The preconditioning phenomenon and its mechanisms in the common carp as affected by Actara insecticide

The effect of Actara insecticide on the common carp (Cyprinus carpio Linnaeus) was studied, and its sublethal concentration (LC50) for this species was estimated. Exposure to Actara at a concentration of 400 mg/L in freshwater was shown to kill all the common carp individuals within 24 h, while 24-h preconditioning at an Actara concentration of 100 mg/L promoted survival of animals when they were subsequently exposed to the insecticide at a concentration of 400 mg/L for 5 days. Estimates of serotonin-modulated anticonsolidation protein (SMAP) in the common carp brain and liver by enzyme-linked immunosorbent assay (ELISA) following exposure to Actara at a concentration of 100 mg/L for 24 h showed its increased level in both organs (p < 0.001), particularly manifest in the liver. It is concluded that preconditioning elevates SMAP tissue levels and promotes thereby protection of the organism against damaging effects of lethal Actara concentrations.     

Methylation of DNA by three N-nitroso compounds: evidence for sequence specific methylation by a common intermediate

Methylation in vitro of calf thymus DNA, a supercoiled plasmid, poly(dG).poly(dC), and poly(dGdC).poly(dGdC) by N-nitroso(acetoxy-methyl)methylamine and N-nitroso(acetoxybenzyl)methylamine in the presence of esterase, and by N-nitrosomethylurea was investigated. Although there were differences in the amounts of 7-methylguanine and O6-methylguanine formed in the various DNA substrates, the methylation pattern was the same for each of these methylating agents. The three compounds reacted identically when methylation of a portion of a 345 bp restriction fragment of the plasmid pBR322 was examined at nucleotide resolution by a sequencing assay. They also showed a tendency to react preferentially with particular guanines. These data suggest that the three N-nitroso compounds methylate DNA via a common intermediate such as the methyl diazonium ion, which exhibits some sequence specificity.     

Reliability of autoregulatory mechanisms of biosystems as affected by ionizing radiation

Reliability of biosystems in processes of adaptation and homeostasis after whole-body irradiation of rats with different doses was determined in terms of the stochastic process theory developed for the autoregulatory systems with random parameters. Fluctuations in the rate of spontaneous chemiluminescence of blood serum and accumulation of lipid peroxidation products by erythrocyte membranes of rat blood were taken as the initial material. The analysis of fluctuations of peculiar parameters permitted to predict the adaptability of the system and to make timely corrections.     

Regulatory mechanisms of ROI generation are affected by rice spl mutations

Reactive oxygen intermediates (ROIs) play a pivotal role in the hypersensitive response (HR) in disease resistance. NADPH oxidase is a major source of ROI; however, the mechanisms of its regulation are unclear. Rice spl mutants spontaneously form lesions which resemble those occurring during the HR, suggesting that the mutations affect regulation of the HR. We found that spl2, spl7 and spl11 mutant cells accumulated increased amounts of H(2)O(2) in response to rice blast fungal elicitor. Increased accumulation of ROIs was suppressed by inhibition of NADPH oxidase in the spl cells, and was also observed in the ozone-exposed spl plants. These mutants have sufficient activities of ROI-scavenging enzymes compared with the wild type. In addition, spl7 mutant cells accumulated higher amounts of H(2)O(2) when treated with calyculin A (CA), an inhibitor of protein phosphatase. Furthermore, spl2 mutant plants exhibited accelerated accumulation of H(2)O(2) and increased rates of cell death in response to wounding. These results suggest that the spl2, spl7 and spl11 mutants are defective in the regulation of NADPH oxidase, and the spl7 mutation may give rise to enhancement of the signaling pathway which protein dephosphorylation controls, while the spl2 mutation affects both the pathogen-induced and wound-induced signaling pathways.     

Gustatory and olfactory function in patients affected by Usher's syndrome

Ten patients (five males and five females, 8–27 yearsof age) diagnosed cases of Usher's syndrome were tested fortheir gustative and olfactory functions. The tasting of thesemultiple handicapped patients was carried out by elicitationof innate reflex-like distinct facial expressions in responseto gustatory and nasal stimulation. Findings indicate normalgustatory and olfactory function as well as adequate hedonicresponses to presented stimuli. In view of the reported findingsit can be stated that Usher's syndrome affect selectively thesenses of vision, hearing and often also labyrinth, while tasteand smell functions are not affected.     

Antiarrhythmic drugs impair hepatic uptake and secretory function by different mechanisms in the isolated perfused rat liver

In the present study the effect of various antiarrhythmic drugs on hepatic perfusion parameters, uptake capacity of organic anions and biliary secretion using the isolated perfused rat liver was examined. Infusion of verapamil (VP), diltiazem, N-propyl-ajmaline (NPAB), and quinidine at pharmacological doses induced consistently a 1.4-1.6-fold increase in portal pressure accompanied by a approximately 60% decrease in bile flow and a approximately 65% inhibition of biliary taurocholate (TC) excretion. Furthermore, hepatic uptake of oxygen, bromosulphthalein (BSP), and TC was significantly reduced. All these effects were dose-dependent and reversible upon withdrawal of the drugs. Studies of the hepatic circulation using a Trypan blue staining technique demonstrated a patchy perfusion pattern during infusion of the antiarrhythmic drugs as compared to the homogenously stained control organ. The hemodynamic alterations and the impairment of the hepatic initial uptake function could be entirely prevented by concomitant administration of the vasodilator papaverine. Bile flow and biliary TC excretion, however, were still inhibited under these conditions. The present results indicate that antiarrhythmic drugs produce cholestasis in the isolated perfused rat liver independently of their adverse effect on hepatic hemodynamics.     

Networks of neuronal genes affected by common and rare variants in autism spectrum disorders

Autism spectrum disorders (ASD) are neurodevelopmental disorders with phenotypic and genetic heterogeneity. Recent studies have reported rare and de novo mutations in ASD, but the allelic architecture of ASD remains unclear. To assess the role of common and rare variations in ASD, we constructed a gene co-expression network based on a widespread survey of gene expression in the human brain. We identified modules associated with specific cell types and processes. By integrating known rare mutations and the results of an ASD genome-wide association study (GWAS), we identified two neuronal modules that are perturbed by both rare and common variations. These modules contain highly connected genes that are involved in synaptic and neuronal plasticity and that are expressed in areas associated with learning and memory and sensory perception. The enrichment of common risk variants was replicated in two additional samples which include both simplex and multiplex families. An analysis of the combined contribution of common variants in the neuronal modules revealed a polygenic component to the risk of ASD. The results of this study point toward contribution of minor and major perturbations in the two sub-networks of neuronal genes to ASD risk.     

Reductive dechlorination of polychlorinated biphenyls as affected by natural halogenated aromatic compounds

We investigated the effects of halogenated aromatic compounds (HACs) including naturally occurring ones (L-thyroxine, 3-chloro-L-tyrosine, 5-chloroindole, 2-chlorophenol, 4-chlorophenol and chlorobenzene) on polychlorinated biphenyl (PCB) dechlorination in sediment cultures. A PCB-dechlorinating enrichment culture of sediment microorganisms from the St. Lawrence River was used as an initial inoculum. When the culture was inoculated into Aroclor 1248 sediments amended with each of the six HACs, the extent of dechlorination was not enhanced by amendment with HACs. The dechlorination patterns in the HAC-amended sediments were nearly identical to that of the HAC-free sediments except the 3-chloro-L-tyrosine-amended ones where no dechlorination activity was observed. When these sediment cultures were transferred into fresh sediments with the same HACs, the dechlorination specificities remained the same as those of the initial inoculations. Thus, in the present study, the substrate range of the highly selected enrichment culture could not be broadened by the HACs. It appears that HACs affect PCB dechlorination mainly through population selection rather than enzyme induction of single population.     

Thermotropic properties of human erythrocyte membrane proteins as affected by hydroxychloroaromatic compounds

The thermal stability of the anion transport protein (band 3) and other proteins of the human erythrocyte membrane, as influenced by hydroxychloroaromatic (HO-Cl2-Ar) compounds, was studied by differential scanning calorimetry. Various hydroxychlorodiphenyl ethers (HO-Clx-DPEs) and hexachlorophene, but not pentachlorophenol, caused a marked decrease in the thermal stability of band 3. Most of the other calorimetric transitions of the erythrocyte membrane were only slightly affected. The activity of HO-Clx-DPEs toward lowering the transition temperature of band 3 generally increased with the degree of chlorination, and was somewhat dependent on the position of hydroxyl substitution. At higher concentrations of HO-Clx-DPEs, there was a decrease in the enthalpy change and a broadening of the endothermic transition of band 3. The order of effectiveness of these compounds, as determined from band 3 denaturation temperatures, was similar to the order of potency previously observed for hemolysis of human erythrocytes.