Formation of a hexagonal lattice structure by an R-form lipopolysaccharide of Klebsiella: relationship between lattice formation and uniform salt forms

Various uniform salt forms of an R-form lipopolysaccharide (LPS) extracted from Klebsiella strain LEN-111 (O3-:K1-) were prepared and their ultrastructure was examined. The LPS, which was extracted by the phenol-water method, freed from contamination with RNA by treatment with RNase, and precipitated by addition of two volumes of 10 mM MgCl2-ethanol, was used as the original preparation for uniform salt forms. The original LPS preparation formed a hexagonal lattice structure with a lattice constant of 14.9 +/- 0.2 nm. The LPS after electrodialysis retained the ability to form a hexagonal lattice structure, although its lattice constant was large (18.7 +/- 0.5 nm) and the lattice structure of the electrodialyzed LPS was labile at pH 8.0 in contrast to that of the original LPS preparation. The magnesium salt form of the LPS formed essentially the same ordered hexagonal lattice structure (lattice constant of 15.0 +/- 0.2 nm) as that of the original LPS preparation. The calcium and ammonium salt forms formed a hexagonal lattice structure, but the lattice constants of the calcium and ammonium salt forms were larger (18.6 +/- 0.6 nm and 19.3 +/- 0.4 nm, respectively) than that of the magnesium salt form. The sodium and potassium salt forms consisted of freely branching ribbon-like structures with an average width of 13 nm and an average thickness of 9 nm. The triethylamine salt form consisted principally of short rods (10 nm X 9-13 nm).     

Ion-specific and general ionic effects on contraction of skinned fast- twitch skeletal muscle from the rabbit

We used single fibers from rabbit psoas muscle, chemically skinned with Triton X-100 nonionic detergent, to determine the salts best suited for adjusting ionic strength of bathing solutions for skinned fibers. As criteria we measured maximal calcium-activated force (Fmax), fiber swelling estimated optically, and protein extraction from single fibers determined by polyacrylamide gel electrophoresis with ultrasensitive silver staining. All things considered, the best uni-univalent salt was potassium methanesulfonate, while a number of uni-divalent potassium salts of phosphocreatine, hexamethylenediamine N,N,N',N'-tetraacetic acid, sulfate, and succinate were equally acceptable. Using these salts, we determined that changes in Fmax correlated best with variations of ionic strength (1/2 sigma ci z2i, where ci is the concentration of ion i, and zi is its valence) rather than ionic equivalents (1/2 sigma ci magnitude of zi). Our data indicate that increased ionic strength per sc decreases Fmax, probably by destabilizing the cross-bridge structure in addition to increasing electrostatic shielding of actomyosin interactions.     

Compressibility,densimetric and calorimetric studies of hydration of carrageenans in the random form

The partial molal volume and adiabatic compressibility were measured, as well as their counterion activity, for sodium and potassium salts of three types of carrageenan (κ-, ι- and λ-components) in aqueous solutions at 25°C. Furthermore, the amount of related unfreezable water was estimated by the differential scanning calorimetry. On the basis of these results, the hydration states of carrageenans in the random form were comparatively discussed in relation to their chemical structure, counterion binding and polymer concentration. The sodium salt of each component showed a larger amount of hydration when compared with the corresponding potassium salt. The amount of hydration estimated from molal volume and compressibility data (in dilute solution) increased in the order of κ < ι < λ, while the amount of unfreezable water (in concentrated solution) decreased in the same order. These characteristics hydration behaviours of carrageenans seemed to be reasonably explained in terms of the effects of the charge density and counterion dissociation of these polyions.     

A new silver staining apparatus and procedure for matrix-assisted laser desorption/ionization-time of flight analysis of proteins after two-dimensional electrophoresis

We report on a new silver stain especially developed for staining large gels (25 cm x 20 cm) from the Hoefer ISO-DALT system for matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of proteins. The staining protocol can be summarized as follows: the gels are sensitised in tetrathionate/potassium acetate solution and washed several times in distilled water. After impregnation with silver nitrate, the silver is reduced in the presence of potassium carbonate, thiosulphate and formaldehyde. The staining procedure is stopped with Tris/acetate after which the gels are rinsed and stored in water before spot picking for MALDI-TOF analysis is performed. This protocol has several advantages over existing ones. The gels are stained in a new apparatus that reduces gel handling to a minimum thus also reducing the contamination with keratins to a minimum. The development times in potassium carbonate are very long (up to 40 min) thus improving batch-to-batch reproducibility. Only the surface of the proteins is stained and the silver can be oxidized, thereafter MALDI-TOF can be performed with protein loads as little as 100 micrograms per gel.     

Biomimetic synthesis silver crystallite by peptide AYSSGAPPMPPF immobilized on PET film in vitro

AG3 (AYSSGAPPMPPF) is an inorganic-binding peptide that specifically and selectively binds to silver demonstrated by phage display library according to the Stone group. In our experiment, synthesized silver-binding peptide AG3 was immobilized on the surface of protonated poly(ethylene terephthalate) (PET) film which was prepared for biomimetic synthesis silver particles in vitro. Silver crystallites formatted on the surface of AG3-PET film showed various shapes and was 1-4 microm in size. In addition to hexagonal and triangular crystallite, a silver crystallite presents a cubical shape that has seldom been reported in the literatures so far. With comparison of the control and silver nitrate salt, the surface energy of the silver particles on AG3-PET film surface XPS analysis suggested that Ag+ was being reduced to Ag0 in the reaction. Moreover, CD spectrum revealed that the secondary structure of AG3 peptide in solution had a little change before and after binding silver.     

Specific ion effects: why the properties of lysozyme in salt solutions follow a Hofmeister series

Protein solubility in aqueous solutions depends in a complicated and not well understood way on pH, salt type, and salt concentration. Why for instance does the use of two different monovalent salts, potassium thiocyanate and potassium chloride, produce such different results? One important and previously neglected source of ion specificity is the ionic dispersion potential that acts between each ion and the protein. This attractive potential is found to be much stronger for SCN(-) than it is for Cl(-). We present model calculations, performed within a modified ion-specific double-layer theory, that demonstrate the large effect of including these ionic dispersion potentials. The results are consistent with experiments performed on hen egg-white lysozymes and on neutral black lipid membranes. The calculated surface pH and net lysozyme charge depend strongly on the choice of anion. We demonstrate that the lysozyme net charge is larger, and the corresponding Debye length shorter, in a thiocyanate salt solution than in a chloride salt solution. Recent experiments have suggested that pK(a) values of histidines depend on salt concentration and on ionic species. We finally demonstrate that once ionic dispersion potentials are included in the theory these results can quantitatively be reinterpreted in terms of a highly specific surface pH (and a salt-independent pK(a)).     

Effects of Potassium Cyanide on Silver Stainability of Specific Cell Structures

Treatment with potassium cyanide prevents the occurrence of diffuse silver precipitates on chromosome preparations. It therefore allows greatly increased times of incubation with silver solutions on both mitotic and meiotic preparations. By this method selective silver staining of active nucleolar organizers, centromeric regions and kinetochores of mitotic chromosomes and of specifically staining structures of meiotic chromosomes has been obtained.     

C-3 glucosiduronates of metabolites of adrenal steroids

On treatment with methyl 2,3,4-tri-O-acetyl-l-bromo-l-deoxy-α-D-glucuronate and silver carbonate, tetrahydrocortisone 21-acetate gave the corresponding 3-glucosiduronate triacetyl methyl ester. This product was converted into the 20-semicarbazone which, by treatment with alkali to hydrolyze the ester functions and acid to hydrolyse the semicarbazone moiety, gave tetrahydrocortisone 3-glucosiduronic acid. The acid was converted into the crystalline barium salt and into the methyl ester. An analogous series of reactions was carried out on tetrahydrocortexolone 21-acetate. Treatment of the 20-semicarbazone of tetrahydrocortisone 3-glucosiduronic acid with potassium borohydride reduced the 11-oxo function to an 11β hydroxyl group; acid-catalyzed removal of the semicarbazone group produced tetrahydrocortisol 3-glucosiduronic acid which also was obtained as the barium salt and the methyl ester.     

A silver impregnation method for embedded central nervous tissue of the rat

A simple and yet reliable silver impregnation method, using potassium ferrocyanide, for demonstrating nervous tissue of the rat central nervous system embedded in paraffin or paraplast is described. The method reported here is compared and discussed with earlier techniques using potassium dicyanoargentate, potassium ferrocyanide and potassium ferricyanide.     

Calcification of Spirostomum ambiguum

SYNOPSIS. A method is described for cultivation of large numbers of Spirostomum ambiguum , calcified intracellularly with hydroxyapatite (bone salt deposits). The structure and activity of living animals at various stages of calcification is described and also illustrated with unstained and silver impregnated ciliates. A suitable modification of von Kossa's method for localization of insoluble phosphate deposits is given.     

Pyrene excimer fluorescence as a probe for parallel G-quadruplex formation

The formation and properties of G-quadruplex structures from short single-strand oligonucleotide conjugates possessing two to four guanines and a 5'-terminal pyrenebutanol are reported. The 4-G conjugate forms a stable G-quadruplex under low or high potassium ion concentrations, whereas the 3-G conjugate forms a stable G-quadruplex only in the presence of high potassium. The 2-G conjugate fails to form a stable G-quadruplex even at low temperature and high potassium concentration. Both pyrene monomer and excimer fluorescence are observed for the G-quadruplex structures, whereas only monomer fluorescence is observed for the single-strand conjugates. Thus, pyrene excimer fluorescence can be used as a probe for the formation of G-quadruplex structures. The excimer/monomer intensity ratios for the G-quadruplex structures are dependent upon both the temperature and potassium or lithium salt concentration. The salt effect is attributed to a change in the structure of the hydrophobic pyrene chromophores, which are assembled on the 5'-face of the G-quadruplex as a consequence of electrostriction.     

L-阿拉伯糖对尿酸的调节作用

转录因子是一类在生物生命活动过程中起到调控作用的重要因子,参与了各种信号转导和调控过程,可以直接或间接结合在顺式作用元件上,实现调控目标基因转录效率的抑制或增强,从而使植物在应对逆境胁迫下做出反应。 WRKY转录因子在大多数植物体内都有分布,是一类进化非常保守的转录因子家族,参与植物生长发育以及响应逆境胁迫的生理过程。众多研究表明,WRKY转录因子在植物中能够应答各种生物胁迫,如细菌、病毒和真菌等;多种非生物胁迫,包括高温、冷害、高光和高盐等;以及在各种植物激素,包括茉莉酸( JA)、水杨酸( SA)、脱落酸( ABA)和赤霉素( GA)等,在其信号传递途径中都起着重要作用。 WRKY转录因子家族蛋白至少含有一段60个氨基酸左右的高度保守序列,被称为WRKY结构域,其中WRKYGQK多肽序列是最为保守的,因此而得名。该转录因子的WRKY结构域能与目标基因启动子中的顺式作用元件W￣box( TTGAC序列)特异结合,从而调节目标基因的表达,其调控基因表达主要受病原菌、虫咬、机械损伤、外界胁迫压力和信号分子的诱导。该文介绍了植物WRKY转录因子在植物应对冷害、干旱、高盐等非生物胁迫与病菌、虫害等生物胁迫反应中的重要调控功能,并总结了WRKY转录因子在调控这些逆境胁迫反应过程中的主要生理机制。     

The structure of sulfated cauloside C

The structure of the sulfated analogue of cauloside C, a biologically active triterpenoid glycoside, was elucidated to be 3-O-[beta-D-glucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl]-he deragenin 23,4',4",6"-tetrasulfate pentasodium salt by the comparison of its 13C NMR spectrum with that of cauloside C potassium salt.     

Growth inhibition ofChlorella pyrenoidosa produced by sodium dihydrogen phosphate and its reversal by calcium

Summary The growth ofChlorella pyrenoidosa in a special medium based on the critical concentrations of nutrients for autotrophic growth has been shown to be stimulated more by chloride with the sodium salt than with the potassium salt, more by sulphate in the presence of sodium than in the presence of potassium, and to be inhibited by sodium dihydrogen phosphate and not by potassium dihydrogen phosphate. Furthermore, it has been found that calcium reversed the growth inhibition produced by sodium dihydrogen phosphate, and that strontium only partially substituted for calcium.     

Differences in salt tolerance of three sugar beet genotypes

The effect of increasing NaCl concentrations (up to 150 m M ) on growth and mineral composition of three genotypes of sugar beet ( Beta vulgaris L., MONOHILL, ADA and FIA) has been studied. Growth was stimulated or little affected in water culture by 50 m M NaCl in all 3 genotypes. Further increase in NaCl concentration depressed growth in ADA more than in MONOHILL, whereas in FIA growth did not significantly differ from the untreated control. In all 3 genotypes, particularly in FIA, increasing NaCl concentrations decreased potassium content in the shoots more than in the fibrous and storage roots. Simultaneously, the accumulation of sodium and chloride in the shoots was considerably higher in FIA than in ADA, where in contrast larger proportions of these ions were retained in the roots. The results demonstrate considerable genotypic differences in salt tolerance of sugar beet and indicate a positive correlation between salt tolerance and accumulation of sodium and chloride in the shoots. FIA but not ADA may be suited for a breeding programme of sugar beet for improved salt tolerance.     

Ouabain-insensitive salt and water movements in duck red cells. I. Kinetics of cation transport under hypertonic conditions

Duck red cells in hypertonic media experience rapid osmotic shrinkage followed by gradual reswelling back toward their original volume. This uptake of salt and water is self limiting and demands a specific ionic composition of the external solution. Although ouabain (10(-4)M) alters the pattern of cation accumulation from predominantly potassium to sodium, it does not affect the rate of the reaction, or the total amount of salt or water taken up. To study the response without the complications of active Na-K transport, ouabain was added to most incubations. All water accumulated by the cells can be accounted for by net salt uptake. Specific external cation requirements for reswelling include: sufficient sodium (more than 23 mM), and elevated potassium (more than 7 mM). In the absence of external potassium cells lose potassium without gaining sodium and continue to shrink instead of reswelling. Adding rubidium to the potassium- free solution promotes an even greater loss of cell potassium, yet causes swelling due to a net uptake of sodium and rubidium followed by chloride. The diuretic furosemide (10(-3)M) inhibits net sodium uptake which depends on potassium (or rubidium), as well as inhibits net sodium uptake which depends on sodium. As a result, cell volume is stabilized in the presence of this drug by inhibition of shrinkage, at low, and of swelling at high external potassium. The response has a high apparent energy of activation (15-20 kcal/mol). We propose that net salt and water movements in hypertonic solutions containing ouabain are mediated by direct coupling or cis-interaction, between sodium and potassium so that the uphill movement of one is driven by the downhill movement of the other in the same direction.     

Properties of a halophil nicotinamide–adenine dinucleotide phosphate-specific isocitrate dehydrogenase. Preliminary studies of the salt relations and kinetics of the crude enzyme

The effects of chlorides on NADP-specific isocitrate dehydrogenase from Halobacterium salinarium were investigated. The enzyme is stabilized by potassium chloride and sodium chloride and this effect is discussed in relation to the Hill (1913) equation. Kinetics of the enzyme were studied within a range of concentrations of potassium chloride and sodium chloride. Apparent Michaelis constants for both substrates were affected by salt concentration, the effect being greater in sodium chloride than in potassium chloride. Minimal apparent Michaelis constants for both substrates were similar to the corresponding constants reported for yeast isocitrate dehydrogenase. V(max.) was maximal in each salt at a concentration of about 1m. The maximum was higher in sodium chloride than in potassium chloride. At salt concentrations above about 2.3m, the apparent V(max.) was lower in sodium chloride than in potassium chloride, and at salt concentrations below 0.75-1.0m, each salt behaved as a linear activator of the enzyme. Within this concentration range salt and NADP(+) acted competitively; the activation by salt was overcome at finite concentrations of NADP(+). At concentrations above about 1m, potassium chloride was a linear non-competitive inhibitor of the enzyme. Within the range 1.0-2.5m, sodium chloride was also a linear non-competitive inhibitor, but above 2.5m it caused more pronounced inhibition.     

新型抗肺癌转移药系列化合物的合成

本文以对氨基苯甲酸为原料,经过重氮化、偶合、成盐等反应,合成4个抗肺癌转移药,并作了红外鉴定。     

Disinfection of microorganisms by use of electrochemically regenerated periodate

A new method for disinfection of microorganisms by electrochemically regenerated periodate was developed. Oxidation of iodate to periodate was observed at 1.25 V versus a silver/silver chloride electrode in a cyclic voltammogram of potassium iodate. When 1.25 V was applied in 1.0 mM potassium iodate, approximately 4-log inactivation of Escherichia coli was observed in 30 min.     

New Plant Growth Stimulants Based on Water-Soluble Nanoparticles of N-Substituted Monoamino-Acid Derivatives of Fullerene C60 and the Study of their Mechanisms of Action

Growth-stimulating effects of water-soluble nanoparticles of N-substituted monoamino-acid derivatives of fullerene C₆₀ (L- and D-alanine, L- and D-valine, L- and D-aspartic acid, β-alanine, and γ-aminobutyric and ε-aminocaproic acids in potassium salt form) were investigated. It was found that the nanoparticle size and relative antiradical activity of fullerene derivatives were factors that influence such physiological parameters of field peas as seed germination rate, germination energy, and root growth capacity. It was shown that the relative antiradical activity of nanoparticles in the selected group of compounds was determined by the total surface area of the nanoparticles regardless of the structure of the amino-acid substituent. The possibility of using amino-acid derivatives of fullerene as effective growth stimulating substances has been demonstrated. A dose-dependent effect of N-(monohydrofullerenyl)-D-alanine potassium salt in a concentration range of 10^–9–10^–11 M on the seed-germination rate and germination energy of field peas has been demonstrated.