The endorphins of the epithelial and subepithelial structures of the rat small intestine and the evolutionary hypotheses of the formation of the mechanisms of the negative regulation of their synthesis]

The effects of the agonist of the glucocorticoid hormones dexamethasone and dopamine antagonist--haloperidol on the concentration of immunoreactive alpha-, beta- and gamma-endorphins in duodenum, ileum, and jejunum of rats were studied. Besides the extracts of the intestines, the immunoreactive endorphins were measured in the extracts of their mucosa-submucosa and muscle-serous layers, that allowed to separate the endorphin-producing cells of the nervous system (muscle-serous layer) from endorphin producing cells of endocrine and immune systems (mucosa-submucosa layer). The injection of dexamethasone (0.2 mg per rat, daily for 6 days) caused the reliable decrease in concentrations of all three types of endorphins in mucosa-submucosa and muscle-serous layer of duodenum, ileum, and jejunum. Under the action of haloperidol (0.6 mg per rat, daily for 6 days) the reliable increase of beta-endorphin concentration was noticed only in jejunum. The suggestion is made that two distinct subpopulations of endorphin-producing cells exist in the intestine: in one cells endorphin synthesis is regulated by glucocorticoids, as in the anterior lobe of pituitary, in the other cells the synthesis of endorphins is regulated by dopamine, as in the cells of the intermediate lobe of pituitary. It is suggested that both glucocorticoid and dopamine types of regulation of endorphins synthesis were formed in the intestine or even in the gastric cavity. In process of evolution the cells with glucocorticoid type of regulation gave rise to the anterior lobe of pituitary, the cells with the dopamine type of regulation--to the intermediate lobe.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Effect of digitonin on the activity of Na,K-ATPase from bovine brain

The kinetic properties of intact and digitonin-treated Na,K-ATPase from bovine brain were studied. The temperature dependence curve for the rate of ATP hydrolysis under optimal conditions (upsilon 0) in the Arrhenius plots shows a break at 19-20 degrees. The temperature dependence curves for Km' and Km" have breaks at the same temperatures, while the Arrhenius plot for V is linear. The value of the Hill coefficient (nH) for ATP at 37 degrees is variable depending on ATP concentration, i. e. it is less than 1 at ATP concentrations below 50 mkM and is increased up to 3.2 at higher concentrations of the substrate. At high ATP concentrations the value of nH depends on temperature, falling down to 2.1 at 23 degrees and then down to 1 within the temperature range of 21-19 degrees. A further decrease in temperature does not significantly affect the nH value. Digitonin irreversibly inhibits Na, K-ATPase. ATP hydrolysis is more sensitive to the effect of the detergent than is nNPP hydrolysis, i. e. after complete inhibition of the ATPase about 40% of the phosphatase activity are retained. Treatment of Na,K-ATPase by digitonin results in elimination of the breaks in the Arrhenius plots for upsilon 0, Km' and Km", whereas the temperature dependence plot of V remains linear. Simultaneously digitonin eliminates the positive cooperativity of the enzyme for ATP. It is assumed that Na, K-ATPase from bovine brain is an oligomer of the (alpha beta) 4 type. Digitonin changes the type of interaction between the protomers within the oligomeric complex by changing the lipid environment of the enzyme or the type of protein -- lipid interactions.     

The response of skeletal muscle to alcohol abuse: Gender differences

A gender analysis has been carried out to analyze changes in intracellular signaling pathways that lead to the development of chronic alcoholic myopathy. It is known that acute or chronic alcohol intoxication can result in alcohol-induced lesions in skeletal muscles. Chronic alcoholic myopathy occurs much more frequently and can develop either independently or in combination with other forms of alcoholic disease (liver and heart lesions, malabsorption syndrome, or alcohol polyneuropathy). This disease is manifested by atrophy of skeletal muscles and a performance decrement. Most of the studies on the pathogenesis of chronic alcoholic myopathy have been carried out on male patients. Studies on alcoholic myopathy-induced muscle damage in females have not been previously reported.     

Electrophoretic detection of protein p53 in human leukocytes

Protein (m.v. 53 kilodalton) with electrophoretic mobility identical to that of protein detected in leukocytes of patients with Down's syndrome and of protein p53 obtained from mouse ascites carcinoma was demonstrated by polyacrylamide gel electrophoresis in healthy donors' leukocytes cultured with PHA and in peripheral blood of patients with chronic myeloleukemia. Appearance of the class p53 proteins in leukocytes of patients may be connected with the presence in their blood of the population of immature or transformed, proliferating or merely DNA-synthesizing leukocytes, particularly those amplifying the gene that codes protein p53.     

Immunogenic complexes of the soluble surface antigens of Sh. sonnei]

The comparative study of the immunogenic properties of Sh. sonnei (phases I and II) soluble surface antigens obtained by the modified method of aqueous-saline extraction and Sh. sonnei (phase I) antigen obtained by Boivin's method was made with the use of the keratoconjunctival test in guinea pigs. The protective activity of a high molecular fraction obtained by the fractionation of phase I soluble surface antigens in Sepharose 4B was studied. Boivin's antigen, when used for immunization in optimum doses, was found to have pronounced protective properties, whereas phase II soluble surface antigens showed no protective activity. A high molecular fraction obtained from phase I soluble surface antigen was found to be the most immunogenic. Protective activity was largely connected with protein antigen. The question whether protein antigen was an independent protective antigen or whether it constituted a part of a complex which determined the protective activity of a high molecular fraction remained unsolved.     

An invisible ubiquitin conformation is required for efficient phosphorylation by PINK1

The Ser/Thr protein kinase PINK1 phosphorylates the well‐folded, globular protein ubiquitin (Ub) at a relatively protected site, Ser65. We previously showed that Ser65 phosphorylation results in a conformational change in which Ub adopts a dynamic equilibrium between the known, common Ub conformation and a distinct, second conformation wherein the last β‐strand is retracted to extend the Ser65 loop and shorten the C‐terminal tail. We show using chemical exchange saturation transfer (CEST) nuclear magnetic resonance experiments that a similar, C‐terminally retracted (Ub‐CR) conformation also exists at low population in wild‐type Ub. Point mutations in the moving β5 and neighbouring β‐strands shift the Ub/Ub‐CR equilibrium. This enabled functional studies of the two states, and we show that while the Ub‐CR conformation is defective for conjugation, it demonstrates improved binding to PINK1 through its extended Ser65 loop, and is a superior PINK1 substrate. Together our data suggest that PINK1 utilises a lowly populated yet more suitable Ub‐CR conformation of Ub for efficient phosphorylation. Our findings could be relevant for many kinases that phosphorylate residues in folded protein domains.     

Soluble surface antigens of virulent Sh. sonnei]

The authors conducted an immunochemical analysis of the surface soluble antigen preparations (SSAP) obtained by extraction with physiological saline of the virulent Sh. sonnei microbes killed with acetone. Immunochemical studies by the immunoelectrophoresis and immunodiffusion methods in agar gel, separation on sepharose 4B and in polyacrylamide gel showed the presence of 3 groups of the antigens in the SSAP composition: 1) protein antigens, determining the commonness with the Sonne microbes of the II phase and intergenera associations with typhoid and enteropathogenic E. coli; 2) specific somatic antigen of the Boiven type present in small amounts in the SSAP; 3) specific antigens differing by specificity from the Boiven antigen detected in the microbes of the I phase only and possibly playing a role in the virulent and immunogenic properties of the causative agent.