Functional response of Fucus vesiculosus communities to tributyltin measured in an in situ continuous flow-through system

The effects of antifouling paint leachate containing tributyltin on community metabolism and nutrient dynamics were measured in situ on natural communities dominated by Fucus vesiculosus. The measurements were made in two areas with different salinities and at various TBT concentrations up to about 5 µg 1^–1. A portable continuous flow-through system was used in which the communities were incubated for a week. Continual measurements of oxygen, temperature, light and flow rate of water were made. A Perturbation Index (PI) and an Absolute Disturbance Index (ADI) were used to describe the changes due to treatment relative to the control, and to obtain a total picture of disturbance using all measured parameters. Photosynthesis was particularly strongly affected and changes were obvious in oxygen production and nutrient uptake at TBT levels as low as 0.6 µg 1–1.     

Thiols and pancreatic beta-cell function: a review

In pancreatic islets insulin secretion in response to a variety of stimulators is sensitive to the redox state of extracellular and intracellular thiols. In this connection variations of plasma glutathione (GSH) may also be of importance. In the process of stimulus-secretion coupling, membrane thiols play an important role. One major localization of critical thiols appears to be related to the influx of calcium through the voltage-dependent channel. Other transmembranal ion movements and the cAMP system seem to be less sensitive to thiol oxidation than calcium influx via voltage-dependent Ca channels.     

Production of fuel alcohol from oats by fermentation

Very high gravity (>30 g dissolved solids per 100 ml) mashes were prepared from hulled and hulless oats and fermented at 20° C with active dry yeast to produce ethanol. Excessive viscosity development during mashing was prevented by hydrolyzing -glucan with crude preparations of -glucanase or Biocellulase. Both these preparations possessed endo--glucanase activity. By using these enzymes and by decreasing the water to grain ratio, very high gravity mashes with low viscosity were prepared. Unlike wheat and barley mashes, oat mashes contained sufficient amounts of assimilable nitrogen to promote a fast rate of fermentation. The free amino nitrogen (FAN) content of oat mash could be predicted by the equation, mg FAN L^–1=8.9n wheren is the number of grams of dissolved solids in 100 ml of mash supernatant fluid. Ethanol yields of 353.2±3.7 L and 317.6±1.3 L were obtained per tonne (dry weight basis) of hulless (59.8% starch) and hulled (50.8% starch) oats respectively. The efficiency of conversion of starch to ethanol was the same in normal and very high gravity mashes.     

Evaluation of health risks from a buried mass of diesel fuel before and after bioremediation

Plans are being formulated for in situ bioremediation of a subsurface plume of diesel fuel No. 2 that resulted from an accidental fuel release. Raoult's law and the aqueous solubilities of the toxic components were used to estimate organic contaminant concentrations in leachate from the untreated fuel mass. Carcinogenic risks and noncarcinogenic hazard indices were calculated for undiluted leachate. An 80% decrease in hydrocarbon mass and increases in the average molecular weights of the component fractions were assumed to result from the treatment. Sample calculations are provided to show how to evaluate results of analyses for petroleum hydrocarbons after bioremediation.     

Assessment of environmental contamination associated with a mammalian cell transformation assay

Summary To estimate worker exposures to, and environmental contamination from, test chemicals and organic solvents used in an in vitro assay to assess the carcinogenic potential of chemicals, sodium fluorescein, a noncarcinogenic fluorescent material, was dissolved in tissue culture medium used to maintain early passage hamster embryo cells. Personal and environmental samples were taken over a 14-d period. The assay was performed according to standard procedures in a ventilated glove box or laminar flow safety cabinet. Considerably more than 99% of the chemical contamination found was recovered from the interiors of the glove box and hood and from disposable equipment. Contamination outside the containment units (less than 1 μg) resulted from intralaboratory transport of chemicals, treated cultures, and contaminated equipment. We conclude that the standard operating practices and procedures provided adequate safeguards for personnel and the environment. Research sponsored by the National Cancer Institute under Contract N01-CO-75380, with Litton Bionetics, Inc.     

Estimating ecotoxicological risk and impact using indigenous aquatic microbial communities

Emphasis has increased on accuracy in predicting the effect that anthropogenic stress has on natural ecosystems. Although toxicity tests low in environmental realism, such as standardized single species procedures, have been useful in providing a certain degree of protection to human health and the environment, the accuracy of such tests for predicting the effects of anthropogenic activities on complex ecosystems is questionable. The use of indigenous communities of microorganisms to assess the hazard of toxicants in aquatic ecosystems has many advantages. Theoretical and practical aspects of microbial community tests are discussed, particularly in related to widely cited problems in the use of multispecies test systems for predicting hazard. Further standardization of testing protocols using microbial colonization dynamics is advocated on the basis of previous studies, which have shown these parameters to be useful in assessing risk and impact of hazardous substances in aquatic ecosystems.