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Reactive oxygen species (ROS) are produced via catabolic and anabolic processes during normal embryonic development, and ROS content in the cell is maintained at a certain level. Peroxiredoxins are a family of selenium-independent peroxidases and play a key role in maintaining redox homeostasis of the cell. In addition to regulating the ROS level, peroxiredoxins are involved in intracellular and intercellular signaling, cell differentiation, and tissue development. The time course of peroxiredoxin gene (prx1-6) expression was studied in Xenopus laevis during early ontogeny (Nieuwkoop and Faber stages 10-63). The highest expression level was observed for prx1 at these developmental stages. The prx1, prx3, and prx4 expression level changed most dramatically in response to oxidative stress artificially induced in X. laevis embryos. In X. laevis adults, prx1-6 were all intensely expressed in all organs examined, the prx1 expression level being the highest. The X. laevis prx1-6 genes were cloned and expressed in Escherichia coli, and physico-chemical characteristics were compared for the recombinant enzymes. The highest peroxidase activity and thermal stability were observed for Prx1 and Prx2. It was assumed that Prx1 plays a leading role in X. laevis early development.

Peroxiredoxins (Prx) are a family of antioxidant proteins with peroxidase activity. The ability of 1-Cys Prx to self-associate was studied with the use of native PAGE and Western blotting. Two protein bands corresponding to monomeric and dimeric forms were detected in the preparation of the recombinant 1-Cys Prx subjected to native PAGE, with dimers being more abundant. The third band corresponding to the oligomeric form was detected after incubation of the recombinant 1-Cys Prx with DTT, although monomers and dimers were also observed. These results indicate that monomeric, dimeric, and oligomeric states of the protein are likely to be interchangeable. Native PAGE in combination with Western blot analysis revealed that self-association of 1-Cys Prx also occurred at physiologically relevant concentrations in vivo. The native 1-Cys Prx existed in the monomeric and dimeric forms in rat olfactory epithelium, with monomers being more common. The structural sensitivity of the recombinant 1-Cys Prx to imidazole was shown.

The effects of the human BCL-xL and ACR-1 genes on dystrophin expression in cross-striated muscle fibers (CSMF) and on CSMF viability were studied in mdx mice after ballistic cotransfection with the human dystrophin minigene. In control mice, the proportion of dystrophin-positive (D(+)) and dying CSMF were 2.1 +/- 0.1 and 2.1 +/- 0.3%, respectively. Introduction of the dystrophin minigene (20 micrograms of the pSG5dys plasmid) increased the proportions of D(+) and dying CSMF to 5.6 +/- 1.4% and 4.5 +/- 0.9%, respectively. When pSG5dys was introduced along with the pSFFV-Neo plasmid carrying the BCL-xL gene (10 micrograms of each plasmid per shot), the death of CSMF decreased to 3.7 +/- 1% and the proportion of D(+) CSMF significantly (P < 0.05) increased to 12.2 +/- 2.2%. Contransfection with the dystrophin minigene and the BCL-xL gene at 20 micrograms of each plasmid per shot did not stimulate generation of D(+) CSMF, but did reduce the CSMF death to 1.5 +/- 0.3%. Introduction of pSG5dys along with the pRc-CMV-10.1 plasmid containing the ACR-1 gene (10 micrograms of each plasmid per shot) reduced the proportion of D(+) CSMF to 1.1 +/- 0.5% and significantly reduced the proportion of dying CSMF to 0.9 +/- 0.3% as compared with the proportions observed in intact mice or in mice subjected to transfection with pSG5dys. Introduction of the pSG5dys plasmid substantially reduced the proportion of CSMF with peripheral nuclei, suggesting disturbed CSMF differentiation. After cotransfection with the human-dystrophin minigene, the BCL-xL and ACR-1 genes did not affect the extent of CSMF differentiation as compared with that observed in the case of the dystrophin minigene alone. Thus, ballistic transfection of mdx mice with the human dystrophin gene used along with the BCL-xL or ACR-1 gene was shown to suppress the death of muscle fibers and to expedite dystrophin synthesis and cell differentiation.

The genetic structure of Arabidopsis thaliana populations from in the Chernobyl zone of radioactive contamination was studied. The dynamics of genotypic and allele frequencies of eight polymorphic loci were described. Analysis of the results obtained and earlier data revealed selection for loci Per1 and Acp2. Sharp fluctuations of allele frequencies were observed in consecutive generations of chronically irradiated A. thaliana populations. These fluctuations led to replacement of the most frequent alleles, including those close to fixation.

The 28 kDa peroxiredoxin from rat exhibited peroxidase activity only in the presence of dithiothreitol. Both organic and nonorganic peroxidases were found to be substrates for the 28-kDa peroxiredoxin activity. Analysis of the protective antioxidant activity of the 28-kDa peroxiredoxin revealed that it is accounted for by its peroxidase activity.

Clone lambda a26.1 isolated from rat olfactory epithelium contains a full-length 28-kDa protein cDNA (1414 b.p.). The reconstructed protein sequence comprises 223 aa with a calculated molecular mass of 24,630 Da. A substantial homology was revealed between the amino acid sequence of the 28-kDa protein and those of thiol-specific antioxidants (peroxiredoxines). The 28-kDa protein belongs to the 1 Cys-subfamily of peroxiredoxines and is the first member of peroxiredoxines identified in the olfactory epithelium.

The secretory 28 kD protein, an abundant water-soluble protein from rat olfactory epithelium, belongs to the 1-Cys subfamily of thiol-specific antioxidants (peroxiredoxins). The 28 kD protein contains a single cysteine residue at the position 46 which accounts for the antioxidant activity. Here we studied the effects of N-ethyilmaleimide and t-butyl hydroperoxide on the antioxidant activity of the 28 kD protein and that of the 23 kD protein from rat erythrocyte which is a member of 2-Cys subfamily of peroxiredoxines. N-ethylmaleimide, modifier for cysteine residues, had no effect on antioxidant activity of the dithiothreitol-treated 28 kD protein but irreversibly inhibited activity of the 23 kD protein under reducing conditions. The 28 kD protein was sensitive to treatment with peroxides: t-butyl hydroperoxide at micromolar concentrations was shown to irreversibly inactivate 28 kD protein. In the presence of dithiothreitol, the lower level of peroxide concentrations was required to inhibit 28 kD protein activity. The mechanism of this effect may be mediated through conversion of sulfhydryl group of 46Cys to oxidized states (46Cys-SO2H and 46Cys-SO3H). Antioxidant property of 23 kD protein was impaired by t-butyl hydroperoxide only in the presence of dithiothreitol. The concentrations of t-butyl hydroperoxide needed to affect the 23 kD protein were at least one order of magnitude higher than were required for the 28 kD protein inhibition. The given results suggest the essential differences between catalytic site of 28 kD protein and that of 2-Cys peroxiredoxins.