Restriction fragment length polymorphism and molecular taxonomy in Vitis vinifera L.

Forty-six accessions of grapevine (V. vinifera L.) were compared by restriction fragment length polmorphism (RFLP) analysis, and 111 informative or unique restriction fragments were found that revealed an important level of polymorphism. RFLP patterns were compared in two ways: by calculating electrophoretic similarity degree values further analyzed by principal component analysis and by studying the distribution of rare restriction fragments. Six taxonomic groups could be defined, which partially confirmed relationships derived from ampelographical data. Our data support the existence of ecogeographical groups.     

Sequence and characterisation of a ribosomal RNA operon fromAgrobacterium vitis

One of the four ribosomal RNA operons (rrnA) from theAgrobacterium vitis vitopine strain S4 was sequenced.rrnA is most closely related to therrn operons ofBradyrhizobium japonicum andRhodobacter sphaeroides and carries an fMet-tRNA gene downstream of its 5S gene, as in the case ofR. sphaeroides. The 16S rRNA sequence of S4 differs from theA. vitis K309 type strain sequence by only one nucleotide, in spite of the fact that S4 and K309 have very different Ti plasmids. The predicted secondary structure of the S4 23S rRNA shows several features that are specific for the alpha proteobacteria, and an unusual branched structure in the universal B8 stem. The 3′ ends of the three otherrrn copies of S4 were also cloned and sequenced. Sequence comparison delimits the 3′ ends of the four repeats and defines two groups:rrnA/rrnB andrrnC/rrnD.     

The effect of nitrate concentration in a flowing solution system on growth and nitrate uptake of twoPlantago species

Summary Juvenile plants ofPlantago lanceolata andP. major ssp.major were grown in a flowing solution system at 7.5 mM or 9.5 M NO₃. The parameters investigated were: RGR, shoot weight percentage, leaf length, length of main root axis, shoot concentrations of major ions and organic N, and the specific uptake rate for NO₃. At 9.5 M NO₃ growth ofP. major was not hampered, whereas shoot growth and leaf length ofP. lanceolata were reduced. The NO₃ concentration ofP. lanceolata decreased more than that ofP. major. The different performances of the species at 9.5 M NO₃ were associated with different specific uptake rates. In both treatments the root system ofP. major was shorter than that ofP. lanceolata. P. lanceolata accumulated more NO₃ in the leaves. The performance of thePlantago species is discussed in relation to the availability of nutrients in their habitats.Grassland Species Research Group. Publication no. 37.     

Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells

Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump.     

Nerve growth factor-mediated induction of tyrosine hydroxylase in rat superior cervical ganglia in vitro.

Exposure of rat sympathetic ganglia to 3 microgram/ml of 2.5 S nerve growth factor (NGF) resulted in a 100% increase in tyrosine hydroxylase activity within 48 h. Pulselabeling of proteins with [3H]leucine, followed by immunoprecipitation with antibodies to tyrosine hydorxylase and isolation of the precipitated enzyme by gel electrophoresis, demonstrated that the increase in tyrosine hydroxylase activity was due to enhanced de novo synthesis. The incorporation of [3H]leucine into tyrosine hydroxylase was increased by 150% compared to a 17% increase in total protein synthesis, which was not statistically significant. The fact that the half-life of pulse-labeled tyrosine hydroxylase was the same for NGF-treated and control organ cultures of superior cervical ganglia excludes the possibility that enhanced tyrosine hydroxylase labeling by NGF is due to decreased degradation. We conclude that, without modulatory factors which play a role in vivo, NGF can enhance the synthesis of tyrosine hydroxylase in sympathetic ganglia in vitro, provided organ culture conditions which permit optimal survival of adrenergic neurons are selected.     

Regulation of secondary metabolism in Streptomyces spp. and overproduction of daunorubicin in Streptomyces peucetius.

Two DNA segments, dnrR1 and dnrR2, from the Streptomyces peucetius ATCC 29050 genome were identified by their ability to stimulate secondary metabolite production and resistance. When introduced into the wild-type ATCC 29050 strain, the 2.0-kb dnrR1 segment caused a 10-fold overproduction of epsilon-rhodomycinone, a key intermediate of daunorubicin biosynthesis, whereas the 1.9-kb dnrR2 segment increased production of both epsilon-rhodomycinone and daunorubicin 10- and 2-fold, respectively. In addition, the dnrR2 segment restored high-level daunorubicin resistance to strain H6101, a daunorubicin-sensitive mutant of S. peucetius subsp. caesius ATCC 27952. Analysis of the sequence of the dnrR1 fragment revealed the presence of two closely situated open reading frames, dnrI and dnrJ, whose deduced products exhibit high similarity to the products of several other Streptomyces genes that have been implicated in the regulation of secondary metabolism. Insertional inactivation of dnrI in the ATCC 29050 strain with the Tn5 kanamycin resistance gene abolished epsilon-rhodomycinone and daunorubicin production and markedly decreased resistance to daunorubicin. Sequence comparison between the products of dnrIJ and the products of the Streptomyces coelicolor actII-orf4, afsR, and redD-orf1 genes and of the Streptomyces griseus strS, the Saccharopolyspora erythraea eryC1, and the Bacillus stearothermophilus degT genes reveals two families of putative regulatory genes. The members of the DegT, DnrJ, EryC1, and StrS family exhibit some of the features characteristic of the protein kinase (sensor) component of two-component regulatory systems from other bacteria (even though none of the sequences of these four proteins show a significant overall or regional similarity to such protein kinases) and have a consensus helix-turn-helix motif typical of DNA binding proteins. A helix-turn-helix motif is also present in two of the proteins of the other family, AfsR and RedD-Orf1. Both sets of Streptomyces proteins are likely to be trans-acting factors involved in regulating secondary metabolism.