is used to control terrestrial arthropod pests on watercress, Rorippa nasturtium-aquaticum L. (Hayek). The use of this pesticide could damage aquatic invertebrate communities in nearby chalk streams, so an in situ experiment was undertaken with the amphipod Gammaruspulex L. to determine the extent of this risk. Caged G. pulex were placed below two selected watercress beds and their associated settling pools, and their mortality, feeding rate, and acetylcholinesterase activity measured before and after the application of Malathion 60 to the watercress crop. The differences found between prespray and postspray samples of G. pulex taken from the stations immediately below both watercress beds follow: (a) the acetylcholinesterase activity was significantly lower at both stations after spray application; (b) the mortality rate was significantly higher at one station after spray application, but not at the other; (c) there were no clear effects on feeding rates at either station. Also, there were no significant detrimental effects at either of the stations located below the settling pools. Results from this study suggest that the use of Malathion 60 on watercress beds at recommended rates presents little risk to G . pulex living in streams below watercress farms if bed effluent passes through a settling pool before release.

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