[Bioinformatic analysis of potential post-translational modification sites of the human O6-methylguanine-DNA methyltransferase (MGMT) protein].

Using in silico analysis a number of potential sites for post-translational modifications has been revealed within the human O6-methylguanine-DNA methyltransferase (MGMT) protein. In particular these were the acetylation of Gly3 residue in the N-terminus of protein and internal residues Lys132 and Lys135; Arg166 residue methylation; Lys63 SUMOylation and ubiquitination of Lys31, Lys39, Lys49, Lys63, Lys67, Lys135, Lys156, Lys196, Lys209. Also it has been predicted 16 novel potential phosphorylation sites of serine residues (positions 13, 124, 144, 182, 183, 190, 215, 216 and 230), tyrosine residues (positions 100 and 189) and threonine residues (positions 23, 69, 94, 126 and 229), as well as five binding sites for kinases and other proteins (Serl3 with 14-3-3, Val21 and Ile172 with D-domain, Pro78 and Pro111 with SH3-domain, Pro111 with MAPK3). Some kinases predicted by the authors are known as partners of the MGMT protein, that confirms the probability of modification of the given sites. Potential sites require further experimental confirmation of modifications and investigation of their influence on stability and DNA-repair activity of this protein.

[Human mobile genetic elements: structure, distribution and functional role].

Data concerning human mobile genetic elements which make up 45% of the genome are reviewed. Much attention is focused on their role in genome functioning, such as recombination, regulation of gene expression and neogenes besides classification and distribution.

[Cytomorphological charasteristics of a novel mouse cell line G1].

Growth and morphological properties of a novel mouse cell line G1 have been investigated. It has been shown that cells of this cell line possess the ability of spontaneous transformation in vitro: the cells have unlimited growth in culture, grow in medium with a low serum content and form multilayer colonies on a cell monolayer and cell colonies inside agar. Using micronucleus test it has been revealed that cells of the G1 cell line possess different forms of aberrant mitosis. The results indicate the neoplastic G1 cell transformation with aberrant mitosis.

[The possible ways of the diploidization of the polyploid germinative stem cells in the mouse BALB/c line].

Quantitative and qualitative chromosome rearrangements in the cell line G1 established from a genital ridge of the 12,5 dpc BALB/c mouse embryo were analysed. Cytogenetic analysis was performed on the 75th passage of in vitro cultivation. It has been shown that by this passage the cell population was heterogenous. It is suggested that such heterogeneity may be caused by realization of two simultaneous processes namely the cell polyploidization and their secondary diploidization. These processes were accompanied by some chromosome destructions, and the creation of small new acrocentric chromosomes and large aberrant chromosomes as well as Robertsonian translocations. The present study demonstrates in vitro karyotype evolution of the mouse cell line G1 including the increased instability of the chromosome apparatus.

[The DNA of recombinant plasmids acquires mutagenic activity in a Bacillus subtilis culture after the insertion of the human genome Alu repeat]. / DNK rekombinantnykh plazmid priobretaiut mutagennuiu aktivnost' v kulture Bacills subtilis posle vvedeniia Alu-povtora genoma cheloveka.

In our previous work the mutagenic activity of recombinant plasmids (pBR322 carrying the human Alu repeat alone or in combination with preproinsulin or apo AI gene) in competent Bacillus subtilis culture was demonstrated. In present work it was shown that among seven tested plasmids only three revealed mutagenic activity (pBR322 and two Alu repeat-containing constructions). It seems that mutagenic activity is not inherent to any recombinant molecule in applied test system but depends on its structure. For example, Alu repeat of human genome may attach mutagenic properties to plasmids which either had no such properties, or lost them after gene engineering manipulations.

[The mutagenic activity of the DNA of recombinant plasmids in a competent Bacillus subtilis culture]. / Mutagennaia aktivnost' DNK rekombinantnykh plazmid v kompetentnoi kul'ture Bacillus subtilis.

The method for testing foreign plasmid DNA mutagenicity on the competent culture of B. subtilis has been developed. High mutagenic effect of DNA of recombinant plasmids carrying a single human Alu-repeat or the same repeat in combination with human apoAi gene or human insulin gene was demonstrated. The vector plasmid pUC18 had no mutagenic activity. According to the data of dot-blotting some fragments of recombinant plasmid DNA of human origin can integrate in B. subtilis chromosome by means of illegitimate recombination. It is concluded that B. subtilis test system is suitable for detection of potential mutagenic polynucleotide sequences in recombinant plasmid constructions produced for gene therapy purposes.

[Manifestation of instability in the leucine-dependent Bacillus subtilis auxotroph induced by herring DNA]. / Proiavlenie nestabil'nosti u leitsinzavisimogo auksotrofa Bacillus subtilis, poluchennogo s pomoshch'iu DNK sel'di.

Unstable leucine-depending Bacillus subtilis auxotroph previously induced by the herring DNA was studied. Instability was manifested as revertability in the leucine-free medium. Average frequency of revertants amounted to 50% of the number of viable cells. A clone analysis has shown that most of such colonies are mosaics consisting of leucine-independent and leucine-sensitive cells. Unstable mutation was cotransformed with leuA marker. Heating followed by material storage in demineralized water stimulated transposition of unstable mutation under study to the tryptophan operon region.