生姜与食盐协同对食品防腐作用的基础研究

探讨生姜以及生姜与食盐协同对空中落下杂菌和引起食品发霉腐烂的主要真菌的抗菌作用及真菌的抗菌作用及其对黄瓜的防腐效果。结果表明,（１）１０％生姜对空中杂菌和供试的纯培养真菌仅有较弱的抗菌作用,食盐对上述微生物发挥抗菌作用也需要相当的浓度,但生姜与低浓度食盐一组合后,对上述微生物有较强的协同抗菌活性;（２）在已有协同抗菌活性的“食盐加醋酸”、“食盐加乳酸”、“食盐和乙醇”中再分别加入生姜,能进一步增加     

Use of carboethoxysulfenyl chloride for disulfide bond formation

The use of carboethoxysulfenyl chloride for disulfide bond formation and concomitant cyclization of five peptides was investigated. Even though cyclic peptides were obtained very rapidly and in good yields when cyclization was performed in aqueous media at different pHs (4 to 7), the final crude peptides were found to contain closely related impurities which, in the case of somatostatin and pressinoic acid, were not generated by air oxidation. This observation may limit the use of carboethoxysulfenyl chloride to those cases where other methods of disulfide bond formation prove inadequate.     

Anion Requirements for Gastric Acid Secretion

The rate of hydrochloric acid production by isolated, bullfrog gastric mucosae depends critically on the supply of chloride ion to the serosal surface. Secretion of acid is negligible if chloride is completely replaced by glucuronate and gluconate ion. The experimental evidence indicates that the rate of acid secretion may be regarded as a reaction velocity, depending on chloride concentration in a manner closely resembling Michaelis-Menten kinetics. Bromide and iodide ions substitute, in varying degree, for chloride as substrate. A familiar inhibitor of gastric acid production, thiocyanate ion, appears to act by competition with chloride in a reaction leading to the formation of acid. This reaction is included in a hypothetical reaction cycle, generalized from the redox model for gastric acid production. Under certain conditions, the model predicts a dependence of secretion rate on chloride supply of the Michaelis-Menten type, as was observed.     

Studies in pteridophytes XVIII. Use of Salvinia auriculata aublet-an obnoxious weed-in paper industry

Clarias batrachus, an air breathing fish, when exposed to the mercuric chloride, shows enhanced activity of alkaline phosphatase in its dendritic organs. However, an inhibiting effect has been observed on the activity of acid phosphatase.     

Characterization of a rice gene showing organ-specific expression in response to salt stress and drought.

Protein changes induced by salinity stress were investigated in the roots of the salt-sensitive rice cultivar Taichung native 1. We found eight proteins to be induced and obtained partial sequences of one with a molecular mass of 15 kilodaltons and an isoelectric point of 5.5. Using an oligonucleotide probe based on this information, a cDNA clone, salT, was selected and found to contain an open reading frame coding for a protein of 145 amino acid residues. salT mRNA accumulates very rapidly in sheaths and roots from mature plants and seedlings upon treatment with Murashige and Skoog salts (1%), air drying, abscisic acid (20 microM), polyethylene glycol (5%), sodium chloride (1%), and potassium chloride (1%). Generally, no induction was seen in the leaf lamina even when the stress should affect all parts of the plant uniformly. The organ-specific response of salT is correlatable with the pattern of Na+ accumulation during salt stress.     

Bacterial degradation of vinyl chloride

Summary Mycobacterium L1 can grow on vinyl chloride as sole carbon and energy source. Application of this bacterium to remove vinyl chloride from waste gases is proposed. From air containing 1% vinyl chloride 93% of the vinyl chloride was removed by passing the air through a fermentor containing a growing population ofMycobacterium L1.     

Sulfhydryl oxidation of reduced insulin in dilute solution

The reduction of insulin by tri-n-butylphosphine followed by air oxidation in dilute solution at pH 9.1 yields A- and B-chain disulfides. A(S-S)2 and B(S-S) have been purified on SP-Sephadex C-25 using a linear gradient of sodium chloride from 0.1 to 0.45 M in 0.5 M acetic acid containing 7 M urea. The overall yield of A(S-S)2 was 70%; and B(S-S), 60%. The A(S-S)2 and B(S-S) had the expected amino acid composition and N-terminal amino acid. The kinetics of reduction and reoxidation of insulin disulfide bonds are discussed.     

Synthesis and Application of Bifunctional Porous Polymers Bearing Chloride and Sulfonic Acid as Cellulase-Mimetic Solid Acids for Cellulose Hydrolysis

A two-step strategy was demonstrated to synthesize porous polymeric solid acids with bifunctionality (chloride and sulfonic acid) to mimic cellulase for hydrolyzing cellulose. The solid acids were synthesized from aromatic monomers bearing chloride through Friedel-Crafts polymerization and then sulfonated with fuming sulfuric acid to introduce sulfonic acid. The chloride and sulfonic acid were expected to function as the cellulose-binding group (CBG) and the cellulose-hydrolytic group (CHG), respectively. It was found that the synthesized cellulase-mimetic solid acids were more effective in hydrolyzing microcrystalline cellulose (Avicel) than non-cellulase-mimetic solid acid (Amberlyst 15) and sulfuric acid at the same acid loading. Ball-milled Avicel could be hydrolyzed by up to 84.9 % by the cellulase-mimetic solid acids. The performance of the solid acids was supposedly attributed to the synergetic roles of the CBG and the CHG and the porous structure of the synthesized solid acids.     

A Method for Injecting Insect Tracheae Permanently

By the use of an alcohol insoluble dye (trypan blue), acetic acid, and a detergent (“Santomerse No. 3”), a resulting dye solution is obtained which will completely penetrate the tracheal system of an insect. The dye is injected by the use of a vacuum and by the pressure produced when the air is allowed to re-enter the dye vessel. The dye itself is permanently fixed in the tracheae by means of a fixing solution containing alcohol, acetic acid and barium chloride as its components. The material must be properly preserved after staining. It may be stored indefinitely in 70% alcohol, xylol, cedar oil or clove oil, depending on whether the material is to be used for sectioning or for whole mounts. Injected material may be sectioned in either celloidin or paraffin, or may be cleared and mounted in toto.     

Interactions of cytochrome c and [14C]-carboxymethylated cytochrome c with monolayers of phosphatidylcholine, phosphatidic acid and cardiolipin

1. The interactions between cytochrome c (native and [(14)C]carboxymethylated) and monolayers of phosphatidylcholine, phosphatidic acid and cardiolipin at the air/water interface was investigated by measurements of surface radioactivity, pressure and potential. 2. On a subphase of 10mm-or m-sodium chloride, penetration of cytochrome c into egg phosphatidylcholine monolayers, as measured by an increase of surface pressure, and the number of molecules penetrating, as judged by surface radioactivity, were inversely proportional to the initial pressure of the monolayer and became zero at 20dynes/cm. The constant of proportionality was increased when the cytochrome c was carboxymethylated or decreased when the phospholipid was hydrogenated, but the cut-off point remained at 20dynes/cm. 3. Penetrated cytochrome c could be removed almost entirely by compression of the phosphatidylcholine monolayer above 20dynes/cm. 4. With phosphatidic acid and cardiolipin monolayers on 10mm-sodium chloride the binding of cytochrome c was much stronger and cytochrome c penetrated into films nearing the collapse pressure (>40dynes/cm.). The penetration was partly electrostatically facilitated, since it was decreased by carrying out the reaction on a subphase of m-sodium chloride, and the relationship between the surface pressure increment and the initial film pressure moved nearer to that observed with phosphatidylcholine. 5. Surface radioactivity determinations showed that [(14)C]carboxymethylated cytochrome c was still adsorbed on phosphatidic acid and cardiolipin monolayers after the cessation of penetration. This adsorption was primarily electrostatic in nature because it could be prevented and substantially reversed by adding m-sodium chloride to the subphase and there was no similar adsorption on phosphatidylcholine films. 6. The penetration into and adsorption on the three phospholipid monolayers was examined as a function of the pH of the subphase and compared with the state of ionization of both the phospholipid and the protein, and the area occupied by the latter at an air/water interface. 7. It is concluded that the binding of cytochrome c to phospholipids can only be partially understood by a consideration of the ionic interaction between the components and that subtle conformational changes in the protein must affect the magnitude and stability of the complex. 8. If cytochrome c is associated with a phospholipid in mitochondria then cardiolipin would fulfil the characteristics of the binding most adequately.     

Effect of foliar application of phosphorus on RNA and DNA under salt-stress in peanut plants (Arachis hypogaea L.)

Summary Peanut (Arachis hypogaea L., var. TMV-2) plants were raised in sand cultures salinized with sodium chloride at 0.4% on air dry weight basis. Phosphate was sprayed to the drip point, once daily for five days from 20th to 25th day and from 30th to 35th day. Shoot apices and mature leaves were harvested for nucleic acid analyses at 30th and 40th day, receiving one and two sets of sprays respectively. Salinity decreased RNA and DNA levels which were partially restored by foliar application of phosphate.     

An effective acid catalyst for biodiesel production from impure raw feedstocks

Biodiesel consists of fatty acids short chain alkyl esters produced through transesterification and esterification of fats and oils. Production of biodiesel is strongly affected by the purity of raw lipids, and catalysts play important role in these processes. Although direct utilization of impure feedstocks is more economical, their use necessitates development of effective catalysts to overcome hindering influences of impurities. In this study, sulfuryl chloride, thionyl chloride, acetyl chloride, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, dimethylsulfate and sulfuric acid were investigated as catalysts for the production of biodiesel because acids have higher tolerance to water and free fatty acids in oils and can simultaneously catalyze both the esterification and transesterification reactions. Sulfuryl chloride was found to be an effective catalyst for production of biodiesel from soybean oil, its waste oil and microalgal lipids.     

Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions

Detailed studies were carried out on the effects of nitrogen source, phosphate, sodium chloride, growth factors, precursors, CO2, temperature, initial pH, and inoculum size on biomass and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum. The EPA content of total fatty acids increased with increasing concentrations of nitrate and urea. Sodium chloride was not required for growth or EPA production. While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation. Maximum EPA production occurred when the air gassing supply was supplemented with 1% CO2. Optimum culture temperature and initial pH for EPA production were 21.5 to 23 degrees C and 7.6, respectively. EPA yields of up to 133 mg/liter of culture were observed. EPA constituted up to 30 to 40% of total fatty acids.     

Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions.

Detailed studies were carried out on the effects of nitrogen source, phosphate, sodium chloride, growth factors, precursors, CO2, temperature, initial pH, and inoculum size on biomass and eicosapentaenoic acid (EPA) production by Phaeodactylum tricornutum. The EPA content of total fatty acids increased with increasing concentrations of nitrate and urea. Sodium chloride was not required for growth or EPA production. While vitamins B1 and B12 did not affect growth significantly, EPA yield was increased by 65% by B12 supplementation. Maximum EPA production occurred when the air gassing supply was supplemented with 1% CO2. Optimum culture temperature and initial pH for EPA production were 21.5 to 23 degrees C and 7.6, respectively. EPA yields of up to 133 mg/liter of culture were observed. EPA constituted up to 30 to 40% of total fatty acids.     

The reduction of hydroxamic acids with titanium(III) chloride: a tool for the characterization of siderophores

Hydroxamic acid siderophores were observed to be inactivated by exposure to titanium(III) chloride. To study the reaction, a series of eight model hydroxamic acids were prepared and reacted with titanium(III) chloride. The products were shown by ir and NMR comparisons with authentic compounds to be the corresponding amides. The reduction was found to require 2 mol of titanium(III) per mol of hydroxamic acid.     

Coordinated regulation of gastric chloride secretion with both acid and alkali secretion

Gastric secretion of hydrochloric acid requires protons and chloride, yet the mechanisms and regulation of gastric chloride secretion remain unclear. We developed an in vivo technique to simultaneously measure acid/base and chloride secretion into the gastric lumen of anesthetized rats. The cannulated stomach lumen was perfused with weakly pH-buffered chloride-free solution containing a chloride-sensitive fluorophore [5 microM N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE)]. Gastric acid and chloride secretion was detected in gastric effluents by 1) flow-through pH electrode and 2) MQAE fluorescence. Gastric effluent was also collected at 1-min intervals for independent determination of chloride amount by chloridometer. In all conditions, both optical and chemical determinations of chloride report similar amounts of secreted chloride. During luminal perfusion with pH 5 solution, net acid and chloride secretion into the lumen was observed. Pentagastrin stimulated both secretions. In contrast, proton pump inhibition (omeprazole) caused alkalinization of the gastric effluent, but chloride secretion was not diminished. During luminal pH 3 perfusion, net alkali secretion was observed, and chloride secretion at luminal pH 3 was greater than pH 5. When tissue is pretreated with omeprazole at luminal pH 3, the addition of prostaglandin E2 synchronously stimulates both alkali and chloride secretion. Results suggest that both acid and alkali secretions are separately coupled with chloride secretion.     

Gas-liquid chromatographic analysis of the monosaccharide composition of acid glycosaminoglycans (mucopolysaccharides) derived from animal tissues

Quantitative, gas-liquid chromatography was investigated for analysis of the monosaccharide composition of acid mucopolysaccharides from animal tissues. The method entailed the analysis of the trimethylsillyl (Me3Si) derivatives of methyl glycosides on two liquid phases. Good resolution of monosaccharides was achieved by use of columns of SE-30 and Apiezon-M. The procedure was tested with chondroitin 4-sulfate, and the results were slightly different from those of Mathews et al. When the analysis is performed according to this method, important points are: (1) absolutely anhydrous, methanolic hydrogen chloride is necessary, to ensure detection of hexosamines and sialic acid; and (2) high moisture in the air obstructs high recovery of methyl glycosides and their Me3Si derivatives, except in the case of neutral sugars.     

Solid phase synthesis of porcine LH-releasing hormone with hydrogen chloride in formic acid as the deblocking reagent.

The decapeptide corresponding to the amino acid sequence of porcine luteinizing hormone-releasing hormone (LH-RH) which involves 1 mol of tryptophan was synthesized via solid phase synthesis with two different deblocking procedures which used hydrogen chloride in formic acid and hydrogen chloride in acetic acid containing 1% 2-mercaptoethanol. After some fundamental studies on the former reagent with respect to deblocking efficiency toward the Boc group, 0.5 M hydrogen chloride (a 10-fold molar excess with respect to the N-terminal Boc group) in formic acid was used in the present synthesis. The two synthetic products exhibited the same chemical and biological properties as an authentic LH-RH. Hydrogen chloride in formic acid has proved effective without a scavenger although loss of peptide from the resin occurred to a somewhat greater extent than that with hydrogen chloride in acetic acid. A derivative of the synthetic LH-RH formylated at the indole nitrogen had a greatly diminished biological activity, indicating that the intact indole side chain is essential for the activity.     

Fruit Softening III. Requirement for Oxygen and pH Effects

The regulation of the softening of the cortical tissue of appleand pear fruits was investigated. Transfer of pear fruits toa nitrogen atmosphere arrested fruit softening and pectin degradationwithin 24 h. Anoxia also inhibited softening of discs cut fromripening pear fruits within 6 h, but polygalacturonase (EC 3.2.1.15 [EC] )activity was not substantially impaired and pectin degradationcontinued as in air. Discs of apple tissue softened more slowlythan pear but apple discs were firmer after 24 h under anoxiathan in air. Softening of pear tissue could be reversed by infiltration withpH 8.0 buffer or calcium chloride solution up to day 3 of ripeningat 18 °C. Buffer at pH 3.0 had no effect on fruit firmnessbut eliminated the effect of calcium in a combined treatment.A mixture of buffer at pH 80 and calcium chloride increasedfirmness more than either treatment alone. A similar reversalof softening could be achieved with apple fruit tissue afterstorage for 28 weeks.     

Morphological and morphometrical changes in chloride cells of the gills of Pimephales promelas after chronic exposure to acid water

Summary Fathead minnows, Pimephales promelas, were exposed for 129 days to Lake Superior water acidified with sulfuric acid by means of a flow-through toxicant injection system. The effects of chronic acid stress (pH 6.5, 6.0, 5.5, 5.0) on gill histology were examined. Most of the histological effects were seen at pH 5.5 and 5.0 and were confined primarily to changes in numbers, distribution, and morphology of chloride cells. At low pH levels there tend to be more chloride cells in the gill epithelium and an increased percentage of these cells in the secondary lamellae. In contrast to normal chloride cells, chloride cells from fish exposed to low pH frequently had apical pits while some had bulbous apical evaginations. The occurrence of structural changes in chloride cells during exposure to acid water suggests that chloride cells may be involved in acclimation to acid stress.