Small-scale spatial variability of selected soil biological properties

A strategy for sampling soil from intact monolith lysimeters was established based on measurements of spatial heterogeneity within the lysimeter area. This was part of an ongoing study to determine relationships between soil microbial diversity and nutrient loss by leaching. The sampling protocol had to allow collection of soil on a regular basis (as opposed to destructive sampling) and ensure high spatial independence of subsamples. On each of the two sites (one developed under organic crop management and the other under conventional crop management), ten 15 cm soil cores (sampling points) were taken from three areas (replicates) of 50 cm diameter (lysimeter surface area) and separately analysed for biotic (microbial biomass carbon and nitrogen; arginine deaminase activity) and abiotic (total carbon and nitrogen) soil properties. The data were tested for variability, expressed as coefficient of variance (biotic and abiotic), and spatial heterogeneity using geostatistics (biotic properties). The biotic soil properties showed significant differences among sampling points, whereas the abiotic parameters were useful in differentiating on a larger scale, i.e. between sites. For all soil properties tested, the differences among the replicates were smaller than those between the sites or among points indicating that, in the main experiment, all treatments can be sampled following the same pattern. Geostatistical analysis and fitting of an exponential model showed that a spatial structure exists in the biotic soil properties and that the samples are independent beyond separation distances of 25-30 cm. A revised sampling pattern consisting of 11 samples per lysimeter is described.     

Long-term effects of different inorganic pollutants on nitrogen transformations in a sandy cambisol

Summary Long-term effects of 12 inorganic pollutants on N transformations were studied in a sandy cambisol. As, Be, Br, Cd, Cr, F, Pb, Hg, Se, Sn, and V were added to the soil as inorganic salts in 1975 and 1976. Soil samples were taken in 1984 to determine total N mineralisation and nitrification. All pollutants except Se and Sn inhibited N mineralisation. The most toxic elements under investigation were Be and Hg. Nitrification was reduced to a lower degree than total N mineralisation. As, Be, Cd, Cr, F, Pb, Se, and Sn failed to inhibit this process at all. It is assumed that nitrifying bacteria became adapted to these pollutants in the course of time. The arginine-ammonification method was less sensitive in detecting the effects of pollutants on N transformation than the N mineralisation test.     

鳖赖氨酸和精氨酸拮抗研究

选体重为14 38±0 38g健康稚鳖45只,平均分成3组,分别为1、2、3组,在试验的0～15d和16～45d分别饲喂含赖氨酸为2 62%、4 33%、5 33%,2 62%、5 33%、8 05%的等能等氮半合成饵料,饵料精氨酸为2 85%。结果表明:处理对增重、饵料系数、肝重、体蛋白沉积、体蛋白净沉积率和肝精氨酸酶活性没有显著影响(P>0 05),但是第3组体蛋白中精氨酸和组氨酸含量、赖氨酸沉积效率、精氨酸沉积效率和肝蛋白精氨酸含量极显著或显著下降(P<0 01或0 05),体脂肪沉积极显著增加(P<0 01)。说明:鳖高赖氨酸/精氨酸对生产性能和体蛋白沉积没有影响,但影响体蛋白和肝蛋白中精氨酸含量和沉积效率,发现有拮抗现象。     

Supplemental l-Arginine Shortens Gestation Length and Increases Mare Uterine Blood Flow before and after Parturition

Supplementing diets with l-Arginine (Arg) improves female reproductive performance and reproductive blood flow in other species. The objectives of this study were to investigate uterine artery blood flow changes before and after parturition, and evaluate blood flow in Arg supplemented and control mares by Doppler ultrasonography. Sixteen light-horse mares began Doppler ultrasonography evaluation, 21 days before expected foaling date (EFD) and continued until day 7 postparturition. The mares under treatment (n = 8) were supplemented with 100 g Arg, once daily, beginning with 21 days before EFD. Blood flow measurements were calculated as pulsatility index (PI) and resistance index (RI) for both uterine arteries, either ipsilateral or contralateral; to uterine horn of established pregnancy; defined gravid uterine artery (GUA) and non-gravid uterine artery (NGUA), respectively. The mares under treatment had a shorter gestation length (337 ± 1.7 days) as compared to control (345 ± 2.1 days; P ≤ .05). No differences in gestation length were observed between groups when examined by age, parity, EFD, or sex of foal. Both GUA and NGUA uterine artery diameter decreased from the day before parturition to day 7 after parturition (P ≤ .001). During this time period, both PI and RI increased (P ≤ .01); indicating less blood flow. A treatment effect was observed with Arginine-treated mares having greater blood flow prepartum in the NGUA (P ≤ .001) and postpartum in the GUA (P ≤ .05), for both indices. The data demonstrated that supplementing mares with Arg shortened gestation length and increased uterine arterial blood flow before and after parturition.     

Role of endogenous arginine vasopressin in tonic thermoregulatory processes in rats during the light phase

AIM: To determine the role of endogenous arginine vasopressin (AVP) in tonic thermoregulatory processes in rats during the light phase. METHODS: The core temperature (Tc) and temperature in brown adipose tissue (BAT) were simultaneously measured by telemetry in adult male Sprague-Dawley rats at an ambient temperature of 22 °C during a 12-h light/12-h dark photoperiod. At 10:00,the rats were intraperitoneally injected with V_1a vasopressin receptor antagonist (30 μg/kg) or AVP (10 μg/kg). Plasma AVP concentration was measured by an enzyme-linked immunosorbant assay during the light phase and dark phase. Serum triglyceride, free fatty acid and glycerol were measured 60 min after AVP treatment. Grooming activities were also observed at 10-min intervals after AVP treatment. RESULTS: V_1a vasopressin receptor antagonist elevated the Tc and BAT temperature during the light period. The plasma AVP level was significantly elevated when Tc and BAT temperature decreased during the light phase. Intraperitoneal injection of AVP elicited rapid drop in Tc concomitant with a marked decrease in BAT temperature, and also increased grooming behavior in the rats. Intraperitoneal injection of AVP produced a decrease in serum free fatty acid and glycerol, and an increase in serum triglyceride. CONCLUSION: Endogenous AVP, acting through V_1a vasopressin receptor, is involved in tonic thermoregulatory processes in male rats during the light phase because plasma AVP concentration is higher during light period than that during dark period, and V_1a vasopressin receptor antagonist elevates the Tc and BAT temperature. AVP decreases BAT temperature, serum free fatty acid and glycerol, and increases grooming behavior, suggesting that the mechanism of AVP-induced hypothermia is involved in suppression of lipolysis, decrease in BAT thermogenesis and increase in heat loss.     

精氨酸对胎鼠宫内生长迟缓的影响

通过探讨日粮添加精氨酸（Arg）对胎鼠宫内生长迟缓的影响,为Arg应用在动物生产上提供理论基础。试验将120只雌性小白鼠随机分为6组：0．0％Arg组、0．25％Arg组（基础日粮添加0．25％Arg,下同）、0．5％Arg组、0．75％Arg组、1．0％Arg组、1．5％Arg组,试验期间各组自由采食和饮水。每组随机抽取10只孕鼠进行眼球摘除采血,颈椎脱臼处死孕鼠,剖腹取胎鼠、胎盘和子宫,分别称重,记录胎鼠数、胎儿宫内发育迟缓（IUGR）数、死胎数（含吸收胎数）、胎鼠重、子宫重和相应的胎盘重。结果：（1）所添加的Arg浓度对孕鼠无毒性作用;（2）与对照组相比,日粮添加0．5％Arg可降低死胎率达54．70％（P〈0．05）,从而极显著提高胎鼠数（P〈0．01）;（3）日粮中添加0．5％ArgIUGR率比对照组降低了约64．9％（P〈0．05）。结论：日粮添加精氨酸可以降低死胎率和IUGR率,提高胎鼠数和胎鼠重。     

花生幼苗内精氨酸脱羧酶的初步研究

花生体内控制多胺生物合成的主要酶是ＡＤＣ，主要定位于代谢活跃的分生组织内。部分纯化（１３倍）的酶最适底物是Ｌ－Ａｒｇ，Ｋｍ值和Ｖｍａｘ依次为０．５６ｍｍｏｌ／Ｌ、０．６６μｌＣＯ２／ｍｇ ｐｒｏｔｅｉｎ．ｍｉｎ。反应最适ｐＨ和温度为８￣８．５和４０￣４５℃。该酶对热、乙醇、脲稳定性差。０．８ｍｍｏｌ／Ｌ ＰＬＰ（磷酸吡哆醛）可提高酶活性２１％，ＤＴＴ（二硫苏糖醇）、ＭＥ（颈基乙醇）提高酶的稳定性，     

Arginine Intake and Carbohydrate to Lipid Ratios Affect Gene Expression of Anabolic Hormones in Largemouth Bass,Micropterus Sahnoides

Nutritional factors influence regulation of growth hormone （GH）, insulin-like growth factor-Ⅰ （IGF-Ⅰ） and insulin （INS） in fish. But so far there are no published studies describing how single indispensable amino acids and different carbohydrate to lipid ratios influence those systems. Therefore, the present study aimed to evaluate whether arginine （Arg） intake and carbohydrate to lipid ratios would affect expression of GH, IGF-Ⅰ and INS in largemouth bass.