Swim Stress Increases the Potency of Glycine at the N-Methyl-d-Aspartate Receptor Complex

Abstract: We have previously demonstrated that chronic administration of antidepressants results in a reduction in the potency of glycine to displace 5,7-[³H]dichlorokynurenic acid (5,7-[³H]-DCKA) from the strychnine-insensitive glycine recognition site of the NMDA receptor complex. We now report that exposure of rats to the forced swim test results in a 56% increase in the potency of glycine to displace 5,7-[³H]DCKA from frontal cortical homogenates. These data are consistent with the hypothesis that the forced swim test, a preclinical screen sensitive to acute administration of antidepressant drugs and NMDA receptor antagonists, also results in adaptation of the NMDA receptor complex. Moreover, these data lend further support to the hypothesis that glutamatergic pathways are involved in the neurobiological response to stress and, potentially, in the pathophysiology of depression.     

R-factor-mediated suppression of the galactose-sensitive phenotype of Escherichia coli K-12 galE mutants

Plasmids S-a and Rts1 suppress the galactose-sensitive phenotype of galE mutants of Escherichia coli K-12, giving rise to both galactose-fermenting and nonfermenting strains. Fermenting strains produce normal inducible UDP-galactose epimerase. Plasmids extracted from either a fermenting or a nonfermenting strain are indistinguishable when examined by either measurements of length of relaxed circular molecules by electron microscopy or electrophoretic pattern of restriction endonuclease digestion products. The phenomenon could be explained by reversible recombination between a plasmid-borne epimerase gene and homologous chromosomal sequences.     

Reactivity of sulphydryl groups of cytosolic and mitochondrial bovine aspartate aminotransferases

Summary Reactivity of sulphydryl groups of cytosolic and mitochondrial aspartate aminotransferases from ox heart has been studied. A total of 5 and 7 cysteine residues per monomer are present in cAATo and mAATo, respectively. In native conditions only a single sulphydryl group can be titrated by Nbs₂ while the catalytic activity remains unchanged, however in the mitochondrial isozyme the reactivity depends on the functional state of the enzyme. Reactivity toward NEM reveals the existence of a syncatalytic sulphydryl group in the cytosolic isozyme. Titration of cAATo with pMB at pH 8 and pH 5 confirms the existence of two exposed sulphydryl groups with a different reactivity. The results compared with those reported on the corresponding isozymes from pig and chicken heart show that syncatalytic sulphydryl groups are of general occurrence in these enzymes.     

Characterization of cytoplasmic arginine-rich basic protein of Guerin epithelioma

Summary Arginine-rich basic protein from cytoplasma of Guerin epitheliomas has been isolated and characterized. It contains five amino acids: arginine, lysine, glycine, alanine and glutamic acid which make together 74 per cent of all amino acid residues. The protein has a cationic character with an isoelectric point of 8.2. No carbohydrate component was found in this protein. The significance of arginine-rich basic protein in the cytoplasma of Guerin epithelioma is discussed briefly.     

Lathyrus nissolia subsp.futakii subsp. nova in der Tschechoslowakei

A new subspecies,Lathyrus nissolia L. subsp.futakii Chrtková subsp. nova is described from East Slovakia. The diacritical characters are: high and rich branched stems, 50–110 cm long and larger, 10–12 mm long, bright orange-red flowers. It differs also in ecology, growing in wet lowland forests with the level of the ground water up to 15 cm over the earth also in summer.     

Selected chromosome counts of the Czechoslovak flora III

Chromosome numbers compared with as yet published data are given for the following 12 Phanerogams (both native species and aliens) from Czechoslovakia:Ambrosia trifida L.,Cardamine chelidonia L.,Dephne cneorum L.,Epipactis albensis Nováková etRydlo,Linum flavum L.subsp flavum, Lunaria rediviva L.,Nepeta grandiflora M.BIEB.,Reseda luteola L.,Thlaspi montanum L.,Tithymalus salicifolius (Host)Klotzsch etGarcke,Tithymalus virgultosus (Klokov) Holub andVerbascum speciosum Schrad. subsp.speciosum. The chromosome number 2n=40 is presented for the first time in autogamousEpipactis albensis Nováková etRydlo. New chromosome numbers were found inCardamine chelidonia L. (2n=32) and inTithymalus salicifolius (Host) Klotzch etGarcke (2n=40). Known but less frequent cytotypes are reported inLinum flavum L. subsp.flavum (2n=28) and inVerbascum speciosum Schrad. subsp.speciosum (2n=30).     

A locus for familial hypertrophic cardiomyopathy is closely linked to the cardiac myosin heavy chain genes, CRI-L436, and CRI-L329 on chromosome 14 at q11-q12

We report that a gene responsible for familial hypertrophic cardiomyopathy (HC) is closely linked to the cardiac alpha and beta myosin heavy chain (MHC) genes on chromosome 14q11. We have recently shown that probe CRI-L436, derived from the anonymous DNA locus D14S26, detects a polymorphic restriction fragment that segregates with familial HC in affected members of a large Canadian family. Using chromosomal in situ hybridization, we have mapped CRI-L436 to chromosome 14 at q11-q12. Because the cardiac MHC genes also map to this chromosomal band, we have determined the genetic distances between the cardiac beta MHC gene, D14S26, and the familial HC locus. Data presented here show that these three loci are linked within 5 centimorgans on chromosome 14 at q11-q12. The possibility that defects in either the cardiac alpha or beta MHC genes are responsible for familial HC is discussed.     

Action of barbiturates on activity of acetylcholinesterase from synaptosomal membranes

The acetylcholinesterase from synaptosomal membranes is inhibited by anesthetics: Nembutal, brietal, and thiopental. Nembutal and brietal decrease theK _m for acetylthiocholine, without changes inV _max. A noncompetitive type of inhibition is produced by thiopental. This anesthetic decreases Arrhenius plot discontinuity by about 4°C and increases activation energies. Nembutal and brietal do not change Arrhenius plot discontinuities, but they increase activation energies. These results suggest that barbiturates change lipid-protein interactions in synaptosomal membranes.