Possible involvement of ethylene-activated {beta}-cyanoalanine synthase in the regulation of cocklebur seed germination

A possible involvement of ß-cyanoalanine synthase(CAS: EC 4.4.1.9 [EC] ) in germination processes of seeds was demonstratedusing pre-soaked upper seeds of cocklebur (Xanthium pennsylvanicumWallr.). Pretreatment in anoxia not only with KCN but also cysteine,as the substrates for CAS, stimulated the subsequent germinationof cocklebur seeds in air. However, the effect of cysteine wasmanifested even in air when applied together with C₂H₄, andits effect was further enhanced in combination with KCN. Thegermination-stimulating effect of KCN was intensified by C₂H₄only when 0₂ was present. In contrast, serine, another substrateof CAS, was effective in air only when combined with C₂H₄ and/orKCN. The addition of cysteine greatly reduced the cyanogenicglycoside content of seeds, but increased HCN evolution. Onthe other hand, glutathione did not have any effect on cockleburseed germination, HCN evolution or bound cyanogen content, suggestingthat cysteine is not acting as a reducing reagent. It is suggestedthat CAS regulates the process of cocklebur seed germinationby the dual action of enlarging the pool of amino acids andsupplying sulphydryl bases, the latter being more determinatelyimportant. Serine is effective only via the former action, whilecysteine would act via both. Key words: Cyanide, cyanogenic glycoside, ß-cyanoalanine synthase, seed germination, Xanthium pennsylvanicum     

Allozyme diversity ofPittosporum (Pittosporaceae) on the Bonin (Ogasawara) Islands

The genusPittosporum includes about 160 species. Four species ofPittosporum occur in the Bonin Islands, and all of these are endemic to the islands. Electrophoretic studies of the four endemic species,P. tobira, from the Japanese mainland, andP. lutchuense var.denudatum from the Ryukyu Islands, were used to determine the origin and speciation pattern of the endemic species. 259 individuals were sampled from ten populations. Twenty loci in nine enzyme systems were resolved and used to calculate the gene frequencies for each population. A low genetic diversity was observed in three of the Bonin Island species, as is reported for other oceanic island plants. The exception,P. boninense, has the largest population size and widest distribution. A dendrogram generated by the UPGMA method shows two clusters. One consists of only the Bonin endemics, suggesting a monophyletic origin for these species.     

A direct evidence for defect in glucose-6-phosphate transport system in hepatic microsomal membrane of glycogen storage disease type IB

Uptake of glucose-6-phosphate by microsomes of hepatocyte in rats, human controls and patients with glycogen storage disease type Ia and Ib was studied. In rat the uptake of glucose-6-phosphate increased rapidly and reached to a plateau, but mannose-6-phosphate was not accumulated. These findings indicate that a glucose-6-phosphate specific transport system exists in the microsomal membrane. In human controls and patients with glycogen storage disease type Ia the uptake of glucose-6-phosphate was clearly observed. On the other hand, no accumulation of it was detected in a patient with glycogen storage disease type Ib. These data provide a direct evidence of the defect in the glucose-6-phosphate transport system of hepatic microsomal membrane in glycogen storage disease type Ib.     

Morphine-like analgesic actions of enkephalin-like peptides containing the Tyr-Arg unit

The analgesic actions of some synthetically prepared peptides having the Tyr-D-Arg unit at the N terminal portion of met- and leu-enkephalin were measured by the intra-cisternal injection method in mice. Among them, Tyr-D-Arg-Gly-Phe (DR-4) induced the most potent naloxone-reversible analgesia and was also effective by s.c. injection. DR-4 showed the good affinity to mu-receptor, and the resistance to the enzymatic degradation.     

Photochemical reaction of 9-cis-retro-γ-rhodopsin at low temperatures

9-cis-Retro-γ;rhodopsin (λ_max = 420 nm) was prepared from 9-cis-retro-γ-retinal and cattle opsin. After cooling to liquid nitrogen temperature (77 K), the pigment was irradiated with light at 380 nm. The spectrum shifted to the longer wavelengths, owing to formation of a batho product. This fact indicates that the conjugated double bond system from C-5 to C-8 of the chromophoric retinal in rhodopsin was not necessary for formation of bathorhodopsin. Reirradiation of the batho product with light at wavelengths longer than 520 nm yielded a mixture composed of presumably 9- or 11-cis forms of retro-γ-rhodopsin. These three isomers are interconvertible by light at liquid nitrogen temperature. Thus the retro-γ-rhodopsin system is similar in photochemical reaction at 77 K to cattle rhodopsin system. Each system has its own batho product. Based on these results, it was infered that the formation of bathorhodopsin is due to photoisomerization of the chromophoric retinal of rhodopsin and is not due to translocation of a proton on the ring or on the side chain from C-6 to C-8 of the chromophoric retinal to the Schiff-base nitrogen.     

Synthetic ColE1 plasmids carrying genes for penicillin-binding proteins in Escherichia coli

Clarke and Carbon's collection of 2000 Escherichia coli strains which harbor ColE1 plasmids carrying small random segments of the E. coli chromosome was screened for the correction of mutational defects in penicillin-binding proteins (PBPs): ponA (PBP-1a), ponB (PBP-1b), dacB (PBP-4), and pfv (PBP-5). We found plasmids carrying chromosomal segments containing ponA⁺-aroB⁺ (pLC29-47), ponB⁺-tonA⁺ (pLC4-43, pLC4-44, and pLC19-19), and argG⁺-dacB⁺ (pLC10-46 and pLC18-38). Characters of these plasmids were analyzed. Two other plasmids (pLC26-6 and pLC4-14) previously found to correct ftsI mutation (Y. Nishimura, Y. Takeda, A. Nishimura, H. Suzuki, M. Inouye, and Y. Hirota (1977)Plasmid1, 67–77) were also investigated further. Restriction maps of chromosomal DNAs carried by pLC29-47, pLC4-44, pLC19-19, pLC18-38, pLC26-6, and pLC4-14 were constructed. The regions of ponB-tonA on pLC4-44 and pLC19-19, and of leuA-ftsI-murE and F on pLC26-6 were located on the restriction maps. Although both pLC26-6 and pLC4-14 corrected a thermosensitive mutation, ftsI, which causes a defect in cell division due to abnormal PBP-3, only pLC26-6 led to restoration of PBP-3 production by an ftsI mutant, while pLC4-14 did not. Restriction and heteroduplex analyses of pLC26-6 and pLC4-14 have shown the absence of nucleotide sequence homology between them. The plasmids, pLC29-47 carrying ponA⁺ and pLC4-43, pLC4-44, and pLC19-19 carrying ponB⁺ led the host cell to overproduce the respective PBP.     

Relationships between nucleic acid,nitrogen, and growth rate of tobacco cells in suspension culture

Summary Changes in the amount of nucleic acid and nitrogen, and the relationships between these amounts and the growth rate of tobacco cells (Nicotiana tabacum L. cv. Bright Yellow-2) at different initial nitrogen concentrations in the medium, were examined in batch cultures. During culture in basal medium, the amount of intracellular nucleic acid expressed per unit of dry biomass was 36.3 mg RNA g^–1 cell and 8.1 mg DNA g^–1 cell at the beginning of batch culture. These values increased 2.5 fold for RNA and 1.5 fold for DNA during the exponential growth phase and then gradually decreased with the decline in the growth rate. Similar changes were also observed in the medium containing less nitrogen. The specific growth rate, (day^–1), of the culture corresponded to the magnitude of the intracellular RNA content (mg RNA g^–1 cell), and the linear relationship, RNA=38+23 was obtained. In addition, there were remarkable positive correlations between the total and protein nitrogen, and during the cultures. The mononucleotide composition of total RNA (AMP+UMP)/(GMP+CMP) which was suggested to be a convenient index of metabolic activity was nearly constant (0.78 to 0.80) during tobacco cell culture in the basal medium.     

Detection of the changes in protein distribution of rat plasma induced by carbon tetrachloride administration by means of two-dimensional electrophoresis

The changes in rat plasma protein distribution after carbon tetrachloride administration were examined using two-dimensional electrophoresis, utilizing isoelectric focusing in polyacrylamide gel in the first dimension and pore gradient polyacrylamide gel electrophoresis in the second dimension. Drastic changes in amount of protein were observed at more than 20 spot positions including those of transferrin, Gc-globulin and low-density lipoprotein. The time course of the changes was examined, and the most drastic changes were observed at 2 days after carbon tetrachloride administration.     

Different structural requirements of endotoxic glycolipid for tumor regression and endotoxic activity

Endotoxic glycolipid extracted from the heptose-less mutant of $\text{Salmonella typhimurium}$ was treated with alkali and acid reagents. The glycolipid freed of all O-ester linked fatty acids by hydroxylamine had lost tumor regression activity and toxicity, whereas a partial removal of O-ester linked fatty acids by mild alkali did not impair with these activities. The glycolipid retained both activities after removal of 2-keto-3-deoxyotonate by sodium acetate (pH 4.5) but was rendered nontoxic while retaining antitumor activity when hydrolyzed by 0.1N HCl whereby 2-keto-3-deoxyoctonate and glycosidic phosphate was split off the glycolipid molecule. Nontoxic and tumor regressive fractions were separated by means of preparative thin layer chromatography of glycolipid hydrolyzed by mild acid. Thus, it was concluded that glycosidic bound phosphate and at least a portion of fatty acids of the lipid A moiety were essential for toxicity, but that this phosphate is not essential for tumor regression activity.