IGF2荧光定量PCR方法建立及其在中外猪胚胎骨骼肌中的表达

胰岛素样生长因子2（IGF2）基因对骨骼肌的生长发育起着非常重要的调控作用。实验建立了猪IGF2基因的SYBR-Green荧光定量PCR方法,并利用此方法分析该基因在通城猪（脂肪型）和长白猪（瘦肉型）妊娠33、65和90d胚胎骨骼肌中的表达。结果表明,建立的SYBR-Green荧光定量方法可以有效地用于IGF2的表达分析。IGF2基因在两品种中都以妊娠65d时表达水平最高,呈波浪式表达模式。在所研究的3个胚胎时期,IGF2的表达在通城猪中均高于长白猪。     

猪MYL4基因的克隆及其在猪胚胎骨骼肌中的表达分析

克隆了猪(Sus scrota)MYL4基因的cDNA序列,并利用生物信息学方法进行验证.所得cDNA序列全长1105 bp,包含1个完整的开放阅读框,编码197个氨基酸.序列分析表明,该基因与已报道的狗(Canis lupus familiaris)、人(Homo sapiens)、黑猩猩(Pan troglodytes)和恒河猴(Macaca mulatta)等物种的MYL4基因高度同源,氨基酸序列同源性分别为98.4%、95.9%、95.4%和95.4%.该基因编码的蛋白具有EFH和FRQ1保守功能域.荧光定量分析该基因在猪胚胎骨骼肌(妊娠33、65和90d)中的表达,发现MYL4基因在通城猪和长白猪中呈波浪式表达模式,在妊娠第33天时中外猪品种间无显著差异,但在第65和90天时长白猪中显著高于通城猪.     

猪MYL4基因的克隆及其在猪胚胎骨骼肌中的差异表达分析

克隆了猪MYL4基因的cDNA序列,并利用生物信息学方法进行验证。所得cDNA序列全长1105bp,包含一个完整的开放阅读框,编码197个氨基酸。序列分析表明,该基因与已报道的狗、人、黑猩猩和恒河猴等物种的MYL4基因高度同源,氨基酸序列同源性分别为98.4%、95.9%、95.4%和95.4%。该基因编码的蛋白具有EFH和FRQ1保守功能域。荧光定量分析该基因在猪胚胎骨骼肌（妊娠33 、65 和90 天）中的表达规律,发现MYL4基因在通城猪和长白猪中呈波浪式表达模式,在妊娠第33 天时中外猪品种间无显著差异,但在65 和90 天时长白猪中显著高于通城猪。     

猪胚胎干细胞培养、分离和传代

摘要:利用五指山小型猪近交系不同发育阶段的早期胚胎为材料，探索猪胚胎干细胞(embryonic stem cells,ES)培养、分离、传代的影响因素，以选择猪胚胎干细胞建系的适宜条件。收集五指山猪第5～10 d胚胎(配种当天记为0 d)，以 STO细胞[STO细胞是来自SIM小鼠(S)胚胎对硫代鸟嘌呤(thioguanine,T)和乌本苷(ouabain,O)有抗性的成纤维细胞系]为饲养层，分别采用两种培养液: 杜氏培养液(Dulbecco's modified eagle medium ，DMEM) + 10%胎牛血清（fetal bovine serum，FBS）+ 10 %新生牛血清（newborn bovine serum，NBS）+1 000 IU/mL白血病抑制因子（leukemia inhibitory factor，LIF）+ 30 ng/mL干细胞生长因子（stem cell growth factor , SCF）+20 ng/mL碱性成纤维细胞生长因子(basic fibroblast growth factor ，bFGF)或DMEM + 10% NBS + 10% FBS + 1 000 IU/mL LIF + 30 ng/mL SCF。比较发现，培养液中是否加入bFGF对胚胎干细胞的培养无显著影响；实验共收集胚胎124枚，其中D5～6胚胎18枚，胚胎贴壁率为68.8% ，内细胞团出现率为6.3% ，未能传代；收集D7孵化囊胚27枚，贴壁率为100% ，内细胞团出现率为38.9% ，传代1次失败；D9胚胎18枚，贴壁率为100%，传代后ES细胞生长较缓慢；收集D10胚胎52枚，胚胎贴壁率为100%，传代率为100%，传代后可出现ES细胞克隆点；实验过程中比较了胚径对干细胞培养的影响，发现胚径越大，培养效果越好，胚径大于100μm,分离ICM后出现干细胞集落成功率达100%，并得到了AP染色呈阳性的传4代的ES细胞集落。     

猪骨骼肌NDUFS7基因的克隆、染色体定位和表达谱分析

摘要：本研究用辐射杂种克隆板对猪的NDUFS7基因进行了染色体的物理定位，克隆了该基因的完整CDS序列，用相关软件进行了基因结构和功能的预测，并用半定量RT-PCR技术分析了NDUFS7基因在猪的11种组织以及在33天、65天、90天胚胎和成年猪的骨骼肌中的表达情况。分析结果首次将NDUFS7基因定位于猪的2号染色体２q21-q24， 与标记 SW395紧密连锁。该基因的CDS全长648bp，编码215个氨基酸，预测编码的产物具有一个高度保守的与能量生成有关的NouB结构域和３个酶的磷酸化位点。同时，RT-PCR结果显示，NDUFS7基因在猪的11种组织中均有表达，但表达量有差异；在不同发育阶段的骨骼肌中，65天和90天胚胎时的表达量较高，而33天胚胎和成年猪的表达量相对较低。     

猪背膘组织二脂酰甘油酰基转移酶基因(DGAT1和DGAT2)的发育性表达分析

酰基辅酶A:二脂酰甘油酰基转移酶(acyl-coA:diacylglycerol acyltransferase,DGAT)是催化甘油三酯合成最后一步反应的关键酶,包括DGAT1和DGAT2两种;阐明其在发育过程中的表达规律对于找到控制中外猪种脂肪沉积能力差异的基因十分必要.本研究分别用RT-PCR和实时荧光定量RT-PCR的方法分别对莱芜猪和杜洛克3日龄仔猪和成年猪背膘组织中DGAT1和DGAT2 mRNA表达量进行了分析.结果表明,莱芜猪和杜洛克成年猪DGAT1 mRNA的表达量均高于3日龄仔猪,分别为5.0倍和2.7倍;成年猪DGAT2 mRNA表达量高于3日龄仔猪,分别为27.6倍(P＜0.01)和4.8倍(P＜0.05).两品种成年猪和3日龄仔猪DGAT2基因表达量的变化均高于DGAT1.品种间同一发育时期比较,杜洛克3日龄仔猪背膘组织中DGAT2基因的表达量高于莱芜猪,但成年莱芜猪背膘组织中DGAT2基因的表达量高于杜洛克,差异均不显著(P＞0.05).提示DGAT2基因可能与中外猪品种脂肪沉积能力的差异有关.     

实时荧光定量PCR技术在转基因猪生长激素基因差异表达中的应用

为确定猪生长激素基因(pGH)在F1代转基因猪体内的遗传稳定性及其在育肥初期表达水平的差异,利用SYBRGreenⅠReal-time PCR法检测精子介导纳米基因载体法获得的F0代母猪与非转基因公猪配种所产的7头转pGH基因猪和9头非转基因猪3月龄生长激素的表达水平。根据16个血液样品荧光定量结果绘制溶解曲线和扩增曲线图谱,并用F=(1+E)﹣ΔΔCt,公式进行Ct均值的分析,得出F1代转pGH基因猪生长激素平均表达水平是同期非转基因猪的1.77倍。结果证实,1)外源pGH基因在转基因猪体内能稳定传代;2)并非每头转基因猪体内pGH基因的表达量均高于非转基因猪;3)在F1代转基因猪体内,pGH的平均表达水平显著高于同期非转基因猪。本实验建立了能够稳定测评家猪生长激素相对基因表达水平的方法,为研究转基因与非转基因动物之间生理指标与定量表达的差异性等提供了科学依据。     

西农萨能羊胰岛素诱导基因2(INSIG2)的克隆及组织表达分析

胰岛素诱导基因2(insulin induced gene2,INSIG2)是参与脂质形成和代谢调控的重要基因,而山羊乳腺中脂质合成和代谢与乳品质密切相关。为进一步明确它们之间的关系进而为改善山羊乳品风味提供科学支持。本实验以西农萨能羊(Capra hircus)乳腺组织为研究材料,采用RT-PCR技术克隆山羊INSIG2基因,并采用实时荧光定量(RT-qPCR)技术在山羊10个组织中对INSIG2基因进行了组织表达分析。研究获得了915bp的cDNA序列(GenBank登录号:JQ361767),其中编码区678bp,该基因编码225个氨基酸,预测蛋白质分子量为24.8730kD,等电点(pI)为8.77。通过核苷酸和氨基酸序列比对分析发现,山羊的INSIG2与GenBank中牛(Bos taurus)的相似性最高。蛋白质结构分析显示,INSIG2存在6个跨膜螺旋;疏水性分析发现,其N端和C端均具有亲水性;遗传距离分析发现,山羊与牛的亲缘关系最近,其次是猪(Susscrofa)。INSIG2基因的组织表达分析表明,INSIG2基因在10个被检测组织中均有表达,且肺组织中表达量最高,肌肉次之,乳腺组织的表达量居中,心脏组织中最低。研究结果为该基因在山羊乳腺组织中的功能研究提供依据。     

莱芜猪和杜洛克猪心脏脂肪酸结合蛋白基因(H-FABP) 表达差异和肉质性状的关系

肌内脂肪(Intramuscular fat,IMF)含量是猪肉品质的一个主要的决定因子,心脏脂肪酸结合蛋白基因(heart fatty-acid-binding protein,H-FABP)是影响肌内脂肪含量的候选基因(Gerbens et al.,2001),本研究利用荧光定量RT-PCR方法.以遗传基础相距较远、肌内脂肪含量差异较大的莱芜猪和杜洛克猪为研究对象,对该基因在两品种背最长肌中的表达及与肌内脂肪等肉质性状相关关系进行了初步研究.     

经改造的猪IGF-I基因在巴斯德毕赤酵母中的分泌表达

采用酵母偏爱密码子合成五条编码猪IGF-I基因的引物，利用重叠PCR技术拼接获得长度为210bp的猪IGF-I成熟蛋白基因。将该基因插入分泌表达载体pPIC9K中，转化巴斯德毕赤酵母菌。经表型鉴定、PCR分析及G418筛选得到Muts型多拷贝整合菌，以1.5%甲醇诱导培养后，经SDS-PAGE检测表达产物，在7.5 kDa处出现一特异蛋白条带，目的蛋白表达量达410mg/L。Dot blot检测表明，重组蛋白可与抗IGF-I多克隆抗体反应。     

Stereospecific analysis of phospholipid classes in skeletal muscle from rats fed different fat sources

The fatty acid (FA) and dimethylacetal profiles of the sn-1 and sn-2 positions of different phospholipid (PL) classes from skeletal muscle of rats as affected by dietary FA profiles were studied. Rats were fed either a control diet, an olive oil-enriched diet, or a sunflower oil-enriched diet. The FA composition of both positions of the studied PL classes was affected by diet to different extents. The FA composition of the sn-2 position of phosphatidylserine was the most influenced by diet, while phosphatidylinositol was less affected by dietary modification. The FA profile of phosphatidylcholine reflected consumed FA better than any other studied PL. Thus, olive oil rats showed higher oleic acid (C18:1 n-9) contents in both positions of phosphatidylcholine, and sunflower oil rats had higher proportions of arachidonic acid (C20:4 n-6) in the sn-1 position of this PL class. Dimethylacetals were scarcely affected by diet, and only the dimethylacetal composition of phosphatidylethanolamine showed significant modifications.     

Effect of tea catechins on regulation of antioxidant enzyme expression in H2O2-induced skeletal muscle cells of goat in vitro

Skeletal muscle cells (SMCs) of goats were stress induced with 1 mM H(2)O(2) in the absence or presence of 0.5, 5, and 50 μg/mL tea catechins (TCs) incubation. Cells were harvested at 48 h postincubation with TCs to investigate the effects of TCs on cell proliferation, cell membrane integrity, antioxidant enzyme activities, and antioxidant enzyme genes and protein expression levels. Results showed that H(2)O(2) induction inhibited cell proliferation with or without TC incubation; moreover, the inhibition effect was enhanced in the presence of TCs (P < 0.001). H(2)O(2)-induced stress increased the lactate dehydrogenase (LDH) activity in the absence or presence of TC incubation, but concentrations of TCs, less than 5 μg/mL, showed protective functions against LDH leakage than in other H(2)O(2)-induced treatments. The catalase (CAT) activity increased when SMCs were stress induced with H(2)O(2) in the absence or presence of TC incubation (P < 0.001). H(2)O(2)-induced stress decreased CuZn superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GPx) activities, whereas this effect was prevented by incubation with TCs in a concentration-dependent manner. H(2)O(2)-induced stress with or without TC incubation had significant effects on mRNA and protein expression levels of CAT, CuZn-SOD, and GPx (P < 0.001). CAT and CuZn-SOD mRNA expression levels were increased by different concentrations of TC incubation, and this tendency was basically consistent with corresponding protein expression levels. The GPx mRNA expression level increased with a low concentration of TCs but decreased with concentrations greater than 5 μg/mL of TCs, whereas GPx protein expression in all TC-incubated groups was lower than in the control treatment. The current findings imply that TCs had an inhibitory effect on cell proliferation and enhanced damage to the cell membrane integrity, but TCs affected antioxidant status in SMCs by modulating antioxidant enzyme activities at mRNA and protein expression levels.     

Cloning and expression of the XPR2 gene from Yarrowia lipolytica in Pichia pastoris

Yarrowia lipolytica is a dimorphic yeast able to secrete different types of proteases depending on the pH of the environment. At neutral pH, the production of an extracellular alkaline protease (AEP) is induced. This protease could be useful in the leather, detergent, or food industries. The XPR2 gene, coding for AEP, was extracted from the pINA154 vector and cloned into the pHIL-D2 vector to obtain a new protease-producing recombinant Pichia pastoris strain. The gene was efficiently integrated in the P. pastoris genome and expressed from the AOX1 promoter actively induced by methanol. Finally, the protease was successfully secreted by P. pastoris GS115.     

Interactions of soluble peptides and proteins from skeletal muscle on the release of volatile compounds

The ability of skeletal dipeptides (carnosine and anserine) and a sarcoplasmic protein (myoglobin) to interact with key flavor compounds (hexanal, octanal, methional, 2-pentanone, 2-methylbutanal, and 3-methylbutanal) has been studied using the solid phase microextraction (SPME) technique. Conditions for SPME analysis (fiber coating, sampling time, and linearity of detection) were optimized. The effect of pH on the binding was also investigated. Thermodynamic models were applied to evaluate the binding parameters n (number of binding sites), K (affinity constant), and DeltaG (Gibb's free energy) to all of the flavor compounds studied, and they showed an absence of cooperative effect. Carnosine was the peptide with the highest affinity for all of the volatile compounds except 2-pentanone. Its interaction with hexanal and methional was significantly affected by pH. Anserine showed a lower level of interactions with hexanal, methional, 2-methylbutanal, and 3-methylbutanal, whereas myoglobin interacted with only hexanal and 2-methylbutanal. Differences in aroma retention can thus result in different sensory perceptions of muscle foods.     

Purification and biochemical properties of dipeptidyl peptidase I from porcine skeletal muscle

Dipeptidyl peptidase I (DPP I; EC 3.4.14.1) was purified from porcine skeletal muscle after several steps such as heat treatment, ammonium sulfate fractionation, gel filtration chromatography, and HPLC anion exchange chromatography. The purified enzyme showed a native molecular mass of approximately 200 kDa on Sephacryl S-200 column chromatography. Two protein bands of 65 and 42 kDa were obtained by SDS-PAGE, indicating its oligomeric nature. Maximum activity was reached at pH 5.5 and 55 degrees C. DPP I shared some common substrate specificities, both on synthetic derivatives and on real peptides, with porcine muscle DPP III. The enzyme required reducing agents for full activation, although the halide requirement was not proved. DPP I was inhibited by the assayed cysteine peptidase inhibitors except p-CMB. The serine peptidase inhibitor 3, 4-DCI also inhibited the enzyme as did the divalent cations Co(2+), Mn(2+), and Zn(2+). On the basis of its properties, DPP I may contribute to the generation of dipeptides during the processing of meat and/or meat products, including cooked ham.     

糖蜜酒精废液蔗渣吸附发酵产物饲喂生长肥育猪的效果研究

选择平均体重约3 0 kg的杜长大三元杂交断奶仔猪70头,随机分成对照组和试验 、 、 、 组,进行为期86d (生长期3 3 d,肥育期5 3 d)的饲养试验。试验处理为:对照组全期饲粮不用糖蜜酒精废液蔗渣吸附发酵产物( MABFP) ,试验 、 、 、 组生长期饲粮分别使用2 %、4%、6%和8%的MABFP;肥育期饲粮分别使用4%、8%、1 2 %和1 6%的MABFP。每期的试验组和对照组均为等能等蛋白质饲粮。饲养试验结果表明:生长期,试验各组的日增重和饲料效率与对照组无显著差异( P>0 .0 5 ) ;肥育期,试验 、组日增重与对照组无显著差异( P>0 .0 5 ) , 、 组日增重低于对照组( P<0 .0 5 ) ;肥育期以及试验全期各试验组饲料效率有所降低。血清生化指标及胴体品质的分析结果表明:生长肥育猪饲粮使用MABFP,对猪血清生化指标、组织器官生理功能、肉猪胴体指标和猪肉品质等无不良影响。综上所述,MABFP可做生长肥育猪配合饲料的原料,建议其用量以6%～8%为宜,同时注意适当补充必需氨基酸     

Effect of oxidation on in vitro digestibility of skeletal muscle myofibrillar proteins

The objective of this study was to investigate the effect of chemical oxidation on myofibrillar protein digestibility. Myofibrils were prepared from pig M. longissimus dorsi and oxidized by a hydroxyl radical generating system. Oxidative modifications of proteins were assessed by the carbonyl content, surface hydrophobicity, electrophoresis, and immunoblotting. Oxidized or nonoxidized myofibrillar proteins were then exposed to proteases of the digestive tract (pepsin, trypsin, and alpha-chymotrypsin). Results showed a direct and quantitative relationship between protein damages by hydroxyl radical and loss of protein digestibility.