[Isolation of genetically modified potato plant containing the gene of defensive peptide from Amaranthus]. / Poluchenie geneticheski modifitsirovannykh rastenii kartofelia, nesushchikh gen zashchitnogo peptida amaranta.

The plants of potato (Solanum tuberosum L., var. Desire) have been transformed with a pH22Kneo vector carrying the gene ac2, encoding the fungicidal peptide (defensin) from the seed of amaranth (Amaranthus caudatus L.). The transformation involved co-cultivation of potato stem explants (excised from aseptically grown plants) and Agrobacterium tumefaciens on solid MS medium. Factors affecting in vitro regeneration of the explants and the transformation efficiency were optimized. Regenerated potato plants harboring the amaranth defensin gene were selected by two traits, growth and ability to form roots on kanamycin-supplemented MS medium. The transgenic state was confirmed PCR analysis of ac2 in tissues of the kanamycin-resistant plants. The transgenic organisms thus obtained differed from the original ambiol-treated plants in growth patterns and proton translocation across the plasma membrane of the tuber cells.

[The role of chemotaxis genes in establishing the associative relations between Azospirillum brasilense and wheat]. / Uchastie genov khemotaksisa v ustanovlenii assotsiativnykh vzaimootnoshenii mezhdu Azopirillum brasilense i pshenitsei.

The chemotactic properties of a number of Azospirillum brasilense natural strains have been studied. Azospirillum demonstrate the positive chemotactic reaction towards the organic acids salts but a poor reaction towards the presence of the attractants like hydrocarbons and aminoacids except for arabinose and glutamic acid. The series of Che- mutants deficient in general chemotaxis has been selected by introducing the transposon Tn5 into the cells of rifampicinresistant mutant strain Azospirillum brasilense 5T-2. The ability of the mutant cells to fast and solid adsorption on the roots of the sterile wheat sprouts is shown to be decreased 2-3 folds as compared with the one of the wild type strain. Chemotaxis is suggested to affect the adsorbtion ability of azospirillum and their associative properties.

[Plasmids of Azospirillum brasilense]. / Plazmidy Azospirillum brasilense.

The cells from natural isolates of A. Brasilense were found to harbour 1 to 4 plasmids with the molecular masses within the 27-300 Md range. 100 Md plasmids are specific for this bacterial species. Strains isolated from the roots of cereals (wheat, maize, barley) have more heterogeneous plasmid composition as compared to the strains isolated from soil.

Revertants of double opal-mutants of bacteriophage T4.

Revertants of double opal-mutants of bacteriophage T4 have been obtained. The properties of these revertants suggest that reversion of double opal-mutants is effected by the activity of some gent-suppressor appeared in the phage genome. Restriction of these revertants by streptomycin-resistant bacterial strains shows that the suppression of the opal-mutants is realized at translation.

[Effect of restricting the action of an amber-mutation suppressor contained in bacteriophage T4 genome]. / Effekt podavleniia deistviia supressora amber-mutatsii, soderzhashchegosia v genome bakteriofaga T4

The action of a bacteriophage suppressor can be restricted due to mutations arising in the genome of the host bacteria. Bacterial strains Escherichia coli BN and CAN were isolated in which a complete restriction of the action of phage suppressor psu+ took place. In thees strains obtained the restriction of serin-specific phage suppressors psu + a and psu + b is brought about. The action of bacteriophage suppressor su3+ containing in E. coli CAN is not abolished in this strain. The abolish of the action of glutamine-specific phage suppressor in both strains is not realized. Thus, in bacterial strains of E. coli BN and CAN the restriction of action of only definite tRNA type takes place. Mutation alterations in the bacterial strains obtained can be due to the change of 1) ribosomes, 2) aminoacyl-tRNA-synthetase, 3) suppressor tRNA. In this case the possibility of mutation alterations in the gene controlling the synthesis of suppressor tRNA is excluded, but there is a possibility of changing the tRNA molecule itself during maturation.