Effect of superoxide dismutase, catalase, chelating agents, and free radical scavengers on the toxicity of alloxan to isolated pancreatic islets in vitro.

The effect of superoxide dismutase, catalase, metal-chelating agents and hydroxyl radical scavengers on the toxicity of alloxan to isolated ob/ob mouse pancreatic islets in vitro has been compared with the reported ability of such substances to protect against alloxan diabetes in vivo. Superoxide dismutase and catalase protected beta-cells of isolated pancreatic islets against alloxan cytotoxicity, as did the hydroxyl radical scavengers dimethyl sulfoxide (DMSO) and butanol. However, 1,3-dimethylurea and thiourea, that are recognised as effective hydroxyl radical scavengers and that protect animals against the diabetogenic effects of alloxan, were without effect. Similarly, desferrioxamine, that inhibits hydroxyl radical formation from alloxan in chemically defined systems, did not protect against alloxan toxicity. Diethylenetriamine pentaacetic acid, which does not inhibit hydroxyl radical formation from alloxan, also gave no significant protection. The results indicate a role for superoxide radical and hydrogen peroxide in the mechanism of toxicity of alloxan but do not support the involvement of the hydroxyl radical in this process. Alternative explanations must be sought for the ability of hydroxyl radical scavengers and metal-chelating agents to protect against alloxan toxicity in vivo.     

A Fresh View of Glycolysis and Glucokinase Regulation: History and Current Status

This minireview looks back at a century of glycolysis research with a focus on the mechanisms of flux regulation. Traditionally, glycolysis is regarded as a feeder pathway that prepares glucose for further catabolism and energy production. However, glycolysis is much more than that, in particular in those tissues that express the low affinity glucose-phosphorylating enzyme glucokinase. This enzyme equips the glycolytic pathway with a special steering function for the regulation of intermediary metabolism. In beta cells, glycolysis acts as a transducer for triggering and amplifying physiological glucose-induced insulin secretion. On the basis of these considerations, I have defined a glycolytic flux regulatory unit composed of the two fructose ester steps of this pathway with various enzymes and metabolites that regulate glycolysis.     

Das Moorschneehuhn (Lagopus lagopus subspec.) im Winter in Transkaukasien

Ohne Zusammenfassung     

Chronobiologic Factors in Experimental Stress Ulcer

The available literature on chronobiologic factors in experimental stress ulcer is extremely small and thematically limited. It focuses almost exclusively on circadian rhythms and, within that, on rhythms related to light-dark cycles, activity and body temperature. Among these, only differences in ulcer induction related to circadian activity patterns have been adequately demonstrated. Other circadian patterns and other temporal phase relationships might be profitably explored, including those related to postnatal development. It is also likely that the important relationships between biorhythms and stress ulcer are not limited to ulcer induction. Future studies should address chronobiologic factors in predisposition, severity of illness, the probability of recovery and response to various therapeutic interventions.     

Application of in situ cage cultures of phytoplankton for monitoring heavy metal pollution in two Norwegian fjords

A simple apparatus for in situ use of the cage culture technique for growing planktonic algae has been developed and used to follow growth and metal uptake of three diatoms in two Norwegian fjords polluted by heavy metals. Continuous pumping of sea water through a chelating resin and continuous water sampling was used to obtain average values for dissolved and particulate heavy metal content at the various test sites. The metals investigated (zinc, copper, lead, cadmium, and mercury) showed differences in the proportion of dissolved to particulate fractions.The three species of diatoms tested gave systematic growth responses to heavy metal pollution in the moderately polluted fjord; one alga died, one showed reduced growth rate at the more contaminated site compared with those at less polluted sites, while the most tolerant alga was apparently not affected. In the heavily polluted fjord only the most tolerant alga survived, showing decreasing growth rate with increasing pollution.Uptake of heavy metals increased generally with increasing heavy metal content in the sea water. The contents in the algae grown in the most polluted fjord were much higher than those obtained in the less polluted fjord, which were higher than the contents reported for algae from non-contaminated areas.     

Some effects of polyvinyl alcohol and polyvinyl pyrrolidone on the activity of lactate dehydrogenase and its isoenzymes

Summary The activity of Sigma type II LDH (containing all LDH isoenzymes), type VII (LDH 1) and type V (LDH 5) has been evaluated in 0.1 M phosphate buffer and 0.4 M tris-HCl buffer, both at pH 7.4, before and after addition of PVP and PVA. A slight reduction of reaction velocity occurred when PVP and PVA were added, probably because of the increased viscosity of the medium. More specifically, PVA seemed to reduce the LDH 1 activity in phosphate buffer, but it seemed to counteract, together with PVP, conformational changes due to tris-HCl buffer of high molarity. None of these effects were found to influence the results of section histochemistry, but it could be shown that PVA was able to reduce urea inhibition of LDH 5 in tris-HCl buffer.The following Abbreviations are used in the Article PVA Polyvinyl alcohol - PVP Polyvinyl pyrrolidone - tris tris (hydroxymethyl)-aminomethan - LDH Lactate dehydrogenase - -NADH -Nicotinamide Adenine Dinucleotide, reduced form - PMS Phenazine methosulfate - BSA Bovine serum albumin     

An Australian Multi‐Regional Waste Supply‐Use Framework

The production of waste creates both direct and indirect environmental impacts. A range of strategies are available to reduce the generation of waste by industry and households, and to select waste treatment approaches that minimize environmental harm. However, evaluating these strategies requires reliable and detailed data on waste production and treatment. Unfortunately, published Australian waste data are typically highly aggregated, published by a variety of entities in different formats, and do not form a complete time‐series. We demonstrate a technique for constructing a multi‐regional waste supply‐use (MRWSU) framework for Australia using information from numerous waste data sources. This is the first MRWSU framework to be constructed (to the authors' knowledge) and the first sub‐national waste input‐output framework to be constructed for Australia. We construct the framework using the Industrial Ecology Virtual Laboratory (IELab), a cloud‐hosted computational platform for building Australian multi‐regional input‐output tables. The structure of the framework complies with the System of Environmental‐Economic Accounting (SEEA). We demonstrate the use of the MRWSU framework by calculating waste footprints that enumerate the full supply chain waste production for Australian consumers.     

Nest distribution shaping within-stream variation in Atlantic salmon juvenile abundance and competition over small spatial scales

1. Spatial heterogeneity in population density is predicted to have important effects on population characteristics, such as competition intensity and carrying capacity. Patchy breeding distributions will tend to increase spatial heterogeneity in population density, whereas dispersal from breeding patches will tend to decrease it. The potential for dispersal to homogenize densities is likely to differ both among organisms (e.g. plants vs. mobile animals) and throughout ontogeny (e.g. larvae vs. adults). However, for mobile organisms, experimental studies of the importance of breeding distributions from the wild are largely lacking. 2. In the present study, experimental manipulations replicated over eight natural streams and 2 years enabled us to test for effects of the distribution of Atlantic salmon eggs over spatial scales which are relevant to local interactions among individuals. Artificial nests were placed along 250 m study reaches at one of two levels of nest dispersion - patchy (two nests per stream) and dispersed (10 nests per stream) - while holding total egg density (eggs m(-2) stream area) constant. 3. Nest dispersion had significant effects on the spatial distribution of the resulting juveniles in their first summer. Patchy nest distributions resulted in a highly right-skewed frequency distribution of local under-yearling densities (among 25 m sampling sections), as sample sections adjacent to the nest sites had relatively high densities. In contrast, dispersed nest distributions yielded approximately normal density distributions. Sections with high relative densities in the patchy nest distribution treatments also had relatively small juvenile body sizes, and patchy egg distribution appeared to produce a higher redistribution of individuals from the first to the second juvenile growth season than the dispersed distribution. 4. Because patchy breeding distribution combined with limited early dispersal can create spatial variation in density over scales directly relevant for individual interactions, this will be one important component in determining mean levels of early juvenile competition and its spatial variation within populations. Assuming random or ideal-free distribution of individuals may therefore underestimate the mean level of density experienced by juveniles over surprisingly small spatial scales (orders of magnitude smaller than total spatial extent of populations), even for mobile organisms.