Genetic Criteria for Establishing Evolutionarily Significant Units in Cryan's Buckmoth

Buckmoths ( Hemileuca spp.) are day-flying saturniid moths with diverse ecologies and host plants. Populations that feed on Menyanthes trifoliata , known commonly as Cryan's buckmoths, have been found in only a few bogs and fens near eastern Lake Ontario in New York and near Ottawa in Ontario, Canada. Because of their unique ecological traits, geographic isolation from other Hemileuca populations, and the small number of sites they occupy, there is concern that the Cryan's buckmoth populations are phylogenetically distinct and should be protected. The Cryan's buckmoths have not yet been taxonomically described and do not appear to have clear distinguishing morphological characters. Both molecular genetic traits (allozymes and mitochondrial DNA sequences) and an ecologically based character (host performance) were investigated to determine whether these populations possess fixed diagnostic characters signifying genetic differentiation from other eastern Hemileuca populations. Such differences would merit separate conservation management as an evolutionarily significant unit. Our studies showed that the Cryan's buckmoths clearly belong to the Hemileuca maia species group, but they could not be readily distinguished from other members of that group by means of molecular genetic techniques. There were no fixed differences in alleles or haplotypes distinguishing any of the populations or species, suggesting recent divergence. Nonetheless, in the host-plant performance experiment only the Cryan's buckmoth larvae were able to develop on M. trifoliata , a significant difference from other Hemileuca larvae tested. The Cryan's buckmoth appears to be unique in host performance and warrants protection and management us an evolutionarily significant unit. In cases such as this where groups appear to have recently diverged, investigations into ecologically significant traits may provide indicators of conservation significance as reliable as molecular genetic markers.     

Xenobiotics: Substrates and inhibitors of the plant cytochrome P450

The ability of a plant cytochrome P450 to bind and metabolise plant endogenous molecules and xenobiotics was investigated. The work was performed on the yeast-expressed CYP73A1, a cinnamate 4-hydroxylase isolated fromHelianthus tuberosus. CYP73 controls the general phenylpropanoid pathway and is likely to be one of the most abundant sources of P450 in the biosphere. The enzyme shows a high selectivity toward plant secondary metabolites. Nevertheless, it oxygenates several small and planar xenobiotics with low efficiency, including an herbicide (chlorotoluron). One xenobiotic molecule, 2naphthoic acid, is hydroxylated with an efficiency comparable to that of the physiological substrate. This reaction was used to devise a fluorimetric test for the rapid measurement of enzyme activity. A series of herbicidal molecules (hydroxybenzonitriles) are shown to bind the active site without being metabolised. These molecules behave as strong competitive inhibitors of CYP73 with a K_i in the same micromolar range as the K_m for the physiological substrate. It is proposed that their inhibition of the phenylpropanoid pathway reinforces their other phytotoxic effects at the level of the chloroplasts. All our results indicate a strong reciprocal interaction between plant P450s and xenobiotics.     

Modeling the Effects of Air Quality Policy Changes on Water Quality in Urban Areas

This paper describes the development and application of an integrated modeling framework composed of an urban air chemistry model, an urban runoff model, and a water-quality model. The models were linked to simulate the fate and transport of air emissions of nitrogen compounds in the air, urban watershed, surface water runoff, and in a coastal receiving-water body. The model linkage is demonstrated by evaluating the potential water quality implications of reducing NO _x emissions by 32%, volatile organic compound emissions by 51%, and ammonia emissions by 30%, representing changes from 1987 levels to proposed 2000 target levels in Los Angeles, California, USA. Simulations of the Los Angeles dry season during the summer of 1987 (June 1 to August 31) indicated that by reducing emissions from 1987 to proposed year 2000 levels, the dry deposition nitrogen loads to Santa Monica Bay and the Ballona Creek watershed were reduced 21.4% and 15.0%, respectively. Water quality modeling results indicated that dry season atmospheric load reductions to the Ballona Creek Estuary did not reduce chlorophyll-a levels or significantly raise nighttime dissolved oxygen levels because the magnitude of the reductions was negligible compared to non-atmospheric inputs of nitrogen compounds. Simulations of the time period from November 18, 1987 to December 4, 1987 during the Los Angeles wet season indicated that air emissions reductions produced an 18.6% reduction in the dry deposition nitrogen load to Santa Monica Bay, a 15.5% reduction in the dry deposition nitrogen load to the Ballona Creek watershed, a 16.8% reduction in the wet deposition nitrogen load to the Ballona Creek watershed, and a 16.1% reduction in the stormwater discharge load from the Ballona Creek watershed. Although the wet season load reductions are significant, modeling results of the ultimate effect on the Ballona Creek Estuary water quality were inconclusive.     

Uptake of aluminum by lipid vesicles

Aluminium uptake and tight binding were studied in multilayered phospholipid liposomes, as a model for cellular uptake of aluminum ions. Most of these studies were conducted with an initial aluminum concentration of 10 μM, while aluminum superficially bound to liposomes was removed by citrate chelation. Maximum uptake and tight binding of aluminium were pH‐dependent. In dimyristoyl phosphatidylcholine (DMPC) liposomes, this maximum occurred in the neutral pH region, while it was shifted towards more acidic pH values in DMPC liposomes containing 20% of acidic phosphatidylserine. The initial rate of aluminum uptake was apparently dependent on the physical state of the liposome membrane. Prior formation of an aluminum‐citrate chelate prevented aluminum uptake and tight binding to DMPC liposomes.     

Pathways of Mycobacterium ulcerans infection: a review

Buruli ulcer (BU), an often-deforming skin ulceration caused by Mycobacterium ulcerans (MU), is now considered by the World Health Organization to be the third most common mycobacterium infection. However, the reservoir of MU in the environment and the epidemiology of BU are poorly understood. The disease is prevalent in riverine, slow-flowing and swampy areas of several tropical and subtropical regions of the world, especially in West Africa where the disease is rapidly increasing in incidence. This paper presents a review of published literature concerning epidemiology of, transmission and susceptibility to MU infection. It considers several endemic natural environments and their influence on infection.     

坦桑尼亚的可持续城市规划

本文概述坦桑尼亚可持续城市规划.它考察城市活动的环境影响以及为推动对环境来说可持续城市发展而达成妥协和形成一致、合作和伙伴关系的方式.环境规划与管理(EPM)过程已在达累斯萨拉姆成功启动并在该国9个城市得到同样应用.     

Determination of chemical warfare agents in soil and material samples

A gas Chromatographic method for the determination of phenylarsenic compounds (sternutators) and their metabolites in soil and material samples is described. The chemical warfare agents (CWA), but not their hydrolysis and oxidation products, can be detected with GC/ECD. After derivatization with thiols or dithiols, the sum of diphenylarsenic and phenylarsenic compounds can be determined with GC/ECD. The comparison of the analytical results with and without derivatization shows that the sternutators in the investigated samples are metabolized in part.