Effect of gibberellic acid on the uptake and loss of inorganic phosphate from sweet potato slices

Uptake and loss of irorganic phosphate was determined in sweet potato slices ‘aged’ in the presence or absence of gibberellic acid. Concentrations of uptake medium were varied from 0.1 to 1.2 mM. Slices, aged in gibberellic acid, took up considerably less phosphate, at all concentrations than control, whereas efflux from GA₃ treated discs was greater than control. Whether treated or untreated, kinetics proved to be biphasic hyperbolas. The results suggested an alteration in membrane permeability induced by gibberellic acid.     

Effects of neutralizing agents on lactic acid production by Rhizopus oryzae using sweet potato starch

A neutralizing agent is usually employed to counteract the pH reduction during lactic acid fermentation by Rhizopus oryzae. Calcium carbonate (CaCO₃) is used as such a pH controlling agent. The low solubility of CaCO₃ in the fermentation broth could however lead to low efficiency in pH control and cause problems in the subsequent purification process. Therefore, an alternative agent in place of CaCO₃ was examined in this study. The effect of four different neutralizing agents, including CaCO₃, sodium hydroxide (NaOH), ammoniacal solution and sodium bicarbonate (NaHCO₃) on lactic acid production and the morphology of the pellets were investigated. Results indicated that CaCO₃ was still the preferred choice, because of the pellet morphology and the highest lactic acid concentration (43.3 g/L) obtained in the batch using 60 g/L of sweet potato starch as feedstock. It is noteworthy that the lactic acid purification is relatively easier when using NaHCO₃ instead of CaCO₃, due to the higher solubility of sodium lactate than calcium lactate. Therefore, even the batch with CaCO₃ had a slightly higher productivity (1.23 g/L/h) than the batch with NaHCO₃ (1.14 g/L/h), NaHCO₃ might be the first choice for process designers whenever recovery is vital.     

Regulation of pentosan biosynthesis in barley aleurone tissue by gibberellic acid

Summary Treatment of isolated barley aleurone layers with gibberellic acid (GA₃) resulted in a progressive inhibition of cell-wall synthesis after a 4-h lag period. The incorporation of both [¹⁴C]arabinose and [¹⁴C]glucose into the cell wall was inhibited by GA₃, but analysis of the labelled sugars in the polymerized product showed that the process most affected by the hormone treatment was pentosan biosynthesis. Labelling kinetics and pulse-chase analysis indicated that the pentosans were synthesized in the cytoplasm and subsequently transferred to the cell wall; GA₃ did not significantly affect the latter step. The GA₃-inhibited labelling of the cell-wall pentosans cannot be explained on the basis of an effect on uptake of radioactive cell-wall precursor, expansion of the free pentose pool, or degradation of newly-formed pentosan. GA₃ inhibited the activity of a membrane-bound arabinosyl transferase present in the aleurone layers. This inhibition may explain the inhibition of cell-wall pentosan synthesis by GA₃.Abbreviations GA gibberellin - GA₃ gibberellic acid     

Supporting material affects the growth and development of in vitro sweet potato plantlets cultured photoautotrophically

Summary A comparative study was conducted to optimize the vegetative growth of sweet potato (Ipomoea batatas L. (Lam), cv. Beniazuma) plantlets cultured in vitro in five different types of supporting materials: agar matrix (a seaweed derivative; Kanto Chemical Co. Inc., Tokyo), gellan gum (a Pseudomonas derivative; Kanto Chemical Co. Inc., Tokyo), vermiculite (a kind of hydrous silicates), a mixture of vermiculite and cellulose fiber (Florialite; Nisshinbo Industries, Inc., Tokyo) and cellulose plug (Sorbarod; Baumgartner Rapiers SA., Switzerland). Single nodal cuttings were cultured photoautotrophically (without any sugar in the medium and with enriched CO₂ and high photosynthetic photon flux) for 21 d on MS basal medium. Plantlets exhibited the greatest growth when Florialite was used as supporting material. The leaf and root fresh and dry mass were 2.4× and 2.9×, and 2.2× and 2.8× greater, respectively, than those of the plantlets grown in the agar matrix (control). Plantlets cultured in Sorbarod supporting material exhibited the second greatest fresh and dry mass of leaves and roots followed by vermiculite and gellan gum supporting material. The most interesting feature was the development of a large number of fine lateral roots from the main adventitious root in the Florialite treatment. Among the treatments, the highest net photosynthetic rate was evident in the Florialite grown plantlets. The percent porosity of the supporting materials was highest in Sorbarod followed by Florialite and vermiculite. Plantlets transplanted from the Florialite supporting material exhibited the highest acclimatization percentage followed by that of the Sorbarod treatment.     

Cyclization and hydroxylation stereochemistry in the biosynthesis of gibberellic acid

In Gibberella fujikuroi cultures, ent-[3β-³H,17-¹⁴C]kaurene is converted to gibberellic acid with retention of the tritium label at the 3α-position. This evidence for the stereochemistry of 3-hydroxylation also permits the stereochemistry of the ‘proton-initiated’ cyclization step in gibberellic acid biosynthesis to be deduced.     

Enhancement of norepinephrine biosynthesis by ascorbic acid in cultured bovine chromaffin cells

Ascorbic acid donates electrons to dopamine beta-monooxygenase during the hydroxylation of dopamine to norepinephrine in vitro. However, the possible role of ascorbic acid in norepinephrine biosynthesis in vivo has not been defined. We therefore investigated the effect of newly accumulated ascorbic acid on catecholamine biosynthesis in cultured bovine adrenal chromaffin cells. Cells supplemented for 3 h with ascorbic acid accumulated 9-fold more ascorbic acid than found in control cells. Under these conditions, the cells loaded with ascorbate were found to double the rate of norepinephrine biosynthesis from [14C]tyrosine compared to control. By contrast, the amounts present of [14C] 3,4-dihydroxyphenylalanine and [14C]dopamine synthesized from [14C]tyrosine were unaffected by the preloading of ascorbic acid. Ascorbate preloaded cells incubated with [3H]dopamine also showed a similar increase in the rate of norepinephrine formation, without any change in dopamine transport into the cells. Thus, these data were consistent with ascorbate action at the dopamine beta-monooxygenase step. In order to determine if ascorbate could interact directly with dopamine beta-monooxygenase localized within chromaffin granules, we studied whether isolated chromaffin granules could accumulate ascorbic acid. Ascorbic acid was not transported into chromaffin granules by an uptake or exchange process, despite coincident [3H]dopamine uptake which was Mg-ATP dependent. These data indicate that ascorbic acid does augment norepinephrine biosynthesis in intact chromaffin cells, but by a mechanism that might enhance the rate of dopamine hydroxylation indirectly.     

Alkynyl polysaccharides: synthesis of propargyl potato starch followed by subsequent derivatizations

Potato starch propargyl ethers (PgS) with degrees of substitution (DS) from 0.1 to 2.2 have been prepared by etherification of starch with sodium hydroxide or Li dimsyl in Me(2)SO and propargyl bromide. DS values and substituent distribution were determined after hydrolysis and acetylation by GC-MS. The order of reactivity was 2>6>3, with O-3 substitution being preferably observed in the trisubstituted units. Repeated analysis of the starch derivatives revealed that propargyl residues were lost during storage, a phenomenon that was not fully understood until now. Selected PgS were further functionalized: (a) O- and C-methylated to O-(2-butynyl)-O-methyl starch (BMS), (b) in a Mannich type reaction with diethylamine and formaldehyde to yield O-(4-diethylamino)-2-butinyl starch (DEABiS), (c) in a 1,3-dipolar cycloaddition with benzyl azide ('click-chemistry') to a N-benzyltriazole derivatized starch (BTrS), and (d) with carbon dioxide to O-(3-carboxy)-2-butinyl starch (CBiS). While the yield of carboxylation was only poor, conversion was high or nearly quantitative for reactions a-c. Thus, it is demonstrated that starch propargyl ethers are valuable intermediates for the preparation of functional polysaccharides.     

甘薯淀粉废水发酵生产微生物油脂的研究

研究了废水预处理方式及添加营养因子对产油菌株FR在甘薯淀粉废水中生长、产油及COD去除的影响。发现不经稀释的废水发酵效果优于稀释后的效果,采用淀粉酶液化处理、添加碳氮比、添加Mn2 均能够促进菌株FR生长、产油和COD去除,淀粉酶液化处理后的产油率可达45.3%,淀粉酶和糖化酶先后处理后的COD去除率可达66.3%。Mg2 的加入可以提高生物量。     

Isolation and characterization of exocellular polysaccharides produced by Bifidobacterium longum

When grown anaerobically at pH values above 5.0, on ultrafiltered complex media containing excess lactose, Bifidobacterium longum formed up to 140 mg 1^–1 (glucose equiv.) exopolysaccharides. The highest yield was obtained when the cells were cultivated in a peptone/yeast extract medium with pH controlled by additions of NH₄OH. Whatever the conditions under study, exopolysaccharides represented about 30% of the polysaccharides produced by B. longum after 48 h of culture. Crude pronase-treated exopolysaccharide preparations were adsorbed on ion-exchange chromatographic resin to yield an anionic heteropolysaccharide fraction. Two subfractions with apparent molecular masses of 1.2 MDa and 0.36 MDa respectively were subsequently recovered after gel filtration on Sepharose 4B. In both subfractions, glucose, galactose and small amounts of uronic acids and hexosamines were present in similar molar proportions, suggesting that the excreted polymers may be synthesized from the same base unit and may have a structure resulting from repeating subunits.     

Phosphate transport in potato cuttings: Effect of gibberellic acid and abscisic acid

Apical cuttings of Solanum tuberosum L. cv. Sirtema were used al different stages of development to study long-distance transport of phosphate. The effects of two hormones, gibberellic acid (GA₃) and abscisic acid (ABA), on this process were also investigated. Before tuberization, phosphate (³²P) supplied to a single leaf was transported preferentially in the young and growing parts of the plant: apical bud, young leaves and roots. After tuberization, the tuber became the principal site of phosphate accumulation. GA³ treatment (10⁻⁴ M) of the tuber as well as of the leaves led to reduced transport of ³²P into the tuber. By contrast, treatment of the tuber with ABA (10⁻⁴M) did not change the ³²P distribution within the plant, while foliar spray with ABA greatly increased the transport into the tuber. The opposite effects of the two hormones on phosphate accumulation by tubers are discussed with regard to their opposite effects on the tuberization process.     

Factors affecting gibberellic acid production by Fusarium moniliforme in solid-state cultivation on starch

The production of gibberellic acid (GA₃) by Fusarium moniliforme M-7121 in solid-state culture was evaluated in flask cultures as well as in 3-I horizontal rotary reactors. The highest production rate of GA₃ was with 80% (w/v) maize flour mixed with wheat bran. The optimum initial moisture content was inversely dependent on the ambient relative humidity. The initial water activity range for optimal growth and GA₃ accumulation was about 0.98 to 0.99, which is unusually high for a filamentous fungus. A low O₂ concentration resulted in a much decreased GA₃ yield and the appearance of a yellow to reddish pigmentation in the mycelium. The lag phase was short and rapid growth continued for up to 2 days in the rotary reactor, with a maximum specific growth rate of 0.12 h^–1. The maximum rate of GA₃ production occurred during the subsequent 3 to 10 days of incubation and the final GA₃ concentration reached was 18.7 mg to 19.3 mg/g dry culture. The point of maximum GA₃ accumulation after 10 to 12 days of incubation was usually marked by a sharp increase in pH.The authors are with the Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, 9300 Bioemfontein, Republic of South Africa     

Control of carbohydrase formation by gibberellic acid in barley endosperm

α-Amylase, limit dextrinase and α-glucosidase were induced by gibberellic acid in barley grain from which the embryos had been excised. The responses to different concentrations of gibberellic acid were similar for the three carbohydrases. However α-glucosidase activity increased before the other two enzymes, and a low level of α-glucosidase was found in ungerminated grain. Experiments with cycloheximide and density-labelling in deuterium oxide suggest that the observed increases in activity are the result of de novo protein synthesis. The induction of these enzymes was reduced by pre-incubation in actinomycin D.     

Elucidation of the structure of a possible intermediate in chlorogenic acid biosynthesis in sweet potato root tissue

The structure of a possible intermediate, compound V, in chlorogenicacid biosynthesis in sweet potato root tissue was determinedas ß-1-cinnamoyl-D-glucose. The role of the compoundin chlorogenic acid biosynthesis is also discussed. ¹ This paper constitutes Part 101 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. (Received June 28, 1972; )     

Histones biosynthesis and turnover in epithelial lens cells cultured in vitro.

"Histone synthesis was compared in epithelial lens cells during exponential growth and in the stationary phase brought by contact inhibition. Double labelling experiments with 3H-lysine and 14C-lysine show a net turnover of histone H1 independent of DNA replication. The nucleosome core histones seem to turn over also, but much more slowly than H1".     

Control of root and shoot-bud formation from potato tuber tissue cultured in vitro

Comparative studies on the control of root and shoot-bud formation and plant regeneration have been undertaken in discs (1 × 6 mm in diameter) excised from tubers of potato ( Solanum tuberosum L. cv. Irish Cobbler) cultured in vitro. The results clarified that the optimal culture conditions for shoot-bud formation were quite different from those for root formation and, in conclusion, that (1) shoot-buds were produced when cultured in modified White's medium containing 0.25 M mannitol with 2.3 μ M zeatin and 0.57 μ M indole-3-acetic acid (IAA) at 20°C under relatively high light irradiation, while (2) roots were readily formed when cultured in modified White's medium containing 29 m M sucrose with 4.7 μ M kinetin plus 1.7 μ M IAA at 30°C in darkness.