Trichinella spiralis: Comparison with an Arctic isolate

The muscle phase of Trichinella spiralis and of Trichinella sp. isolated in the Arctic was compared in experimental and wild animals. Reproductive capacity indices (RCI) of the Trichinella sp. isolate were significantly lower in laboratory rodents but were similar to T. spiralis in wild rodents. Sprague-Dawley rats were the most refractory to the Trichinella sp. isolate of all laboratory rodents. Outbred strains of mice were more susceptible to both T. spiralis and the Trichinella sp. isolate than inbred strains of mice. T. spiralis muscle larvae survived longer in mice and the survival of both T. spiralis and the Trichinella sp. isolate larvae was higher in female mice. While single pair interbreeding experiments showed reproductive isolation between T. spiralis and the Trichinella sp. isolate, multiple pair and transplant breeding experiments showed reproductive compatibility. Male and female infective larvae of T. spiralis and the Trichinella sp. isolate differed morphometrically, but a convergence in size of worms was observed after prolonged passages of the parasites in mice. Passaging history of the isolate and host species was found to have a significant effect on Trichinella morphology. It is proposed that the Trichinella sp. isolate is a physiological variant of T. spiralis and not a distinct species.     

Structural Decomposition Analysis of Raw Material Consumption

The aim of this article is to quantify the drivers for the changes in raw material consumption (domestic material consumption expressed in the form of all materials extracted and used in the production phase) in terms of technology, which refers to the concept of sustainable production; the product structure of final demand, which refers to the concept of sustainable consumption; and the volume of final demand, which is related to economic growth. We also aim to determine to what extent the technological development and a shift in product structure of the final demand compensate for the growth in final consumption volume. Therefore, we apply structural decomposition analysis (SDA) to the change in raw material consumption (RMC) of the Czech Republic between 2000 and 2007. To present the study in a broader context, we also show other material flow indicators for the Czech Republic for 2000 and 2007. Our findings of SDA show that final demand structure has a very limited effect on the change in material flows. The rapid change in final demand volume was not compensated for crude oil, metal ores, construction materials, food crops, and timber. For the material category of non‐iron metal ores, even the change in technology contributes to an increase in material flows. The largest relative increases are reported for non‐iron metal ores (38%) and construction materials (30%). The main changes in material flows related to the Czech Republic are driven by exports and enabled by imports, the main source of these increased material flows. This emphasizes the increasing role of international trade.     

Cross-linking of DNA in liver and testes of rats fed 1,3-propanediol

1,3-Propanediol (PAD) was fed to rats for 15 weeks, and its effects on hepatic and testicular DNA were studied. The control rats were fed a casein-based diet that contained 10% tocopherol-stripped corn oil with 30 IU of d,l-α-tocopherol acetate/kg; the experimental rats were fed the same diet with 500 ppm of PAD. Homogenates prepared from the livers of each group of rats converted 1,3-propanediol to malondialdehyde (MDA) with equal efficacy, but homogenates of testes did not catalyze this conversion. After 10–15 weeks of feeding the diets, the hepatic DNA of the rats fed PAD had less template activity, more bound tryptophan and more DNA-protein and interstrand DNA cross-links than that of the control rats. As measured by template activity and bound tryptophan, testicular DNA of the experimental rats was not different from that of the control rats; however, there was slightly more cross-linking in the testicular DNA of experimental rats than in that of control rats. Testes of the experimental rats contained more lipid-soluble fluorophores than did those of the control rats. The results are consistent with the conclusion that PAD was converted to MDA in vivo and that MDA is the reactive species that caused the observed biological damage.     

Solubility characteristics of Micrococcus lysodeikticus membrane components in detergents and chaotropic salts analyzed by immunoelectrophoresis

In order to evaluate the effectiveness and selectivity of various reagents in the solubilization of bacterial membranes, membranes of Micrococcus lysodeikticus were treated with detergents and chaotropic agents. The composition of the extracts so obtained was analyzed by rocket and two-dimensional immunoelectrophoretic techniques. Recovery of succinate-, malate-, and reduced nicotinamide adenine dinucleotide- (NADH) dehydrogenases, ATPase, succinylated lipomannan and cytochromes in the extracts was measured. Treatment with a variety of non-denaturing detergents produced extracts that were generally qualitatively uniform although quantitative differences were observed. The degree of extraction of various components was correlated with the hydrophile-lipophile balance. Several chaotropic agents were also evaluated as reagents for membrane solubilization. These agents were less effective in extraction of bulk protein, but produced extracts enriched in some membrane components.     

Grouped sequential exploitation of food patches in a flock feeder,the feral pigeon

Feral and laboratory flocks of rock doves ($\text{Columba}$$\text{livia}$) show a pattern of grouped sequential exploitation when simultaneously presented with two dispersed, depleting patches of seed. This behavior contrasts with the ideal free distribution pattern shown when patches are small and concentrated. Grouped sequential exploitation consists of two phases: all pigeons first land together and feed at one patch, then leave one by one for the other patch. Departure times of individuals for the second patch are correlated with feeding rate at patch 1, which is in turn correlated with position in the dominance hierarchy. The decision to switch from patch 1 to patch 2 improves individual feeding rates in all cases, but is done slightly later than it should according to optimal foraging theory.     

A new tubulin-binding protein

A new brain protein is described which forms an insoluble complex with tubulin, with concomitant stoichiometric hydrolysis of GTP. The complex contains a maximum of one tubulin-binding protein (MW 52,500) per two tubulin dimers. The tubulin-binding protein (TBP) does not compete with colchicine, but in the presence of microtubule-associated proteins tubulin appeared less accessible to it. Proteins such as TBP might sequester tubulin and thereby function either to inhibit indiscriminate polymerization, or to promote ordered nucleation by maintaining high local concentrations.     

Limited proteolysis patterns of the B chain of insulin.

The oxidized B chain of insulin was used as a simple model for further consideration of limited proteolysis with low substrate:enzyme ratios. With low B chain:trypsin ratios, the ordinarily slower cleavage rate of the -Lys₂₉-Ala₃₀ bond essentially equaled the cleavage saturation rate of the -Arg₂₂-Gly₂₃ bond. This led to the disappearance of octapeptide which ordinarily forms most rapidly. Heptapeptide and alanine, formed mainly by cleavage of the octapeptide, decreased somewhat at high enzyme relative levels. Trypsin added to B chain formed a single chromatographic peak.     

Evidence of increased synthesis of δ-aminolevulinic acid dehydratase in experimental lead-poisoned rats

δ-Aminolevulinic acid dehydratase (porphobilinogen synthase; 5-aminolevulinate hydro-lyase, EC 4.2.1.24) was purified from rat and rabbit erythrocytes to a homogeneous state. Specific activities were 26.0 and 26.6 units/mg protein for the rat and rabbit enzymes, respectively, and their estimated molecular weight was 280 000, each consisting of 8 subunits of M_r 35 000. In order to quantitate rat δ-aminolevulinic acid dehydratase at several stages of lead-poisoning, a radioimmunoassay technique using goat antiserum against the rat enzyme was developed for the first time. This technique was specific, reproducible and high sensitive allowing determination of 1 ng enzyme. When drinking water containing 25 mM lead acetate was given daily to rats ad lib. the δ-aminolevulinic acid dehydratase activity in the blood, assayed without any pretreatment, decreased to 8% of the control level on the next day. On the contrary, the restored enzyme activity, assayed in the presence of Zn²⁺ and dithiothreitol, was greater than normal by the fourth day of lead administration in bone-marrow cells and by the ninth day in the peripheral blood. The increased activity level stayed the same from the ninth day onward. The enzyme content as determined directly by the radioimmunoassay technique at this stage was about 2-fold above that the control. There was no significant difference in the number of reticulocytes and the distribution profile of different types of reticulocytes between the lead-exposed and non-exposed rats. Therefore, the increase in the amount of δ-aminolevulinic acid dehydratase in erythrocytes of lead-poisoned rats was suggested to be due to an increased rate of synthesis in the bone-marrow cells.     

The disposition of citric acid cycle intermediates by isolated rat heart mitochondria

The mechanism of depletion of tricarboxylic acid cycle intermediates by isolated rat heart mitochondria was studied using hydroxymalonate (an inhibitor of malic enzymes) and mercaptopicolinate (an inhibitor of phosphoenolpyruvate carboxykinase) as tools. Hydroxymalonate inhibited the respiration rate of isolated mitochondria in state 3 by 40% when 2 mM malate was the only external substrate, but no inhibition was found with 2 mM malate plus 0.5 mM pyruvate as substrates. In the prescence od bicarbonate, arsenite and ATP, propionate was converted to pyruvate and malate at the rates of 14.0 ± 2.9 and 2.8 ± 1.8 nmol/mg protein in 5 min, respectively. Under these conditions, 0.1 mM mercaptopicolinate did not affect this conversion, but 2 mM hydroxymalonate inhibited pyruvate formation completely and resulted in an accumulation of malate up to 13.2 ± 2.9 nmol/mg protein. No accumulation of phosphoenolpyruvate was found under any condition tested. It is concluded that malic enzymes but not phosphoenolpyruvate carboxykinase, are involved in conversion of propionate to pyruvate in isolated rat heart mitochondria.