Nucleotide sequence of Physarum polycephalum 5.8S rRNA gene and its flanking regions.

The nucleotide sequence of Physarum polycephalum 5.8S rRNA gene and its flanking regions has been determined. The homologies of the 5.8S rRNA sequence with those of Saccharomyces, Chlamydomonas and Xenopus were 56%, 50% and 52%, respectively. In spite of these relatively low homologies, its possible secondary structure was very similar to those of other species.     

A simple method for preparation of valency hybrid hemoglobins, (α3+β2+)2 and (α2+β3+)2

The improved methods for the preparation of valency hybrid hemoglobins, (α³⁺β²⁺)₂ and (α²⁺β³⁺)₂ were presented. The (α³⁺β²⁺)₂ valency hybrid was separated from the solutions of partially reduced methemoglobin with ascorbic acid, by using CM 32 column chromatography. The (α²⁺β³⁺)₂ valency hybrid was also isolated from hemoglobin solutions, which were partially oxidized with ferricyanide, by chromatography on CM 32 column. These valency hybrid hemoglobins were found to be single on isoelectric focusing electrophoresis. Present procedures are very simple and are suitable for the bulk preparation of (α³⁺β²⁺)₂ and (α²⁺β³⁺)₂ valency hybrids.     

Effects of Phosphate in Medium on Protein Secretion in a Protein-Producing Bacterium, Bacillus brevis 47

Bacillus brevis 47 secreted up to 1 mg of protein per ml in a chemically defined medium, depending on phosphate concentration. The composition of exoproteins was altered quantitatively by the concentration of external phosphate. Morphologically, B. brevis 47 showed a distinct three-layered cell wall structure and shed the outer two layers during growth.     

Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach

Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO₂ under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO₂.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO₂ at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO₂-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO₂was due to superoxide radicals (O₂^–). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO₂-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D₂O. These results suggest thatlipid peroxidation in SO₂-fumigated leaves was due to singletoxygen ¹O₂ produced from O_2^–. (Received May 15, 1980; )     

Participation of a cytochrome b5-like hemoprotein of outer mitochondrial membrane (OM cytochrome b) in NADH-semidehydroascorbic acid reductase activity of rat liver

The participation of a cytochrome b₅-like hemoprotein of outer mitochondrial membrane (OM cytochrome b) in the NADH-semidehydroascorbate (SDA) reductase activity of rat liver was studied. NADH-SDA reductase activity was strongly inhibited by antibodies against OM cytochrome b and NADH-cytochrome b₅ reductase, whereas no inhibition was caused by anti-cytochrome b₅ antibody. NADH-SDA reductase exhibited the same distribution pattern as OM cytochrome b-mediated rotenone-insensitive NADH-cytochrome c reductase activity among various subcellular fractions and submitochondrial fractions. Both activities were localized in outer mitochondrial membrane. These observations suggest that OM cytochrome b-mediated rotenone-insensitive NADH-cytochrome c reductase system participates in the NADH-SDA reductase activity of rat liver.     

Adjuvant actions of polyclonal lymphocyte activators: III. Two distinct types of T-initiating adjuvant action demonstrated under different experimental conditions

We demonstrated that each of various polyclonal lymphocyte activators (PLA) exhibits two types of adjuvant action to initiate the carrier-specific helper T-cell response to otherwise nonimmunogenic antigen. Type 1 action was characterized as that to initiate the T-cell response to subcutaneous injection of soluble bovine γ-globulin (BGG), and type 2 as that to initiate the response to intravenous injection of aggregated BGG. Each of various PLA showed these two types of adjuvant action in a dissociated fashion. The capsular polysaccharide of Klebsiella pneumoniae (CPS-K) showed both types of action to the highest degrees. Lipopolysaccharide of Escherichia coli exhibited type 2 action as markedly as CPS-K, but failed to show type 1 action. Concanavalin A showed definite type 1 action, but not type 2 action. Polyadenylic-uridylic acid showed definite type 2 action, but not type 1 action. Type 1 and type 2 actions of dextran sulfate were minimal. A hypothetical view is presented to consider that type 1 adjuvant action is directed to two mutually independent sites whereas type 2 action is directed to one site.     

X-ray-induced recombination during oogenesis in the silkworm (Bombyx mori L.)

Summary The physical induction of recombinational events has been studied in the female silkworm (Bombyx mori), in which crossing-over does not normally occur. Female silkworms heterozygous in the trans type of two egg-color genes,pe (V-0.0) andre (V-31.7), received a single dose of X-rays (1000 R) at various developmental stages. Then they were crossed to marked males homozygous for both genes. The results indicated that X-rays increase the occurrence of recombinational events in silkworm females from first instar larvae to late stage pupae. The spontaneous frequency of exchange type recombinants in the control series was 2.5 x 10^–5, while after irradiation the frequency of these recombinants was up to 38.8 x^10–5. The sensitive stage to X-ray-induced recombinational events was late stage larvae from fourth to fifth instar. Exchange (cross-over) type recombinants were about three times more frequent than interchange types among the 122 recombinants recovered. The biological significance of the present finding is discussed.     

Enzymatic synthesis of poly-β-hydroxybutyrate inZoogloea ramigera

The enzyme activity synthesizing poly--hydroxybutyrate (PHB) was mainly localized in the PHB-containing particulate fraction ofZoogloea ramigera I-16-M, when it grew flocculatedly in a medium supplemented with glucose. On the other hand, the enzyme activity remained in the soluble fraction, when the bacterium grew dispersedly in a glucose-starved medium.The soluble PHB synthase activity became associated with the particulate fraction as PHB synthesis was initiated on the addition of glucose to the dispersed culture. Conversely, the enzyme activity was released from the PHB-containing granules to the soluble fraction when the flocculated culture was kept incubated without supplementing the medium with glucose.PHB synthase was also incorporated into the newly formed PHB fraction when partially purified soluble PHB synthase was incubated withd(-)--hydroxybutyryl CoA in vitro.Although attempts to solubilize the particulate enzyme were unsuccessful, and the soluble enzyme became extremely unstable in advanced stages of purification, both PHB synthases had the same strict substrate specificity ford(-)--hydroxybutyryl CoA, and showed the same pH optimum at 7.0.Non-Standard Abbreviations PHB poly--hydroxybutyrate     

The peripheral inhibition of the tarsal sugar receptor by sodium chloride in the proboscis extension response of the blowfly,Phormia regina M.

Summary The proboscis extension reponse of the blowfly during stimulation of the tarsal sugar receptors was inhibited by the presence of NaCl. Acceptance thresholds for sucrose in various concentrations of NaCl were measured. The median acceptance thresholds for sucrose in mixtures of 0.01, 0.25, 0.5 and 1.0 M NaCl were 1.8 × 10^–3, 6.0 × 10^–3, 1.2 × 10^–2, and 2.0 × 10^–2 M, respectively. Concentration-response curves for sucrose in the tarsal D-type sugar receptor shifted to the right under the existence of high concentration of NaCl. Number of impulses per D-type sugar receptor at the median acceptance thresholds described above were 7.5, 8.4, 6.8 and 10.4 for the first 0.1 s of stimulation, respectively. The average number was 8.2 impulses per 0.1 s. Comparisons were made between the behavioral acceptance thresholds (1) on one leg exposed to sucrose mixed with 0.01 M NaCl and (2) on two contralateral legs, one of which was exposed to sucrose in 0.01 M NaCl and the other to 0.5 M NaCl alone. The acceptance thresholds from two experiments agreed with each other. The median threshold value was 1.7 × 10^–2 M sucrose. Behavioral inhibition by NaCl in mixtures with sucrose can be explained by its peripheral inhibition of sugar receptors.This research was supported in part by ITO foundation and Scientific Research Fund from the Ministry of Education of Japan.