Identification of a Gene Involved in the Control of the Root System Development in Arabidopsis thaliana

Genetic and molecular genetic analysis of a lethal root mutant of Arabidopsis thaliana was carried out. The mutant was obtained from a collection created earlier by means of insertion mutagenesis. The mutation was found to be recessive. It was caused by an insertion of the T region of vector pLD3 used for transformation of germinating seeds when creating the collection of insertion mutants. A 118-bp DNA fragment flanking the left border of the insertion was isolated using the TAIL PCR technique, and its nucleotide sequence was determined. Computer analysis of this DNA region demonstrated that it was located in exon 32 of the YUP8H12R.44 gene in chromosome 1.     

Saving Insertional Recessive Lethal Mutants of Arabidopsis thaliana

A group of 13 recessive lethal mutants was selected on the basis of the collection of Arabidopsis thaliana transgenic plants with insertions of T-DNA vector plasmid pLD3 or pPCVRN4, which was produced by agrobacterial transformation of germinating seeds. The use of media containing exogenous hormones made it possible to compensate the lethal effect, identify phenotypes, and characterize six lines of recessive lethal germlings using genetic and molecular-genetic methods.     

Collection of Arabidopsis thalianaMorphological Insertion Mutants

A collection of transgenic Arabidopsis thalianaplants has been obtained by Agrobacterium-mediated transformation. The genomes of the transgenic plants contain insertions of T-DNA of the vector plasmids pLD3 or pPCVRN4. Genes bearing T-DNA insertions were shown to constitute 12–18% of the total number of A. thalianagenes. Seventy-five lines have been chosen from the collection and subjected to genetic and molecular-genetic analysis. Of these, 5 were dominant mutants, and 70, recessive insertion mutants with various morphological defects. Identification of mutant phenotypes and genetic characterization of the transgenic lines have been performed with the use of nutrient media supplemented with exogenous hormones, which revealed five recessive lethal mutants and one dominant sterile mutant.     

Cytokinins do not noticeably change the methylation of adenine residues of DNA in cultured Escherichia coli B

6-Benzylaminopurine (6-BAP) (1 mg/ml) does not influence the growth of E. coli B cell cultures or the number of [8-14C] labeled N6-methyladenine (m6A) residues in the total DNA [(100.m6A/(A x m6A) = 1.7]. The growth of bacterial cells in the presence of adenine or cytokinins (6-BAP, kinetin, zeatin) (1 mg/ml) was unaccompanied by significant changes in the intracellular content of plasmid pBR 322. The mode of restriction by endonuclease Cfu I hydrolyzing the Gm6ATC site of plasmids pBR 322 from E. coli B cells grown in the presence of adenine or one of the above-mentioned cytokinins is identical. These plasmids also have identical restriction products Mbo I or Sau 3AI. Thus, the cytokinins under study do not markedly affect the methylation of adenine residues in total DNA of E. coli B cell cultures and the GATC sequence in plasmids pBR 322 isolated from these cells.     

Cloning of alpha-hemolysin gene from Staphylococcus aureus strain 015

The genomic library of Staphylococcus aureus O15 has been constructed on the EMBL-3 vector. The synthetic oligonucleotide probes to N- and C-end regions of alpha-hemolysin permitted identification of the recombinant bacteriophage clone RS-1 containing a gene for this protein. The restriction map of the cloned fragment has been constructed for restriction endonucleases SalGI, EcoRV, PstI, PvuII. Expression of the alpha-hemolysin gene in phagolysate of the recombinant clone RS-1 (1000 units per ml) has been demonstrated.