Molecular regulation of sink–source transition in rice leaf sheaths during the heading period

The upper leaf sheath of rice (Oryza sativa L.) serves as a temporary starch sink before heading, subsequently becoming a carbon source tissue to the growing panicle at the post-heading stage. The time of sink–source transition in upper leaf sheaths is highly correlated to the panicle exsertion. Here, we found that the expression profiles of starch synthesis genes such as ADP-glucose pyrophosphorylase large subunit 2, granule-bound starch synthase II, soluble starch synthase I, starch branching enzyme (SBE) I, SBEIII, and SBEIV were highly correlated with starch content changes during the heading period in the second leaf sheath below the flag leaf. In addition, the α-amylase2A and β-amylase were considered as major genes that were in charge of starch degradation at the post-heading period. Of the five sucrose transporter (OsSUT) genes, OsSUT1 and OsSUT4 appeared to play an important role in sucrose loading into the phloem of source leaf sheaths. Moreover, the microarray-based data implied that the dominant processes associated with functional leaf sheath transition from sink to source were carbohydrate metabolism and the translocation of the carbon and nitrogen sources and inorganic phosphate.     

Preparation of α and β anomers of various isomeric methyl O-d-galactopyranosyl-d-galactopyranosides. Standards for interpretation of 13C-n.m.r. spectra of d-galactopyranans

The four isomers of methyl O-β-d-galactopyranosyl-β-d-galactopyranoside were prepared by condensation of 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide with appropriate, partially O-substituted derivatives of methyl β-d-galactopyranoside. Reaction of 3,4,6-tri-O-acetyl-1,2-O-(1-ethoxyethylidene)-α-d-galactopyranose with the same acceptors, in the presence of mercuric bromide, led to the formation of α and β linkages. Thus, it was possible to assign ¹³C-n.m.r. resonances of α and β anomers of methyl O-d-galactopyranosyl-β-d-galactopyranosides. In terms of application of these shift values and those of related d-galactobioses to the structural analysis of d-galactopyranans by shift comparisons, some generalizations can be made. For β-d-galactopyranans, the resonances of glycosyloxylated carbon atoms of methyl O-β-d-galactopyranosyl-β-d-galactopyranosides are sensitive to structure and appear to have typical values, whereas limited variation was observed with shifts of C-1′ signals. On the other hand, for assigning structures to d-galactopyranans containing α linkages, the C-1′ shifts (at higher field) of methyl O-α-d-galactopyranosyl-β-d-galactopyranosides are sensitive to linkage position, whereas those of glycosyloxylated carbon atoms vary only a little.     

Activity and distribution of thermophilic prokaryotes in hydrothermal fluid, sulfidic structures, and sheaths of alvinellids (East Pacific Rise, 13°N)

Processes of inorganic carbon assimilation, methanogenesis, sulfate reduction, and acetate oxidation to CO(2) occurring in samples from the East Pacific Rise at 13°N were traced, using radioisotopically labeled substrates, at temperatures ranging from 65 to 100°C. Molecular hydrogen stimulated lithotrophic methanogenesis and sulfate reduction but inhibited inorganic carbon assimilation. Active mineralization of acetate was observed in an organic-rich Alvinella-associated system at 80°C. Members of the Thermococcales were the most numerous hyperthermophilic archaea in these samples, their density achieving 10(8) cells per cm(3), while the numbers of cultured hydrogen-utilizing thermophilic lithotrophs were several orders of magnitude lower.     

Studies on the Constituents of Typha L.—IV. A Preliminary Study of Chemosystematics of Typha L.

From pollen grains of Typha davidiana, T. latifolia, T. angustata the same eight flavonoids have been isolated. They are identified as naringenin I, isorhamnetin II, quercetin III, isorhamnetin-3-O-(2^G-α-L-rhamnopyranosyl)-rutioside IV, quercetin-3-O-(2^G-α-L-rhamnopyranosyl)-rutinosida, V, isorhamnetio-3-O-rutinoside VI, isorhamnetino-3-O-neohesperidoside VII, kampferol-3-O-neohesperidoside VIII. Flavonoids of pollen grains of five species of Typha, including the above three species, were analysed by TLC with the result showing that the constituents in the pollen grains of the five species are very similar. The chemical comparison among Typha and Sparganium and 16 possibly related families shows that Typha is different from Pandanaceae or Pandanales and is similar to Restionaceae, Flagellariaceae, Juncaceae and Cyperaceae in some respects. Typha and Sparganium are very similar in many respects, and they could be treated in the same family, Typhaceae, which merit the rank of order, Typhales.     

Phylogenenetic approach of the section Bulbocodii D.C. of Narcissus based on cpDNA. A case of taxonomic inflation?

In this paper, we analyzed the phylogeny of the section Bulbocodii (genus Narcissus; Amarillydaceae) using the matK and trnL-F fragments of cpDNA in order to review the validity of the recognized taxa. Our results indicate that Narcissus obesus should be considered a valid species, and that N. blancoi is a distinct taxon. In addition, seven previously recognized species, N. juressianus, N. subnivalis, N. graellsii, N. conspicuus, N. citrinus, N. nivalis, and N. quintanilhae, should be assigned to an infraspecific rank under N. bulbocodium, as they are not valid species. In addition, we analyzed the distribution of the three morphological characters widely used in the systematics of this section and found that their variation does not agree with the phylogenetic results, rendering these characters limited taxonomical utility. This result suggests that the section Bulbocodii shows high morphological lability, which can explain the proliferation of nominal species.     

Genetics of esterases in Drosophila. V. Characteristics of the “pupal” esterase in D. virilis

From analysis of the properties of the pupal esterase (p-esterase) in Drosophila virilis, it is concluded that it is heat stable, its electrophoretic detection depends on culture density, its expression is stage specific, and it is not a variant of esterase 2. It was also demonstrated that p-esterase, like esterase 6, is activated by injections of the juvenile hormone into larvae. Heat treatment of heat-resistant D. virilis stocks led to decreased activities of the juvenile hormone dependent esterases but did not affect those of the heat-sensitive stocks. It is suggested that heat resistance in D. virilis is related to some functional features of the system of modifier genes controlling the phenotypic expression of esterases.     

Use of protoplasts in the improvement of filamentous microorganisms. I. Action of N-methyl-N′-nitro-N-nitrosoguanidine on protoplasts of Streptomycetes

Summary The effects of N-methyl-N–nitro-N-nitroso-guanidine (NTG) on protoplasts of Streptomycetes are markedly different from its action on spores, showing high mutagenic activity even at concentrations having no marked effect on protoplast survival. Strain improvement, eg in chlorotetracycline-producing strains of S. aureofaciens, was most effective when protoplasts were subjected to prolonged treatment (2 h) with low concentrations of NTG (50 /ug/ml).     

Microbial metabolism of aromatic nitriles. Enzymology of C–N cleavage by Nocardia sp. (Rhodochrous group) N.C.I.B. 11216

1. An organism utilizing benzonitrile as sole carbon and nitrogen source was isolated by the enrichment-culture technique and identified as a Nocardia sp. of the rhodochrous group. 2. Respiration studies indicate that nitrile degradation proceeds through benzoic acid and catechol. 3. Cell-free extracts of benzonitrile-grown cells contain an enzyme that catalyses the conversion of benzonitrile directly into benzoic acid without intermediate formation of benzamide. 4. This nitrilase enzyme was purified by DEAE-cellulose chromatography and gel filtration on Sephadex G-100 in the presence and absence of substrate. The purity of the enzyme was confirmed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and isoelectric focusing on polyacrylamide gel. 5. The enzyme shows a time-dependent substrate-activation process in which the substrate catalyses the association of inactive subunits of mol.wt. 45000 to form the polymeric 12-unit active enzyme of mol.wt. 560000. The time required for complete association is highly dependent on the concentration of the enzyme, temperature and pH. 6. The associated enzyme has a pH optimum of 8.0 and K(m) with benzonitrile as substrate of 4mm. The activation energy of the reaction as deduced from the Arrhenius plot is 51.8kJ/mol. 7. Enzyme activity is inhibited by thiol-specific reagents and several metal ions. 8. Studies with different substrates indicate that the nitrilase is specific for nitrile groups directly attached to the benzene ring. Various substituents in the ring are compatible with activity, though ortho-substitution, except by fluorine, renders the nitrile invulnerable to attack. 9. The environmental implications of these findings and the possible significance of the enzyme in the regulation of metabolism are discussed.