Effect of D,L-buthionine-S,R-sulfoximine on the ratio of glutathione forms and the growth of Tatar buckwheat calli

We studied the intracellular content of reduced (GSH) and oxidized (GSSG) glutathione, glutathione reductase activity, glutathione-S-transferase, and ascorbate peroxidase in morphogenic and nonmorphogenic Tatar buckwheat calli during the culture cycle as well as under the treatment with D,L-buthionine-S,R-sulfoximine (BSO), an inhibitor of γ-glutamylcysteine synthase, the first enzyme of glutathione biosynthesis. We found that, during passaging, cultures only slightly differed in total glutathione content; however, the content of GSH was higher in the morphogenic culture, whereas the content of GSSG was higher in the nonmorphogenic culture. In the morphogenic callus, the glutathione-S-transferase activity was 10–20 times higher and the glutathione reductase activity was 2–2.5 times lower than in the nonmorphogenic callus. Under the treatment with BSO, the decrease in the GSH content in the morphogenic callus was temporary (on day 6–8 of passage), whereas that in the nonmorphogenic callus decreased within a day and remained lower than in the control throughout the entire passage. In the morphogenic callus, BSO did not affect the content of GSSG, whereas it caused GSSG accumulation in the nonmorphogenic callus. These differences are probably due to the fact that, in the BSO-containing medium, glutathione reductase is activated in the morphogenic callus and, conversely, inhibited in the nonmorphogenic callus. Although BSO caused a decrease in the total glutathione content only in the nonmorphogenic culture, the cytostatic effect of BSO was more pronounced in the morphogenic callus. In addition, BSO also had a negative effect on the differentiation of proembryonic cell complexes in the morphogenic callus. The role of the glutathione redox status in maintaining the embryogenic activity of cultured plant cells is discussed.     

Activity and growth efficiency of heterotrophic bacteria in Rybinsk Reservoir

The active fraction, production, and respiration of heterotrophic bacteria are determined to assess their growth efficiency and their role in the carbon cycle in the pelagic zone of Rybinsk Reservoir in summer. The greater part of organic substances assimilated by bacteria is mineralized to CO₂. It has been established that the essential part of the constructive and energy metabolism of bacteria is supported by the input of allochthonous substances. Bacterioplankton, producing the biomass at their expense, performs functions similar to the functions of phytoplankton, and substantially supports the structural and functional organization of the planktonic food web in the reservoir.     

Halogenation of metalloporphyrins

We found that thionyl chloride can chlorinate porphyrin complexes with transient metals (Pd, Ni, or Cu) at the free β andmeso-positions of the porphyrin macrocycle. A more prolonged or rigorous treatment also causes the chlorination of side alkyl substituents, mainly, methyl groups.     

Trace transition metal-catalyzed reactions in the microsomal metabolism of alkyl hydrazines to carbon-centered free radicals.

Radical production from alkyl hydrazines (i.e. phenelzine and benzylhydrazine) in rat liver microsomes has been proposed to occur via cytochrome P-450-catalyzed one-electron oxidation followed by beta-scission of an alkyl radical. In microsomes treated with phenelzine (2-phenylethylhydrazine), NADPH, and the spin trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN), the 4-POBN/2-phenylethyl radical adduct was detected by electron paramagnetic resonance spectroscopy. The addition of catalase and superoxide dismutase resulted in a 28.5 and 24% decrease in radical production, respectively. The concentration of the 4-POBN/2-phenylethyl radical adduct decreased significantly in the presence of metal chelators, i.e. EDTA, diethylenetriaminepentaacetic acid (DTPA), or deferoxamine mesylate. When phenelzine was incubated with deferoxamine mesylate-washed microsomes and NADPH in Chelex-treated incubation buffer, no significant radical adduct formation was detected. Addition of iron-chelator complexes (either Fe(3+)-DTPA or Fe(3+)-EDTA) greatly stimulated production of the 4-POBN/2-phenylethyl radical adduct in this system. These results show that the 2-phenylethyl radical produced from phenelzine in a microsomal system arises via a trace transition metal-catalyzed reaction. This reaction may occur through oxidation of phenelzine by the hydroxyl radical, which has also been spin-trapped with 4-POBN in this system.     

Stimulation of root development on buckwheat thin cell-layer explants by pectic fragments from pea stem cell walls

Buckwheat (Fagopyrum esculentum Moench.) thin cell-layers (TCLs) cultured individually in a liquid medium were used to test the root-inducing activity of pectic polysaccharides with a degree of polymerization (DP) of 20–25, isolated from pea (Pisum sativum L.) stem cell walls. These pectic fragments induced more rapid root formation on the explants in comparison with untreated controls. This pectic fragment treatment also promoted root growth as measured by both fresh and dry weights and about doubled the number of roots formed. This buckwheat TCL system is proposed as a new bioassay for oligosaccharins due to its sensitivity, reproducibility and ease of preparation.     

1,2-O-alkylidene-3(5,6)-thio-α-d-glucofuranose 3,5,6-thiophosphites

The first representatives of sugar bicyclothiophosphites have been synthesised and their structures confirmed by chemical and spectral (¹³C- and ³¹P-n.m.r.) data. Chlorination of the sugar bicyclothiophosphites has been studied and new representatives of cyclic thiolo- and thioxo-chlorophosphates of hexofuranoses have been obtained.     

Trisomy 20p: case report and genetic review

Partial trisomy for the distal part of the short arm of chromosome 20 reported in a girl aged 11/2 years with typical craniofacial dysmorphies and psychomotor retardation. The trisomy resulted from a paternal translocation t(14;20) (q32.3;p11.1). The review of 25 cases of partial trisomy 20p showed that most cases (22 : 25) were due to parental translocations. Predominant involvement of small chromosomes in translocations with chromosome 20 was also detected.     

Comparison of redox state of cells of tatar buckwheat morphogenic calluses and non-morphogenic calluses obtained from them

Intracellular content of hydrogen peroxide and of the product of lipid peroxidation malonic dialdehyde as well as activity of antioxidant enzymes catalase, ascorbate peroxidase, and superoxide dismutase were studied in cells of morphogenic and derived from them non-morphogenic calluses of tatar buckwheat Fagopyrum tataricum L. Non-morphogenic calluses were characterized by significantly higher content of hydrogen peroxide and malonic dialdehyde, low catalase activity, and high activity of superoxide dismutase compared to morphogenic cultures. The results may indicate that cells of non-morphogenic calluses are in the state of continuous oxidative stress. Nevertheless, proliferative activity of non-morphogenic cultures and the biomass increase significantly exceeded these parameters in morphogenic calluses. An analogy is drawn between animal cancer cells and non-morphogenic plant calluses.     

Expression of 1-Cys peroxiredoxin in morphogenic and nonmorphogenic tatar buckwheat calli

Using two-dimensional gel electrophoresis and MALDI-TOF MS, we identified a protein with a mol wt of 24.5 kD and pI = 7.5 as 1-Cys peroxiredoxin. This protein was present among soluble proteins of morphogenic but not nonmorphogenic calli of tatar buckwheat (Fagopyrum tataricum (L.) Gaertn). Its expression was evidently related to the presence of proembryonal cell complexes in morphogenic calli.