Relationship between mutagenic potency in Salmonella typhimurium strains and the chemical structure of nitro biphenyls

Most of the positional isomers of mono-, di-, tri- and tetranitrobiphenyls were synthesized and assayed for their mutagenicity in Salmonella typhimurium strains TA98, TA98NR and TA98/1,8DNP6 in the absence of S9 mix. In mono- and dinitrobiphenyls, the structure requirements favoring mutagenic activity are the presence of a nitro group at the 4-position and its absence at the 2-position. TA98 and TA98/1,8DNP6 were reverted by 2-position-free 4-nitro analogues, but TA98NR was not reverted. The results suggest that direct-acting mutagenicity involves the reduction of the nitro group by bacterial nitroreductase but does not involve specific esterification enzymes. Some of the tri- and tetranitrobiphenyls e.g. 3,4,3'-, 3,4,4'-, 3,4,3',4'- and 3,4,2',4'-derivatives reverted not only TA98 and TA98/1,8DNP6 but also TA98NR. Those derivatives commonly have 2 nitro groups at an adjoining position (3,4-dinitro group), whereas 2,4,2',4'-tetranitrobiphenyl, which has strong potency not only in TA98 and TA98/1,8DNP6 but also in TA98NR, possesses 2 nitro groups at the 2-position of each benzene ring.     

Evaluation of tri-combinant vaccine for feline herpesvirus, calicivirus and panleukopenia virus infections in Japanese native cats

Tri-combinant vaccine consisting of attenuated feline herpesvirus (FHV) and feline calicivirus (FCV) and inactivated feline panleukopenia virus (FPLV), were evaluated for safety and efficacy, using Japanese native cats and the viral strains isolated in Japan. Thirty-eight 9- to 12-week-old kittens were inoculated intramuscularly and subcutaneously with the vaccine. Consequently, no adverse reaction was found, and protective efficacy was confirmed by challenge tests with the virulent strains of each virus. Serum-neutralizing antibodies against FCV and FPLV were maintained for at least one year after vaccination, whereas antibody against FHV disappeared in two cases at 24 weeks after vaccination. Application of this vaccine seemed effective for control of feline viral disease in cats for experimental use.     

General recombination mechanisms in extracts of meiotic cells

RecA-like proteins have been purified from somatic and meiotic cells of mouse and lily. The rec proteins have been designated s-rec and m-rec to indicate their respective tissues of origin. The two proteins differ in molecular weight and in their response to temperature, the latter being consistent with the optimal temperature for physiological function of their tissues of origin. There is a major increase in m-rec protein with the entry of cells into meiosis, the peak of activity being early pachytene. Extracts of the cells and also those of yeast (Saccharomyces cerevisiae) have been prepared that have the capacity to catalyze homologous recombination. These extracts behave similarly to the m-rec proteins upon entry of cells into meiosis. Yeast transferred to sporulation medium displays a 100-fold increase in the recombination activity of the extract at about the time of entry into meiosis. The occurrence of peak levels of m-rec and recombination activity in extracts from cells in early pachytene points strongly to that stage as the time at which the enzymatic phase of recombination occurs.     

Preliminary crystallographic data for cross-linked (lysine7-lysine41)-ribonuclease A

A cross-linked derivative of ribonuclease A, N^ε,N^ε′-(2,4-dinitrophenylene-1,5)-(lysine⁷-lysine⁴¹)-RNase A, has been crystallized by dialysis against 30% ($\text{v}\text{v}$) ethanol/water mixtures buffered at high pH. Single crystals belong to the orthorhombic space group P2₁2₁2₁, $\text{a = 37.2}\text{A}\text{?}\text{, b = 41.2}\text{A}\text{?}\text{, b = 41.2}\text{A}\text{?}$, with one molecule in the Crystallographic asymmetric unit.     

Cloning of the Escherichia coli gene for the stringent starvation protein

Summary In order to clone the Escherichia coli gene for the stringent starvation protein (SSP), we determined its N-terminal sequence as well as the sequence of two peptide fragments obtained by cyanogen bromide cleavage of the protein. We then chemically synthesized four sets of oligodeoxyribonucleotide mixtures that represented possible codon combinations for parts of these amino acid sequences. The synthetic oligonucleotides were labelled with ³²P at their 5-termini and used as hybridization probes to detect DNA fragments containing the complementary sequences. Genomic Southern hybridization of E. coli chromosomal DNA gave up to ten DNA fragments hybridizing with each probe but only a few hybridized with two or more of the probes. The latter fragments were coloned in pBR322. By determining partial base sequences with a rapid method and examining proteins encoded by the DNA fragments, we were able to show that we had isolated a clone containing the complete SSP structural gene.Abbreviations SSP stringent starvation protein - PTH phenylthiohydantoin     

Water-soluble glucans from the seed of Coix lacryma-jobi var. ma-yuen

The water-soluble major polysaccharides from the seed of Coix lacryma-jobi var. ma-yuen eluted as a broad peak by gel filtration on Sepharose CL-2B. The mixture (CS-Glucan) was resolved into 7 glucans by HPLC on the column of Asahi-Pak GS-510 + GS-320. Similarities were observed between M, shown in the gel filtration profile and the elution volume in HPLC. Methylation analysis indicated that the ethanol-fractionated CS-glucan contained 4-O- and 4,6-di-O-substituted glucosyl residues. ¹H and ¹³C NMR data accorded with the results of methylation analysis, and the glycosidic linkages were shown to have an α-configuration. Thus, CS-glucan contained (1 → 4) linked α-d-glucans to which are attached glucosyl side chains at O-6 of the main chain in a similar way to amylopectin. Each purified glucan was shown to have different absorption maxima ( > 550 nm or 530 nm) in the iodine reaction. The results of the methylation analysis and of the pullulanase digestion suggest that the 550 nm-glucan has a lower branching frequency and shorter side chains than the 530 nm-glucan. Although CS-glucan was found to have weak anti-complementary activity, HPLC-purified > 550 nm-glucan was found to be more potent than the 530 nm-glucan. Thus CS-glucan is highly heterogeneous, and the glucans which form a tight complex when tested with iodine, generally tend to have considerable anti-complementary activity.     

Reactivation of Cytoplasmic Streaming in a Tonoplast-Permeabilized Cell Model of Acetabularia

To find whether cytoplasmic streaming in Acetabularia is controlledby Ca²⁺, a tonoplast-permeabilized cell model was prepared usinga vacuolar perfusion technique. The cytoplasmic streaming remainedalmost normal after perfusion with EGTA medium (10 mM EGTA,40 mM PIPES, 5mM MgCl₂ and 800 mM sorbitol, pH 6.9), but stoppedwithin 10 min when saponin medium (EGTA medium plus 50 µg/mlsaponin, 50 µg/ml hexokinase and 5 mM glucose) was perfused.This model system was reactivated with a solution containing0.5 mM ATP and different concentrations of Ca²⁺ (reactivationmedium). With the reactivation medium at pCa 6–5, theresumed streaming lasted for about 10 min before the cytoplasmaggregated. At pCa 4–3, the streaming was observed onlyfor a few minutes because the cytoplasm aggregated quickly.At pCa 7, no reactivated movement was observed. Reactivationwas not induced in an ATP- or Mg²⁺-deficient medium even inthe presence of an adequate concentration of Ca²⁺, and was inhibitedby 50 µg/ml cytochalasin B or 1 mM N-ethylmaleimide. We concluded from these observations that the cytoplasmic streamingin Acetabularia is very likely to be driven by the actomyosinsystem in the presence of Mg-ATP and Ca²⁺ at pCa 6–5. (Received October 31, 1984; Accepted April 1, 1985)     

Distribution of vasopressin and oxytocin in rat brain

Arginine-vasopressin and oxytocin in various portions of rat brain were determined by radioimmunoassays. The hormones were extracted from tissue samples into 0.1 N HCl and then purified partially with acetone-petroleum ether extraction. The non-equilibration method was used for the assays. In this method recovery rates of arginine-vasopressin and oxytocin were 73.0 +/- 4.4% and 75.0 +/- 3.8%, respectively. Sensitivities of the assays were 1 pg of arginine-vasopressin and 0.75 pg (0.3 microU) of oxytocin per assay tube. The higher concentrations of arginine-vasopressin and oxytocin were confirmed in the hypothalamo-neurohypophyseal system, where these hormones are synthesized, transported and stored. Relatively high concentrations of these hormones, especially oxytocin, were detected in spinal cord. Amygdala, hippocampus, limbic forebrain and pineal body contained a certain amount of arginine-vasopressin (2-20 pg/mg protein). Oxytocin (1-7 pg/mg protein) was also detected in amygdala, pons and medulla oblongata, pineal body and midbrain. The low concentrations of these hormones were also found in cerebral cortex and cerebellum.     

Polymorphic extracellular glucoamylase genes and their evolutionary origin in the yeast Saccharomyces diastaticus.

DNA coding for extracellular glucoamylase genes STA1 and STA3 was isolated from DNA libraries of two Saccharomyces diastaticus strains, each carrying STA1 or STA3. Cells transformed with a plasmid carrying either the STA1 or STA3 gene secreted glucoamylases having the same enzymatic and immunological properties and the same electrophoretic mobilities in acrylamide gel electrophoresis as those of authentic glucoamylases. Southern blot analysis of genomic DNA from S. diastaticus and a glucoamylase-non-secreting yeast, Saccharomyces cerevisiae, revealed that the STA1 and STA3 loci of S. diastaticus showed a high degree of homology, and that both yeast species (S. diastaticus and S. cerevisiae) contained DNA segments highly homologous to those of the extracellular glucoamylase genes. Restriction maps of the homologous DNA segments suggested that the extracellular glucoamylase genes of S. diastaticus may have arisen from recombination among the resident DNA segments in S. cerevisiae.