绿原酸对凡纳滨对虾抗氧化系统及抗低盐度胁迫的影响

对绿原酸调节凡纳滨对虾(Litopenaeus vannamei)血淋巴抗氧化系统功能及抗低盐度胁迫的效果进行了评价。360尾凡纳滨对虾随机分为4组,分别投喂含有0、100、200和400 mg/kg绿原酸的饲料28 d,随后将对虾从盐度为32的天然海水直接转入至盐度为10的水中胁迫72 h。结果表明,在正常养殖条件下,绿原酸对凡纳滨对虾的成活率、血淋巴总抗氧化能力(Total antioxidative capacity, T-AOC)、超氧化物歧化酶(Superoxide dismutase, SOD)及过氧化氢酶(Catalase, CAT)活力均无明显影响,然而投喂含有绿原酸的饲料14 d,对虾血淋巴谷胱甘肽过氧化物酶(Glutathione peroxidase, GPx)活性和血淋巴细胞GPx和CAT基因表达水平均显著高于对照组(P<0.05);低盐度胁迫24 h,绿原酸组凡纳滨对虾的存活率较对照组提高10%,但各组之间无显著性差异(P>0.05);低盐度胁迫24 h,各组凡纳滨对虾血淋巴T-AOC、SOD和GPx活性与胁迫前相比均显著增加,说明低盐度胁迫条件下机体产生了抗氧化胁迫反应,同时绿原酸组对虾血淋巴GPx、CAT活性均显著高于对照组(P<0.05);低盐度胁迫72 h,绿原酸组对虾血淋巴T-AOC、GPx和CAT活性和血淋巴细胞GPx和CAT基因表达水平均明显高于对照组。上述结果表明绿原酸可有效调节凡纳滨对虾的抗氧化系统功能,增强对虾对于低盐度胁迫下的适应能力。     

蝇蛆蛋白粉对凡纳滨对虾生长的影响

设计了4种实验饲料(ABCD)并进行了8周饲养试验来评定添加蝇蛆粉对凡纳滨对虾生长性能的影响.以实用饲料D作为对照组,ABC是在D的基础上,分别以5%,10%和15%的蝇蛆粉替代鱼粉.养殖试验结束后,分别计算体长、全长和背甲宽等生长性能.实验结果显示,AB组凡纳滨对虾的生长性能与对照组差异不显著(P>0.05).C组与对照组差异极显著(P<0.01).结果表明,饲料中添加适量的蝇蛆蛋白粉对凡纳滨对虾有一定的促生长作用,可用适量的蝇蛆蛋白粉替代对虾配合饲料中的部分鱼粉.     

凡纳滨对虾低盐度高产虾池环境微生物生态研究

对广东珠三角地区,凡纳滨对虾低盐度高产虾池环境微生物调查结果,养殖水体异养菌平均数量为5.15×10⁴cfu·mL^-1,致病性弧菌为5.00×10³cfu·mL^-1,池底泥浆中异养细菌平均数量为2.41×10⁶cfu·mL^-1,致病性弧菌为1.45×10⁵cfu·mL^-1。不同虾池异养细菌的数量差别小而稳定,致病性弧菌的数量差别及波动大。淤泥较深的老化虾池,水体和泥浆中异养细菌平均分别为6.10×10⁴cfu·mL^-1和2.89×10⁶cfu·mL^-1,致病性弧菌为6.00×10³cfu·mL^-1和2.14×10⁵cfu·mL^-1;无淤泥虾池水体和泥浆中异养细菌平均分别为4.53×10⁴cfu·mL^-1和2.08×10⁶cfu·mL^-1,致病性弧菌为4.34×10³cfu·mL^-1和9.86×10⁴cfu·mL^-1。老化虾池底泥致病性弧菌明显偏高,成为老化虾池易爆发虾病的重要原因。低盐度虾池水体异养菌和致病性弧菌的数量变化,表现为养殖前期高,中后期低而稳定;池底泥浆中异养菌和致病性弧菌的数量变化,呈不规则波动。高的养殖水温对养殖环境异养菌和致病性弧菌表现抑制作用,养殖环境微生物与水体浮游藻类也有一定的关系。     

环境因子对凡纳滨对虾性别分化的影响

通过外部形态观察和组织学连续切片,探讨温度[(251)℃、(291)℃和(331)℃]、光照周期(6L∶18D、12L∶12D、18L∶6D和24L∶0D)、光照强度(800、3000和5000 lx)、盐度(10、20、30和40)和环境雌激素壬基酚(40、80和120g/L)对凡纳滨对虾仔虾性别分化的影响。结果表明:温度和光照对凡纳滨对虾性别比例无显著影响(P0.05),但显著地影响性分化时间;10、20和40盐度组以及120g/L的壬基酚处理组的凡纳滨对虾雌雄比分别为0.81∶1,0.67∶1,1.29∶1和1.24∶1,显著偏离1∶1的性别比例,且盐度和壬基酚处理也影响性腺分化时间。此外,凡纳滨对虾触鞭长与体长之比1.0时与其性腺及外部形态分化时期相一致,提示可以将触鞭长与体长之比1.0作为判定凡纳滨对虾性分化开始的指标。     

凡纳滨对虾红体病病原

2001年7月辽宁省盘锦市大洼对虾养殖厂凡纳滨对虾大面积暴发红体病。主要表现为全身发红,活动减弱,食欲减退,壳变硬,死亡率高等。本研究从患红体病的凡纳滨对虾肌肉组织中分离到三株优势菌,经回归感染证实其中一株为引发本次凡纳滨对虾红体病的病原菌,编号为0107。对该菌进行了生理生化鉴定和16SrRNA基因序列同源性分析,将其判定为副溶血弧菌(V.parahaemolyticus)。药敏实验结果显示,该菌对头孢哌酮、头孢曲松等多种抗生素敏感,对氨苄西林、青霉素等抗生素不敏感。     

低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活和全虾氨基酸组成的影响

研究旨在探讨低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活以及全虾氨基酸组成的影响。试验选取初始体重为(2.000.01) g对虾960尾, 随机分成6组, 每组4个重复。各组分别投喂含40.79%粗蛋白质的高蛋白基础饲料(HT0)、含37.01%粗蛋白质的低蛋白基础饲料并添加0 (LT0)、1.20(LT1)、2.50 (LT2)、5.00 (LT3)和10.00 (LT4)g/kg色氨酸的6种饲料。饲养56d后采样、分析蛋白酶活和全虾氨基酸组成; 在此基础上投喂含0.04%三氧化二钇(Y2O3)的相应饲料进行消化率试验。结果表明:低蛋白质饲料中添加色氨酸可提高对虾蛋白质、氨基酸、干物质、能量的表观消化率, 蛋白酶活和影响全虾氨基酸组成(P0.05)。LT3、LT4粗蛋白质表观消化率显著高于LT0(P0.05)。LT3蛋氨酸表观消化率显著高于LT0, LT3酪氨酸表观消化率显著高于HT0 (P0.05)。LT3和LT4干物质表观消化率显著高于LT0 (P0.05)。LT1、LT2、LT3和LT4总能表观消化率均高于LT0, 但仅LT4达显著水平(P0.05)。LT2肠蛋白酶活最高, 并显著高于HT0和LT1 (P0.05), LT2、LT3、LT4肝胰腺蛋白酶活显著高于LT0 (P0.05), 但与HT0相比无明显差异(P0.05)。LT4全虾天门冬氨酸、甘氨酸、丙氨酸、蛋氨酸、亮氨酸含量均明显高于LT0 (P0.05)。LT1全虾赖氨酸含量显著高于LT0 (P0.05)。由此可见, 低蛋白质饲料中添加色氨酸可明显提高凡纳滨对虾饲料蛋白质、氨基酸、干物质和能量的表观消化率、蛋白酶活, 并改善全虾氨基酸的组成。     

维生素C对凡纳滨对虾生长及抗病力的影响

以不同水平维生素C 2 磷酸酯 (添加量分别为 0、75、15 0、30 0和 6 0 0mg/kg)的饲料喂养凡纳滨对虾 10周 ,研究维生素C 2 磷酸酯对凡纳滨对虾生长及抗病力的影响。结果显示 :在养殖前 4周 ,饲料中添加维生素C 2 磷酸酯显著促进凡纳滨对虾的生长 ,然而对对虾的成活以及饲料利用不产生影响 (P >0 0 5 ) ;而到实验后期添加维生素C 2 磷酸酯不能促进凡纳滨对虾的生长 ,却显著提高凡纳滨对虾的成活率 (P <0 0 5 )。维生素C 2 磷酸酯对对虾体水分、脂肪、蛋白质和维生素C在肝胰脏中的积累量的影响显著 (P <0 0 5 ) ,对对虾体灰分影响不显著 (P >0 0 5 )。维生素C 2 磷酸酯对对虾血清中超氧化物歧化酶活力无显著影响 ,饲料中未添加维生素C或过量添加 (超过 30 0mg/kg饲料 )均导致血清中酚氧化酶活力、血细胞总数和溶菌酶活力的显著下降。以生长、成活和酚氧化酶活力为指标 ,饲料中维生素C 2 磷酸酯的适宜添加量为 15 0mg/kg。     

鸡肉粉完全替代鱼粉饲料中补充包被氨基酸对凡纳滨对虾生长、体成分及组织氨基酸含量的影响

为了探讨鸡肉粉完全替代鱼粉时饲料氨基酸的平衡性以及外源氨基酸的添加方式与凡纳滨对虾生长、体成分、血浆游离氨基酸及肌肉氨基酸含量的关系, 本试验采用26因子试验设计进行了为期56d的饲养试验。2个饲料蛋白质水平分别为40%和32%, 6个饲料处理分别为鱼粉组(对照组)、鸡肉粉组、鸡肉粉+晶体EAA组、鸡肉粉+晶体EAA+晶体NEAA组、鸡肉粉+包被EAA组、鸡肉粉+包被EAA+包被NEAA组, 配制12组饲料。将凡纳滨对虾(0.300.01) g随机分配到36个圆桶(150 L)中, 每桶30尾, 每3个桶为一个处理组, 饲喂一种饲料, 每天饱食投喂三次。在每一饲料蛋白质水平下, 无论是补充晶体氨基酸(CAA)组还是包被氨基酸组对虾的增重率均显著高于鸡肉粉组(P0.05), 且在32%蛋白质水平下, 包被EAA组对虾增重率达到了鱼粉组水平(P0.05); 补充晶体EAA+NEAA组对虾增重率与补充晶体EAA组无差异(P0.05), 但均显著低于补充包被氨基酸组(P0.05); 补充包被EAA组对虾增重率显著高于补充包被EAA+NEAA组(P0.05)。饲料系数的变化正好与增重率变化相反(P0.05)。饲喂高蛋白质水平饲料较之饲喂低蛋白质饲料明显提高对虾增重率、虾体蛋白含量(P0.05), 但降低虾体脂肪含量(P0.05)。包被氨基酸组凡纳滨对虾血浆游离氨基酸含量总体显著低于CAA组(P0.05)。除谷氨酸、甘氨酸以及脯氨酸外, 各组对虾肌肉氨基酸含量无显著差异(P0.05)。结果表明, 在32%饲料蛋白质水平下, 用鸡肉粉完全替代鱼粉时, 饲料中补充包被EAA可明显促进凡纳滨对虾的生长, 且达到了鱼粉组的饲喂效果。     

亚硝酸盐氮对凡纳滨对虾毒性和抗病相关因子影响

用常规生物毒性实验方法,在不同盐度下进行亚硝酸盐氮对凡纳滨对虾的急性毒性实验;并加亚硝酸盐氮于凡纳滨对虾的养殖环境中,检测与抗病力相关因子的变化。研究亚硝酸盐氮对凡纳滨对虾的毒性和抗病力相关因子的影响。结果表明:盐度对亚硝酸盐氮的毒性有较大影响。盐度为31时,24hLC50、48hLC50、72hLC50和96hLC50分别为314.9mg/L1、75.3mg/L1、00.2mg/L和89.0mg/L;盐度为17时,分别为132.3mg/L、65.6mg/L、51.3mg/L和39.5mg/L。盐度31实验组的亚硝酸盐氮半致死浓度均显著(P<0.05)高于盐度17实验组。在低盐度条件下亚硝酸盐氮的毒性较强。亚硝酸盐氮对凡纳滨对虾抗病力相关因子有显著的影响。亚硝酸盐氮浓度为4.0mg/L和8.0mg/L时,其血细胞数、超氧化物歧化酶(SOD)活力、酚氧化酶(PO)活力、抗菌活力(Ua)、溶菌活力(UL)和血清蛋白含量均显著(P<0.05)低于对照组;不吸污组抗病力相关因子活性均显著(P<0.05)低于吸污组。低浓度的亚硝酸盐氮可降低凡纳滨对虾抗病能力,亚硝酸盐氮浓度越高,其抗病能力越弱。     

Protein and free amino acids in wheat grain as affected by soil types and salinity levels in irrigation water

Summary The effects of four lysimeter soil series under three salinity levels were evaluated for grain yield, wt/1000 seeds, protein, and amino acids in Mexican dwarf wheat (Triticum aestivum L. var. Cajeme 71). The soil series consisted of: Holtville clay loam, Greenfield sandy loam, San Emigdio sandy loam, and Altamont clay loam. The irrigation water salinity levels were designated: low –2.2 mmho, medium –4.2 mmho, and high –7.1 mmho.No significant differences were found in the amount of grain harvested or wt/1000 seeds in the 1976 crop produced on the differential soil series. The yield of the 1977 crop was significantly affected by the soil types.Effects of soil type on the protein amino acids in the grain in both years were similar. Significantly higher protein amino acid levels of histidine, arginine, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine were found in the grain grown on Altamont clay loam soil than the other types.The free amino acids in grain from the 1976 and 1977 crops were similarly affected by the soil types, except that the quantitative values of the free amino acids were substantially lower in 1977 than in 1976. The free amino acids significantly influenced by soil types were tryptophane, lysine, arginine, aspartic acid, threonine, serine, glycine, alanine, valine, isoleucine, tyrosine, and phenylalanine. In both years' crops, the sum of the free amino acid fractions was significantly higher in the grain produced on the Altamont soil than on the other soils.Salinity level in the irrigation water did not affect the 1976 crop yield or wt/1000 seeds. Although yields of the 1977 crop were significantly reduced by salinity, the wt/1000 seeds was not. The sum of protein amino acids was significantly higher in the 1976 and 1977 grain crops irrigated with high salinity water than in low salinity irrigated crops.An increased salinity irrigation water significantly reduced the sum of free amino acid fractions in the 1976 grain crop. Since some of the free amino acids in the 1977 grain crop increased while the others decreased due to the salinity level in the irrigation water, the sum of the free amino acid fractions was not significantly influenced.Significant interactions were found between soil types and salinity levels on free arginine, threonine, serine, glutamic acid, and alanine, and also on the sum of the free amino acids in the 1976 wheat grain. In the 1977 wheat grain, there were significant interactions between soil types and salinity levels on the free glutamic acid, valine, leucine, tyrosine, and phenylalanine, and on protein serine, glutamic acid, glycine, alanine, and the sum of the protein amino acids.The amounts of essential amino acids expressed as mg of amino acid/g of protein were not affected by the soil types or salinity levels. With the exception of lysine, and possibly threonine and methionine plus cystine, the essential amino acids were present in the grain at concentrations equal to or greater than recommended by WHO and FAO.     

基于氨基酸分类的基本氨基酸秩序的研究

在分析了基本氛基酸分类的基础上,提出基本氛基酸存在着一种参考排列秩序,以此固定的氛基酸排列秩序为参考标准,分析蛋白质一级结构相对此参考秩序的变化规律,能够找到构成蛋白质的二级结构的某些信息．     

Impact of separating amino acids between plasma, extracellular and intracellular compartments on estimating protein synthesis in rodents

Summary. Three models representing different separations of amino acid sources were used to simulate experimental specific radioactivity data and to predict protein fractional synthesis rate (FSR). Data were from a pulse dose of ¹⁴C-U Leu given to a non-growing 20 g mouse and a flooding dose of ³H Phe given to a non-growing 200 g rat. Protein synthesis rates estimated using the combined extracellular and intracellular (Ec + Ic) source pool and extracellular and plasma (Ec + Pls) source pool mouse models were 78 and 120% d⁻¹ in liver, 14 and 16% d⁻¹ in brain and 15 and 14% d⁻¹ in muscle. Predicted protein synthesis rates using the Ec + Ic, Ec + Ic + Tr (combined extracellular, intracellular and aminoacyl tRNA source pool) and Ec + Pls rat models were 57, 3.4 and 57% d⁻¹ in gastrocnemius, 58, 71 and 62% d⁻¹ in gut, 8.3, 8.4 and 7.9% d⁻¹ in heart, 32, 23 and 25% d⁻¹ in kidney, 160, 90 and 80% d⁻¹ in liver, 57, 5.5 and 57% d⁻¹ in soleus and 56, 3.4 and 57% d⁻¹ in tibialis. The Ec + Ic + Tr model underestimated protein synthesis rates in mouse tissues (5.0, 27 and 2.5% d⁻¹ for brain, liver and muscle) and rat muscles (3.4, 5.5 and 3.4% d⁻¹ for gastrocnemius, soleus and tibialis). The Ec + Pls model predicted the mouse pulse dose data best and the Ec + Ic model predicted the rat flooding dose data best. Model predictions of FSR imply that identification and separation of the source specific radioactivity is critical to accurately estimate FSR. Received June 11, 2000 Accepted September 26, 2000     

Comparative study on microwave and conventional methods for protein hydrolysis in food

Summary A rapid microwave hydrolysis procedure was developed for amino acid determination in food. The hydrolysis was performed with 6M HCl in sealed vessels using a microwave digestion system.Bovine Serum Albumin was chosen as a model protein to compare its theoric amino acid sequence with the experimental results obtained after hydrolysis by both the traditional oven heating and the microwave methods. Furthermore the selected microwave methods were carried out on different food matrices (cheese and durum wheat) and the obtained data were compared with the traditional method results.This comparative study shows that the rapid microwave hydrolysis is as accurate and precise as the traditional hydrolysis for determining amino acids in food.These results were presented at the Third International Congress on Amino Acids, Vienna, August 23–27th, 1993.     

Amino acid flooding doses for measuring rates of protein synthesis

Summary The development, advantages and disadvantages of using the amino acid flooding dose technique to determinein vivo rates of protein synthesis are examined in this review. A discussion of the use of this procedure in animals greater than 5 kg is included. The flooding dose procedure reduces the disparity between isotope enrichment in different amino acid precursor pools, which should theoretically improve the precision and accuracy of protein synthesis measurements. However, the possibility must be considered that the large doses of amino acids injected or infused in conjunction with this technique may influence protein turnover due to attendant metabolic effects. Therefore, a judicious choice of an amino acid and an evaluation of the experimental parameters involved in this procedure are required to optimize the accuracy of results obtained.Scientific Paper No. 710. Agriculture Canada, Lacombe Research Station, Bag Service 5000, Lacombe, Alberta T0C 1S0.     

Source of amino acids for tRNA acylation in growing chicks

Summary Specific radioactivity in three amino acid compartments was examined in broiler chicks following a flooding dose of leucine or phenylalanine. In general, specific radioactivity of leucine and phenylalanine in deproteinated plasma (SA_e) and tissue (SA_i) compartments, exceeded that in acylated-tRNA (SA_t). In most tissues, SA_e and SA_i rapidly reached a similar peak level by 5 min followed by a slow decline for the next 30 minutes. Many tissues (eg. GI tract, liver, skin, and thigh) failed to maintain equilibrium between SA_e and SA_i over time. More metabolically active tissues, such as GI and liver had the greatest differences between these compartments. The difference between SA_e and SA_i for both leucine and phenylalanine were due to SA_i decreasing faster than SA_e, indicating dilution with unlabelled amino acids from proteolysis. Plasma and tissue specific radioactivity overestimated tRNA specific radioactivity by as much as 5 and 2.8 fold using leucine or 2.7 and 1.4 fold using phenylalanine, respectively. These data suggest that intracellular compartmentation of protein metabolism and the coupling of protein degradation and synthesis occur, in vivo.     

Use of fuzzy clustering technique and matrices to classify amino acids and its impact to Chou's pseudo amino acid composition

In this paper we present a study of classification of the 20 amino acids via a fuzzy clustering technique. In order to calculate distances among the various elements we employ two different distance functions: the Minkowski distance function and the NTV metric. In the clustering procedure we take into account several physical properties of the amino acids. We examine the effect of the number and nature of properties taken into account to the clustering procedure as a function of the degree of similarity and the distance function used. It turns out that one should use the properties that determine in the more important way the behavior of the amino acids and that the use of the appropriate metric can help in defining the separation into groups.     

The ectomycorrhizal fungus (Paxillus involutus) modulates leaf physiology of poplar towards improved salt tolerance

Ectomycorrhizas (EMs) are mutualistic associations between soil fungi and plant roots. Although the physical interaction occurs only in roots, mycorrhizas may alter the physiology of the whole plant, resulting in changes in host responses to abiotic stress. To elucidate the influence of an ectomycorrhizal fungus on leaf physiology and performance under salt stress, we analysed the levels of nutrient elements, phytohormones, carbohydrates, amino compounds and fatty acids in leaves of Populus × canescens. The poplars were cultivated either in the presence or absence of Paxillus involutus and either with or without salt stress imposed by 150 mM NaCl. Leaves of ectomycorrhizal plants displayed higher quantum yield of photochemistry (Φ_PSII), increased concentrations of phosphorus and potassium, decreased concentrations of galactose, increased concentrations of the stress metabolite γ-amino butyric acid and a lower unsaturated-to-saturated fatty acid ratios than those of non-ectomycorrhizal plants. Salt exposure of P. × canescens led to leaf chlorosis and shedding, decreases in Φ_PSII, K⁺-to-Na⁺ ratio, 9Z-hexadecenoic acid, 9Z-octadecenoic acid and unsaturated-to-saturated fatty acid ratio, and increases in ABA, glucose, fructose and some amino compounds. Under salinity leaves of ectomycorrhizal plants showed an alleviation of leaf chlorosis, improved water status, higher Φ_PSII and K⁺-to-Na⁺ ratio, less accumulation of major amino compounds and lower unsaturated-to-saturated fatty acid ratios than those of non-mycorrhizal plants. These results indicate that ectomycorrhizas attenuate salinity induced injury in leaves of P. × canescens, which may be ascribed to the improved nutrient status, osmo-regulation and changes in fatty acid composition in leaves of ectomycorrhizal plants.     

Site specificity of protein glycation

Summary The rate of nonenzymatic glycation of a protein amino group is dependent upon a number of factors, such as the accessibility to glucose molecules in solution, and local acid-base catalysis of the rearrangement of the Schiff base that is formed initially. This is illustrated by a study of the site specificity of liver alcohol dehydrogenase, in which an attempt has been made to interpret the data in terms of the three-dimensional structure of the enzyme molecule.