Reserve nutrient substance accumulation in Brassica rapa L. seeds in microgravity conditions (STS-87)

The results of study of Brassica embryo differentiation and reserve nutrient substance accumulation in the seeds were represented. Near resemblance of the spaceflight and around control embryo development was revealed. Different character of the reserve substance accumulation was noted, despite of the morphologic similarity in seeds produced in spaceflight and on the ground. It allows to consider spaceflight embryos morphologically more younger compared to the ground control.     

Carbon Dioxide Fixation in Roots and Nodules of Alnus glutinosa: I. Role of Phosphoenolpyruvate Carboxylase and Carbamyl Phosphate Synthetase in Dark CO(2) Fixation, Citrulline Synthesis, and N(2) Fixation

Detached roots and nodules of the N₂-fixing species, Albus glutinosa (European black alder), actively assimilate CO₂. The maximum rates of dark CO₂ fixation observed for detached nodules and roots were 15 and 3 micromoles CO₂ fixed per gram dry weight per hour, respectively. The net incorporation of CO₂ in these tissues was catalyzed by phosphoenolpyruvate carboxylase which produces organic acids, some of which are used in the synthesis of the amino acids, aspartate, glutamate, and citrulline and by carbamyl phosphate synthetase. The latter accounts for approximately 30 to 40% of the CO₂ fixed and provides carbamyl phosphate for the synthesis of citrulline. Results of labeling studies suggest that there are multiple pools of malate present in nodules. The major pool is apparently metabolically inactive and of unknown function while the smaller pool is rapidly utilized in the synthesis of amino acids. Dark CO₂ fixation and N₂ fixation in nodules decreased after treatment of nodulated plants with nitrate while the percentage of the total ¹⁴C incorporated into organic acids increased. Phosphoenolpyruvate carboxylase and carbamyl phosphate synthetase play key roles in the synthesis of amino acids including citrulline and in the metabolism of N₂-fixing nodules and roots of alder.     

Interactions of DNA with a new electron-deficient tentacle porphyrin: meso-Tetrakis[2,3,5,6-tetrafluoro-4-(2-trimethylammoniumethylamine)phenyl]porphyrin

A new electron-deficient tentacle porphyrin meso-tetrakis[2,3,5,6-tetrafluoro-4-(2-trimethylammoniumethylamine)phenyl]porphyrin (TθF₄TAP) has been synthesized. The binding interactions of TθF₄TAP with DNA polymers were studied for comparison to those of an electron-deficient tentacle porphyrin and an electron-rich tentacle porphyrin; these previously studied porphyrins bind to DNA primarily by intercalative and outside-binding modes, respectively. The three tentacle porphyrins have similar size and shape. The basicity of TθF₄TAP indicated that it has electronic characteristics similar to those of the intercalating electron-deficient tentacle porphyrin. However, TθF₄TAP binds to calf thymus DNA, [poly(dA-dT)]₂, and [poly(dG-dC)]₂ in a self-stacking, outside-binding manner under all conditions. Evidence for this binding mode included a significant hypochromicity of the Soret band, a conservative induced CD spectrum, and the absence of an increase in DNA solution viscosity. As found previously for the electron-rich porphyrin, the results suggest that combinations of closely related self-stacked forms coexist. The mix of forms depended on the DNA and the solution conditions. There are probably differences in the detailed features of the self-stacking adducts for the two types of tentacle porphyrins, especially at high R (ratio of porphyrin to DNA). At low R values, the induced CD signal of TθF₄TAP/CT DNA resembled that of TθF₄TAP/[poly(dA-dT)]₂, suggesting that TθF₄TAP binds preferentially at AT regions. Competitive binding experiments gave evidence that TθF₄TAP binds preferentially to [poly(dA-dT)]₂ over [poly(dG-dC)]₂. Thus, despite the long, positively charged, flexible substituents on the porphyrin, the binding of TθF₄TAP is significantly affected by base-pair composition. Similar characteristics were found previously for the electron-rich tentacle porphyrin. Thus, significant changes in electron richness have relatively minor effects on this outside binding selectivity for AT regions. TθF₄TAP is the first porphyrin with electron deficiency and shape similar to intercalating porphyrins that does not appear to intercalate. All porphyrins reported to intercalate have had pyridinium substituents. Thus, the electronic distribution in the porphyrin ring, not just the overall electron richness, may play a role in facilitating intercalation. © 1997 John Wiley & Sons, Inc. Biopoly 42: 203–217, 1997     

CHLOROGENIC ACID ACCUMULATION AND WOUND HEALING IN SWEET POTATO ROOTS

Mc Clure , T. T. (Plant Pest Control Division, ARS, USDA, Washington, D. C.) Chlorogenic acid accumulation and wound healing in sweet potato roots . Amer. Jour. Bot. 47(4) : 277—280. Illus. 1960.–Chlorogenic acid accumulation in cells adjacent to a wound occurs before suberization and wound-periderm formation. Suberization during wound healing was highly correlated with chlorogenic acid accumulation and with wound-periderm formation. The possible role of chlorogenic acid as a source of chemical units for suberization is suggested. Histochemical tests indicate that suberization during wound healing may be a form of lignification. Over 5 times as much lignin was found by chemical analysis in the tissues of healed surfaces as in controls.     

Sensitization of rhabdo-, lenti-, and spumaviruses to human serum by galactosyl(alpha1-3)galactosylation.

Vesicular stomatitis virus, human immunodeficiency virus type 2, and human foamy virus, which were produced by cell lines expressing galactosyl(alpha1-3)galactosyl (alphaGal) sugars, were found to be less stable in human serum than those from alphaGal-negative cells, indicating that galactosyl(alpha1-3)galactosylation sensitizes these viruses as well as mammalian type C oncoviruses (Rother et al., J. Exp. Med. 182:1345-1355, 1995; Takeuchi et al., Nature (London) 379:85-88, 1996) to complement killing via natural anti-alphaGal antibodies. Thus, virus killing mediated by anti-alphaGal antibodies may play a role as a barrier to animal-to-human infection of various enveloped viruses. Virus vectors for human in vivo gene therapy based on the viruses mentioned above should be produced from alphaGal-negative cells.     

Effects of UV-B on flavonoids, ferulic acid, growth and photosynthesis in barley primary leaves

Barley (Hordeum vulgare L.) was grown with UV-B (280–320 nm) at levels simulating 25 nr 5% ozone depletion on the date of the summer solstice al 40°N latitude, with UV-A (320–400 nm), or with no supplemental irradiation. In plant growth chambers providing 300 μmol m^?2 s^?1 photosynthetically active radiation (PAR). UV-B-grown leaves elongated more slowly than controls but reached the same final length 1 day later. Leal specific fresh weight (mass leaf area^?1) was significantly increased by UV-B after the 7th day of growth. IV-B did not significantly affect leaf area, fresh weight, dry weight, total chlorophylls, total carotenoids or photosynthetic quantum efficiency. CO₂ assimilation was decreased by UV-B only at internal CO₂ levels above 250 μl l^?1. By the 8th day of growth, UV-B increased flavonoid (saponarin and lutonarin) accumulation in both the lower epidermis and the mesophyll: about 40% of the saponarin and 20% of the lutonarin were in the lower epidermis under all experimental conditions. Glasshouse conditions proved too variable for reproducible determination of growth and photosynthesis but were reliable for determining developmental changes in flavonoid (saponarin and lutonarin) accumulation and provided up to 800 μmol m^?2 s^?1 PAR. In the glasshouse UV-B-grown leaves had more flavonoids than controls al all stages from 5 to 30 days after planting: ca 509 more saponarin and 100% more lutonarin. Levels of soluble (vacuolar) ferulic acid esters were similar under all conditions on day 5. and on day 20 or later, but were significantly higher in UV-B-grown plants on days 10 and 15. UV-B decreased insoluble (cell-wall-bound) ferulic acid esters on a whole leaf basis but significantly increased this fraction in the lower epidermis. UV-A had no significant effects on growth, photosynthesis or ferulic acid, but it slightly increased flavonoid accumulation. The results are discussed in terms of secondary phenolics as a tissue-specific, developmentally regulated adaptive response to UV-B.     

Inhibition by styrylpyridines of purified rat and bovine brain choline acetyltransferase

Nine styrylpyridine analogs were tested as inhibitors of choline acetyltransferase which had been highly purified from rat cerebrum and bovine caudate nuclei. In general, concentrations required to achieve 50% inhibiion (I₅₀ values) were in the micromolar range. For some analogs, I₅₀ values were similar to those obtained previously by other investigators who used less purified enzyme preparations. With certain analogs, however, the measured values of I₅₀ changed as the transferase became more purified, which may indicate the presence in the extract of other molecules which can interact with the enzyme. The methods used in purification of the enzyme suggest that the molecule which modifies the activity of CAT is probably a protein. The mode of inhibition by naphthylvinylpyridinium was found to be uncompetitive with respect to both choline and acetyl coenzyme A for both the rat and bovine transferases.     

C-glycosylflavone accumulation in Sandoz 6706-treated barley seedlings is a photocontrolled response

Sandoz 6706 pretreatment of white light grown barley seedlings causes a 60% increase in saponarin (6-C-glucosyl-7-O-glucosylapigenin) but a 300% increase in lutonarin (3′-hydroxysaponarin). Norflurazon has little effect on saponarin levels but is almost as effective as Sandoz 6706 in enhancing lutonarin net synthesis. Barley roots contain saponarin and lutonarin only after herbicide treatment. Mung bean seedlings respond to Sandoz 6706 by accumulating higher levels of rutin and delphinidin 3-glucoside. The results are discussed in relation to the site of action of the herbicides, the High Energy photoresponse, and control of flavonoid 3′-hydroxylation.