半胱胺对猪生长性能、胴体品质和肉质的影响

半胱胺作为生长抑素(SS)抑制剂,可有效降低体内生长抑素,促进动物生长,是一种较好的通过神经内分泌途径调控动物生长的生理调节剂。文章综述了近年来半胱胺对猪生长性能、胴体品质和肉质的研究进展。     

THIS ARTICLE HAS BEEN RETRACTED Exergy as an ecological application used in the recovery process of benthic communities

Exergy, the thermodynamic function that represents the distance of an open system from equilibrium, is proposed as an ecological indicator for summarizing the complex dynamics occurring in a disturbed community during its recovery processes. These complex dynamics can be difficult to capture by using classical indices. In this study, we sampled macrobenthos using the BACI scheme (before versus after; control versus impact) in tidal wetlands of west Chongming Island, China, an area that has been disturbed by ecological engineering measures. Exergy storage is estimated for benthic communities. The control area is proposed as dynamic reference for estimating local exergy storage of the benthic community. Three different methods were used for estimating exergy on the basis of coefficients: (a) taken for taxa groups; (b) estimated from coding genes given for broad taxonomic groups; and (c) estimated from genome size taken as close as possible to the taxonomic level of the species, providing a basis for inferring similarities. We found a decrease of local exergy content in the disturbed area 9 days after the disturbance. Subsequently, the reference exergy of the benthic community increased (i.e. in the surrounding control area) in accordance with the proposed hypothesis regarding the dynamics of exergy storage during a system's development. Estimates of local exergy arrived at using the three methods provided comparable results. Based on this, we then discuss the feasibility of using the more readily available genome size data for estimating exergy. This result may have important implications for broader application of this indicator to biological systems. Moreover, the adjacent control samples seem to represent an appropriate dynamic reference for estimating the local exergy of disturbed communities. We found that exergy was a useful indicator that integrates the processes underlying the recovery of the benthic community after disturbance.     

Isolation and Identification of a Variant Porcine Epidemic Diarrhea Virus and the Immune Efficacy of Its Inactivated Vaccine

This study was aimed to isolate a mutant strain of porcine epidemic diarrhea virus and prepare a PEDV inactivated vaccine with high valence by suspension culture process for immunizing against PEDV effectively in China.200 small intestines and theirs contents of diarrhea piglets died of diarrhea,collected from many large-scale pig farms in China,were detected by RT-PCR and sequenced,a mutant strain of porcine epidemic diarrhea virus was selected and put on the suspension-cultured Vero cells in a 2 L reactor for virus isolation and continuous cell culture,the harvested virus suspension,which was identified and determined TCID₅₀,was inactivated by formaldehyde and mixed with aluminum hydroxide gel adjuvant to prepare PEDV inactivated vaccine.After its physical behavior,stability viscosity,sterility test were checked out,the safety and immune efficacy were studied by immunizing the pregnant pigs and theirs piglets.The results were as follows:86 samples were detected positive in 200 samples,cytopathy occurred after the mutant strain samples screened were passaged to 5th generation,the virus suspension was harvested in 10th generation and identified as a mutant strain of PEDV,named PEDV-GF10 strain.The virus titer of harvested virus suspension was measured up to 1×10^8.0 TCID₅₀/mL after concentrated.After the vaccine was checked out,the sows,40 and 25 days before delivery in experimental groups,were injected into Xuehai acupoint with 4 mL vaccine and the pigs in blank group were free of immunifications.The results showed that there were no obvious differences in the production status of the sows in experimental groups and blank group and the temperature of theirs 3-day-old healthy piglets injected different doses of vaccine,and the vaccine was safe to the sows and piglets.Forty 3-day-old piglets producted by pregnant sows in experimental groups and blank group were randomly selected and taken 4 mL 1×10^8.0TCID₅₀/mL F10 virus culture.The PEDV morbidity of piglets in blank group was 100% after injection and the antibodies were negative;10% piglets in blank group had mild diarrhea symptoms,the protection rate was up to 90%,antibody of passive immunity in piglets lasted for more than 35 days.Virus titer of mutant strain of PEDV-GF10 improved a lot by suspension cell culture,the PEDV-GF10 inactivated vaccine was safe,and could effectively prevent and control the variation strain of PEDV in China.     

马传染性贫血病毒驴白细胞弱毒疫苗株囊膜基因的优化及其DNA疫苗体外瞬时表达研究

马传染性贫血病毒(Equine infectious anemia virus,EIAV)的密码子使用频率与哺乳动物间存在着明显差异。为此,对马传染性贫血病毒驴白细胞弱毒疫苗株(DLA-EIAV)囊膜全长基因按照哺乳动物优势密码子的使用原则进行了重新设计和合成,并以此为基础通过重叠延伸PCR、限制酶切等方法得到结合型和分泌型囊膜基因,将其插入含有鸡beta-actin/兔beta-globin复合启动子(AG)的高效表达载体pCAGGS中,构建了EIAV驴白细胞弱毒疫苗株结合型和分泌型囊膜基因的DNA疫苗质粒pCAGGS-opti-bou-env、pCAGGS- opti-sec-env。将构建的质粒纯化后分别转染293T细胞,以间接免疫荧光和Western blot方法检测转染48 h后细胞及上清中囊膜蛋白的表达。结果显示,两种表达质粒均可正确表达EIAV囊膜蛋白,与相对应未优化的表达载体pCAGGS-wt-bou-env和pCAGGS-wt-sec—env相比,密码子优化的基因体外瞬时表达水平有极为显著的提高,而且蛋白表达部位也与预期的结果符合。这一结果为EIAV囊膜蛋白的单抗制备、表位鉴定、免疫试验、新疫苗的开发等奠定了基础。     

马γ-干扰素成熟蛋白基因在大肠埃希氏茵中表达及其多克隆抗体制备

采用RT-PCR从ConA刺激的马外周血单核细胞（PBMC）中扩增获得含信号肽的马γ-干扰素（Equine interferon-γ，EIFN-γ）基因，将其克隆至载体pCR2．1-TOPO中。通过PCR方法从重组质粒（pCR-EIFN-γ）中扩增马干扰素成熟蛋白（MatureEIFN-γ，mEIFN-γ）基因，并将其亚克隆至原核表达载体pET-28a（＋）。重组子经测序鉴定正确后转化至大肠杆菌BL21（DE3），经IPTG诱导，对其产物进行SDS-PAGE分析和Western blot鉴定，将纯化后的表达产物免疫新西兰白兔制备多克隆抗体。结果表明，mEIFN-γ基因全长为441b口，含一个开放阅读框，编码146个氨基酸的成熟蛋白；对其表达产物以可溶性和包涵体两种形式存在，重组蛋白相对分子量约为18Ku，且具有免疫反应活性。mEIFN-γ基因在大肠杆菌中高效表达并在非变性和变性条件下，采用Ni^＋亲和层析纯化方法均可获得高纯度的重组马γ-干扰素制备的多克隆抗体，为建立马γ-干扰素检测方法、监测机体免疫状态和研究机体免疫机制奠定了基础。     

PCV2感染性分子克隆的制备及体内外感染性试验

将猪圆环病毒2型（Type2 porcine circovirus，PCV2）JXL株cDNA插入到载体pMD18-T中，获得的pMDT-PCV转染猪肾细胞PK15细胞系，盲传4代后，利用PCV2阳性猪血清进行间接免疫荧光抗体试验（IFA），能检测到特异性荧光。将pMDT-PCV质粒DNA腹股沟淋巴结注射40日龄仔猪2头，分别接种2、3次，接种剂量500μg／次，首次注射35d心脏放血致死。在体内感染性试验期间，动物未出现明显临床症状。试验结束，病理切片结果显示，不同淋巴组织中分别存在淋巴细胞缺失或增多的现象；肾小球、扁桃体、空肠淋巴结和股前淋巴结等冰冻组织切片中存在大量PCV2病毒抗原；血清中PCV2特异性的ELISA抗体效价迭1：2560，IFA效价为1：1280；通过聚合酶链式反应（PCR）可以分别从体外感染PK15细胞和体内感染动物及同圈饲养的空白对照猪的淋巴组织中扩增到病毒特异性基因片段。本研究证明含有单拷贝PCV2的重组质粒pMDT—PCV在体内、外均具有感染性，能衍生出病毒，并产生符合自然感染PCV2的大体病变和组织病理学变化，并激发较强的体液免癌应答。     

猪链球菌对红霉素耐药性的研究

从发病猪体内分离、鉴定猪链球菌，采用肉汤稀释法和纸片琼脂扩散法筛选对红霉素耐药的猪链球菌，用双纸片法确定耐药株的耐药表型，通过聚合酶链反应检测对红霉素耐药的基因ermb/mefA。猪链球菌对红霉素的耐药表型为cMLS表型，即同时对克林霉素耐药。在3株红霉素耐药株中扩增到ermb基因，其余未能检测到ermb或mefA基因。     

菜薹无蜡粉性状遗传规律初探

菜薹（Brassica campestris L. ssp.chinensis var.utilis Tsen et Lee）又称菜心,是广东乃至华南地区主要蔬菜之一.其商品品质重要性状之一是叶和薹无蜡粉有光泽.本试验初步研究了菜薹蜡粉性状的遗传规律.     

Effects of mitochondrial ATP-sensitive potassium channel opener and hypoxic preconditioning on the hyperpolarization-activated current of sinoatrial node cells in neonatal rats

AIM: To compare the effects of hypoxic preconditioning (HP) and mitochondrial ATP-sensitive potassium (K_ATP) channel opener pretreatment on the hyperpolarization-activated current (I_f) in sinoatrial node cells.METHODS: Sinoatrial node cells were randomized to five groups: ① Control;②Hypoxia/reoxygenation (H/R);③ HP;④ Diazoxide (mitochondrial K_ATP channel opener)+H/R;⑤ 5-HD (mitochondrial K_ATP channel blocker)+HP.At the end of the experiment, I_f was recorded by whole-cell patch clamp technology.RESULTS: ①H/R significantly enhanced the current densities of I_f, shifted the current activation curve to more positive value by changing the half-activation voltage from (-98.9±2.4)mV to (-85.2±2.5) mV (P＜0.01).② Both diazoxide pretreatment and HP remarkably reduced the augmented current density caused by H/R and shifted the current activation curve to more negative value by changing the half-activation voltage to (-90.7±5.0) mV (P＜0.01) and (-92.2±1.9) mV (P＜0.01).③ 5-HD pretreatment blocked the effects of HP and reversed the half-activation voltage to (-86.3±2.7) mV (P＜0.01).CONCLUSION: The study demonstrates that both mitochondrial K_ATP channel opener pretreatment and HP make current density and kinetics of I_f to approach normal level and to maintain electrophysiological stability of sinoatrial node cells during H/R.     

FAD-dependent sulfhydryl oxidase activity of augmenter of liver regeneration protein and its activity motif

AIM:To establish a sensitive and effective method to determine whether augmenter of liver regeneration protein (ALRp) has the activity of sulfhydryl oxidase.METHODS:The cysteine at the position of 65 in CXXC motif contained in ALRp was changed into alanine through site-directed mutation.There were four groups in the experiment:① ALR group;② ALR-FAD group;③Mutated ALR-FAD group;④ Control group.Using GSH as substrate,at different time points,the concentration of thiol in each group was measured.RESULTS:The concentration of thiol groups in the ALR-FAD group was decreased during the time of the experiment.But the thiol in the other groups didn’t show any significant decrease.CONCLUSION:A sensitive and effective method to determine the sulfhydryl oxidase activity of ALRp was established.ALRp is a FAD-dependent sulfhydryl oxidase,and the conserved CXXC motif is indispensable to ALRp.