Involvement of L-Type-Like Amino Acid Transporters in S-Nitrosocysteine-Stimulated Noradrenaline Release in the Rat Hippocampus

Abstract: Nitrogen oxides, such as nitric oxide, have been shown to regulate neuronal functions, including neurotransmitter release. We investigated the effect of S-nitroso-l -cysteine (SNC) on noradrenaline (NA) release in the rat hippocampus in vivo and in vitro. SNC stimulated [³H]NA release from prelabeled hippocampal slices in a dose-dependent manner. SNC stimulated endogenous NA release within 30 min to almost five times the basal level in vivo (microdialysis in freely moving rats). In a Na⁺-containing Tyrode's buffer, SNC-stimulated [³H]NA release was inhibited 30% by the coaddition of l -leucine. In the Na⁺-free, choline-containing buffer, SNC-stimulated [³H]NA release, which was similar to that in the Na⁺-containing buffer, was inhibited markedly by l -leucine, l -alanine, l -methionine, l -phenylalanine, and l -tyrosine. The effects of the other amino acids examined were smaller or very limited. The effect of l -leucine was stronger than that of d -leucine. A specific inhibitor of the L-type amino acid transporter, 2-aminobicyclo[2.2.1]-heptane-2-carboxylate (BCH), inhibited the effects of SNC on [³H]NA release in the Na⁺-free buffer. Uptake of l -[³H]leucine into the slices in the Na⁺-free buffer was inhibited by SNC, BCH, and l -phenylalanine, but not by l -lysine. The effect of SNC on cyclic GMP accumulation was not inhibited by l -leucine, although SNC stimulated cyclic GMP accumulation at concentrations up to 25 µM, much less than the concentration that stimulates NA release. These findings suggest that SNC is incorporated into rat hippocampus via the L-type-like amino acid transporter, at least in Na⁺-free conditions, and that SNC stimulates NA release in vivo and in vitro in a cyclic GMP-independent manner.     

Mammalian expression of single chain variable region fragments dimerized by Fc regions

To promote application of a single chain variable region fragment (sFv) in immunoglobulins, a sFv gene was connected to an IgG1 Fc gene, designated as a sFvc gene, and used for transfection of Sp2/0. As a result, the sFvc protein was found to be secreted in a dimeric form. It is thus felt that the sFvc protein, which mimicks the shape of a naturally occurring antibody, can be simple and useful to reproduce divalency and Fc-associated effecter functions as seen in a natural antibody.Abbreviations Abbreviations sFv single chain variable region fragment - Fc constant region of immunoglobulin - sFvc single chain variable region fragment with an Fc region     

Novel mutation at the initiation codon in the Norrie disease gene in two Japanese families

We have identified a new mutation of Norrie disease (ND) gene in two Japanese males from unrelated families; they showed typical ocular features of ND but no mental retardation or hearing impairment. A mutation was found in both patients at the initation codon of exon 2 of the ND gene (ATG to GTG), with otherwise normal nucleotide sequences. Their mothers had the normal and mutant types of the gene, which was expected for heterozygotes of the disease. The mutation of the initiation codon would cause the failure of ND gene expression or a defect in translation thereby truncating the amino terminus of ND protein. In view of the rarity and marked heterogeneity of mutations in the ND gene, the present apparently unrelated Japanese families who have lived in the same area for over two centuries presumably share the origin of the mutation.     

Selective inhibition of transition from sexual agglutination to zygote formation by ethyl N-phenylcarbamate in Saccharomyces cerevisiae

Effects of ethyl N-phenylcarbamate (EPC) on the mating reaction of Saccharomyces cerevisiae were studied, with special attention on the effect on the pheromone action. EPC inhibited zygote formation at a concentration which promoted induction of sexual agglutinability. EPC enhanced agglutinability induction by pheromone, but inhibited -pheromone-induced formation of large pearshaped cells in a mating type. The enhancement of agglutinability induction was accompanied with increased production of a agglutination substance and inhibition of pheromone inactivation. EPC arrested the cell cycle of a cells probably in the step controlled by CDC19, CDC35, cAMP etc., just before the step controlled by CDC28, pheromone etc.Abbreviations EPC Ethyl N-phenylcarbamate - PBS 0.01 M phosphate buffer solution, pH 5.5 - SPB spindle pole body     

Frequencies of Twelve Ascus-Types and Arrangement of Three Genes from Tetrad Data

Equations expressing the theoretical frequencies of twelve ascus-types in the tetrad analysis of a triply heterozygous diploid are described. Using these equations, a mapping procedure for a gene X, is proposed. The procedure requires that two genes, X and Y, of the same phenotype be heterozygous and that the map position of Y be known, and that another standard gene, Z, show an independent phenotype from X and Y. This procedure does not require the laborious allelism test of the segregants to determine the allelic 2:2 segregation in tetrads for the X and Y genes, which is indispensable for mapping by the conventional procedure. The exact placement of the X gene on a chromosome is possible by the chi2 minimization procedure in comparison with the expected frequencies of the six ascus-types or four spore-types deduced from the twelve expected ascus-types to give the optimal fit with the observed data.     

Alteration of thermal stability of glucose oxidase associated with the redox states

By the method of differential scanning calorimetry, it was found that thermal stability of glucose oxidase was dependent on its redox states. The oxidized form showed an apparent denaturation temperature at 76°C and the denaturation enthalpy was approximately 865 kcal/mol. On reduction of the enzyme, the denaturation temperature increased by about 10°, but no significant change was seen in the denaturation enthalpy. The activation energies of the denaturation of the oxidized and the reduced enzymes were about 89 and 103 kcal/mol, respectively. These results may imply conformational changes in the catalytic turnover of this enzyme.     

Continuous synthesis of the dnaA gene product of Escherichia coli in the cell cycle

Summary The dnaA gene product of Escherichia coli, identified as a weakly basic protein of about 48,000 daltons (Yuasa and Sakakibara 1980), can be separated from other celluar proteins by means of two-dimensional gel electrophoresis. Synthesis of the dnaA protein took place continuously during a cell growth cycle. The newly synthesized dnaA protein persisted stably for one generation. Thermosensitive dnaA protein produced by the dnaA167 mutant was stable at 30° C, but was disintegrated at 42° C. The amount of intact dnaA protein present in the mutant exposed to the high temperature for 60 min was less than a quarter of the amount at the time of the shift. The cells having the reduced amount of intact dnaA protein were capable of initiating a new round of chromosome replication at the low temperature without de novo synthesis of the dnaA protein. The potential of the mutant for initiation of DNA replication decreased with reduction in the amount of the thermoreversible dnaA protein. The mutations dnaA167 and dnaA46 had no significant effect on the syntheses of the dnaA mRNA and the protein product at the low and high temperatures.Abbreviations used SDS sodium dodecyl sulfate - kb kilobase pairs - TCA trichloroacetic acid     

Participation and Properties of Lipoxygenase and Hydroperoxide Lyase in Volatile C6-Aldehyde Formation from C18-Unsaturated. Fatty Acids in Isolated Tea Chloroplasts

Isolated tea chloroplasts utilized linoleic acid, linolenicacid and their 13-hydroperoxides as substrates for volatileC₆-aldehyde formation. Optimal pH values for oxygen uptake,hydroperoxide lyase and the overall reaction from C₁₈-fattyacids to C₆-aldehydes were 6.3, 7.0 and 6.3, respectively. Methyllinoleate, linoleyl alcohol and -linolenic acid were poor substratesfor the overall reaction, but linoleic and linolenic acids weregood substrates. The 13-hydroperoxides of the above fatty acidsand alcohol also showed substrate specificity similar to thatof fatty acids. Oxygen uptakes (relative V_max) with methyl linoleate,linoleyl alcohol, linolenic acid, -linolenic acid and arachidonicacid were comparable to or higher than that with linoleic acid.In winter leaves, the activity for C₆-aldehyde formation fromC₁₈-fatty acids was raduced to almost zero. This was due tothe reduction in oxygenation. The findings presented here provideevidence for the involvement of lipoxygenase and hydroperoxidelyase in C₆-aldehyde formation in isolated chloroplasts. (Received July 11, 1981; Accepted November 5, 1981)     

Social behavior of the pygmy chimpanzees

The affinitive interactions among the pygmy chimps seem to be the most frequent in the male/female combination, next in the female/female, and the least frequent in the male/male. The differences of frequencies among the combinations, however, are little, and it may be said that the pygmy chimps are not so much biased by sex in the affinitive relations. Their aggressive behavior is mild, and their behavior in general shows high tolerance, especially between different sexes and among females. Similar tendency is also seen in grouping (Kuroda, 1979). Therefore, the pygmy chimp’s society may be said to be integrated by the male/female affinity, little differentiated by sex in the grouping and the affinitive relations, and with high inter-individual tolerance and coherence.     

Grouping of the pygmy chimpanzees

The group formation inPan paniscus is flexible as inP. troglodytes. A group consisted of 16.9 chimps on the average, and a large groups of more than 30 chimps were often observed. The most frequent groups are of the mixed group type, which occupied 80% of the observed cases. The group size varies in accordance with the seasonal changes of the abundance and distribution of food resources, but in general it is larger than that ofP. troglodytes. The socionomic sex ratio does not seem to be highly correlated with the group size, and was around 76 on the average. And neither the proportion of females with infants in a group nor that of estrous females seems to be correlated with the group size. Therefore, the group composition appears to be rather uniform. This uniformity may be attributable toP. paniscus's concentrative nature and high male/female affinity. In comparison with the other African anthropoid apes,P. paniscus shows less sexual differentiation in its social structure. This study was financed by the Scientific Research Fund of the Ministry of Education, Science, and Culture of the Japanese Government.