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—Changes in the level of DNA damage induced by atmospheric factors were evaluated from the percentage of tail DNA (%TDNA) in the comet assay of mouse cells for blood leukocytes, Ehrlich ascites carcinoma, and P388 lymphocytic leukemia. It was shown that (1) the values of DNA damage of blood leukocytes (%TDNA) were high within narrow ranges of atmospheric temperature (from –4°С to +3°С) and atmospheric partial oxygen contents within 298–304 mg/L; (2) the range of variations in %TDNA of leukocytes increased with increasing geomagnetic activity; (3) the changes in %TDNA of intact and X-irradiated (4 Gy) leukocytes and of tumor cells were associated with changes in air temperature; and (4) %TDNA correlated with atmospheric temperature in both types of intact tumor cells and irradiated P388 cells. Thus, variations in %TDNA appear to be caused by reactive oxygen species generated in the environment at temperatures of phase transitions of water. It is conceivable that changes in the basal %TDNA of cells modulate their radiation response.

The structure of telomeric repeat (TTAGGG)n was determined and the length of telomeric DNA (tDNA) was measured in three species of gastropods from the family Benedictiidae that are endemic to Lake Baikal. Fluorescence in situ hybridization (FISH) confirmed the localization of a telomeric repeat at the chromosome ends. The sizes of tDNA in “giant” eurybathic, psammo-pelobiontic species Benedictia fragilis and shallow water litho-psammobiontic species B. baicalensis with medium shell sizes were similar (16 ± 2.9 and 15 ± 2.1 kb, respectively), but they had a greater length than that of the shallow water spongio-litobiontic species Kobeltocochlea martensiana with small shells (10.5 ± 1.5 kb). We discuss tendencies in age-related changes in tDNA length in snails and a possible mechanism for maintaining tDNA size in ontogeny.

Agrobacterium is a genus of soil bacteria with the ability to transform plant cells by a T-DNA-sequence located on the pTi/pRi-plasmid containing a set of genes expressed in plant cells. Expression of these genes leads to a proliferation of transformed cells, with the subsequent formation of tumors or growths of roots and the synthesis of opines—products of the condensation of amino acids with ketoacids or sugars used by agrobacteria as a source of carbon and nitrogen. In this review, we systematized the information about most common opines in plant-Agrobacterium systems and their biosynthesis and catabolism genes, as well as the role of opines in the interaction of pathogenic Agrobacterium with plants and with other Agrobacterium strains, including the genetic consequences of such interactions.

This review summarizes information about rol-genes which constitute a part of the T-DNA of Agrobacterium rhizogenes Ri-plasmid. The structure of each of rol-genes, their regulatory sequences, and the possible roles of rol-genes being transferred into the plant are discussed.

The iaaM gene encodes a monooxygenase, an enzyme that can catalyze the synthesis of IAA from tryptophan and is functional in plants. We cloned the iaaM into the T-DNA region of a Ti binary vector pWM101 under the control of the cotton fiber specific E6 promoter, and the recombinant was transformed into Nicotiana tabacum WS38 via leaf disc infection with Agrobacterium tumefaciencs GV3101 that harbored the Ti plasmid. Some 25 transformed seedlings were screened out, and the trichomes of the transgenic leaves were both denser and lengthier. The E6 promoter-specific expression of iaaM in trichomes led to the more active auxin synthesis in the cells and allowed the transgenic leaves to develop tidier and longer trichomes. As more trichomes developed on the transgenic leaves, the leaf epidermis appeared fuzzier than the wild control. The research showed that iaaM expression in trichomes influenced the development of trichomes both during their initiation and elongation.

Dynamics of the telomeric DNA (tDNA) length and the phylogeny of Baikal and Siberian planar� ians have been studied based on analysis of 18S rDNA and β�actin gene fragments. It was shown that there is a relationship between tDNA length and planarian size. Giant planarians, with a minor exception, have longer tDNA than do smaller planarians. Phylogenetic affinity between species that have stretched tracks of tDNA, large sizes, and similar habitats denotes the possible role of tDNA in the development of the high regenerative capacity of planarians.

In this review, methods of Agrobacterium TDNA transfer into plant cells in planta are discussed. The main focus is on the technologies of gene transfer into generative plant cells as a part of Agrobacterium TDNA. The influence of the plant genotype, bacterial strain, vector construction type, inoculation medium composition, and the conditions of plant treatment with Agrobacterium on the efficiency of Agrobacterium transformation in planta is analysed. Based on literature and personal experimental data, the possible mech� anism of Agrobacterium transformation of generative plant cells in planta is discussed.

A transfer DNA (T-DNA) carrying the marker gene nptII was detected in the genomes of diploid and haploid maize plants obtained after the treatment of pistil filaments with a suspension of Agrobacterium during artificial pollination. PCR analysis of total DNA isolated from 155 canamycin-resistant diploid F1 seedlings revealed T-DNA insertions in the genomes of 111 plants (32.7% of the total number of analyzed seeds). The example of matroclinal haploids was used to demonstrate that T-DNA may be transported to the egg cell by the growing pollen tube (PT). Twelve out of 16 analyzed haploid plants contained the T-DNA insertion. The possible mechanism of the transfer of the Agrobacterium T-DNA to the maize genome during pollination is discussed.