Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

Catalytic properties of tryptophanless recombinant horseradish peroxidase

Heme-containing plant peroxidases (EC 1.11.1.7) contain a highly conserved single tryptophan residue. Its replacement with Phe in recombinant horseradish peroxidase (rHRP) increased the stability of the mutant enzyme in acid media. The kinetic properties of native, wild-type, and W117F mutant recombinant horseradish peroxidase in the reactions of ammonium 2, 2;-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), guaiacol, and o-phenylenediamine oxidation are very similar. However, significant changes in the reaction rate constant characteristic for the monomolecular rate-limiting step ascribed either to product dissociation from its complex with the enzyme or electron transfer from the substrate to the active site within the Michaelis complex were observed. The data indirectly indicate the participation of the single Trp residue in oxidation of ABTS and guaiacol and possible differences in kinetic mechanisms for oxidation of ABTS, guaiacol, and o-phenylenediamine.     

Catalytic mechanism and substrate specificity of HIF prolyl hydroxylases

This review describes the catalytic mechanism, substrate specificity, and structural peculiarities of alpha-ketoglutarate dependent nonheme iron dioxygenases catalyzing prolyl hydroxylation of hypoxia-inducible factor (HIF). Distinct localization and regulation of three isoforms of HIF prolyl hydroxylases suggest their different roles in cells. The recent identification of novel substrates other than HIF, namely β2-adrenergic receptor and the large subunit of RNA polymerase II, places these enzymes in the focus of drug development efforts aimed at development of isoform-specific inhibitors. The challenges and prospects of designing isoform-specific inhibitors are discussed.     

Comparative phylogeography of a vulnerable bat and its ectoparasite reveals dispersal of a non-mobile parasite among distinct evolutionarily significant units of the host

Knowledge about phylogeographical structuring and genetic diversity is of key importance for the conservation of endangered species. Comparative phylogeography of a host and its parasite has the potential to reveal cryptic dispersal and behaviour in both species, and can thus be used to guide conservation management. In this study, we investigate the phylogeographic structure of the Bechstein’s bat, Myotis bechsteinii, and its ectoparasitic bat fly, Basilia nana, at 12 sites across their entire distribution. For both species, a mitochondrial sequence fragment (ND1 and COI respectively) and nuclear microsatellite genotypes (14 and 10 loci respectively) were generated and used to compare the phylogeography of host and parasite. Our findings confirm the presence of three distinct genetic subpopulations of the Bechstein’s bat in (1) Europe, (2) the Caucasus and (3) Iran, which remain isolated from one another. The genetic distinctiveness of host populations in the Caucasus region and Iran emphasize that these populations must be managed as distinct evolutionarily significant units. This phylogeographical pattern is however not reflected in its parasite, B. nana, which shows evidence for more recent dispersal between host subpopulations. The discordant genetic pattern between host and parasite suggest that despite the long-term genetic isolation of the different host subpopulations, long-range dispersal of the parasite has occurred more recently, either as the result of secondary contact in the primary host or via secondary host species. This indicates that a novel pathogenic threat to one host subpopulation may be able to disperse, and thus have important consequences for all subpopulations.     

Communally breeding Bechstein's bats have a stable social system that is independent from the postglacial history and location of the populations

Investigating macro-geographical genetic structures of animal populations is crucial to reconstruct population histories and to identify significant units for conservation. This approach may also provide information about the intraspecific flexibility of social systems. We investigated the history and current structure of a large number of populations in the communally breeding Bechstein's bat ( Myotis bechsteinii ). Our aim was to understand which factors shape the species' social system over a large ecological and geographical range. Using sequence data from one coding and one noncoding mitochondrial DNA region, we identified the Balkan Peninsula as the main and probably only glacial refugium of the species in Europe. Sequence data also suggest the presence of a cryptic taxon in the Caucasus and Anatolia. In a second step, we used seven autosomal and two mitochondrial microsatellite loci to compare population structures inside and outside of the Balkan glacial refugium. Central European and Balkan populations both were more strongly differentiated for mitochondrial DNA than for nuclear DNA, had higher genetic diversities and lower levels of relatedness at swarming (mating) sites than in maternity (breeding) colonies, and showed more differentiation between colonies than between swarming sites. All these suggest that populations are shaped by strong female philopatry, male dispersal, and outbreeding throughout their European range. We conclude that Bechstein's bats have a stable social system that is independent from the postglacial history and location of the populations. Our findings have implications for the understanding of the benefits of sociality in female Bechstein's bats and for the conservation of this endangered species.     

Rearrangements of microinjected recombinant DNA in the genome of transgenic mice

Summary Previously, mouse zygotes were microinjected with the recombinant plasmid pMA3, which contains the Herpes simplex virus thymidine kinase gene attached to the promoter region of the Rous sarcoma virus (Gazaryan et al. 1984a). In the present work the pMA3 fragment with the flanking genomic sequences was isolated from the DNA of one transgenic F_o mouse by the plasmid rescue technique. The rescued plasmid (pMAR1) lacked all virus-specific sequences and retained only some pBR322 sequences. The flanking region at one end of the integrated pBR322-specific fragment contained a highly conserved mouse repetitive sequence. The possible mechanisms of rearrangement of foreign DNA in germ line cells are discussed.     

Effect of microinjections of cAMP-dependent protein kinase subunits on macromolecular syntheses in loach Misgurnus fossilis L. embryos

The level of cAMP and the effects of the regulatory and catalytic subunits of cAMP-dependent protein kinase of type II on protein, RNA and DNA synthesis in loach embryos were analysed. It was found that the injections of the catalytic subunit cause a sharp decrease in the rate of macromolecular synthesis while an increase in the concentration of this protein leads to the death of the embryo. Injections of the regulatory subunit result in marked stimulation of protein, RNA and DNA synthesis. The effect of the regulatory subunit on these processes is rather complex. Experiments on the transplantation of the nuclei from the embryos treated with the protein kinase subunits into normal embryos were carried out.