The Titrimetric Assay of OH- and HCO3- Excreted by Ricinus Cultivated on NO3--containing Nutrient Media: The Influence of Ionic Strength, End Point pH and CO2 Supersaturation

Allen, S. and Allen, C. R. 1987. The titrimetric assay of OH^–and excreted by Ricinus cultivatedon -containing nutrient media: the influence of ionic strength, end point pH and CO² supersaturation.–J. exp. Bot. 38: 607–617. When spent -containing nutrient media were titrated to the starting pH of 6.5 the titre wasequivalent to 50%orless of the base (i.e. ) excreted. Calculation of the total amount of baseexcreted could only be made from data obtained by titrationto pH 4–5. An accurate calculation of the amount of baserequired the inclusion of activity coefficients, estimated fromionic strength, in the calculations. Spent nutrient media contained from four to ten times the concentrationof CO₂ predicted from equilibrium values. It is probable that is very slow. Key words: Ricinus, nitrate-N nutrient medium, base excretion, ionic activity coefficients, carbon dioxide supersaturation     

Effects of Ionic Strength of Nutrient Solutions on Phosphate Uptake by Sunflower

Active phosphate uptake by the roots of young sunflower plants was stimulated nonspecifically by increasing the total salt concentration of the uptake solution. Inhibition of active uptake by DNP-treatment removed the salt stimulation. Independently of the rate of active uptake the amount of phosphate present in the free space of the roots increased as the salt concentration was raised. It is suggested that at low ionic strength of the nutrient solution the initial passive step of ion transport through the root free space can limit the overall uptake rate.     

Relative Uptake Rates of Inorganic Nutrients by NO3- and NH4+ Grown Ricinus communis and by two Plantago Species

Allen, S., Thomas, G. E. and Raven, J. A. 1986. Relative uptakerates of inorganic nutrients by and grown Ricinus communis and by two Plantago species.—J. exp. Bot. 37: 419–428. The relative rates of uptake and assimilation of C, N, P, S,Cl^–, K⁺ , Na⁺ Ca²⁺ and Mg²⁺ by and grown Ricinus conimunisand by NH₄NO₃- grown Plantago lanceolata and P. major were calculatedfrom data presented elsewhere. Results showed that for grown Ricinus the short term relativeuptake rates, for each nutrient X did not change significantly over the steady-state periodof exponential growth. The average gave , the mean relative uptake rate during exponential growth, for each nutrient. The amountof each nutrient taken up from a nutrient solution over a periodof time could, therefore, be calculated. For and -grown R. communis,the relative uptake rate of each nutrient was a constant fractionof the relative rate of carbon assimilation. It is suggestedthat this is typical of plants of cauline habit. For both Plantago spp., the relative rates of nitrogen uptakeand assimilation fell significantly during the exponential growthphase It is suggested that this could be a characteristic ofthe growth habit of the rosette plant. Key words: Relative uptake rates, Ricinus, Plantago, ammonium, nitrate, cauline, rosette     

不同营养条件下竹叶眼子菜NH4^＋-N吸收动力学的初步研究

以竹叶眼子菜(Potamogeton malaianus)无菌系种苗为试验材料,研究了不同水体营养浓度水平(低营养:TN 0.213 mg·L-1,TP 0.0093 mg·L-1;中营养:TN 0.71 mg·L-1,TP 0.031 mg·L-1;高营养:TN 7.1 mg·L-1,TP 0.31 mg·L-1)对其生长与NH+4-N的吸收动力学参数的影响.结果表明,不同浓度水体营养对竹叶眼子菜生长的影响较小,而NH+4-N的吸收动力学参数有显著差异.竹叶眼子菜在高、中和低营养培养条件下的NH+4-N最大吸收速率Vmax分别为 41.1、 29.1、 21.1 μmol·g-1·h-1,米氏常数Km分别为 0.356、 0.306、 0.122 mmol·L-1.竹叶眼子菜营养吸收动力学与其生长环境关系紧密,在低浓度生长环境中时,竹叶眼子菜可以通过降低Km值来提高对营养离子的亲和力以满足营养需求;在高浓度生长环境中,该植物通过增大吸收潜力来适应高营养.     

NH_4~+-N、TN、TP和DO对泥鳅的氧化损伤作用研究

目的:水体富营养化给渔业的发展造成严重的负面影响,成为全球瞩目的环境问题之一。方法:本研究利用泥鳅(Misgurnus anguillicaudatus)作为实验生物,选择氨氮(NH4+-N)、总氮(TN)、总磷(TP)和溶解氧(DO)含量作为富营养化水体的影响因素。研究富营养化水体中NH4+-N、TN、TP和DO含量对泥鳅抗氧化酶活性和脂质过氧化水平的影响,旨在阐明富营养化水体对鱼类的氧化损伤作用。结果:随着水体中NH4+-N、TN、TP和DO含量的增加,泥鳅的SOD活性显著降低(P0.05),MDA含量显著增加(P0.05)。与正常的DO水平相比,水中高浓度和低浓度的氧含量都会造成SOD活性的显著下降(P0.05)和MDA含量的显著上升(P0.05)。其中NH4+-N和DO的影响最大。结论:富营养化水体对鱼类的危害与其造成的鱼类氧化损伤有直接关系,实验的开展为富营养化水体的生物监测与评价具有一定指导作用。     

The effect of catecholamines on H+ and NH+4 excretion in toad urinary bladder

The catecholamines epinephrine and norepinephrine, when placed on the toad urinary bladder in vitro, at a final concentration of 50 microM, caused a significant increase in H+ and NH+4 excretion by the bladder. Isoprenaline in a final concentration of 50 microM also increased H+ and NH+4 excretion in the bladder. Propranolol at a concentration of 50 microM blocked the stimulation of H+ excretion by isoprenaline but propranolol at 100 microM was required to block the stimulation of NH+4 by isoprenaline. The dose-response analysis indicates that the concentration of epinephrine used (50 microM) is at or near the maximal effective dose. These findings indicate that catecholamines stimulate H+ and NH+4 excretion in the toad urinary bladder and evidence suggests this may be mediated via the beta receptor mechanism.     

Effect of metabolic inhibitors on the agglutination of tumor cells by concanavalin A and Ricinus communis agglutinin

The agglutinations of rat ascites tumor cells by concanavalin A and by $\text{Ricinus communis}$ agglutinin were inhibited by low temperature, 2,4-dinitrophenol and cytochalasin B but not by cycloheximide. These metabolic inhibitors, however, did not inhibit the binding of the agglutinins to the cells. These results suggest that the agglutination was dependent on an active process; probably on a microfilament system responsible for cell surface movement which requires ATP, but not on protein synthesis.     

The role of the adrenal gland in control of H+ and NH4+ excretion by toad urinary bladder

The urinary bladder of Bufo marinus has been shown to excrete H+ and NH4+ and this excretion is increased by metabolic acidosis. The involvement of the adrenal gland and its steroid secretions in the adaptation for increased acid and ammonia excretion by the bladder was tested during the course of this study. Groups of toads were adrenalectomized and maintained in chronic NH4Cl-induced acidosis. Three other groups of toads were adrenalectomized and put in acidosis but repleted with 2.5 mg/day of either cortisol (CT), dexamethasone (Dexa), or deoxycorticosterone acetate (DOCA). All control groups were sham-operated. The bladders were excised after 3 days and mounted between 2-ml Lucite chambers. Net H+ and NH4+ fluxes into the mucosal media were measured and reported in units of nanomoles per 100 mg bladder per minute. In control acidotic toads H+ excretion was 20.1 +/- 2.0 and the adrenalectomized nonreplete group H+ excretion was 14.2 +/- 1.87 (P less than 0.04). For the same groups NH4+ excretion was 2.90 +/- 0.26 for the controls and 1.38 +/- 0.19 for the adrenalectomized (P less than 0.001). The H+ excretion in CT-, Dexa-, and DOCA-repleted toads was not significantly different from the control group. NH4+ excretion, however, showed a 55% decrease (P less than 0.001) in the CT group, and a 45% decrease (P less than 0.05) in the Dexa group. The NH4+ excretion in the DOCA repleted group was significantly different from the control group. Therefore, we conclude that the adrenal gland plays a role in the adaptive increase of H+ and NH4+ excretion by the urinary bladder in acidosis through the secretion of steroid hormones. The increase in NH4+ excretion appears to be a mineralocorticoid-stimulated process. We were not able to determine in this study if the steroid hormones had an exacting regulatory role or one of a permissive role over H+ and NH4+ excretion in the toad urinary bladder.     

Effect of NH4 +:NO3 - ratios on growth and nitrogen uptake by onions

The modelling of ion uptake by plants requires the measurement of kinetic and growth parameters under specific conditions. The objective of this study was to evaluate the effect of nine NH _inf4 ^sup+ :NO _inf3 ^sup− ratios on onions (Allium cepa L.). Twenty-eight to 84 day-old onion plants were treated with NH _inf4 ^sup+ :NO_f3/sup− ratios ranging from 0 to 100% of each ionic species in one mM solutions in a growth chamber. Maximum N influx (I_max) was assessed using the N depletion method. Except at an early stage, ionic species did not influence significantly I_max, the Michaelis constant (K_m) and the minimum concentration for net uptake (C_min). I_max for ammonium decreased from 101 to 59 pmole cm^-2 s^-1 while I_max for nitrate increased from 26 to 54 pmole cm^-2 s^-1 as the plant matured. On average, K_m and C_min values were 14.29 μM, and 5.06 μM for ammonium, and 11.90 μM and 4.54 μM for nitrate, respectively. In general, the effect of NH₄ ⁺:NO₃ ^- ratios on root weight, shoot weight and total weight depended on plant age. At an early stage, maximum plant growth and N uptake were obtained with ammonium as the sole source of N. At later stages, maximum plant growth and N uptake were obtained as the proportion of nitrate increased in the nutrient solution. The was no apparent nutrient deficiency whatever NH₄ ⁺:NO₃ ^- ratio was applied, although ammonium reduced the uptake of cations and increased the uptake of phosphorus. The research was supported by the Natural Sciences and Engineering Research Council of Canada.     

NH + 4 -N recovery from ammonia-treated straw-whey ensilage and cell biomass formation by Rhodobacter capsulatus ATCC 23782 on silage filtrates

Summary Growth of Rhodobacter capsulatus ATCC 23782 on silage filtrates under both axenic and non-axenic conditions was evaluated. Under both conditions, 96% assimilation of NH ₊ ⁴ -N at rates of about 0.1 g/l·d was attained. Assimilation was complete when the C/N ratio was adjusted to ca. 5. Thus assimilation rates of 0.2 g/l·d were achieved for an acid-C and NH ₊ ⁴ -N concentration of 2.0 and 0.4 g/l respectively. The corresponding biomass production amounted about 104 mg/g silage, dry matter.     

Effects of parathyroid hormone on H+ and NH 4 + excretion in toad urinary bladder

Summary The urinary bladder ofBufo marinus excretes H⁺ and NH ₄ ⁺ , and the H⁺ excretion is increased after the animal is placed in metabolic acidosis. The present study was done to determine if parathyroid hormone could stimulate the bladder to increase the excretion of H⁺ and/or NH ₄ ⁺ . Parathyroid hormone added to the serosal solution in a final concentration of 10 g/ml was found to increase H⁺ excretion by 50% above the control hemibladders, while there was no effect on NH ₄ ⁺ excretion. Parathyroid hormone had no effect on H⁺ excretion when added to the mucosal solution. We also performed experiments utilizing theophylline and dibutyryl cyclic AMP which mimicked those of the parathyroid hormone experiments. A dose-response analysis was performed and the results indicate that 1 g/ml of parathyroid hormone was the minimal effective dose. These results suggest that parathyroid hormone can stimulate H⁺ excretion in the toad urinary bladder and this effect seems to be mediated by cyclic AMP. In addition, it was found that parathyroid hormone has no effect on NH ₄ ⁺ excretion.     

Action of steroids on H+ and NH 4 + excretion in the toad urinary bladder

Summary This study was done to determine if steroid compounds will stimulate the urinary bladder of the toad to increase its capacity to acidify the urine and excrete NH ₄ ⁺ , Aldosterone, 17-estradiol, dexamethasone, pregnenolone, and cholesterol were tested on the bladder. All compounds tested were found to stimulate the rate of acidification by the bladder, above that of a paired control hemibladder. In contrast, only the steroids aldosterone and 17-estradiol were found to stimulate NH ₄ ⁺ excretion in the bladder. Cycloheximide was found to block the action of aldosterone on the NH ₄ ⁺ excretion, but did not have a significant effect on the stimulation of acidification by aldosterone. We conclude that steroids stimulate H⁺ and NH ₄ ⁺ excretion in the toad urinary bladder. In addition, the NH ₄ ⁺ excretory system seems to be more specific to this effect than is the H⁺ excretory system.This work was presented in part at the 62nd annual meeting, Federation of American Societies for Experimental Biology, Atlantic City, N.J., April 1978.     

Effect of pH, Protein Concentration, and Ionic Strength on Heat Inactivation of Staphylococcal Enterotoxin B

Heat treatment of highly purified staphylococcal enterotoxin B causes a more rapid loss of immunological activity at 70 to 80 C than at 90 to 100 C. Toxicological results based on intravenous injection of dogs paralleled the results obtained by immunological means (single gel diffusion). The loss of immunological activity did not follow first-order kinetics. Results are given on the effects on heat inactivation of changing pH, ionic strength, and initial concentration of enterotoxin. Disc-gel electrophoresis of purified enterotoxin B showed a major and minor band. The minor band was a size isomer of the major band.     

NH4+浓度对黄色短杆菌XV0505发酵生产L-缬氨酸的影响

以L-缬氨酸(L-Val)生产菌黄色短杆菌XV0505为供试菌株,以(NH4)2SO4为唯一添加N源,考察不同NH 4+浓度对发酵过程中菌体干质量、L-Val产量和葡萄糖消耗速率以及菌体内代谢流量的影响。研究表明:NH 4+浓度过高或不足都会影响发酵水平,降低L-Val的产量。合适的初始NH4+浓度为225 mmol/L,产酸期NH4+维持浓度为35 mmol/L时,有利菌体产酸。在此NH4+浓度下,在30 L发酵罐发酵60 h,发酵液中菌体生物量和L-Val质量浓度分别可达22.35和59.12 g/L。     

Effects of parathyroid hormone on H+ and NH+4 excretion in toad urinary bladder.

The urinary bladder of Bufo marinus excretes H+ and NH+4, and the H+ excretion is increased after the animal is placed in metabolic acidosis. The present study was done to determine if parathyroid hormone could stimulate the bladder to increase the excretion of H+ and/or NH+4. Parathyroid hormone added to the serosal solution in a final concentration of 10 mug/ml was found to increase H+ excretion by 50 per cent above the control hemibladders, while there was no effect on NH+4 excretion. Parathyroid hormone had no effect on H+ excretion when added to the mucosal solution. We also performed experiments utilizing theophylline and dibutyryl cyclic AMP which mimicked those of the parathyroid hormone experiments. A dose-response analysis was performed and the results indicate that 1 mug/ml of parathyroid hormone was the minimal effective dose. These results suggest that parathyroid hormone can stimulate H+ excretion in the toad urinary bladder and this effect seems to be mediated by cyclic AMP. In addition, it was found that parathyroid hormone has no effect on NH+4 excretion.     

Inhibition of Sindbis Virus Production by Media of Low Ionic Strength: Intracellular Events and Requirements for Reversal

Incubation of Sindbis virus-infected cultures in medium with an ionic strength of 0.105 reduced the virus yield more than 99%. This inhibition was rapidly reversed by exposing the cultures to normal medium: within 20 min the previously inhibited cultures had released as much infectious virus as normal controls had produced during hours of incubation. The following intracellular processes were essentially normal in inhibited, infected monolayers: protein and phospholipid synthesis, the synthesis of infectious viral ribonucleic acid and its incorporation into nucleocapsids, and viral modification of the cell membrane. Accelerated virus production was detected within 20 sec after exposure of inhibited cultures to normal medium. It required an ionic strength greater than 0.145, a pH above 6.7, and a temperature above 21 C. It was not dependent on osmotic pressure, de novo protein synthesis, or a functional energy metabolism. Virus release also occurred in sonic-treated materials of inhibited cells under the same conditions as in living cells. Potential applications of the inhibition to concentration of virus stocks or to obtaining virus in nonphysiological solutions are noted. Preliminary studies with Semiliki Forest virus, Newcastle disease virus, and vesicular stomatitis virus suggest that this phenomenon may be limited to arboviruses.     

有机酸去除污泥重金属前后硝态氮和铵态氮浓度变化

研究了柠檬酸、草酸和乙酸溶液对污泥中重金属(Cd、Pb、Cu和Zn)的去除效果,以及处理前后析出液和污泥中硝态氮和铵态氮的浓度变化.结果表明,0.8mol.L-1柠檬酸溶液可去除污泥中76.0%的Pb和92.5%的Zn,是较好的重金属去除剂.污泥经有机酸处理后,有大量的硝态氮和铵态氮溶解于析出液中,与加入蒸馏水的对照处理相比,有机酸可大幅度增加析出液中铵态氮的含量,减少硝态氮含量.由于污泥处理过程中有其他形态的氮的转化,处理后污泥中仍含有较高浓度的硝态氮和铵态氮.0.5mol.L-1草酸处理的析出液中硝态氮和铵态氮浓度分别为2.8和888.1mg.L-1,且重金属含量不高,可作为较好的液体肥料进行回收利用.