Study of reparative DNA synthesis in lymphocytes of persons occupationally exposed to radiation

The UDS efficiency in lymphocytes of professionals chronically exposed to gamma/neutron radiation, as well as for a control cohort was estimated. A credible reduction of UV-induced UDS (KUV) index as compared to the control was demonstrated. This shows an invalid repair state of blood cells in professionals. As for the control cohort, the decreasing tendency of UDS index with age was found. The correlative analysis of UDS index dependence upon an absorbed dose (based on physical dosimetry data) revealed the trend towards repair index reduction along with a higher total absorbed doze, that is followed by UDS index coming onto a plateau. It was also demonstrated that after a sharp and/or accidental irradiation UDS index reduces as compared to permanent portioned irradiation. It was not observed the influence of smoking upon UDS efficiency in blood lymphocytes neither for control, nor for experimental group. The analysis of vitamin therapy of the both cohorts showed that such therapy raises UDS index of the control (i.e., non-professional) group. Besides, it was found out an additional positive effect of vitamin therapy, i.e. doze leveling in long-term perspective after irradiation. The most expressed KUV/doze correlation was characteristic for professionals, who do not take vitamins and do not smoke. This proves that in blood cells of professionals it is preserved a dependence of repair system invalidity upon the absorbed doze without similar external factors.     

Comparison of the nucleotide sequences of wheat dwarf virus (WDV) isolates from Hungary and Ukraine

Wheat dwarf virus (WDV) is the most ubiquitous virus in cereals causing huge losses in both Hungary and Ukraine. The presence of barley-and wheat-adapted strains has been confirmed, suggesting that the barley strain is restricted to barley, while the wheat strain is present in both wheat and barley plants. Five WDV isolates from wheat plants sampled in Hungary and Ukraine were sequenced and compared with known WDV isolates from GenBank. Four WDV isolates belonged to the wheat strain. Our results indicate that WDV-Odessa is an isolate of special interest since it has originated from wheat, but belongs to the barley-adapted strain, providing novel data on WDV biology and raising issues of pathogen epidemiology.     

Genetic containment of forest plantations

Dispersal of pollen, seeds, or vegetative propagules from intensively bred, exotic, or recombinant DNA modified forest plantations may cause detrimental or beneficial ecological impacts on wild or managed ecosystems. Insertion of genes designed to prevent or substantially reduce dispersal could reduce the risk and extent of undesired impacts. Containment measures may also be required by law or marketplace constraints, regardless of risks or benefits. We discuss: (1) the context for when genetic containment or mitigation systems may be needed; (2) technology approaches and mechanisms; (3) the state of knowledge on genes/genomics of sexual reproduction in forest trees; (4) stability of transgene expression during vegetative growth; (5) simulation studies to define the level of containment needed; and (6) needed research to deliver effective containment technologies. We illustrate progress with several examples from our research on recombinant DNA modified poplars. Our simulations show that even partial sterility can provide very substantial reductions in gene flow into wild trees. We conclude that it is impossible to define the most effective containment approaches, nor their reliability, based on current genomic knowledge and technological tools. Additional genomic and technological studies of a wide variety of options are needed. Studies in field environments are essential to provide data relevant to ecological analysis and regulatory decisions and need to be carried out in phylogenetically diverse representatives of the economically most important taxa of forest trees.

The Schizosaccharomyces pombe JmjC-Protein,Msc1, Prevents H2A.Z Localization in Centromeric and Subtelomeric Chromatin Domains

Eukaryotic genomes are repetitively packaged into chromatin by nucleosomes, however they are regulated by the differences between nucleosomes, which establish various chromatin states. Local chromatin cues direct the inheritance and propagation of chromatin status via self-reinforcing epigenetic mechanisms. Replication-independent histone exchange could potentially perturb chromatin status if histone exchange chaperones, such as Swr1C, loaded histone variants into wrong sites. Here we show that in Schizosaccharomyces pombe, like Saccharomyces cerevisiae, Swr1C is required for loading H2A.Z into specific sites, including the promoters of lowly expressed genes. However S. pombe Swr1C has an extra subunit, Msc1, which is a JumonjiC-domain protein of the Lid/Jarid1 family. Deletion of Msc1 did not disrupt the S. pombe Swr1C or its ability to bind and load H2A.Z into euchromatin, however H2A.Z was ectopically found in the inner centromere and in subtelomeric chromatin. Normally this subtelomeric region not only lacks H2A.Z but also shows uniformly lower levels of H3K4me2, H4K5, and K12 acetylation than euchromatin and disproportionately contains the most lowly expressed genes during vegetative growth, including many meiotic-specific genes. Genes within and adjacent to subtelomeric chromatin become overexpressed in the absence of either Msc1, Swr1, or paradoxically H2A.Z itself. We also show that H2A.Z is N-terminally acetylated before, and lysine acetylated after, loading into chromatin and that it physically associates with the Nap1 histone chaperone. However, we find a negative correlation between the genomic distributions of H2A.Z and Nap1/Hrp1/Hrp3, suggesting that the Nap1 chaperones remove H2A.Z from chromatin. These data describe H2A.Z action in S. pombe and identify a new mode of chromatin surveillance and maintenance based on negative regulation of histone variant misincorporation.     

Antioxidant properties of conjugates of polyethylene glycols containing terpenophenolic fragments

A series of water-soluble conjugates has been synthesized from polyethylene glycols of various lengths and 4-bromomethyl-2,6-diisobornylphenol. The membrane protective and antioxidant activities of the synthesized products were evaluated on the model of the H₂O₂-induced hemolysis of erythrocytes. It was shown that the studied conjugates have a significant antioxidant activity, and a significant membrane protective effect was shown for the conjugates containing 0.2% and 0.8% of the 2,6-diisobornyl-4-methylenephenolic fragments.     

Variation of nitric oxide content regulates the development of apoptosis in the retina

It was shown that retinal ischemia entailed apoptosis in the inner layers of the retina. Administration of an NO-synthase inhibitor suppressed the development of ischemic apoptosis. To ascertain whether nitric oxide could induce the retinal apoptosis by itself, a nontoxic NO donor—dinitrosyl iron complex (DNIC) with glutathione—was injected into the vitreous body. DNIC at low concentrations induced apoptosis in the same retinal layers as in ischemia. However, with increasing DNIC doses, the number of apoptotic nuclei decreased markedly. Simultaneous administration of excess glutathione prevented apoptosis at any DNIC dose. The obtained data demonstrate the neurotoxic properties of the excess of nitric oxide in the retina.     

Surface active properties of isobornylphenols in systems with different degrees of complexity

Interrelations between the structure of the semi-synthetic phenolic antioxidants — isobornylphenols and their surface active properties were studied in the chemical (the lecithin aggregation in hexane) and biological (the incubation with the blood erythrocytes) model systems. It has been shown that all studied compounds are able to affect the lecithin aggregation in hexane: the share of the main fraction of the L micelles decreases with increasing the share of particles of greater size. The effect substantially depends on hindered OH group and the presence of the intramolecular hydrogen bond in molecule. The cytotoxic properties of isobornylphenols (the concentration is 100 μM) are predominantly due to the molecule structure. The interrelation between the aggregate size of the main fraction of L in the presence of the studied compounds and the discocyte share during mice blood erythrocyte incubation in their presence for 4 h is revealed. Thus, this provides the possibility to assume that the ability of the different biological active substances to affect the lecithin aggregation in non-polar solvent could be used as a model system for the initial assessment of their surface active properties.     

Effect of fucoidans on the developing embryos of the sea urchin <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis>

Effect of fucoidans from the Far Eastern brown algae Laminaria japonica, L. cichoroides, and Fucus evanescens on developing embryos of the sea urchin Strongylocentrotus intermedius was studied. Fucoidans from these algae were shown to have different (immunostimulating, inhibitory) effects on the developing embryos. All studied fucoidan fractions added at the zygote stage had a stimulatory effect (acceleration of developmental stages and an increase of life spans) on the developing embryos, with differences by their effective concentrations. Many fucoidans added at the late blastula stage did not produce the stimulatory effect. The lowest number of immunostimulators (only a half of the tested substances) were present among fucoidans from L. japonica cichoriodes. The best immunostimulators that increased 2–3 times the life span of the embryos were heteropolysaccharides containing mannose or xylose apart from L-fucose. Some fucoidans at high concentrations produced an inhibitory effect; they were mainly composed of L-fucose or their monosaccharide composition included, apart from fucose, a significant amount of galactose, but no mannose. The method that we used turned out to be sensitive to structural peculiarities of charged polysaccharides, so it most likely can be applied for evaluation of their immunostimulating properties. From two variants of the experiment the most sensitive was the second one, in which polysaccharides were added at the late blastula stage.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 51–58.Original Russian Text Copyright © 2005 by Kiseleva, Shevchenko, Krupnova, Zvyagintseva.