DISC1 gene polymorphisms and the risk of schizophrenia in an Iranian population: A preliminary study

Background: Schizophrenia, schizoaffective disorder, and bipolar illness are common psychological disorders with high heritability and variable phenotypes. The disrupted in schizophrenia 1 ( DISC1) gene, on chromosome 1q42, has an essential role in neurite outgrowth and cell signaling. The purpose of this study was to investigate the association of three single-nucleotide polymorphisms (SNPs; rs6675281, rs2255340, and rs2738864) with schizophrenia disorder. These three SNPs were chosen as they had been used in most of the previous studies. Methods: In a case-control study of Iranian population for the first time 778 blood samples were collected including, 402 schizophrenic patients and 376 healthy controls. Genomic DNA was extracted from peripheral blood using DNA extraction kit (BioFlux Co). The genotypes of rs6675281, rs2255340, and rs2738864 were detected by nested allele-specific multiplex polymersae chain reaction (PCR). Results: Our data revealed that the three SNPs are significantly associated with schizophrenia (rs2255349 C>T: confidence interval (CI), 2.115 to 3.268; P = 0.0000 OR: 2.629; rs2738864 C>T: CI, 1.538 to 2.339; P = 0.0000 OR: 1.897; rs6675281 C>T: CI, 2.788 to 4.662; P = 0.0009241 OR: 3.605). Through applying the expectation-maximization (EM) algorithm, we calculated the haplotype frequency, and finally performed haplotype analysis with Bonferroni correction and data preprocessing methods and the results showed rs66875281 to have the highest association. Discussion: Our findings primarily showed that DISC1 gene polymorphisms contribute to schizophrenia risk and have a significant association with this disorder among Iranian population. The strategy was found to be easy, rapid, specific, and consistent for the co-occurring detection of the DISC1 polymorphisms. We could finally confirm that the polymorphisms are related to schizophrenia studied in Iranian population.     

A comparative study of the characteristics of eIF-2 and eIF-2-ancillary factor activities from yeast Saccharomyces cerevisiae and rabbit reticulocytes

The characteristics of yeast eukaryotic initiation factor 2 (eIF-2) and Co-eIF-2A have been studied and compared with those of the corresponding factors from rabbit reticulocytes. 1) Unlike eIF-2r, purified eIF-2y did not contain bound GDP. 2) Purified eIF-2y preparation contained GTPase activity and dephosphorylated GTP to GDP. 3) An anti-eIF-2r preparation which predominantly precipitated the gamma-subunit (Mr 54,000) of eIF-2r also precipitated the larger subunit (Mr 54,000) of eIF-2y. 4) Unlike eIF-2r, ternary complex formation by eIF-2y was not inhibited by Mg2+. 5) Both Co-eIF-2A20y and Co-eIF-2r significantly enhanced Met-tRNAf binding to eIF-2y and, again, Mg2+ did not have any effect on this stimulated Met-tRNAf binding to eIF-2y. 6) Both Co-eIF-2A20y and Co-eIF-2r were similarly effective in stimulating Met-tRNAf binding to eIF-2r in the absence of Mg2+. However, in the presence of Mg2+, Co-eIF-2A20y was significantly less effective than Co-eIF-2r as Co-eIF-2A20y did not promote displacement of GDP from eIF-2r X GDP. 7) eIF-2y bound [3H]GDP and this binding was significantly enhanced in the presence of Mg2+. Also, [3H]GDP in the preformed eIF-2y X [3H]GDP complex was rapidly exchanged with exogenously added unlabeled GDP in the presence of Mg2+. Co-eIF-2A20y had no effect on GDP binding to eIF-2y nor on GDP exchange reactions. 8) Reticulocyte heme-regulated protein synthesis inhibitor, which phosphorylated almost completely (in excess of 80%) the alpha-subunit (Mr 38,000) of eIF-2r, also phosphorylated similarly the smaller subunit (Mr 36,000) of eIF-2y. However, such phosphorylation had no significant effect on ternary complex formation, GDP binding, and GDP exchange reactions.     

Epidermal cells in activation of suppressor lymphocytes: further characterization

Intravenous administration of hapten-coupled, high-density (density greater than 1.077) epidermal cells (HD-EC) to mice results in the appearance of transferable splenic T suppressor (Ts) cells as assayed in adoptive transfer experiments. Depletion of I-A bearing cells from the HD-EC population before hapten coupling prevents these cells from inducing Ts cell formation, whereas depletion of Thy-1-bearing cells from the HD-EC cell preparation has no effect. When HD-EC are adhered to glass for 2 hr, the ability to induce Ts cell formation resides in the adherent population. Exposure of HD-EC to a dose of ultraviolet radiation (UVR) that largely abrogates the ability of hapten-coupled EC to immunize mice for a DTH response does not affect the ability of these cells to activate Ts cells. Treatment of mice with i.p. administration of 20 mg/kg of cyclophosphamide 2 days before EC harvesting abrogates the ability of HD-EC from these mice to induce Ts cell formation. HD-EC from B10.A(3R) (I-Jb) but not B10.A(5R) (I-Jk) mice induce Ts cell formation in B10.A(3R) mice, demonstrating that the ability to do so is restricted by the I-J locus. Transmission electron microscopy of adherent HD-EC populations demonstrated that two cell types were present. One type had the characteristics of keratinocytes; the other was monocyte-like and resembled Langerhans cells or indeterminate cells in many aspects. Immunoelectron microscopy revealed this second cell type to bear I-A/I-E antigen. These cells were T-200 positive and Mac-1 negative by immunoperoxidase staining. Extensive examination by light and electron microscopy failed to reveal any dermal components in the EC populations; however, a very small degree of dermal contamination cannot be excluded. Thus, EC that activate afferent-acting Ts cells are high-density, I-A+, Thy-1-, I-J restricted, glass adherent, and functionally UVR resistant and cyclophosphamide sensitive.     

Reaction of (Na+ + K+)-dependent adenosine triphosphatase with inorganic phosphate. Regulation by Na+, K+, and nucleotides

Effects of Na+, K+, and nucleotides on Mg2+-dependent phosphorylation of (Na+ + K+)-dependent adenosine triphosphatase by Pi were studied under equilibrium conditions. Na+ was a linear competitive inhibitor with respect to Mg2+ and a mixed inhibitor with respect to Pi. K+ was a partial inhibitor; it interacted with positive cooperativity and induced negative cooperativities in the interactions of Mg2+ and Pi with the enzyme. Adenyl-5'-yl (beta, gamma-methylene)diphosphonate, a nonhydrolyzable analog of ATP, interacted with negative cooperativity to inhibit phosphorylation in competition with Pi. ATP was also a competitive inhibitor. Na+ and K+ acted antagonistically, Na+ and nucleotides inhibited synergistically, and K+ and nucleotides were mutually exclusive. In the presence of ouabain, when nucleotides were excluded from the site inhibiting phosphorylation, a low affinity regulatory site for nucleotides became apparent, the occupation of which reduced the rate of dephosphorylation and the initial rate of phosphorylation of the enzyme without affecting the equilibrium constant of the reaction of Pi with the ouabain-complexed enzyme. The regulatory site was also detected in the absence of ouabain. The data suggest that catalytic and transport functions of the oligomeric enzyme may be regulated by homotropic and heterotropic site-site interactions, ligand-induced slow isomerizations, and distinct catalytic and regulatory sites for ATP.     

Macro- and microscopic morphology of the flank scales of families Lutjanidae and Serranidae from the Persian Gulf Coral Reefs (Teleosts: Perciformes)

Macro- and microscopic characteristics of flank scales for 12 species were investigated from the Persian Gulf Coral Reefs. In Lutjanus argentimaculatus and L. russellii (family Lutjanidae), the scales of different flank regions were not different, while four characters showed variation in the scale of L. lutjanus i.e., scale shape (pentagonal, hexagonal and square), anterior margin (waved, scalloped and smooth), focus shape (circular and oblong) and focus position (postero-central and central), displayed variation. Scale type (ctenoid) and posterior margin (transforming ctenii) did not show variation and could be considered to be specific in this family. In Epinephelus chlorostigma (family Serranidae), the scales of flank regions did not display variation, while in E. areolatus, E. diacanthus and E. radiates, the scales showed considerable variation. The most variable characters were scale shape, posterior margin and focus shape. Therefore, in fish systematics studies on the base of scale, it is particularly important to compare scales from the same flank regions. Also, some criteria such as size-dependent alternation, ontogenetic changes and variation between flank regions, should be considered. This study supports the potential of scale morphology to help for the understanding of fish diversity in the coral reef ecosystem.     

Ion specificity of cardiac sarcolemmal Na+/H+ antiporter

In bovine cardiac sarcolemmal vesicles, an outward H+ gradient stimulated the initial rate of amiloride-sensitive uptake of 22Na+, 42K+, or 86Rb+. Release of H+ from the vesicles was stimulated by extravesicular Na+, K+, Rb+, or Li+ but not by choline or N-methylglucamine. Uptakes of Na+ and Rb+ were half-saturated at 3 mM Na+ and 3 mM Rb+, but the maximal velocity of Na+ uptake was 1.5 times that of Rb+ uptake. Na+ uptake was inhibited by extravesicular K+, Rb+, or Li+, and Rb+ uptake was inhibited by extravesicular Na+ or Li+. Amiloride-sensitive uptake of Na+ or Rb+ increased with increase in extravesicular pH and decrease in intravesicular pH. In the absence of pH gradient, there were stimulations of Na+ uptake by intravesicular Na+ and K+ and of Rb+ uptake by intravesicular Rb+ and Na+. Similarly, there were trans stimulations of Na+ and Rb+ efflux by extravesicular alkali cations. The data suggest the existence of a nonselective antiporter catalyzing either alkali cation/H+ exchange or alkali cation/alkali cation exchange. Since increasing Na+ caused complete inhibition of Rb+/H+ exchange, but saturating K+ caused partial inhibitions of Na+/H+ exchange and Na+/Na+ exchange, the presence of a Na(+)-selective antiporter is also indicated. Although both antiporters may be involved in pH homeostasis, a role of the nonselective antiporter may be in the control of Na+/K+ exchange across the cardiac sarcolemma.     

Potent beta-adrenergic antagonist possessing chemically reactive group

A highly potent beta-adrenergic antagonist based on the structure of alprenolol has been prepared by replacement of the isopropylamine residue of alprenolol by 1, 8-diamino-p-menthane (AlpM). The resulting mixture of isomers (AlpM) competes for occupancy of beta-adrenergic receptors in frog erythrocycte membranes with an apparent K_D of 210 pM. The bromoacetylated derivative of AlpM (BrAlpM) leads to an irreversible inactivation of the [³H]dihydroalprenolol ([³H]DHA) binding sites. Various adrenergic agonists and antagonists afford specific and stereoselective protection of the receptor against inactivation by BrAlpM. Tritiation of AlpM followed by bromoacetylation and chromatographic separation yielded two isomers, Br-1-AlpM and Br-8-AlpM of high specific radioactivity (～ 40 Ci/mmol). Both radiolabelled isomers interacted specifically and with high affinity with the beta-adrenergic receptor, but only a small amount of the ligands could be covalently incorporated into the receptor subunit. This agent provides a powerful new probe for studies of beta-adrenergic receptors in analogy with bungarotoxin for the nicotinic cholinergic receptor.     

(Na+ + K+)-ATPase : phosphorylation-dependent cross-linking of the alpha-subunits in the presence of Ca2+ and o-phenanthroline

In previous studies we had demonstrated that in the presence of 0.25 mM Cu2+ and 1.25 mM o-phenanthroline, cross-linking of the alpha-subunits of Na+ + K+)-dependent adenosine triphosphatase was induced by the addition of Na+ + ATP, and that the formation of the alpha,alpha-dimer was preceded by that of phosphoenzyme. The purpose of the present studies was the further evaluation of the role of phosphoenzyme in the process of cross-linking. Na+ + UTP did not induce cross-linking unless Mg2+ was also added. In contrast, Na+ + ATP-induced cross-linking did not require the addition of Mg2+. The different effects of ATP and UTP in the absence of added Mg2+ could be accounted for by the presence in the enzyme preparation of bound Mg2+ which supported enzyme phosphorylation by ATP but not by UTP. When the enzyme was phosphorylated by Pi, in the presence of Mg2 and ouabain, and the exposed to Cu2+ and o-phenanthroline, the alpha,alpha-dimer was obtained. Under these conditions, Na+ blocked both phosphorylation and cross-linking. These results indicate that it is the formation of phosphoenzyme per se that leads to conformational transitions favorable to cross-linking. They also suggest that Cu2+ and o-phenanthroline participate in the cross-linking reaction, but not in the phosphorylation reactions. In the digitonin-treated enzyme, Na+ and ATP induced the formation of phosphoenzyme, but not that of alpha,alpha-dimer. These findings indicate that in addition to phosphorylation, a proper orientation o alpha-subunits in an oligomer is also necessary for cross-linking.     

Na+,K+-ATPase: on the nature of the "cross-linked" subunits obtained in the presence of o-phenanthroline and cupric ion.

In previous studies on the quaternary structure of Na⁺,K⁺-ATPase, cupric-phenanthroline complex (CP) has been used for the cross-linking of the enzyme subunits. Here we show that the same products obtained in the presence of CP (α,α-dimer, α,β-dimer, and products of higher molecular weight) are also obtained when the enzyme is exposed to Cu²⁺ without o-phenanthroline. The α,β-dimer (but not the α,α-dimer) is dissociated in the presence of EDTA; indicating that this product is not the result of the covalent cross-linking of the subunits through a disulfide bond. The nature of the α,α-dimer remains to be determined. The findings suggest that the results of “cross-linking” experiments with CP should be interpreted with caution until the products are more clearly identified.