Changes in beta-1,3-Glucan Synthase Activity in Developing Lima Bean Plants.

A plasma membrane-enriched fraction was isolated from various tissues of developing lima bean seedlings, Phaseolus lunatus var Cangreen, to study beta-1,3-glucan synthase activity changes. All tissues contained an active beta-glucan synthase, including the cotyledons that will be senescent in mature lima bean plants. Young primary leaves exhibited a very active beta-glucan synthase; but this activity dropped markedly, about fivefold, as the leaves gained weight and became photosynthetic.

Fructose 2,6-bisphosphate inhibition of phosphoglucomutase.

Fructose 2,6-bisphosphate inhibits phosphoglucomutase noncompetitively with respect to the cofactor glucose 1,6-bisphosphate. Previous studies from our laboratory had shown that phosphoglucomutase was activated by fructose 2,6-bisphosphate in the absence of added glucose 1,6-bisphosphate. The fructose 2,6-bisphosphate activation previously reported was due to the presence of glucose 1,6-bisphosphate in the commercial preparation of fructose 2,6-bisphosphate.

Changes in the C-Labeled Cell Wall Components with Chase Time after Incorporation of UDP[C]Glucose by Intact Cotton Fibers.

Intact, in vitro-grown cotton fibers will incorporate [(14)C]glucose from externally supplied UDP[(14)C]glucose into a variety of cell wall components including cellulose; this labeled fraction will continue to increase up to 4 hours chase time. In the fraction soluble in hot water there was no significant change in total label; however, the largest fraction after the 30 minute pulse with UDP[(14)C]glucose was chloroform-methanol soluble (70%) and showed a significant decrease with chase. The lipids that make up about 85% of this fraction were identified by TLC as steryl glucosides, acylated steryl glucosides, and glucosyl-phosphoryl-polyprenol.

Levels of Free and Conjugated Abscisic Acid in Developing Floral Organs of the Navel Orange (Citrus sinensi [L.] Osbeck cv Washington).

The levels of abscisic acid (ABA) and alkaline-hydrolyzable ABA-conjugate (putatively identified as the glucosyl ester, abscisyl-beta-d-glucopyranoside) were determined by enzyme immunoassay in the organs of developing navel orange (Citrus sinensis [L.] Osbeck cv Washington) flowers. Although both compounds were detected in every tissue, developmentally related differences between organs in the total and relative contents were observed.

The Occurrence of Abscisic Acid and Abscisyl-beta-d-Glucopyranoside in Developing and Mature Citrus Fruit as Determined by Enzyme Immunoassay.

The contents of (+)-cis-abscisic acid (ABA) and alkaline-hydrolyzable ABA-conjugate(s) were analyzed by means of enzyme immunoassay in partially purified extracts of developing and mature sweet orange fruit (Citrus sinensis [L.] Osbeck cv Washington navel). A relatively small increase in ABA was observed in the fruit exocarp during the natural color transition from green to orange.

Incorporation of UDPGlucose into Cell Wall Glucans and Lipids by Intact Cotton Fibers.

The [(14)C] moiety from [(3)H]UDP[(14)C]glucose was incorporated by intact cotton fibers into hot water soluble, acetic-nitric reagent soluble and insoluble components, and chloroform-methanol soluble lipids; the [(3)H] UDP moiety was not incorporated. The (3)H-label can be exchanged rapidly with unlabeled substrate in a chase experiment. The cell wall apparent free space of cotton fibers was in the order of 30 picomoles per milligram of dry fibers; 25 picomoles per milligram easily exchanged and about 5 picomoles per milligram more tightly adsorbed.

In vitro activation of phosphoglucomutase by fructose 2,6-bisphosphate.

The hexose bisphosphate activation of phosphoglucomutase was investigated with both plant (pea and mung bean) and animal (rabbit muscle) sources of the enzyme. Plant phosphoglucomutase was purified about 50-fold from seeds, and to a lesser extent, from seedlings of Pisum sativum L. cv Grenadier and seedlings of Phaseolus aureus.

Ventilatory response to hypercapnia during sleep and wakefulness in cats.

Eucapnic breathing and ventilatory responses to hypercapnia were studied in seven cats during sleep and wakefulness. No significant differences were found in minute ventilation (VE), alveolar ventilation (VA), or alveolar PCO2 (PACO2) between wakefulness (W) and non-rapid-eye-movement (NREM) sleep, but VA and VE were less during rapid-eye-movement (REM) sleep than W, and PACO2 declined during REM compared with NREM. To test the hypercapnic response, cats were required to rebreathe from a bag containing 6% CO2 and 94% O2 (to eliminate the hypoxic response).

Effects of Boron Deficiency on Rubidium Uptake and Photosynthesis in the Diatom Cylindrotheca fusiformis.

Culturing the diatom Cylindrotheca fusiformis under boron-deficient conditions leads to changes in (86)Rb uptake and photosynthesis prior to any effect on the rate of cell division. The influx rate of (86)Rb into boron-deficient cells was 79% of the control rate after 5 to 5.5 hours culture.

Pyrimidine Pathway in Boron-deficient Cotton Fiber.

Cotton ovules cultured in an insufficiency of boron (10 micromolar), showed inhibition of fiber growth by the ninth day in culture. Averaging data from eight to eleven days of culture under these conditions, total incorporation of [6-(14)C]orotic acid into fiber was inhibited by 59%. Inhibition was evident in all radioactively labeled pools, indicating that the effect may be at the membrane transport level or at an early stage of orotic acid metabolism.

Effect of Boron on the Incorporation of Glucose from UDP-Glucose into Cotton Fibers Grown in Vitro.

Boron is required for fiber growth and development in cotton ovules cultured in vitro. Incorporation of [(14)C]glucose by such fiber from supplied UDP-[(14)C]glucose into the hot alkali-insoluble fraction is rapid and linear for about 30 minutes. Incorporation of [(14)C]glucose from such substrate by fibers grown in boron-deficient ovule cultures is much less than in the case with fibers from ovules cultured with boron in the medium.

Interaction of boron with components of nucleic Acid metabolism in cotton ovules cultured in vitro.

Cotton (Gossypium hirsutum L.) ovules grown in a defined nutrient medium undergo normal morphogenesis, including fiber production. In identical medium lacking boron, ovules callus and accumulate brown substances.

Boron Deficiency in Unfertilized Cotton (Gossypium hirsutum) Ovules Grown in Vitro.

Boron deficiency and phytohormone interactions have been studied in unfertilized cotton (Gossypium hirsutum) ovules grown in vitro. Such ovules required exogenous indoleacetic acid and/or gibberellic acid for fiber elongation. Boron also was required for maintenance of fiber elongation and normal morphogenesis throughout 14 days of culture.

Observations on the mechanism of copper damage in chlorella.

Addition of excess copper to nongrowing cells of a normal, green Chlorella caused a reduction in total pigments and a blue shift of chlorophyll absorption, concurrent with the inhibition of photosynthesis. Chlorophylless yellow and white mutant strains of the same alga showed a rise in nonspecific absorption (i.e.

Inhibitory effect of peroxyacetyl nitrate on cyclic photophosphorylation by chloroplasts from black valentine bean leaves.

The inhibitory effect of peroxyacetyl nitrate on the cyclic photophosphorylation of chloroplasts isolated from Black Valentine variety bean leaves (Phaseolis vulgaris L.) has been studied. Peroxyacetyl nitrate caused inhibition to photophosphorylation, in either the dark or the light, by affecting the chloroplast.

CO(2) Metabolism in Corn Roots. I. Kinetics of Carboxylation and Decarboxylation.

The kinetics of (14)CO(2) carboxylation and decarboxylation in corn root tips were determined to ascertain the sequence of product formation and subsequent utilization, and to obtain further evidence to predict the enzymes mediating the carboxylation and decarboxylations. The carboxylation data indicated that the first product was oxaloacetate followed by malate and aspartate. Malate was the first stable product which could be detected.