Effect of ions and other compatible solutes on enzyme activity, and its implication for biocatalysis using ionic liquids

The effect of ions on enzyme activity and stability usually follows the Hofmeister series (or the kosmotropicity order): kosmotropic anions and chaotropic cations stabilize enzymes while chaotropic anions and kosmotropic cations destabilize them. The effect of ionic liquids (ILs) on the enzyme activity/stability/enantioselectivity is complicated especially when there is no or little water presence in the IL media. However, when aqueous solutions of hydrophilic ILs are employed as reaction media, the enzyme seems to follow the Hofmeister series since ILs dissociate into individual ions in water.     

A method for controlling the activities of free metal,hydrogen, and phosphate ions in hydroponic solutions using ion exchange and chelating resins

Summary An ion exchange and chelating resin system was developed to buffer the activities of selected free cations and phosphate in hydroponic solutions at concentrations similar to those that occur naturally in soil solutions. Free-ion activities of Cd, Cu, Ni, Zn, Mn, H, Ca, Mg, and K were maintained by ion exchange and chelating resins in a controlled ionic strength system. Iron was controlled by EDDHA and chelating resin, and P by a cation-exchange resin containing adsorbed polynuclear hydroxyaluminum. This mixed-resin hydroponic system was used to establish a range of ionic Cd activities similar to that found in soil solutions of soils amended with sewage sludge. Activities of other nutrients were maintained at realistic soil-solution levels. A metal complexing agent (EDTA) was used to increase total metal concentration in the hydroponic solutions without significantly altering the ionic activities of the metals maintained in solution. This allowed differentiation of the effects of free ions and complexed metals on metal uptake. Concentrations of metal complexes in solution were controlled by the ion activities of the metals maintained and the concentrations and selectivities of the complexing agent. The mixed-resin system supplied sufficient nutrients for the growth of tomato plants (Lycopersicon esculentum, cv. Wisconsin-55) in hydroponic culture. Research supported by the College of Agricultural and Life Sciences, University of Wisonsin-Madison and by United States Environmental Protection Agency through Grant CR807270010.     

Antimicrobial activities of cinnamyl rifamycin derivatives, T-9 and T-11, against Mycobacterium tuberculosis and Mycobacterium avium complex (MAC) with special reference to the activities against intracellular MAC

The mycobacterial activities of cinamyl rifamycin derivatives, T-9 and T-11, especially against extracellular and intracellular Mycobacterium avium complex residing within macrophages and type II pneumocytes were compared with those of other rifamycins. The activities of test rifamycins were found to be in the order rifalazil, rifabutin, T-9, T-11, and rifampicin.     

Modeling the interaction of a neutral polymer with small ions in solution. A theoretical study of ion binding to a neutral polymer

The interaction between NaCl and 1,2-dimethoxyethylene is used to model ion binding to a neutral polymer. The relative binding energies involving different ion-polymer structures were calculated using minimal basis STO-3G and split valence 3-21Gab-initio and CNDO/2 semi-empirical wavefunctions. The results obtained are consistent with an adsorption model in which the cation is primarily adsorbed on the oxygen sites. The counter ion is then bound by the charged polymer in a form consistent with an ion pair structure. These results are consistent with recent experimental studies on polyoxyethylene (POE). Additional calculations were performed to include specific interactions with the liquid environment. Electrostatic solvation effects, introduced through the self-consistent reaction field (SCRF) model, appear to be significant in the stabilization of a solvent-separated ion-pair structure. However, the global stabilization produced by both specific and electrostatic solvations predicts the preferential stabilization of an externally hydrated intimate ion pair.Dedicated to the memory of the late Professor Luis Sepulveda (1988).CMCA Contribution No 3.     

Enhancement of rat hepatic macrophages by treatment with interleukin-2 and streptococcal preparation OK432, with reference to antitumor activity,soluble factor production and Ia expression

Summary The effect of biological response modifiers, such as interleukin-2 (IL-2) and streptococcal preparation OK432, on the functions of hepatic macrophages was investigated. The macrophages, even with no exogenous stimulation, produced superoxide anion (O ₂ ^- ) and tumor necrosis factor (TNF), displayed cytotoxicity against K562 cells and cytostasis against P815 cells and expressed immune-region-associated antigen (Ia). IL-2 administered in vitro or in vivo enhanced O ₂ ^- production by hepatic macrophages and the intravenous injection of OK432 also enhanced O ₂ ^- production. Furthermore, IL-2 added to the culture medium of hepatic macrophages isolated from OK432-injected rats augmented O ₂ ^- production even more. The TNF production and Ia expression of the macrophages were also increased by the intravenous injection of OK432. As with O ₂ ^- production, the cytotoxicity of the cells was enhanced by OK432 injection or by IL-2 added to the culture medium and the combination of OK432 and IL-2 augmented their cytotoxicity even more. Thus, the present study suggested that IL-2 and OK432 induce the augmentation of the antitumor activity of hepatic macrophages, partly as a result of the increase in production of O ₂ ^- and TNF and Ia expression.     

A note on the karyotypes and chromosome associations of the Hylobatidae, with special reference to Hylobates (Nomascus) concolor

The somatic chromosomes, obtained from short term leukocyte cultures, were studied of four species of the Hylobatidae: Hylobates lar, H. agilis, H. (Nomascus) concolor and Symphalangus syndactylus. In accordance with earlier observations by others, the diploid chromosome numbers were found to be 44 in both Hylobates lar and H. agilis, 52 in H. concolor and 50 in Symphalangus syndactylus. The chromosome associations observed in metaphase spreads are clearly different in the three types of chromosome complements. In Hylobates lar and H. agilis associations are found between both members of the marked chromosome pair. In Symphalangus syndactylus the only two acrocentric elements of the karyo-type, which are of medium size, associate frequently. In H. concolor finally, the members of three pairs of small acrocentrics are involved in chromosome associations. G-banding patterns (obtained by trypsin treatment) showed that in a male individual of this species also the small acrocentric Y chromosome sometimes participates in these associations. The evolutionary aspects of these observations are briefly discussed.     

不同肥料对稻田红壤碳、氮、磷循环相关酶活性的影响

采用中国科学院千烟洲生态站1998年开始的定位试验数据,研究不同肥料(猪粪、秸秆、化肥)对稻田红壤碳、氮、磷养分及相关酶活性\[β-1,4-葡萄糖苷酶(βG)、β 1,4-N-乙酰葡糖氨糖苷酶(NAG)、L-亮氨酸氨基肽酶(LAP)、酸性磷酸酶(AP)\]的影响.结果表明：施用猪粪(OM)土壤中的βG、NAG和LAP活性显著高于其他处理,比对照(不施任何肥料)分别高1.4、2.6和1.9倍;土壤C/N提高、βG/(NAG+LAP)降低,说明施用猪粪有利于土壤中纤维素的降解和有机碳的积累.施用化肥提高了土壤中βG、NAG和LAP活性,而AP活性比对照低34%;土壤βG/AP和(NAG+LAP)/AP较高,而C/P和N/P较低,说明施用化肥导致稻田红壤无机磷的积累,抑制了土壤中分解磷酸多糖和磷脂的微生物功能.     

A mathematical model for the temporal pattern of a population structure,with particular reference to the flour beetle: II. Competition between species

The effect of competition between species is considered in terms of a mathematical model. It is found that, except for special relations among the parameters, only one species should remain, as is found experimentally. It is also found that unless new factors arise in the competition, one can calculate an index to predict which of the two species is most likely to become extinct. The index involves quantities measured from isolated populations. A preliminary extimate yields satisfactory values when compared with the experimental results of competition.     

The effect of ionic strength on a Mg2+-ATPase and its relevance to the determination of (Na++K+)-ATPase

A ouabain-insensitive Mg²⁺-ATPase present in a microsomal fraction prepared from the dog submandibular gland was studied. This Mg²⁺-ATPase was inhibited by increasing concentrations of NaCl, KCl, RbCl and CsCl. The addition of an osmotically equal amount of sucrose was without effect. This inhibition was obtained over a pH range of from 6.3 to 8.8. The Mg²⁺-ATPase present in microsomes treated with NaI showed a similar inhibition. These results indicate that it is advisable to keep the ionic strength constant in solutions used to obtain (Na⁺+K⁺)-ATPase activities.     

Effects of N source on proton excretion,ionic balance and growth ofAlnus glutinosa (L.) Gaertner: comparison of N2 fixation with single and mixed sources of NO3 and NH4

Summary Non-nodulatedalnus glutinosa plants were grown for 6 weeks in nutrient solutions using 3 combined-N treatments (NO₃; NO₃/NH₄; and NH₄) at a total N level of 4 meq.l^–1, and growth was ccmpared with nodulated plants at zero N (N₂ fixation). Of the combined-N sources, 100 per cent NH₄ resulted in the highest dry matter yields when the solution pH was adjusted daily atc. 6. The dry matter yield was lowest with NO₃.During the first 3 weeks, the yield of the N₂-fixing plants was as high as that of the NH₄ plants, but fell relatively behind during the second 3-week period. These effects could be attributed to higher initial N contents and higher shoot:root ratios, respectively, in the N₂-fixing plants. Specific rates of N acquisition in the root were of a comparable order of magnitude for the combined-N and zero-N treatments.When NO₃ was taken up, it was almost completely reduced in the roots. Regardless of N source there was a large excess of cations (C) relative to inorganic anions (A) in the plants, which was presumed to be balanced by an equivalent amount of organic anions (C-A). The relatively small differences in generation of organic anions for the various modes of N supply indicated the relative importance of the proton pump when NH₄ or N₂ was the N source. Proton or hydroxyl-ion effluxes, calculated on the basis of plant analyses, were generally in good agreement with measured excretion values. The acidity generation with N₂ fixation amounted toc. 0.5 meq H⁺.mmol^–1 N_org, which was distinctly higher than the range of 0.1–0.2 mentioned by Raven and Smith⁴³ for dinitrogen-fixing plants.Without pH adjustment, specific rates of cation uptake and carboxylate generation were strongly depressed as the acidity increased, when NO₃/NH₄, NH₄ and N₂ were the N sources. Growth ofAlnus glutinosa appeared to be still normal at a pH ofc. 2.8. During the final 3 weeks, only the NH₄ plants ceased growing at a pH of 2.6.     

A review of the likely effects of climate change on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta,with particular reference to water temperature and flow

The present paper reviews the effects of water temperature and flow on migrations, embryonic development, hatching, emergence, growth and life‐history traits in light of the ongoing climate change with emphasis on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta. The expected climate change in the Atlantic is for milder and wetter winters, with more precipitation falling as rain and less as snow, decrease in ice‐covered periods and frequent periods with extreme weather. Overall, thermal limits for salmonids are species specific. Scope for activity and growth and optimal temperature for growth increase with temperature to an optimal point before constrain by the oxygen content of the water. The optimal temperature for growth decreases with increasing fish size and varies little among populations within species, whereas the growth efficiency may be locally adapted to the temperature conditions of the home stream during the growth season. Indirectly, temperature influences age and size at smolting through its effect on growth. Time of spawning, egg hatching and emergence of the larvae vary with temperature and selective effects on time of first feeding. Traits such as age at first maturity, longevity and fecundity decrease with increasing temperature whilst egg size increases with temperature. Water flow influences the accessibility of rivers for returning adults and speed of both upstream and downstream migration. Extremes in water flow and temperature can decrease recruitment and survival. There is reason to expect a northward movement of the thermal niche of anadromous salmonids with decreased production and population extinction in the southern part of the distribution areas, migrations earlier in the season, later spawning, younger age at smolting and sexual maturity and increased disease susceptibility and mortality. Future research challenges are summarized at the end of the paper.     

A new species and three new combinations in Cyphellophora, with a note on the taxonomic affinities of the genus, and its relation to Kumbhamaya and Pseudomicrodochium.

Cyphellophora guyanensis sp. nov., isolated from leaf litter in French Guyana, is described and illustrated. This fungus is characterized by ampulliform to flask-shaped phialides, with a conspicuous, funnel-shaped collarette, and nearly straight to falcate or slightly sigmoid, (2−)3–6 septate conidia. Cyphellophora guyanensis is compared to the other Cyphellophora species, and the latter genus is compared to Kumbhamaya and Pseudomicrodochium. Kumbhamaya indica, P. fusarioides, and P. suttonii are transferred to Cyphellophora. The phylogenetic relationships of Cyphellophora with other genera of ascomycetes and related mitosporic fungi were inferred from the analysis of the partial nuclear ribosomal DNA SSU sequences data. The analysis supports a placement of Cyphellophora in Chaetothyriales, and probably in the Herpotrichiellaceae This revised version was published online in August 2006 with corrections to the Cover Date.     

Studies on 17-1A antigen gene regulation in nonexpressing A549 and A431 cells,as compared to expressing pancreatic carcinoma (CAPAN 2) cells,reveal a complex mechanism of repression of this gene.

Elements controlling high expression of the 17-1A antigen gene in pancreatic carcinoma cells (Capan 2) reside within the two regions: proximal (?193 to +3) and distal (?877 to ?518). We demonstrate here that some factors present in nuclear extracts from nonexpressing cells bind specifically to the control elements, important for gene expression. Our results suggest that nonexpressing cells may either lack at least one of the factors necessary for activation or may contain their modified forms. A major difference between expressing and nonexpressing cells was found in the region containing core enhancer sequence. Moreover, nonexpressing cells display a complex pattern of DNA-protein interactions in this region, suggesting that these cells contain factors acting negatively mainly on the enhancer sequence. Our results however, indicate that the mechanism of repression is much more complicated than expected.     

The stimulation of liver phosphorylase b by AMP, fluoride and sulfate. A technical note on the specific determination of the a and b forms of liver glycogen phosphorylase.

1. The activity of liver phosphorylase b from several mammalian species has been studied. The enzyme from rat or mouse has a higher activity than the rabbit enzyme, which is itself more active than pig liver phosphorylase b. 2 The activity of liver phosphorylase b is influenced by anions and by AMP, and these effects are influenced by pH. Fluoride, which is currently added to the assay mixture of phosphorylase a in crude preparations, is about as active as sulfate as a stimulator of phosphorylase b. 3. When assayed at pH 6.1 and in the presence of 0.15 M NaF, the activity of rat liver phosphorylase b reaches 25% of that of the a enzyme; if 1 mM AMP is also present, this value rises to 50%. 4. Methods are described that allow the determination of liver phosphorylase a without interference of b, and the determination of total phosphorylase (a+b) in rat liver.