One-step RT-PCR for the Detection of Infectious Bursal Disease Virus in Clinical Samples

A single-tube, non-interrupted, one-step RT-PCR has been standardized to amplify the hypervariable region of the VP2 gene sequence of infectious bursal disease virus (IBDV). The technique standardized on purified viral RNA was successfully applied to the detection of the virus directly in clinical samples. The amplified products were confirmed to be IBDV specific by their size in ethidium bromide-stained agarose gel, nested PCR and restriction enzyme digestion. Digestion of the amplicons with StyI restriction enzyme also differentiated classical virus from six very virulent field isolates. The sensitivity of the one-step RT-PCR was found to be 0.2 pg of viral RNA.     

Tyrosine Ameliorates Some of the Clinical,Biochemical and Haematological Effects of Acute Stress Associated with Transportation of Desert Sheep

We studied some clinical, biochemical and haematological variables in Desert (Najdi) sheep acutely stressed in the course of individual road transportation, and the influence thereon of pretreatment with tyrosine. Transportation for 30 min resulted in variable but statistically insignificant increases in heart, pulse and respiratory rates. It also caused significant increases in the plasma concentration of cortisol (from 43.5 to 101.7 mmol/L) and glucose (from 3.1 to 4.5 mmol/L), and a decrease in that of magnesium (from 0.85 to 0.72 mmol/L). The endogenous thiocyanate level was unaffected. The transportation stress also decreased the haematocrit (PCV) and the number of lymphocytes, and increased the concentration of haemoglobin. Pretreatment of sheep with tyrosine at a dose of 100 mg/kg by the intravenous route significantly ameliorated the stress-induced clinical, biochemical and haematological changes. The treatment caused no overt adverse effects.     

加强交通运输网络建设,促进柴达木地区发展

柴达木地区是我国 2 1世纪实现可持续发展重要的战略资源接替重点地区 ,也是西部大开发战略实施的重点建设地区。区域现代交通运输网络已初步形成 ,但远不能满足和保障大开发战略实施和可持续发展的需要 ,需要在未来的发展中继续加强交通运输设施建设 ,并实现适度“超前”发展 ,进一步提高各类运输方式的等级和质量 ,特别是铁路运输、管道运输的建设与发展     

一种溶质运移数学模型的应用研究

土壤中溶质运移的过程、规律和机理是土壤溶质运移研究的主要内容。本文的目的是对模拟非饱和介质中水分和溶质迁移的二维数值模型SWMS－2D进行研究和验证。以硝酸盐形式存在的溶解氮是地下水中最常见的污染物，将硝态氮视为土壤溶质，考虑其根系吸收、生物固持、吸附、解吸、硝化和反硝化等作用，土壤表面即上边界条件用大气边界条件描述，下边界条件定为第一类边界条件，在田间条件下对模型作了检验。     

A Universal `One-tube' RT-PCR Protocol for Amplifying Isolates of Bovine Viral Diarrhoea Virus

The increase in the knowledge of the genetic variability of BVDV and the identification of some of the genetic determinants of its pathogenicity require robust and practical tools for rapid molecular characterization of the various genotypes of this virus. This study was undertaken to develop a standard protocol for RT-PCR that allows the amplification of various parts of the genome of BVDV without the need for optimizing each individual reaction. The reaction set-up is very flexible because it consists of two pre-mixes. These are a master mix, with all the required reagents except the desired primers, which are the components of the second pre-mix and are therefore easily interchangeable between the different reactions. After adding any primer-containing pre-mix to the fixed master mix, a non-interrupted cycling protocol led to the generation of amplicons of up to 4 kbp in size in amounts sufficient for subsequent sequencing reactions. The method was applied to five different regions of the BVDV genome: (i) the well-known 5-UTR to differentiate genotypes I and II; (ii) the entire E2 gene, or an approximately 550 bp region within the E2 gene, in order to find the molecular equivalent of antigenic varieties; (iii) the entire structural protein coding region covering the Npro, capsid, E ^RNS, E1 and E2 genes; (iv) a 2.1 kbp region embracing the NS2/3 junction which is known to be cleaved in cytopathic biotypes of BVDV; and (v) the region covering the entire NS4B and NS5A/B genes. All six RT-PCRs were successfully applied using (i) primers with lengths of between 20 and 52 nucleotides, (ii) an aliquot of RNA extracted from either 10⁶ infected bovine embryonal lung cells or the same number of leukocytes from viraemic cattle, and (iii) all the genotype I and II strains of BVDV tested. The technique described was used to generate various Sindbis virus/BVDV recombinants. The correct processing of the amplicon-derived E2 glycoprotein of BVDV strain PT810 was demonstrated by its reaction with a monoclonal antibody in an immunofluorescence assay. Given the variety of RT-PCRs tested, we conclude that this universal protocol may be useful with other RNA viruses.     

An experimental study of hypercholesterolemia-induced disorder of Oddi's sphincter

AIM:To investigate the functional changes and histopathological basis of Oddi’s sphincter under hypercholesterolemia. METHODS:Twenty - four New Zealand rabbits were equally divided into be groups ran- domly. Experimental groups Ⅰ and Ⅱ fed with cholesterol - added forage for 4 and 8 weeks respectively before sacri- ficed. Images, functions and histopathological characteristics of Oddi’s sphincters of experimental groups were studied and compared with control group by cholangiography, catheter manometry, and quantitative analysis of nitric oxide synthase. RESULTS: The hasal pressures of proximal low - pressure segment of Oddi’s sphincter of hath experimen- tal groups Ⅰand Ⅱ (20.9±6.1 mmHg, 25 .6±9.1 mmHg, respectively) were higher than those of control group sig- nificantly (11.7±2.8 mmHg, P < 0.01, P < 0.01 ). The hasal pressures of distal high - pressure "valve" segment of both experimental pops (138 .4±45. 5 mmHg and 144. 5 ±40 .4 mmHg, respectively) were significantly higher than those of coned group (69.3±9.8 mmHg, P < 0.01 and P<0.01). The gallbladder volUmes of experimental group Ⅰ and Ⅱ (3.4±1.0 mL and 3.9±1.9 mL) were significantly larger than those of control group (2.0 ±1.9 mL, P < 0.05 and P < 0.01 ). Between groups there were no significant differences in nitric oxide synthase con- tents. Enlargement of the cell volume, wavy distortion of the cell membrane, loosening and disarrangement of myofila- ment, uneven in size and distribution of dense body, angulation of longitudinal axis between dense body and myofila- ment, swelling, congregated at one end of nucleoulus and disappearance of cristae of plasmosomes and concertration of chromosome at nucleolus margin were observed in experimental groups under electron-microscope. CONCLUSION: The diastole function of Oddi’s sphincter could be damaged by hyperecholesterolemia, inducing a functional disorder of Oddi’s sphincter with increased resistance in bile excretion. The result is retertion of bile in the gallbladder.     

二花脸仔猪在运输过程中的行为特征和血浆皮质醇水平的变化

本试验采用实时跟踪摄像和颈静脉血管瘘连续采样,观察二花脸断奶仔猪在2h运输过程中的行为表现,并测定血浆皮质醇水平的动态变化。结果表明:运输前期(出发后15min)仔猪的探究行为和异常行为发生次数较多且持续时间较长,运输中期(出发后60~75min)此类行为显著减少(P<0.05),而到运输后期(最后15min)几乎观察不到此类行为;仔猪的躺卧行为在运输前期和中期发生次数较少,持续时间较短,而在运输后期仔猪大部分时间都处于躺卧状态(P<0.05);运输至中期仔猪大部分时间处于站立状态,而到运输后期站立行为显著减少(P<0.05);仔猪蹲坐行为发生的次数和持续时间在运输的前中后无显著差异(P>0.05)。仔猪上车后皮质醇水平迅速上升(P<0.05),出发15min升至峰值,且保持该高水平直到2h运输结束,下车后15min皮质醇水平迅速下降至上车前15min的基础水平。     

Transport of nutrients and electrolytes across the intestinal wall in pigs

In recent years, intestinal transport processes have been studied in detail regarding both, functional and structural aspects. For monosaccharides different systems have been demonstrated for apical uptake: this includes the high-affinity SGLT1 as a distinct d-glucose system and GLUT5 for fructose. Specifically in pigs a low affinity, high-capacity system for d-glucose and d-mannose with no preference for Na⁺ over K⁺ and a very low affinity system are suggested as further uptake systems. As in other species, basolateral extrusion is mediated by GLUT2. The distributions of monosaccharide transport along the gastrointestinal axis as well as the potential role of paracellular monosaccharide absorption have not yet been clarified.

Amino acids can principally be absorbed by the paracellular and transcellular pathway whereas transcellular transport can either be mediated by facilitated diffusion or secondary active Na⁺-coupled transport. This includes different transport systems for neutral, anionic and cationic acids. In addition, the presence of the di-/tripeptides transport system PEPT1 which depends on an inwardly directed H⁺-gradient has also been confirmed for the pig small intestine, its quantitative proportion is still under debate.

Short chain fatty acids (SCFA) are the major end products of microbial carbohydrate fermentation which occurs along the gastrointestinal tract with the highest production rates in the large intestines. At least two uptake mechanisms have to be assumed, i.e., non-ionic diffusion and anionic exchange via SCFA⁻/HCO₃⁻-exchange. Controversial views still exist to what extent SCFA are metabolized within the epithelial tissue.

Segmental differences between small and large intestines have been demonstrated for Na⁺ absorption. Whereas in the small intestines the major part of Na⁺ absorption is mediated by coupled nutrient transport systems, aldosterone sensitive Na⁺ channels and Na⁺/H⁺-exchange are the dominant mechanisms in the hindgut. For Cl⁻ paracellular transport and anionic Cl⁻/HCO₃⁻-exchange are the major absorptive mechanisms. Cl⁻ secretion is mediated by apical channels which may be activated by toxins of different origin. Different types of Cl⁻ channels have been identified, such as Cystic Fibrosis Transmembrane Regulator (CFTR), Ca-activated Cl⁻ channels (CLCA) and Outwardly Rectifying Cl⁻ Channels (ORCC). Whereas CFTR has clearly been shown for jejunal and colonic epithelial and goblet cells controversy still exists on the relevance of CLCA and ORCC in pigs.

For Ca²⁺ there is evidence that both recently published channels TRPV5 and TRPV6 are also expressed in pig intestinal tissues, however, this has not yet been shown on protein level. From several functional approaches it was demonstrated that phosphate uptake can be mediated by both, a Na⁺-dependent transcellular component and paracellularly. On a molecular basis it is uncertain whether the transport protein of transcellular mechanism belongs to the NaPi-IIb cotransporter family.     

新西兰鹿的福利及实施措施

新西兰鹿业协会为加大鹿及鹿产品在国际市场上的竞争力,积极实施鹿福利制度。文中主要介绍了新西兰在鹿的运输、锯茸及饲养管理等方面所实施的具体福利措施。