Physiological responses to water deficiency in bread wheat (Triticum aestivum L.) lines with genetically different leaf pubescence.

Studying the relationship between leaf pubescence and drought resistance is important for assessing Triticum aestivum L. genetic resources. The aim of the work was to assess resistance of common wheat genotypes with different composition and allelic state of genes that determine the leaf pubescence phenotype. We compared the drought resistance wheat variety Saratovskaya 29 (S29) with densely pubescent leaves, carrying the dominant alleles of the Hl1 and Hl3 genes, and two near isogenic lines, i: S29 hl1, hl3 and i: S29 Hl2aesp, with the introgression of the additional pubescence gene from diploid species Aegilops speltoides. Under controlled conditions of the climatic chamber, the photosynthetic pigments content, the activity of ascorbate-glutathione cycle enzymes and also the parameters of chlorophyll fluorescence used to assess the physiological state of the plants photosynthetic apparatus were studied in the leaves of S29 and the lines. Tolerance was evaluated using the comprehensive index D, calculated on the basis of the studied physiological characteristics. The recessive state of pubescence genes, as well as the introduction of the additional Hl2aesp gene, led to a 6-fold decrease in D. Under the water deficit influence, the fluorescence parameters profile changed in the lines, and the viability index decreased compared with S29. Under drought, the activity of ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase in the line i: S29 hl1, hl3 decreased 1.9, 3.3 and 2.3 times, in the line i: S29 Hl2aesp it decreased 1.8, 3.6 and 1.8 times respectively, compared with S29. In a hydroponic greenhouse, line productivity was studied. Compared with S29, the thousand grains mass in the line i: S29 hl1, hl3 under water deficit was reduced. The productivity of the line i: S29 Hl2aesp was significantly reduced regardless of water supply conditions in comparison with S29. Presumably, the revealed effects are associated with violations of cross-regulatory interactions between the proteins of the trichome formation network and transcription factors that regulate plant growth and stress response.

[Lipoxygenase from the leaves of wheat grown under different water supply conditions].

Lipoxygenase (LOG) in protein fractions isolated from the leaves of substituted wheat lines was investigated. Three molecular forms of the enzyme were detected. A water deficiency caused the induction of a membrane-bound form (mLOG) and resulted in a decrease in the activity of "soluble" enzymes (s1LOG) and (s2LOG) in most genotypes. A correlation analysis demonstrated the dependence between the level of enzymatic activity and indices of resistance to drought. A genetic control of the s 1 LOG and s2LOG activity at an optimal water supply level was associated with chromosomes 1A, 1D, 3A, 5A, 5B, and 5D, while under the conditions of the modeled soil drought, it was associated with chromosomes 1B and 1D.

[Mapping of quantitative trait loci (QTL) associated with activity of disulfide reductase and lipoxygenase in grains of durum wheat Triticum aestivum L. seeds].

Activity of two enzymes of thiol-disulfide cell metabolism, lipoxygenase (LOX, EC 1.13.11.12) and disulfide-reductase (TPDO, EC 1.8.4.2) was studied in recombinant inbred lines of common wheat ITMI. Their activity in the caryopsis may be connected with the gluten quality, one of the most important traits significant for selection. The activity of lipoxygenase under favorable and droughty environmental conditions was shown to be associated with the quantitative trait locus (QTL) located on chromosome 4BS near the structural gene of a subunit of this enzyme. However, no QTL common to this enzyme and any characteristic of gluten quality have been found. Four loci responsible for the activity of disulfide reductase were identified on chromosomes 4A, 5D, 6A, and7D. Previously, indicators of grain and flour properties, such as elasticity, flour vigor, and grain hardiness were mapped at the same loci. This indicates that the given enzyme participates in the formation of the protein complex upon maturation of wheatgrain. The detected QTL can be involved in further genetic studies designed to establish the regularities of gluten formation.

Characteristics of thiol:protein disulfide oxidoreductase from wheat (Triticum aestivum L.) grain.

Biochemical properties of a homogenous preparation of thiol:protein disulfide oxidoreductase (TPDO, EC 1.8.4.2) isolated for the first time from mature wheat (Triticum aestivum L.) grain were studied. According to polyacrylamide gel electrophoresis data, the molecular weight of TPDO is around 167 kD, the enzyme consisting of two subunits of 77 and 73 kD, which differentiates TPDO from known enzymes of SH/SS-metabolism of wheat caryopses. In substrate specificity and enzymatic characteristics (pH and temperature optima) TPDO is similar to analogous enzymes of animal tissues. Inhibition of disulfide reductase activity by alkylating agents and heavy metal ions suggests the participation of active center SH-groups in the catalytic act and classes the enzyme as a member of the thioredoxin superfamily. The SS-reductase reduces aggregating capacity of acetic acid-soluble fraction of wheat storage proteins. The proposed physiological role of TPDO is participation in creation and regulation of SH/SS-status of wheat endosperm proteins and formation of the rheological properties of gluten.

Products of the reaction of cholesterol with hypochlorite anion.

Products of the reaction of cholesterol with hypochlorite (OCI) in various systems (egg phosphatidylcholine liposomes, low-density lipoproteins, and aqueous colloidal dispersion of cholesterol) were separated and analyzed by TLC, HPLC, and gas chromatography-mass spectrometry. The reactions of hypochlorite with cholesterol result in the same reaction products in all treated systems. Eighteen fractions were isolated from the reaction mixture by normal-phase HPLC in hexane-isopropanol (95:5 v/v); these were then examined by gas chromatography-mass spectrometry. Six products less polar than cholesterol were isolated from the reaction mixture; two of them were identified as 4,6-cholesten-3-one and 4-cholesten-3,6-dione. Among the oxidation products more polar than cholesterol, nine compounds were identified; they are 5,7-cholestadien-3 beta-ol,3,5-cholestadien-7-one, 4-cholesten-3 beta, 6 beta-diol, 5-cholesten-3 beta, 7 beta-diol, cholestan-3 beta, 5 alpha, 6 beta-triol, 5 alpha-cholestan-3 beta-ol-6-one, 5-cholesten-3 beta-ol-7-one, 5 alpha, 6 alpha-epoxycholestan-3 beta-ol, and 5 alpha-cholesten-3,6-dione.

The interaction of block copolymers of ethylene oxide and propylene oxide and their polymer-protein conjugates with lipids.

The interaction of block copolymers of ethylene oxide and propylene oxide with lipid structures-monolamellar and multilamellar vesicles from egg yolk lecithin and dipalmitoylphosphatidylcholine-was studied by differential scanning calorimetry, light scattering, and electron spin resonance. Copolymers with different ratios of hydrophilic: hydrophobic portions, numbers of polymers, and arrangements or positions of the blocks, as well as conjugates of polymers with proteins, were used. Peculiarities in the macromolecular structure of the copolymers influence the character of their interactions with lipids. The effects of copolymers which become incorporated into the lipid bilayer are compared with that of polyethyleneglycol which influences lipid structure in an indirect manner.

Block copolymers of ethylene oxide and propylene oxide (pluronics) as immunomodulators and antitumour agents.

Block copolymers of ethylene oxide and propylene oxide (pluronics) are nontoxic water-soluble membranotropic surfactants available as polymers with various compositions, molecular masses, number, and arrangement of blocks. In vivo experiments are reported which demonstrate that these polymers and their functional derivatives stimulate the production of anti-sheep-erythrocyte antibodies in mice. The introduction of reactive (hydroperoxide) groups into the polymers by chemical modification or by solubilization of low-molecular-mass hydroperoxides alters the properties of these immunostimulators. In vitro experiments revealed that these modified polymers enhance the activity of natural killer cells without reducing their viability. It is proposed that the immunomodulatory properties of pluronics and their derivatives play an important role in the antitumour activity of these substances in vivo.