Phenomenon of human peripheral blood lymphocyte interaction with autologous erythrocytes]

Phenomenon of the lymphocyte interaction with autologous erythrocytes was revealed in the patients with auto-immune diseases. Macroscopically this phenomenon appeared in the form of hemagglutination, and microscopically--of "rosette" formation. No lymphocyte interaction with autologous erythrocytes was found in the group of normal subjects and patients without autoimmune disorders.     

Phase-Specific Elements of the stringGene Regulatory Region in Drosophila melanogaster

The phases of the reporter gene expression controlled by different fragments of the string(stg) gene regulatory region were determined in Drosophilaneuroblasts by detection of -galactosidase activity and radioautography. In the D10 and D22 lines carrying the constructs pstg-E4.9 and pstg-E5.3, respectively, the reporter gene activity was detected in the G1 phase of the cell cycle. In the D12 and D20 lines (pstg-E6.4 and pstg-E2.6), no periodic expression was observed. The regulatory regions of the stgfrom lines D10 and D22 and that of Drosophilagene cyclin Dshared consensus aagaactttg, which was also expressed in the G1 phase. The phase-specific expression of the cell-cycle genes was compared in a model for the mitotic-wave cells of eye imaginal disk and neuroblasts of the nerve ganglia.     

Transformation of tobacco with a gene for the thermophilic acyl-lipid desaturase enhances the chilling tolerance of plants

The desC gene for the acyl-lipid Delta9-desaturase from the thermophilic cyanobacterium Synechococcus vulcanus was introduced into Nicotiana tabacum under control of the 35S promoter. Expression of the desaturase was confirmed by Western blotting. Lipid analysis revealed that lipid content and the extent of fatty acid unsaturation significantly increased in leaves of transgenic plants. Chilling tolerance of those plants also increased, as estimated by the electrolyte leakage from the tissues damaged by cold treatments. Seeds of plants that expressed the desC gene imbibed at low temperatures demonstrated higher chilling tolerance than those of the control plants. The results demonstrate that the cyanobacterial thermophilic acyl-lipid desaturase was efficiently expressed in tobacco at ambient temperatures, and its expression resulted in the enhanced chilling tolerance of the transgenic plants.     

Chloroplast ultrastructure in leaves of tobacco plants with the introduced gene for the acyl-lipid Δ9-desaturase from <Emphasis Type="Italic">Synechococcus vulcanus</Emphasis> at normal and low temperature

Ultrastructural changes in chloroplasts of tobacco plants (Nicotiana tabacum L.) with the introduced desC gene for the acyl-lipid Δ9-desaturase from the thermophilic cyanobacterium Synechococcus vulcanus were investigated during plant acclimation to cold. Control plants were transformed with an empty pGA482 binary vector. At optimum growth temperature, a decreased number of grana and thylakoids and an increased number of plastoglobules and their larger area were observed in transgenic plants when compared to control ones. In control plants, acclimation to cold (6 days at 10°C) resulted in the larger areas of chloroplasts and grana. These changes indicated starting cold-induced injuries manifested in swelling of the stroma and a slight decrease in the total number of thylakoids in the chloroplast. In contrast, transgenic plants responded to cold by reducing the chloroplast, granal, and plastoglobule areas. Meantime, the number of thylakoids per granum increased noticeably. The total number of thylakoids in the chloroplast increased from 123 to 203. It was concluded that expression of the acyl-lipid Δ9-desaturase gene in tobacco plants provided for the formation of the cell ultrastructure similar to one characteristic of cold-tolerant plants.     

Mitosis: regulation and organization of cell division

Modern views on genetic, cytological and molecular bases of the structure and regulation of preparing and implementing mitotic chromosome segregation are discussed.     

Key Events of the Cell Cycle: Regulation and Organization

The review surveys the studies of molecular genetic mechanisms of the cell cycle control on various eukaryotic models. The major cell cycle phenomena are considered: (1) checkpoints and their role in preserving DNA integrity and fidelity of mitosis, (2) the cell oscillator model, and (3) the role of cyclins in timing of cell division and coordination of mitotic events. The main classes of regulatory proteins involved in the cell cycle are discussed in detail.     

Primary and secondary metabolism of winter wheat under cold hardening and treatment with antioxidants

The content of saccharides and phenolic compounds (including flavonoids and lignin) and the activity of L-phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) were determined in leaves and tillering nodes of winter wheat Triticum aestivum L.) cultivars Inna and Moskovskaya 39, differing in the level of frost resistance. These parameters were determined in three groups of plants—control, hardened, and treated with synthetic antioxidants (ambiol and amerol 2000). Cold hardening increased accumulation of primary and secondary metabolites in tissues but decreased the enzyme activity. Treatment with antioxidants also increased the content of saccharides and phenolic compounds (primarily flavonoids) and PAL activity. These changes were more pronounced in cultivar Inna, which is less frost resistant than Moskovskaya 39.     

The Decreased Cold-Resistance of Chilling-Sensitive Plants Is Related to Suppressed CO2 Assimilation in Leaves and Sugar Accumulation in Roots

Tomato (Lycopersicon esculentum L., cv. Sibirskii skorospelyi) and cucumber (Cucumis sativus L., cv. Konkurent) plants were grown in a soil culture in a greenhouse at an average daily temperature of 20°C and ambient illumination until the development of five and eight true leaves, respectively. During the subsequent three days, some plants were kept in a climatic chamber at 6°C in the light, whereas other plants remained in a greenhouse (control). The cold-resistance of cucumber leaves and roots, as assayed from the electrolyte leakage, was reduced after cold exposure stronger than cold-resistance of tomato organs. The ratio photosynthesis/dark respiration was lower in cucumber than in tomato leaves at all measurement temperatures. The concentrations of sugars (sucrose + glucose + fructose) increased in chilled tomato roots but decreased in cucumber roots. Cold exposure changed the activities of various invertase forms (soluble and insoluble acidic and alkaline invertases). The total invertase activity and the ratio of mono- to disaccharides increased. The lower cucumber cold-resistance is related to the higher sensitivity of its photosynthetic apparatus to chilling and, as a consequence, insufficient root supply with sugars.     

Torsional tension in metaphase chromosome DNA]

The torsional tension in DNA of isolated metaphase chromosomes from murine fibroblasts was measured by the microfluorescent method. The method is based on the ability of a fluorescent dye ethidium bromide to compensate for the negative torsional tension in topologically closed DNA by intercalation between DNA base pairs. The value of the relative twist difference delta Tw/Tw = -0.1 was found in a bulk (about 3/4) of unconstrained chromosomal DNA. In interphase nuclei, the torsionally stressed DNA comprises about 15%, with value of delta Tw/Tw = -0.075. We suppose that the tension in chromosomal DNA was created in the prophase stage of mitosis by condensines, the drivers of chromosomal condensation.     

Genetic Control of Mitosis: Features of Anaphase Separation of Sister Chromatid Sets in Mutant Strain aar V158 in Drosophila melanogaster

The effect of mutation aar ^V158 on anaphase separation of chromatids was studied on fixed cells of neural ganglia of Drosophila melanogaster larvae. It was shown that mutation aar ^V158 causes three types of defective chromosome segregation manifested as (1) monopolar anaphase, (2) separation of chromatids to an abnormally short distance in anaphase, and (3) bridging and lagging of some chromatids or prolonged asynchronous separation of sister chromatid sets to the poles in anaphase. We believe that the former two types of defective segregation are caused by disturbed centrosome separation at the beginning of mitosis and the third type, by defects in chromatid separation during anaphase. During the two-year maintenance of the mutation in a heterozygous state, partial correction (adaptive modification) of the defects of type 1 and type 2 (but not type 3) occurred. The correction of type 1 and type 2 defects during adaptogenesis depended on the genotype: in heterozygotes and homozygotes, respectively type 1 and type 2 were preferentially corrected. The frequency of type 3 defects remained constant during the two-year period of maintenance of the mutation in a heterozygous state. However, in all variants of the experiment, their frequency decreased with increasing distance between the sister chromatid sets. In the cells that completed the previous division with abnormalities, the checkpoint system is supposed to effectively arrest the cell cycle in the subsequent division.