Stability of α-chymotrypsin conjugated with poly (ethylene glycols) and proxanols at high temperature and in watercosolvent mixtures

Summary -Chymotrypsin has been modified with poly(ethylene glycols) and proxanols, block-copolymers of poly(propylene oxide) and poly(ethylene oxide). These conjugates were several-fold more thermostable and showed high catalytic activity at elevated concentrations of water-miscible organic cosolvents (alcohols and dimethyl sulfoxide) which caused inactivation of free (non-modified) -chymotrypsin.     

Identification and certification of common wheat cultivars using RAPD and SSRP methods of analysis

Based on RAPD and SSRP analysis of wheats of different ecological-geographical origin, the procedures for composing genetic formulas of cultivars and their certification have been elaborated. The application of RAPD and SSRP analysis to the identification of wheat cultivars is discussed.     

Cross adaptation of potato plants to low temperatures and potato cyst nematode infestation

Effect of short-term (2 h a day) and long-term (6 days) exposure to low temperature (5°C) on cold tolerance was investigated in two cultivars of potato (Solanum tuberosum L.): resistant (Sudarynya) and susceptible (Nevskii) to potato cyst nematode (Globodera rostochiensis Woll.). The extent of their infestation and changes in the expression of the genes of resistance to nematode (H1 and Gro1-4) were also analyzed. In both cultivars, exposure to low temperature enhanced cold resistance of potato plants. Enhancing cold resistance of cv. Sudarynya induced by a short-term exposure to chilling did not affect the extent of nematode infestation, whereas in susceptible cv. Nevskii, the extent of infestation decreased by almost three times. The level of expression of H1 gene in the leaves of the susceptible cultivar rose almost twofold both after short-term and long exposure to chilling, while in the resistant cultivar, gene expression increased only after a short-term effect of cold. The level of Gro1-4 gene expression increased after both temperature treatments only in the resistant cv. Sudarynya. Thus, the expression of genes for potato resistance to nematode infestation became more active in the susceptible cultivar as regards the gene H1 and in the resistant cultivar, regarding the gene Gro1-4. In the nematode-susceptible cv. Nevskii, the level of infestation decreased and cold resistance increased, apparently indicating cross adaptation to two factors of different nature.     

Comparative analysis of genetic structure in natural populations of two <Emphasis Type="Italic">Arabidopsis</Emphasis> species with different degree of panmixia

Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P _99% = 62.50%; H _exp = 0.169) than the populations of A. thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P _99% = 42.27%; H _exp = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average D _N = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.     

Effect of abscisic acid on the resistance of cucumber seedlings to combined exposure to high temperature and chloride

The effect of abscisic acid (ABA) on heat and salt resistance of cucumber seedlings exposed (consecutively or simultaneously) to high temperature and chloride was studied. Exogenous ABA proved to additionally increase the heat and salt resistance after both consecutive and simultaneous exposure of cucumber seedlings to 38∞N and NaCl. The involvement of this hormone in the common (nonspecific) mechanisms increasing plant resistance to the studied environmental factors is concluded.     

Estimation of the Genetic Diversity of Willow Warbler Populations of the Subspecies <Emphasis Type="Italic">Phylloscopus trochilus acredula</Emphasis> (L.) in Different Parts of Its Nesting Area in the European Part of Russia

The genetic diversity (GD) of the Phylloscopus trochilus acredula subspecies populations was studied in different parts of the breeding area in the European part of Russia using microsatellite analysis. It was detected that the level of GD sufficient for the preservation of population genetic structure of the species with optimal ratio of intra- and interpopulation components of the gene diversity and minimal deviations from panmixia is maintained in the studied populations. The maximal values of GD indices were registered in an ecologically suboptimum zone on the periphery of the breeding range.     

Barley plant response to cadmium action as dependent on plant age

Age-dependent differences in the responses of 3-day-old (the phase of seed germination) and 7-day-old (the phase of seedlings) of barley (Hordeum vulgare L., cv. Zazerskii 85) plants to treatment with cadmium (100 μM). Four-day-long exposure to the cadmium solution retarded root growth and suppression of the photosynthetic apparatus in germinating seeds, whereas in seedlings, the roots continued to grow actively and parameters characterizing functioning of the photosynthetic apparatus were close to control values. In the presence of cadmium, in the roots of plants the level of HvPCS gene encoding phytochelatin synthase and the content of phytochelatins (PC) increased independently of the plant age. Distinctly, changes in the content of reduced glutathione (GSH) depended on the plant age: in 3-day-old seedlings the content of GSH reduced after 40-day-long exposure to cadmium; in contrast, in 7-day-old plants, it increased. We concluded that differences in the tolerance to cadmium of plants differing in age are related to their anatomic, morphological, physiological, and biochemical properties corresponding to particular developmental stages and also to differences in functioning of different mechanisms of metal detoxification, in particular, to activation of GSH synthesis and a great increase in the content of PC in the older plants.