UV light-induced DNA damage detection in the unicellular green alga <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>

Exposure of cells to ultraviolet radiation (UVR) is one of the best studied and most used model system for the examination of the biological effects of DNA damage, its repair and tolerance. The major product after UVR treatment is cyclobutane pyrimidine dimer (TT, TC, CC). Pyrimidine dimers are repaired by a direct reversal called photoreactivation or by excision of damage in a process of nucleotide excision repair. Several methods have been developed for the detection and quantification of pyrimidine dimers in DNA. The technique of Small and Greimann, in which DNA is incubated with the pyrimidine dimer-specific endonuclease, was used for the analysis of mutant strains with impaired excision repair system of the unicellular green alga Chlamydomonas reinhardtii. Another method is based on the binding of specific monoclonal antibodies to pyrimidine dimers. The aim of our work was to compare these two techniques with the use of mutant strains of C. reinhardtii — uvsX1 and uvsX2 which are assumed to be deficient in DNA damage recognition. One of their traits was sensitivity to UVR which could be caused by breakdown of the excision repair pathway. The results suggest that the immuno-approach is suitable for the detection of DNA damage induced by UVR. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Study of <Emphasis Type="Italic">Yersinia pseudotuberculosis</Emphasis> antigenic structure to obtain a sensitin for design of species-specific diagnostic kits

A method for isolation of outer membrane proteins from Yersinia pseudotuberculosis, which are perspective for further application as sensitin for design of species-specific pseudotuberculosis antigenic diagnostic kits, has been modified. Common species-specific antigens of nine Y. pseudotuberculosis serovars (with molecular weight from 80.62 to 12.2 kDa) were detected by SDS-PAAGE electrophoresis and immunoblotting of the outer-membrane protein preparations. These antigens react with neither the rabbit experimental antiplague antiserum nor antiserum to 39 Y. enterocolitica serovars and normal rabbit serum.     

Plant fiber intrusive growth characterized by NMR method

Intrusively growing plant cells insert themselves between surrounding cells, thus increasing the number of membranes on the tissue cross-section. This parameter can be assessed by spin echo NMR method with a magnetic field pulse gradient. Diffusion echo decay was measured for stem regions of long-fiber flax (Linum usitatissimum L.) differing in the stages of primary fiber development, which elongate thousand-fold during intrusive growth. Additionally, the number of fibers on stem cross-sections was counted under microscope. An increase in the slow component of the echo diffusion decay was correlated with an increase in the number of fibers on the stem cross-section in the zone of intrusive growth, while other stem-structure characteristics remained unchanged. Thus, NMR method can be used for characterization of intrusive fiber growth in situ.     

Spring migration dynamics and sex-specific patterns in stopover strategy in the Wood Sandpiper Tringa glareola

Due to being a virtually monomorphic wader species, migration dynamics and sex-related migration patterns in the Wood Sandpiper (Tringa glareola) have rarely been investigated. We captured spring migrants at an important stopover site in northeastern Austria. Birds were individually color-marked, and sex was determined by an analysis of DNA from tail feather material. Among temporary residents (birds seen again after day of capture), males migrated on average 3 days earlier than females. However, since sexes did not differ in fat score, the length of stay and the proportion of transients (birds not seen again after day of capture) and temporary residents, we suggest that males and females adopt similar migration strategies in the spring. The large number of transients captured as well as shorter stopover durations in later temporary residents indicate that Wood Sandpipers minimize time at this stage of their northbound migration. Temporary residents earlier in the season exhibited lower fat stores than later ones. Nevertheless, since the fat stores of transients and temporary residents were similar even after the progress of the season had been accounted for, we assume that Wood Sandpipers may afford to exhibit individual flexibility in migration strategy and the use of stopover sites, especially early in the season. This variability may be a necessary adaptation to cope with possible varying environmental conditions at dynamic and unpredictable inland stopover sites. After having reached North Mediterranean regions, mean body mass of spring migrants gradually increases during successive stopovers, indicating that Wood Sandpipers follow a ‘hopping’ migration strategy. This emphasizes the high conservation value of even small artificial mudflat pools as important stepping stones in order to maintain a continuous network of wetland habitats for this continental migrant.     

Extracellular hydrolases of strain <Emphasis Type="Italic">Bacillus</Emphasis> sp. 739 and their involvement in the lysis of micromycete cell walls

The mycolytic bacterial strain Bacillus sp. 739 produces extracellular enzymes which degrade in vitro the cell walls of a number of phytopathogenic and saprophytic fungi. When Bacillus sp. 739 was cultivated with Bipolaris sorokiniana, a cereal root-rot pathogen, the fungus degradation process correlated with the levels of the β-1,3-glucanase and protease activity. The comparative characteristic of Bacillus sp. 739 enzymatic preparations showed that efficient hydrolysis of the fungus cell walls was the result of the action of the complex of enzymes produced by the strain when grown on chitin-containing media. Among the enzymes of this complex, chitinases and β-1,3-glucanases hydrolyzed most actively the disintegrated cell walls of B. sorokiniana. However, only β-1,3-glucanases were able to degrade the cell walls of native fungal mycelium in the absence of other hydrolases, which is indicative of their key role in the mycolytic activity of Bacillus sp. 739.     

Cyanide-induced death of cells in plant leaves

Destruction of guard cell nuclei in epidermis isolated from leaves of pea, maize, sunflower, and haricot bean, as well as destruction of cell nuclei in leaves of the aquatic plants waterweed and eelgrass were induced by cyanide. Destruction of nuclei was strengthened by illumination, prevented by the antioxidant alpha-tocopherol and an electron acceptor N,N,N ,N -tetramethyl-p-phenylenediamine, and removed by quinacrine. Photosynthetic O2 evolution by the leaf slices of a C3 plant (pea), or a C4 plant (maize) was inhibited by CN- inactivating ribulose-1,5-bisphosphate carboxylase, and was renewed by subsequent addition of the electron acceptor p-benzoquinone.     

A comparative analysis of the <Emphasis Type="Italic">hsp70</Emphasis> gene system in two species of the family stratiomyidae (Diptera)

The structure of the hsp70 gene cluster was investigated for two species of the family Stratiomyidae (Diptera), Stratiomys singularior and Oxycera pardalina. Their larvae inhabit nearshore-aquatic biotopes with contrasting temperature regimes, composition and concentration of salts. It was shown that the S. singularior hsp70 gene cluster contains five copies and has a compact structural organization (the interval length did not exceed 5 kb). The O. pardalina hsp70 gene cluster contains four copies located at larger distances in comparison with the S. singularior and also includes the hsp68 gene. High variability in the structure of the S. singularior hsp70 gene cluster was detected.     

Study of structural and rheological properties of starch isolated from genetically modified potato

It has been found in this work that the starchiness and starch content in tubers of GM potato and tubers of initial Lugovskoi potato variety are identical. No differences and difficulties were observed upon starch preparation from GM and common potato. Starch samples isolated from GM potato conform to the current standard for potato starch. The starch isolated from GM potato has a higher melting point, i.e., it is more thermally stable as compared with the starch isolated from a control sample. The bulk modulus of gels obtained from starch isolated from GM potato is higher in comparison with that of gels prepared from starch isolated from the control sample. Thermodynamic and rheological properties of starch from GM potato provide a possibility to predict its application in the manufacture of thermostable and strong polymeric materials.     

Phospholipids and cholesterol of liver nuclei during artificial hypobiosis of rats

The contents of lipids in the tissue and the nuclei of liver cells during artificial hypobiosis, as well as in the nuclei of liver cells for 3 days after the cessation of cooling in rats, were studied. In the artificial hypobiosis and in the state of normothermia 24 h after the cessation of cooling, the total phospholipid content of the liver cell nuclei increased by 20% due to minor phospholipids. The levels of sphingomyelin, phosphatidylinositol, phosphatidylserine, cardiolipin, and lysophosphatidylcholine were doubled in hypobiosis and then nonmonotonically returned to the normal level within 72 h. In the state of artificial hypobiosis, the levels of fatty acids, cholesterol, and diglycerides increased by 30–40%. The state of artificial hypobiosis did not affect the level of lipids in the liver tissue of Wistar rats. The increase of the lipid content in the liver cell nuclei of Wistar rats indicates the important role of lipids in functions of the nucleus when the energy supply and protein synthesis are inhibited under conditions of artificial hypobiosis.