New Views of the Wasteland

Abstract

Gitlin, Todd, editor. Watching Television. New York: Pantheon Books, 248 pages. $9.95 paperback     

The anaerobic utilisation of cyanide in the presence of sugars by microbial cultures can involve an abiotic process

The degradation of cyanide under anaerobic conditions in the presence of a growing culture of a strain of Klebsiella planticola has been shown to be due to a chemical process dependent upon the presence of a reducing sugar in the medium. The conversion of cyanide to ammonia was independent of any biological factors under these conditions.     

Special report of the Massachusetts weight‐of‐evidence workgroup A weight‐of‐evidence approach for evaluating ecological risks

Weight‐of‐evidence is the process by which multiple measurement endpoints are related to an assessment endpoint to evaluate whether significant risk of harm is posed to the environment. In this paper, a methodology is offered for reconciling or balancing multiple lines of evidence pertaining to an assessment endpoint. Weight‐of‐evidence is reflected in three characteristics of measurement endpoints: (a) the weight assigned to each measurement endpoint; (b) the magnitude of response observed in the measurement endpoint; and (c) the concurrence among outcomes of multiple measurement endpoints. First, weights are assigned to measurement endpoints based on attributes related to: (a) strength of association between assessment and measurement endpoints; (b) data quality; and (c) study design and execution. Second, the magnitude of response in the measurement endpoint is evaluated with respect to whether the measurement endpoint indicates the presence or absence of harm; as well as the magnitude. Third, concurrence among measurement endpoints is evaluated by plotting the findings of the two preceding steps on a matrix for each measurement endpoint evaluated. The matrix allows easy visual examination of agreements or divergences among measurement endpoints, facilitating interpretation of the collection of measurement endpoints with respect to the assessment endpoint. A qualitative adaptation of the weight‐of‐evidence approach is also presented.     

Dopaminergic agonists increase [3H]estradiol binding in hypothalamus of female rats, but not of males

Specific nuclear binding of [3H]estradiol in the hypothalamus was increased by acute dopaminergic treatment in female, but not in male, gonadectomized-adrenalectomized rats. In the female this increase could be blocked by the dopaminergic receptor blocker perphenazine and was noted from 1 to 3 hours after injection of [3H]estradiol. Binding was not different in male and female rats in the absence of dopaminergic treatment. These results suggest that acute dopaminergic stimulation may modulate estradiol binding in neural areas known to be important in endocrine function.     

Provisional mapping of the gene for a cell surface marker, GA-1, in the red-necked wallaby Macropus rufogriseus

A series of M. rufogriseus-mouse somatic cell hybrids was constructed and analysed cytologically, enzymatically and immunologically. A monoclonal antibody, GA-1, was prepared against an M. rufogriseus cell surface antigen on an M. rufogriseus-mouse somatic cell hybrid. A gene determining the expression of this antigen was provisionally assigned to the long arm of the M. rufogriseus chromosome 3. The monoclonal antibody also reacted with an M. rufus (red kangaroo)-mouse somatic cell hybrid containing only the M. rufus chromosome 5, the G-banded chromosome identical to M. rufogriseus 3q. The results also suggest synteny of the genes for the marsupial enzymes hypoxanthine phosphoribosyltransferase and phosphoglycerate kinase-A.     

Efficacy of Translators for Establishing Mercury Total Maximum Daily Loads

In Oregon's Willamette River, methylmercury levels in fish triggered health advisories and the need for a mercury Total Maximum Daily Load (TMDL). A translator was used to relate surface water total mercury (C_THg) to dissolved methylmercury concentrations (C_DMeHg). The USEPA's Spreadsheet-based Ecological Risk Assessment for the Fate of Mercury (SERAFM) was used to elucidate the annual relationship between mercury loads, C_THg, and C_DMeHg, to investigate whether C_THg is a reasonable predictor for C_DMeHg, and to consider how load reductions may be affected by the differing annual trajectories of total and methylmercury concentrations. Modeling and observations suggest that C_THg and C_DMeHg are not directly proportional, that C_THg is an inconsistent predictor of C_DMeHg, that a single point estimate translator could easily misjudge their relationship, and that C_DMeHg may be more responsive to environmental factors than to load alone. While a translator is convenient for relating C_THg and C_DMeHg for regulatory purposes, it may not, due to environmental factors unrelated to loading, be the most efficacious means for this purpose. TMDLs relying on a translator are advised to conduct co-located total and methylmercury sampling with sufficient frequency to provide information on the watershed-specific annual relationship between total mercury and methylmercury.     

Intervesicular exchange of lipids with weak acid and weak base characteristics: influence of transmembrane pH gradients

Transmembrane pH gradients have previously been shown to induce an asymmetric transmembrane distribution of simple lipids that exhibit weak acid or basic characteristics (Hope, M.J. and Cullis, P.R. (1987) J. Biol. Chem. 262, 4360-4366). In the present study we have examined the influence of proton gradients on the inter-vesicular exchange of stearylamine and oleic acid. We show that vesicles containing stearylamine immediately aggregate with vesicles containing phosphatidylserine and that disaggregation occurs subsequently as stearylamine equilibrates between the two vesicle populations. Despite visible flocculation during the aggregation phase, vesicle integrity is maintained. Stearylamine is the only lipid to exchange, fusion does not occur and vesicles are able to maintain a proton gradient. When stearylamine is sequestered to the inner monolayer in response to a transmembrane pH gradient (inside acidic) aggregation is not observed and diffusion of stearylamine to acceptor vesicles is greatly reduced. The ability of delta pH-dependent lipid asymmetry to modulate lipid exchange is also demonstrated for fatty acids. Oleic acid can be induced to transfer from one population of vesicles to another by maintaining a basic interior pH in the acceptor vesicles. Moreover, it is shown that the same acceptor vesicles are capable of depleting serum albumin of bound fatty acid. These results are discussed with respect to the mechanism and modulation of lipid flow between membranes both in vitro and in vivo.