Annual uptake and distribution of N15-labelled ammonia and nitrate in young Jonathan/MM104 apple trees grown in solution cultures

Summary By using N¹⁵-labelled calcium nitrate and ammonium sulphate, the uptake of ammonia and nitrate by young Jonathan/MM104 apple trees grown in a glasshouse in water culture was determined. A batch of 4 trees was exposed to the appropriate tracer for seven days and then sampled. This procedure was repeated at 4 weekly intervals during a 12-month period. The results show that the uptake by apple trees of either ammonia or nitrate is continuous throughout the year with a relative high peak (expressed in μg N/100 mg dry weight) in December (summer period) and low values during August-September (winter period). The total uptake in the whole tree was steady for December to June inclusive and decreased from July, with the lowest uptake during August-September period. The young trees, previously receiving nitrogen as ammonium plus nitrate (1: 7), absorbed both ions in nearly equivalent amounts, except for the winter period when the uptake of ammonia was in excess of that for nitrate. This difference in uptake of both ions probably results from a lower activity of the enzymic nitrate reducing system during the time of low temperature. Low activity of the nitrate reductase enzyme results also in a restricted uptake of nitrate by apple trees previously receiving only ammonia nitrogen. A detailed analysis of total nitrogen content showed the lowest nitrogen values (0.77%) in February, near the end of the second growth period of the first year. From then on, the total nitrogen percentage of the apple trees steadily increased to reach a peak of 1.57% N during the flush of early spring growth of the second year. Leaves, fruit, soft twig growth, blossoms and roots had the highest N levels at this time. The total nitrogen percentage of the whole tree then gradually decreased. The established distribution pattern of absorbed nitrogen from both N¹⁵-labelled compounds showed that the relatively highest incorporation of absorbed nitrogen from both sources was in newly grown tissues during early spring growth flush of the second year, indicating the importance of currently absorbed nitrogen for early spring growth. With the increase in rate of growth in the later period, the value of the nitrogen stored within the apple trees became evident.     

Options for reducing the negative effects of nitrogen in agriculture

After addition to farms by fertilizer, crop residues, biological fixation and animal excreta, nitrogen can be lost through gaseous emission, runoff and leaching to contaminate the atmosphere and water bodies, and cause adverse health effects. The efficiency of fertilizer nitrogen can be increased and losses reduced, by matching supply with crop demand, optimizing split application schemes, changing the form to suit the conditions, and use of slow-release fertilizers and inhibitors. In addition, agronomic practices such as higher plant densities, weed and pest control and balanced fertilization with other nutrients can also increase efficiency of nitrogen use. Efficiency of use by animals can be increased by diet manipulation. Feeding dairy cattle low degradable protein and high starch diets, and grazing sheep and cattle on grasses high in water soluble carbohydrate result in less nitrogen excretion in urine and reduced ammonia volatilization.     

Effects of naloxone on renal responses to noxious stimuli in the cynomolgus monkey

Behavioral influences on excretion of Na⁺ and H₂O were studied during saline diuresis in three unanesthetized adult female cynomolgus monkeys. During control infusions of isotonic saline, the average rates of urine and Na⁺ excretion were 210μl/kg/min and 36.1μl/kg/min, respectively, and the average rate of inulin clearance was 4.6 ml/kg/min. Intermittent exposure to an electrical stimulus applied to the monkey's tail for a 30-min period modestly reduced rates of excretion of Na⁺ and H₂O; these reductions were 58% and 56% of baseline values respectively during the first 10 min, but excretion rates returned to baseline values or exceeded them by the end of the 30-min period. The effects of naloxone hydrochloride (10 mg/kg), an opiate antagonist, were studied by administering the drug immediately before the period of electrical-stimulus delivery. After naloxone, the electrical-stimulus markedly reduced the rates of Na⁺ and H₂O excretion to 29% and 31% of baseline values during the first 10 min, and delayed the return to baseline values. Inulin clearance was not altered significantly by the electrical stimulus in the absence of naloxone, but was decreased to 32% of the baseline rate during the first 10 min of exposure to the electric stimulus in the presence of naloxone. Naloxone had similar effects on rates of Na⁺ and urine excretion in response to 30 min of 108 dBA noise. These results show that renal responses to noxious environmental stimuli (electrical stimulus or noise) can be altered by naloxone.     

Cloning and sequencing of nifBHDKENX genes of Paenibacillus massiliensis T7 and its nif promoter analysis

Biological nitrogen fixation, that is, reduction of atmospheric dinitrogen to ammonia, is catalyzed by a complex metalloenzyme called nitrogenase. Nitro-genase is composed of the iron protein (dinitrogenase reductase) encoded by the nifH gene, and the mol…     

Evidences of Hfq associates with tryptophanase and affects extracellular indole levels

In this study, we observed a novel property of Escherichia coli Hfq protein： it possibly influenced extracellular indole levels. The extracellular indole concentrations were increased in Hfq mutant cells and decreased in Hfq overexpression cells in a cell densitydependent manner. The decreased extracellular indole levels in Hfq overexpression cells caused the postponement of entering into stationary phase. Indole was produced by tryptophanase, the gene product of tnaA, which catalyzed tryptophan into indole, ammonia and pyruvate. Further studies showed that at cell density of 0.8 but not at 0.4, tryptophanase activities of total cell extracts were affected by Hfq mutation or overexpression. Protein puff-down assay and co-immunoprecipitation experiments revealed that Hfq associated with tryptophanase under relatively higher extracellular indole levels, suggesting this was a feedback control of indole production. The association of Hfq and tryptophanase might be indirect because purified Hfq could not affect the values of Km and Vmax of purified tryptophanase.     

不同生态因子对黄鳝受精卵孵化率的影响

This paper studied the effects of some ecological factors (temperature, pH, hatching method and ammonia) on the embryonic development of ricefield eel. The results indicated that the optimum hatching temperature of ricefield eel was 25～28℃, and no significant difference was found about the effects of pH within the range of pH 5.5～9.5 on the hatching rate of oosperm. Dripping water incubation had a higher hatching rate of oosperm than staticing water incubation, and the hatching rate of oosperm decreased with increasing ammonia content. The present study provided an available suggestion for the all-artificial and half-artificial breeding of ricefield eel.     

Excessive hepatic copper accumulation in jaundiced rats fed a high-copper diet

The response of copper metabolism to dietary copper challenge was investigated in jaundiced rats with elevated plasma concentrations of conjugated bilirubin as a result of impaired canicular transport of bilirubin glucuronides. Control and jaundiced rats were fed purified diets with either normal (64 μmol Cu/kg) or high (640 μmol Cu/kg) concentration of added copper. Copper loading produced a greater increase in hepatic copper concentrations in the jaundiced than in control rats. The greater dietary-copper-induced increase in hepatic copper in the jaundiced rats can be explained by the observed smaller rise in biliary copper excretion and a greater efficiency of dietary copper absorption. In individual rats, there was a positive relationship between hepatic copper concentrations and biliary copper concentrations. It is suggested that not the transport of copper from liver cells to bile but that from plasma to bile is diminished in the jaundiced rats. The elevated plasma copper concentrations in the jaundiced rats may support this suggestion.     

Dental amalgam affects urinary selenium excretion

Selenium may have a protective effect against mercury toxicity. The aim of the present study was to investigate if selenium excretion in urine was affected in persons with dental amalgam fillings. The reason for this study is that dental amalgam is the most important source of inorganic mercury exposure in the general population, although the potential toxic effects of this exposure remain a subject for debate. The chelating agent 2,3 dimercaptopropane-1-sulfonate (DMPS) was injected intravenously (2 mg/kg) to provoke metal excretion. Urine samples were subsequently collected at intervals over a 24-h period. Selenium concentration was determined by hydride-generation atomic absorption spectrometry. The study was comprised of 20 persons who claimed symptoms from dental amalgam and 21 healthy persons with amalgam fillings. There were two control groups without amalgam. One control group had amalgam replaced because of concern about illness resulting from mercury release (n=20), whereas the other control group never had amalgam (n=19). Individuals with amalgam excreted less selenium (36.4 μg, median value) over 24 hours than those without amalgam (47.5 μg) (p=0.016). There was no difference in selenium excretion between groups with (42.4 μg) and without (39.4 μg) amalgam-related symptoms (p=0.15). The findings indicate that individuals exposed to low levels of elemental mercury from dental amalgam excrete less selenium to urine than unexposed individuals.     

Colorimetric determination of chloride in biological samples by using mercuric nitrate and diphenylcarbazone

A colorimetic method is outlined for the determination of the chloride ion in biological samples (blood serum, plasma, and urine). The present method is based on the quantitative reduction of free mercuric ions by chloride ions. Chloride ions form an indissociable complex with mercuric ions. The remaining free mercuric ions form a purple complex with diphenylcarbazone with an absorption maximum at 550 nm. The reduction of color intensity at 550 nm is directly proportional to chloride concentration in the sample. The linear concentration range in the final reaction mixture was 0–100 μM with a correlation coefficient of −0.9997. The coefficient of variation for the 50 μM chloride ion in the final reaction mixture was 0.9% (n=6). The analyzed value of chloride concentration in the human control serum Accutrol™ Normal (Sigma) was 101±4 mM (mean±SD, n=12). The certified value of chloride in Accutrol Normal by Sigma is 102 mM, with a mean in the range 91–113 mM. This method was applied to the measurement of urinary chloride excretion in experimental rats. During 16-h urine collection, no food was given and rats had free access to purified water. The urinary excretion rate of chloride was 23.6±9.3 μmol/h (mean±SD, n=8) and 126.2±28.0 μmol/h (n=8) for rats fed a normal diet (2.6 g NaCl/kg diet) and a high-salt diet (82.6 g NaCl/kg diet) for 70 d prior to urine collection, respectively. This method is appropriate for low concentrations of chloride in samples or when sample volume is limiting, as in many animal studies such as metabolic urine collection from rats. The U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of the products that may also be suitable.     

Expression and Characterization of European Sea Bass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>) Somatolactin: Assessment of In Vivo Metabolic Effects

Abstract The complementary DNA coding for European sea bass somatolactin was expressed in the pET-3a bacteria expression vector. The recombinant somatolactin (rbSL) was purified by size exclusion chromatography, and 95% of the protein remained in the oxidized form with negligible aggregation over prolonged cold storage. The identity of the recombinant protein was demonstrated by Western blotting with a rabbit polyclonal antibody against gilthead sea bream somatolactin. The same antibody was utilized in a radioimmunoassay procedure, using rbSL as standard and radioiodinated tracer. Curve displacements of pituitary and plasma samples paralleled the rbSL standard, and the midrange of the assay (8 ng/ml) was low enough to measure in a consistent manner the circulating SL concentration. To assess biological activity a single dose of rbSL (0.1 μg/g of body mass) was administered to juvenile gilthead sea bream by intraperitioneal injection. In comparison with saline-treated fish, rbSL did not modify the circulating amount of insulin-like growth factor I, whereas a 50% increase was found with the same dose of recombinant trout growth hormone (rtGH). Hormone treatment did not modify nitrogen-ammonia excretion, but both rbSL and rtGH increased carbon dioxide output and oxygen uptake, which in turn decreased the respiratory quotient (CO₂ output per O₂ uptake). This pattern of gas exchange suggests the enhancement of lipid catabolism, which is consistent with the observation that both hormones were able to inhibit the hepatic activity of acetyl–coenzyme A carboxylase. These new insights provide direct evidence for the involvement of fish somatolactin in energy homeostasis, which may serve to maintain the lipolytic tonus in different physiologic states.     

温度和个体大小对单齿螺耗氧率和排氨率的影响

采用静水法测定了不同温度、不同个体大小的单齿螺耗氧率和排氨率。结果表明:在16-33℃的实验温度范围内单齿螺的耗氧率(R_O)和排氨率(R_N)与软体部干重(W)都呈负相关,它们之间关系可以分别用幂函数R_O=aW^-b和R_N=a₁W^-b1表示。16～29℃温度范围内单齿螺的耗氧率和排氨率均随温度的升高而增加,29℃时耗氧率和排氨率达到最大值,当温度继续升高超过29℃后,耗氧率和排氨率则随温度的升高而下降,耗氧率、排氨率与温度之间呈显著的指数函数关系R_O=ce^dT和R_N=c₁e^d1T;不同个体大小单齿螺的O:N比在16～20℃时较大,Q₁₀取值范围0.56-3.74,平均值为1.64。方差分析表明,温度、软体部干重对单齿螺的耗氧率和排氨率均有极显著的影响(P<0.01)。     

温度和体重对克氏双锯鱼仔鱼代谢率的影响

采用实验生态学的方法研究了不同温度和体重对克氏双锯鱼仔鱼呼吸和排泄的影响。结果表明,在23、26和29℃下,仔鱼个体日常呼吸率和排氨率与鱼体重呈幂函数(R=aWb)关系,即鱼体重越大其呼吸率和排氨率越大,b值随温度升高而增大,分别为0.8873,0.9033和0.9323(呼吸率),以及0.7625,0.8012和0.8278(排氨率)。温度和体重对克氏双锯鱼仔鱼个体呼吸率和排氨率的影响可用复合线性公式表示:RR=0.042(±0.007)W0.889(±0.026)×e0.122(±0.005)T,ER=0.002(±0.000)W0.797(±0.029)×e0.115(±0.007)T。比体重呼吸率和排氨率在相同温度条件下随个体增长而降低;在整个仔鱼期,比体重呼吸率和排氨率随温度升高而增加。克氏双锯鱼仔鱼呼吸和排泄Q10值在26—29℃较低,其可能是克氏双锯鱼仔鱼生长发育的最佳温度范围。克氏双锯鱼仔鱼在温度23—29℃时O/N范围为52—57,表明在温度23—29℃时克氏双锯鱼仔鱼代谢底物除了蛋白质外,脂肪和碳水化合物为能源也占了比较大的比例。     

Physiological energetics of the zebra musselDreissena polymorpha in lakes III. Metabolism and net growth efficiency

Oxygen consumption and ammonia excretion of the zebra musselDreissena polymorpha from 3 sites in lakes were estimated regularly over the course of 1 1/2 years at ambient temperature. They showed a pronounced annual cycle, when expressed in absolute terms (at standard shell length) and in weight specific terms (at standard tissue weight). The atomic ratio of oxygen consumed to ammonia-N released (O/N ratio) was lowest in late summer at all sites (10 to 20) and highest during winter and spring (50 to > 100). The mean body weight exponent pooled from these sites was 0.78 (95% confidence interval±0.07) for the oxygen consumption rate and 0.80 (confidence interval±0.10) for the ammonia excretion rate. Both oxygen consumption and ammonia excretion were significantly correlated with the water temperature at the 2 shallow water sites, where temperature variation was most pronounced. Correlation with seston content or gonad volume were insignificant at these sites. The quotient of filtration capacity to oxygen consumption rate was about 3 times higher at the site with the poorest food conditions compared to the other sites. Net growth efficiency was highly variable; its annual average was 35 to 40 per cent and independent of locality and animal size.     

Bioenergetics of growth of a cyprinid, Phoxinus phoxinus: the effect of ration, temperature and body size on food consumption, faecal production and nitrogenous excretion

Food consumption, faecal production and nitrogen excretion by minnows, Phoxinus phoxinus , weighing 1–5.5 g were studied at five rations ranging from starvation to ad libitum and four temperatures ranging from 5 to 15°C.
The maximum rate of food consumption (C_max) was related to body weight ( W ) and temperature ( T ) by the relationship: C _max= aW^b1T^b2 . There were significant daily variations in C_max, which tended to decline over time. Absorption efficiency increased with increasing ration size and decreasing temperature. Body weight had no significant effect on the faecal production. The equation F = a C^b1e^b2 T described the relationship between faecal production ( F ), food consumption ( C ) and temperature. Ammonia-N predominated over urea-N in the excreta of most experimental fish. The proportion of urea-N in the total nitrogen excreted was generally higher at lower rations than at higher rations. Rates of nitrogen excretion increased with increased ration size and were, to a lesser extent, influenced by temperature. Body weight had no significant effect on the nitrogen excretion by feeding minnows. The equation N = a+b_lT+b₂C described the effects of food consumption and temperature on nitrogen excretion ( N ) other than urea-N excretion. The relationship between urea-N excretion ( N_u ), food consumption and temperature was described by the equation N_u= ae^b1T ((C+1) ^b 2.
On the average, 11 % of food energy was lost in faecal production and nitrogen excretion by minnows feeding on whiteworms, Enchytraeus spp.     

多鳞四须鲃耗氧率、排氨率和窒息点的初步研究

控制水温在(20±0.5)℃条件下,采用Winkler法和奈氏试剂法分别测定水中的溶氧含量和氨氮含量,通过比较流水呼吸室进、出口水中的溶解氧和氨氮含量之差以确定多鳞四须鲃(Barbodes schwanenfeldi)的耗氧率、排氨率及窒息点.结果表明,多鳞四须鲃耗氧率随体重增加而减小,关系式为Y=0.24X^-0.09(R²=0.9028);随放养密度的增大而减小,关系式为Y=-0.029X+0.3301 (R²=0.9291).排氨率随体重的增加而减小,关系式为Y=-0.0008X+0.2433 (R²=0.9817);随放养密度的增大而增加,关系式为Y=-0.050X+0.4979 (R²=0.9889).多鳞四须隹巴晚间(18:00～4:00)的耗氧率明显高于白天(6:00-1:00),排氨率则相反,白天的排氨率相对较高,表明多鳞四须鲃巴属于"昼伏夜出"型鱼类.多鳞四须啬巴的窒息点为1.2572mg·L^-1,耐氧性较差.     

温度和摄食对溪红点鲑幼鱼呼吸代谢的影响

在不同水温［(5.5±0.5) ℃、(8.5±0.5) ℃、(11.5±0.5) ℃、(14.5±0.5) ℃、(17.5±0.) ℃］条件下,分别测定了饱食和空腹状态下溪红点鲑幼鱼的耗氧率和排 氨率,分析了温度和摄食对溪红点鲑幼鱼呼吸代谢的影响.结果表明：饱食后,5个温度梯度组溪红点鲑幼鱼的耗氧率和排氨率均迅速上升,达最大值后缓慢下降,并逐渐恢复到初始水平;饱食状态下,溪红点鲑幼鱼耗氧率（OR）和排氨率（NR）与温度（t）的回归方程分别为OR=-0.0601t⁴+2.5542t³-39.256t²+276.26t-598.75(n=650,R²=1,4.5 ℃4+0.0826t³-1.2318t²+8.6186t-18.838(n=650,R²=1,4.5 ℃0.9738(n=650,R²=0.9974,4.5 ℃1.0896( n=650,R²=0.9977,4.5 ℃相似文献   

温度和盐度突变对菲律宾蛤仔斑马蛤耗氧率和排氨率的影响

为研究温度和盐度对蛤仔新品种斑马蛤耗氧排氨的影响,以野生蛤仔为对照,实验设置15、20、25、30和35℃五个温度梯度和20、25、30、35和40五个盐度梯度,结果表明:温度和盐度对斑马蛤的耗氧率和排氨率影响显著（P < 0.05）。在温度15-35℃内,随着温度的增加,耗氧率和排氨率整体上呈增加的趋势。在20-40盐度内,耗氧率随着盐度的升高先减少后增加,排氨率随着盐度的升高先增加后减少,在盐度为30时达到最高值。在水温为15℃,盐度20-40内,斑马蛤的O:N为9.534-62.008;在盐度为35,水温在15-35℃内,斑马蛤的O:N是20.700-74.138。与野生蛤仔比较,斑马蛤的耐高温能力要强于野生蛤仔,从Q₁₀的变化反映出斑马蛤对温度的敏感性相对较弱,适应温度变化的能力比较强;斑马蛤的耐低盐和耐高盐能力强于野生蛤仔。研究结果为进一步完善蛤仔斑马蛤的人工养殖技术提供参考。     

Ammonia-nitrogen excretion in Daphnia pulex

Ammonia-nitrogen excretion rates were measured in natural summer and cultured populations of Daphnia pulex from Silver Lake, Clay County, Minnesota, USA during 1973. The mean rate of ammonia-nitrogen excretion for the summer populations was 0.20 µg N animal^–1 day^–1 or 5.11 µg N mg^–1 dry body weight day^–1 (N = 80) measured at 15°, 20°, and 25°C. These rates appear to be temperature and weight dependent, but they are probably affected by factors other than temperature and dry body weight. Ammonia-nitrogen excretion rates of Daphnia pulex cultured on Chlamydomonas reinhardi yielded the following relationship with temperature: Log₁₀E = (0.061) T 1.773, where E is µg N animal^–1 day^–1 and T is temperature °C. The ammonia-nitrogen excretion on a mg^–1 dry body weight day^–1 basis was related to temperature according to the following similar expression Log₁₀E = (0.043) T + 0.153, where E is µg N mg^–1 dry body weight day^–1, and T is temperature °C. The length-weight relationship of Daphnia pulex for the summer populations (N = 1583) was log₁₀W = (0.526) Log₁₀L + 1.357, where W is weight in µg and L is length in mm.     

卵形鲳鲹幼鱼耗氧率和排氨率的初步研究

运用封闭流水式实验方法对不同体重和放养密度的卵形鲳鲹(Trachinoms ovatus)幼鱼耗氧率和排氨率进行了初步的研究。结果表明,卵形鲳鲹幼鱼的耗氧率随着鱼体重的增加而逐渐下降,排氨率总体上也呈降低的趋势,体重对卵形鲳鲹耗氧率、排氨率的影响均达到显著水平(P0.05);光照对卵形鲳鲹幼鱼的耗氧率和排氨率影响非常显著(P0.01),幼鱼在遮光条件下的耗氧率和排氨率分别比在自然光照条件下要低25.18%～40.76%和16.28%～40.28%;随着放养密度的增加,卵形鲳鲹幼鱼的耗氧率逐渐降低,排氨率随着密度的增加呈先上升后下降的趋势,放养密度对卵形鲳鲹耗氧率、排氨率的影响均达到显著水平(P0.05)。卵形鲳鲹的耗氧率和排氨率具有明显的昼夜变化,白天的耗氧率和排氨率均高于夜间值,耗氧率的低谷值为高峰值的69.68%,排氨率的低谷值为高峰值的30.91%。卵形鲳鲹幼鱼的窒息点溶解氧含量为(0.991±0.058)mg/L。     

Oxygen consumption and ammonia excretion rates in Octopus maya,loligo forbesi and Lolliguncula brevis (Mollusca: Cephalopoda)

Oxygen consumption and ammonia excretion rates were investigated in young Octopus maya (hatching to 139 days old; 0.11–81.23 g wet body weight, BW; 22.5–23.9°C), young squids of Loligo forbesi (hatching to 45 days old; 9.4–115.3 mg BW; 12.3–13.1°C) and young squids of Lolliguncula brevis (2.00–39.98 g BW; 23.8–24.7°C). Except at hatching, oxygen consumption and ammonia excretion rates on an individual basis (M) of these three cephalopods increased linearly with increasing body weight (BW) expressed as M = aBW^b . Values of b for oxygen consumption were 0.900, 0.910 and 0.848 and for ammonia excretion were 0.744, 0.809 and 0.751 for O. maya, L. forbesi and L. brevis, respectively. Among the three species the value a varied widely, while b was similar for both oxygen consumption and ammonia excretion rates. Based upon these data, metabolism for hatchlings of O. maya and L. forbesi was estimated to be relatively lower than that of older juveniles. The O/N ratios for hatchlings of O. maya and L. forbesi were relatively high and indicate an apparent dependence upon lipids in the immediate post‐hatching period, followed by standard protein energy utilization thereafter.