General features of chromosome substitutions in Triticum aestivum x T. timopheevii hybrids

Summary Tissue culture of the Zea mays inbred line A188 resulted in the regeneration of plants having a high level of phenotypic variation compared to seed-grown control plants. To determine how such variation was induced and whether this could be related to specific in vitro culture methods, callus cultures were established and maintained on different, commonly used culture media. Plants were regenerated and the genomic DNA of callus cultures and regenerants analysed for RFLP differences. The results show that regardless of the gene probe used, callus formation resulted in significant deviations from the DNA pattern normally found in seed-grown control plants. Alterations in gene copy number also occurred. As differentiation and organogenesis began, the level of DNA variation fell, and most of the regenerated plants showed a genetic similarity to the controls; those with RFLP differences were the somaclonal variants.     

Synthesis of peptides of the preS1-region of the viral hepatitis B envelope protein and localization of antigenic determinants]

We synthesized the 24-41, 30-36, 31-36, 24-30 fragments of the preS1-region of the hepatitis B (subtype ayw) envelope. The peptides were prepared by the solid phase synthesis on perfluorpolyethylene polymer grafted with polystyrene. The peptide chains were elongated from C-terminus using activated esters and symmetrical anhydrides of Boc-amino acids, cleaved off the solid phase by HBr or TFMSA in TFA, purified by gel filtration, and, after conjugation with protein carriers, inoculated into test animals. The resultant antibodies were shown to react with peptides. The blood sera from patients with acute hepatitis B reacted with the conjugates of peptides 24-41, 30-36, 31-36 in the immunoenzymic solid phase assay. The monoclonal antibodies for the preS1-polypeptide were shown to react with peptides 24-41, 30-36, 31-36 and with their conjugates. The results obtained were proved by the data of the epitope-mapping with overlapping hexapeptides.     

Evolution of the Zfx and Zfy genes: rates and interdependence between the genes

A phylogenetic analysis of sex-chromosomal zinc-finger genes (Zfx and Zfy) indicates that the genes have not evolved completely independently since their initial separation. The sequence similarities suggest gene conversion in the last exon between the duplicated Y-chromosomal genes Zfy-1 and Zfy-2 in the mouse. There are also indications of conversion (or recombination) between the X- and Y-chromosomal genes in the crab- eating fox and in the mouse. The method for estimating synonymous and nonsynonymous substitutions is modified by incorporating the substitutions in the twofold-degenerate sites in a novel way. The estimates of synonymous substitutions support the generation-time hypothesis in that the obtained rates are higher in mice (by a factor of 4.7) than in humans and higher in the Y-chromosomal genes (by a factor of 1.9) than in the X-chromosomal genes.      

Change of the hereditary properties of Amoeba proteus during micrurgic intervention at the time of mitosis (metaphase ane early anaphase)]

Studies have been made on viability and hereditary properties of the progeny of amoebae after micrurgical coercions (sectioning of cells, suction of cytoplasm) during metaphase and early anaphase. The progeny of the fragments as well as of the cells with the reduced bulk of the cytoplasm exhibits unusual methionine resistance. Possible mechanism of the observed phenomemon are discussed.     

Effect of structure of the initiator codon on translation in E. coli

A set of plasmids carrying different initiator codons--either AUG, or GUG, or UUG, or CUG (as a control) in the hybrid gene lacIZ--was constructed by using synthetic oligonucleotides. GUG and UUG codons were demonstrated to be 2-3 times less effective than AUG in translation initiation. Furthermore, the correlation between the efficiencies of different initiator codons in translation initiation proved to vary, depending on the phase of bacterial growth. The rarely occurring usage in nature of the initiator codons GUG and UUG is supposed to be due to the particular role played by the initiator triplets in regulation of gene expression.     

Assessment of the functional activity of lymphokine-activated killer cells in healthy donors and in patients with interleukin-2-dependent immunodeficiency

The methodological aspects of Lak-cells functional activity test were determined. NK-resistance of P-815 culture cells and NK-sensitive K-562 cells were used as target cells. The highest cytotoxicity level was registered at the 5-th day of culturing MNC with rIL-2 at the final concentration (100 U/ml). The method developed was used for testing healthy donors group and group of patients with IL-2 dependent immunodeficiency (ophthalmic herpes). Data obtained show the significant decrease of LAK-cells functional activity of patients in comparison with healthy donors. Thus, the developed method is recommended for complex estimation of immune status of patients with IL-2-dependent immuno deficiency.     

Oxidative Stress and Redox-Dependent Signaling in Prostate Cancer

Biochemistry (Moscow) - Tumor emergence and progression is complicated by the dual role of reactive oxygen species (ROS). Low concentrations of ROS are essential for many intracellular metabolic...     

Changes in expression of genes encoding antioxidant enzymes, heme oxygenase-1, Bcl-2, and Bcl-xl and in level of reactive oxygen species in tumor cells resistant to doxorubicin

The relationship between expression of genes encoding key antioxidant enzymes, heme oxygenase-1, Bcl-2, and Bcl-xl and change in production of reactive oxygen species (ROS) resulting from development of resistance of cancer cells K562, MCF-7, and SKOV-3 to the prooxidant chemotherapeutic agent doxorubicin (DOX) has been studied. Significant increase in mRNA level and activity of Mn-superoxide dismutase (Mn-SOD), catalase, and selenium-dependent glutathione peroxidase-1 (GPx-1) and reduced ROS level was found in resistant K562/DOX and SKVLB cells. In contrast, no change in ROS level was observed in MCF-7/DOX cells in parallel with decrease in Mn-SOD and catalase mRNAs and corresponding activities concurrently with high increase in GPx-1 mRNA and activity. As a result of the development of resistance, a similarity was found between the change in ROS level and the change in ho-1 and bcl-2 gene expression, whereas elevation of bcl-xl gene expression was observed in all three types of resistant cells. Particular features of development of adaptive antioxidant response as well as redox-dependent change in bcl-2 gene expression under formation of DOX resistance of cancer cells of different genesis are discussed.