Plant-growth regulators from common starfish (<Emphasis Type="Italic">Asterias amurensis</Emphasis> Lütken) waste

Starfish waste has been shown to be an effective compost material not only in the promotion of plant growth but also in terms of having insecticidal activity. In the present study, plant growth regulation by chemicals from starfish was examined. The aqueous fraction from a hot water extract of the starfish Asterias amurensis Lütken showed plant-growth activity, while the aqueous fraction from a methanol extract inhibited growth of Brassica campestris. The lipophilic fraction from the methanol extract also exhibited a plant growth-promoting effect. The active components from each extract were identified. Asterubine from the hot water extract promoted plant growth. A ceramide from the lipophilic fraction showed root growth promoting effect, and three glucocerebrosides had promotive effects on the entire plant. Asterosaponins were identified as the main growth inhibitors in the aqueous fraction of the methanol extract. These active compounds from starfish waste could be analyzed as potential plant growth regulators in agricultural applications in the future.     

Electronic structure and molecular design of simplified polyimide systems

The electronic structures of newly designed polyimide systems (ethenetetracarboxylic 1,2:1,2-dianhydride-diaminoethyne (PI-A) and ethenetetracarboxylic 1,1:2,2-dianhydride-diaminoethyne(PI-B)) are studied in detail with respect to their optimized geometries on the basis of the one-dimensional tight-binding self-consistent field crystal-orbital method. The computational results have revealed that PI-B shows intriguing properties such as a very small band gap and a wide bandwidth near the frontier level, compared with PI-A and other polyimides. Since PI-B would be a promising candidate for a new electric conducting material, a reaction diagram for this polymer is also proposed.Also affiliated to Central Research Laboratories, Matsushita Electric Industrial Co., Moriguchi 570, Japan.     

Morphology,physics, chemistry and biology of Lake Rara in West Nepal

A survey of oligotrophic Lake Rara, the biggest lake in Nepal, was carried out from 1982 till 1984. Mean depth is 100 m, and maximum depth is 167 m. The surface area covers 9.8 km², and the lake contains 0.98 km³ volume of water. Transparency was about 16 m, photoquantum yield decreased exponentially with depth below 5 m, and the extinction coefficient was 8.3 × 10⁻². The concentration of Chl.-a was in the range of 0.06–0.46 mg m⁻³, and total nitrogen was 18–30 μg 1⁻¹. The whole water column was well oxygenated. Primary productivity was extremely low. It has more than 30 inflowing brooks and one outlet. The water quality of the brooks changes drastically with their location. The pH, electrical conductivity, and EDTA hardness in the waters from a landslide area were high. In the waters from a rich pine forest they were extremely low. The zooplankton consisted of two species of protozoa, five species of rotifers, two species of Cladocera, and two species of Copepoda. The zooplankton density range was 6200–16200 individuals m⁻³. The minimum was on November 11th, 1983 and the maximum on August 19th, 1983.     

Multiple gene-like sequences related to the rabbit hepatic progesterone 21-hydroxylase cytochrome P-450 1

Rabbits exhibit phenotypic differences, 21H and 21L, in the rate of hepatic progesterone 21-hydroxylation that reflect 10-fold higher microsomal concentrations of cytochrome P-450 1 in 21H rabbits. A cDNA library in pBR322 was prepared from liver mRNA isolated from a 21H rabbit. A clone, p1-8, producing a hybrid protein resulting from the insertion of the cDNA into the beta-lactamase gene of the plasmid expressed 5 distinct epitopes that were recognized by a panel of monoclonal antibodies developed toward P-450 1. RNAs selected from total hepatic mRNA by filter hybridization with p1-8 yield at least two electrophoretically distinct proteins when translated in vitro and immunoprecipitated with the 3C3 monoclonal antibody. Only one of the two proteins is recognized by the 1F11 monoclonal antibody, which is highly specific for P-450 1, and the immunoprecipitated protein exhibits the electrophoretic mobility of P-450 1. The other protein remains unidentified. Northern blot analysis indicates that the 3' noncoding portion of p1-8 hybridizes to higher steady state concentrations of polyadenylated RNA in the 21H as compared to 21L rabbits. This correspondence in expression with that of P-450 1 in the 21H and 21L phenotypes further suggests that p1-8 encodes P-450 1 or a closely related protein. The cDNA is 1871 base pairs in length and encodes a protein of 487 amino acids. Southern blot analysis indicates that several independent, gene-like sequences hybridize with the 3' noncoding region of p1-8 under conditions of high stringency. These results indicate that P-450 1 is a member of an extensive multigene family.     

Nonselective Incorporation into Sporangium of Either “Older” or “Younger” Chromosome of the Vegetative Cell During Sporulation in Bacillus cereus

Employing Bacillus cereus strain 2, we examined the fate of two chromosomes contained in vegetative cells in the course of sporulation. Cytological observations and quantitative estimation of deoxyribonucleic acid (DNA) confirmed the earlier observations that, during the course of sporulation, one of two chromosomes of the vegetative cell was incorporated into the sporangium and the other disappeared into the medium as the result of cell lysis. Log-phase cells, labeled completely with thymine-2-(14)C in the presence of deoxyadenosine, were cultured in the "cold" glucose-glutamate-glycine-salts medium, and culture samples, taken at intervals at successive generations, were subjected to sporulation in glutamate-salts medium. The percentage of radioactivity in the spores separated from each culture remained almost unchanged at nearly 50% and was independent of the number of generations of the preceding culture in the "cold" medium. This suggests that the selective incorporation into the sporangium of either the "older" or "younger" chromosome of a vegetative cell does not occur in the course of spore formation. Some examples of the selective and nonselective behavior of DNA molecules in cellular events in microorganisms are cited.     

In vivo and in vitro synergistic antitumor effect of interleukin-2-cultured tumor-bearer spleen cells and immune fresh spleen cells

Summary The synergistic antitumor effect of interleukin-2(IL-2)-cultured tumor-bearer spleen cells (cultured lymphocytes) and immune fresh spleen cells was examined. Tumor-bearer cultured lymphocytes were obtained by culturing BALB/c spleen cells from syngeneic MOPC104E-tumor-bearing mice for 11 days with crude IL-2 and a soluble tumor extract. These cultured lymphocytes had weak antitumor activity when transferred i.p. into tumor-bearing mice that had been inoculated i.p. with 10⁵ tumor cells 5 days previously. Immune fresh spleen cells, obtained from mice in complete remission after the treatment with cyclophosphamide, also had weak antitumor activity when transferred at the same schedule. The cultured cells and the fresh cells, mixed together before transfer, significantly augmented the therapeutic effect. At least 1×10⁷ tumor-bearer cultured lymphocytes and 4×10⁷ immune cells were needed for the synergistic effect. A tumor-specific combination was needed for both cultured and fresh cells. The effective subpopulation of tumor-bearer cultured lymphocytes was a cytotoxic one from an Lyt2⁺ precursor, and that of the immune fresh spleen cells was noncytotoxic, Lytl⁺ and Lyt2⁺ T-cells.A similar synergistic effect was also observed during in vitro coculture of tumor-bearer and immune cells. Cytotoxicity, as assessed by the ⁵¹Cr-release test, of tumor-bearer IL-2-cultured lymphocytes was maintained most effectively after 3 or 4 days of culture without IL-2 when the lymphocytes were cocultured with immune fresh spleen cells and tumor cells.     

RecA, Tus protein and constitutive stable DNA replication inEscherichia coli rnhA mutants

Constitutive stable DNA replication (cSDR), which uniquely occurs inEscherichia coli rnhA mutants deficient in ribonuclease HI activity, requires RecA function. TherecA428 mutation, which inactivates the recombinase activity but imparts a constitutive coprotease activity, blocks cSDR inrnhA mutants. The result indicates that the recombinase activity of RecA, which promotes homologous pairing and strand exchange, is essential for cSDR. Despite the requirement for RecA recombinase activity, mutations inrecB, recD, recJ, ruvA andruvC neither inhibit nor stimulate cSDR. It was proposed that the property of RecA essential for homologous pairing and strand exchange is uniquely required for initiation of cSDR inrnhA mutants without involving the homologous recombination process. The possibility that RecA protein is necessary to counteract the action of Tus protein, a contra-helicase which stalls replication forks in theter region of the chromosome, was ruled out because introduction of thetus : :kan mutation, which inactivates Tus protein, did not alleviate the RecA requirement for cSDR.     

Nitric Oxide Reversibly Suppresses Xanthine Oxidase Activity

The effects of nitric oxide (NO) on xanthine oxidase (XOD) activity and the site(s) of the redox center(s) affected were investigated. XOD activity was determined by superoxide (O₂^-) generation and uric acid formation. NO reversibly and dose-dependently suppressed XOD activity in both determination methods. The suppression interval also disclosed a dose-dependent prolongation. The suppression occurred irrespective of the presence or absence of xanthine; indicating that the reaction product of NO and O₂^-, peroxynitrite, is not responsible for the suppression. Application of synthesized peroxynitrite did not affect XOD activity up to 2 μM. Methylene blue, which is an electron acceptor from Fe/S center, prevented the NO-induced inactivation. The results indicate that NO suppresses XOD activity through reversible alteration of the flavin prosthetic site.     

Electronic structures of donor-acceptor polymers based on polythiophene,polyfuran and polypyrrole

Theoretical results on the geometric and electronic structures of some donor-acceptor polymers based on polythiophene (X=S), polyfuran (X=O) and polypyrrole (X=NH) were obtained, using a one-dimensional tight-binding self-consistent field crystal-orbital (SCF-CO) method at the MNDO-AM1 level of approximation. The repeat unit of these polymers consits of a bithiophene, furan or bipyrrole unit bridged by an electron-accepting group or. The optimized geometries of the polymers show a strong dependence on the nature of the electron donating group X. All the polymers studied are predicted to have band gap values ranging between 1 eV and 2 eV. An analysis of their -bond order data and of the patterns of their frontier orbitals shows they have benzenoid-like electronic structures.     

Tryptophan hydroxylase system in brain tissue slices assayed by high-performance liquid chromatography

A new method was developed to study the unsupplemented tryptophan hydroxylase system in brain tissue slices from the raphe nuclei of the rat by high-performance liquid chromatography (HPLC) with fluorescence detection. Tryptophan hydroxylase activity was measured by determining 5-hydroxytryptophan (5-HTP) accumulation in raphe nuclei slices containing all of the enzyme system (the hydroxylase, tetrahydrobiopterin, and dihydropteridine reductase) in the presence of NSD-1055 (an inhibitor of aromatic l-amino acid decarboxylase). An optimum temperature was observed at 25°C and the reaction progressed linearly for 60 min. The hydroxylation of tryptophan was maximal by the addition of 0.2 mM tryptophan in the medium. A maximum 1.5-fold activation was shown at 0.2 mM 6-methyltetrahydropterin in the presence of 10 mM dithiothreitol. Dithiothreitol alone did not affect the activity. A 1.5-fold activation was observed when incubation was carried out under gas phase of 95% oxygen and 5% CO₂ instead of air. The activity was inhibited by 75% at 10^?4 M p-chlorophenylalanine. Both A-23187, a calcium ionophore, and dibutyryl cyclic AMP (DBc-AMP) stimulated the hydroxylation of tryptophan. The activation by A-23187 plus DBc-AMP was more than additive, suggesting the two activating mechanisms by Ca²⁺ and cyclic AMP may be operating synergistically.