Establishment of the Method of Immunohistochemistry Assay for the Detection of Scrapie in Chinese Short-Tailed Han Sheep by Monoclonal Antibody

The method of immunohistochemistry assay for the detection of scrapie in Chinese Short-tailed Han sheep was established using monoclonal antibody. Genomic DNA was isolated from Chinese Short-tailed Hart sheep blood. Using the polymerase chain reaction technique, PrP27-30 gene sequence was amplified from Chinese Short-tailed Han sheep genomic DNA. By recombinant DNA technology, the recombinant protein of Chinese Short-tailed Han sheep PrP27-30 was obtained. Then, using standard methodology of myeloma cell fusion, a panel of monoclonal antibodies was generated. With mAbs, scrapie in Chinese Short-tailed Han sheep was detected by immunohistochemistry assay. The recombinant protein of Chinese Short-tailed Han sheep PrP27-30 was obtained and a panel of six hybridoma cell lines secreting specific antibodies to Chinese Short-tailed Han sheep PrP27-30 related to scrapie was obtained with one fusion between myeloma Sp2/0 and spleen ceils from mice immunized with the purified recombinant protein. Four hybridoma cell lines can be used in immunohistochemistry assay for the detection of scrapie in Chinese Short-tailed Han sheep. So that the special monoclonal antibody developed in author＇s institute can be used to detect PrP^sc of scrapie in Chinese Short-tailed Han sheep by immunohistochemistry in China.

Serum Esterase Polymorphisms and Their Associations with Prolificacy in Small Tail Han Sheep

[ Objective] The aim of this research was to provide a theoretical basis for the.breeding and identification of multiparous Small Tail Han sheep. [ Method] The polymorphisms of serum esterase （Es） locus in Small Tail Han sheep were detected by vertical discontinuous polyacrylamide gel electrophoresis （PAGE）. According to the statistical analysis of different genotypes and their litter size, the correlation between Es polymor- phisms and litter size was analyzed. [ Result] There were three genotypes in Es locus, and Es^＋- was the dominate genotype. The differences of ewe litter size in the 1 ,t parity among these three genotypes were nonsignificant （ P 〉 0.05）, As far as the 2^nd and 3rd parity was considered, the litter size of genotype Es＋＋ was significantly （P〈0.05） higher than that of Es-- and Es^＋- ; the average litter size of Es＋＋ was extremely significant （ P 〈 0.01 ） higher than that of Es - - and Es ＋ - while there was no significant difference （ P 〉 0.05） between the latter two. [ Conclusion] The Es lo- cus could be regarded as a genetic marker locus for early selection of high-yielding ewes and Es ＋＋ is the high-yielding genotype of Small Tail Han sheep.

The Levels of Genetic Differentiation of Small-Tailed Han Sheep and Tan Sheep Populations Using Structural Loci

Using the method of ＂random sampling in typical colonies of the central area of the habitat＂ and several electrophoresis techniques, the variations of 17 structural loci encoding blood proteins in 60 Small-Tailed Han sheep and 73 Tan sheep were examined and compared with those of 14 other sheep populations in China and other countries to investigate their levels of genetic differentiation. The average heterozygosities of Small-Tailed Han sheep and Tan sheep were 0.2360 and 0.2587, respectively. The average polymorphic information content values were 0.1974 and 0.2102, respectively. The average effective numbers of alleles were 1.5723 and 1.5751, respectively. The coefficients of gene differentiation in the four groups （including 4, 6, 13, and 16 sheep populations, respectively） were 0.049323, 0.059987, 0.1728, and 0.201256, respectively, indicating that the degree of gene differentiation at the structural loci was the least in Hu sheep, Tong sheep, Small-Tailed Hart sheep, and Tan sheep; followed by the above-mentioned four sheep populations and two Mongolian sheep populations; and was the highest in sheep populations belonging to the Mongolian sheep group, South Asian sheep, and European sheep. The earlier researchers＇ conclusions that both Small-Tailed Han sheep and Tan sheep evolved from Mongolian sheep were further verified by the results of this study. Hu sheep, Tong sheep, Small-Tailed Han sheep, and Tan sheep were decreasingly affected by the bloodline of Mongolian sheep to different degrees. The relationships among sheep populations were not closely related to the geographical distances among sheep populations.

Study on FSHR and LHR mRNA Levels of Different BMPRIB Genotypes of Small Tail Han Sheep During the Oestrum

The relationship between different BMPRIB genotypes of Small Tail Han sheep and FSHR and LHR mRNA levels during the oestrum was studied using semiquantitative PCR. The results indicated that FSHR mRNA extracted from the right ovary of BB （1.14±0.11） ewes showed higher levels compared with AA （0.44±0.11） and AB （0.36±0.08） ewes （P〈0.01）, and LHR mRNA extracted from the right ovary of BB （0.42±0.02） ewes showed significantly higher levels compared with AA （0.23±0.02） and AB （0.25±0.04） ewes （P〈0.01）; however, the mRNA extracted from the left ovary showed no significant difference in levels among the genotypes during the oestrum. It indicated that the fecundity induced by a mutation of BMPRIB in Small Tail Han sheep may be related to the changes of the mRNA expression of LHR and FSHR in ovary.

Polymorphism of BMPR-IB Gene and its Relationship with Litter Size in Small Tail Han Sheep

[ Objective] To open an exit for breeding high-fecundity Small Tail Han sheep according to genotypes. [ Method] By the PCR-RFLP, the polymorphism of ovine BMPR-IB gene was detected in Small Tail Han sheep of basic population and breeding population. And its relationship with litter size was analyzed. [ Result] In the basic population, the frequencies of B ＋ and BB genotypes were 77.78% and 14.81%, respectively, and their litter size per parity was 1.77 and 2.40, respectively. In the breeding population, the frequencies of B ＋ and BB genotypes were 51.79% and 40.18%, respectively, and their litter size per parity was 2.54 and 3.02, respectively. [ Conclusion] The ovine BMPR-IB gene can be used as a molecular Qenetic marker for fecundity traits to establish high-fecundity Small Tail Han sheep.

Relevance between BMPR-IB Genotypes and Litter Size in Small Tail Han Sheep

[ Objective] To detect the polymorphism of BMPR-IB gene and analyze the relevance between genotype frequency of FecB gene and litter size. [Method] Mutation sites in the BMPR-IB gene of Small Tail Hart sheep were analyzed by PCR-RFLP. [ Resluts] The percentages of individuals with BB, B ＋ and ＋ ＋ genotypes were 24.69%, 54.89% and 20.42%, respectively, and their average litter size per parity was 3.01,2.81 and 2.16, respectively. E Conclusion] The BMPR-IB gene can be used as a molecular genetic marker in fecundity traits. The FecB gene can effectively increase litter size of the Small Tail Han sheep and has additive action on litter size.

小尾寒羊不同部位风味物质与风味前体物的相关性分析

以6~7月龄、体质量为50 kg的小尾寒羊为实验对象,选取颈肉(NM)、里脊(LLDM)和腿肉(RG),对小尾寒羊挥发性风味物质、脂肪酸和氨基酸进行相关性分析。结果表明:在3个部位共检测到45种挥发性风味物质,其中醛类是最主要的挥发性风味物质,占总挥发性风味物质的50%左右。经主成分分析得知,庚醛、壬醛、苯甲醛等24种风味物质是导致不同部位间挥发性风味物质差异的主要影响因素。LLDM中对人体有益的单不饱和脂肪酸和多不饱和脂肪酸含量均为最高,脂肪酸比例更符合人体对羊肉脂肪酸营养价值的需求,对人体健康更有益。氨基酸中以谷氨酸(Glu)和赖氨酸(Lys)为主,约占总氨基酸的17%和10%,其中RG除蛋氨酸(Met)、酪氨酸(Tyr)、赖氨酸(Lys)外含量均为最高,且除谷氨酸(Glu)和脯氨酸(Pro)外与LLDM差异不显著,与NM差异均显著。相关性分析表明,多不饱和脂肪酸与大多数挥发性风味物质呈正相关,且与醛类、醇类和芳香类等挥发性风味物质呈显著正相关,这可能是因为多不饱和脂肪酸极易氧化,在氧化过程中生成醛类、醇类和芳香类等物质。氨基酸与大多数醛类和醇类都呈正相关,这可能是因为氨基酸通过转氨反应等一系列反应,最终生成醛类和醇类等物质。

国产脊髓电刺激系统在小尾寒羊植入的长期安全性和组织相容性研究

目的:验证国产脊髓电刺激(spinal cord stimulation,SCS)系统的可操作性、长期安全性和组织相容性。方法:成年雄性小尾寒羊9只,其中3只为短期植入组(S组)即SCS电极植入2周;另6只为长期植入组(L组)即SCS电极和脉冲发生器植入长达26周。观察术前(T_(0))、术后1周(T_(1))、2周(T_(2))、4周(T_(3))、8周(T_(4))、12周(T_(5))、20周(T_(6))、26周(T_(7))实验羊的行为学改变、实验室检查、设备电阻抗值、高频低频刺激情况、电极移位等,S组和L组分别于术后2周和26周取SCS周围组织行苏木精-伊红染色行病理性检查。结果:S组和L组植入SCS后运动正常。与术前相比,S组与L组的血常规、肝肾功能和凝血功能无明显变化(P>0.05)。但与术前相比,L组实验羊血糖水平在术后2、4、8、12周均明显降低(P<0.05)。术中及术后阻抗值正常,电极未见移位。刺激节段脊髓形态结构正常,未见明显坏死、水肿、缺血、炎症等病理改变。结论:国产植入式SCS系统可操作性良好,长期植入后具有良好的生物相容性和安全性,符合临床应用需求。

Comparison of Growth and Development Traits among Crossbreds of Dorset and Local Sheep Varieties in Gansu Province

In order to improve the meat production performance of local sheep varieties in Gansu Province, Dorset was introduced to crossbreed with the local sheep varieties, including Tan sheep, Small Tail Han sheep and Mongolia sheep. The offspring of different crossbreeding combinations were sampled randomly at different growth stages, and their growth and development traits were measured so as to screen out the best crossbreeding mode. The results showed that under the same crossbreeding mode, the growth rate of F3 was higher than that of F2, and of F2 was higher than that of F1. Among the F3 population, the growth rates of Dorset ×Han and Dorset × Mongolia hybrids were higher. Compared with those of Dorset ×Tan F3 hybrids, the body weights of male and female Dorset × Han and Dorset ×Mongolia F3 hybrids were increased by 5.59%, 4.40%, 5.93% and 3.76%, respectively. Among the F2 population, the growth rates of Dorset × Han and Dorset ×Mongolia hybrids were also higher. The body weights of male and female Dorset ×Han and Dorset × Mongolia F2 hybrids were higher than those of Dorset × Tan ×Han F2 hybrids by 5.99%, 3.67%, 9.80% and 5.00%, respectively. In the F1 population, the growth rates of Dorset × Han and Dorset × Mongolia hybrids were higher.Compared with those of Tan × Han F1 hybrids, the body weights of male and female Dorset × Han and Dorset × Mongolia F1 hybrids were increased by 11.32%,5.22%, 7.60% and 7.20%, respectively. Therefore, in the feeding area of Small Tai Han sheep, Mongolia sheep and Tan sheep, Dorset was the best sire for producing hybrid lambs. The economic benefit of crossbred offspring was obvious.

外源激素处理提高小尾寒羊和蒙古羊春季繁殖力的研究

旨在研究春季对小尾寒羊、蒙古羊进行同期发情与人工授精处理时,不同外源激素使用对两品种羊繁殖指标和血液生殖激素浓度的影响。挑选春季小尾寒羊、蒙古羊母羊各120只,按不同外源激素处理方法随机均分为4组,其中对照组处理方法为阴道氟孕酮海绵栓(FGA)+撤栓后即注射孕马血清促性腺激素(PMSG),试验Ⅰ组为FGA+撤栓前24 h注射PMSG,试验Ⅱ组为FGA+撤栓前24 h注射PMSG+注射促黄体素释放激素A_(3)(LHRH-A_(3)),试验Ⅲ组为FGA+撤栓前24 h注射PMSG+注射LHRH-A_(3)+稀释精液中添加催产素(OXT)。结果:试验I组与对照组相比,蒙古羊放栓第14天孕激素(P_(4))浓度显著升高(P<0.05),卵泡刺激素(FSH)浓度和发情反应率均极显著升高(P<0.01);试验Ⅱ组与试验Ⅰ组相比,小尾寒羊产羔率极显著提高(P<0.01),蒙古羊放栓第14天FSH、促性腺激素释放激素(GnRH)浓度和同期受胎率均极显著升高(P<0.01),同期妊娠率显著提高(P<0.05);试验Ⅲ组与试验Ⅱ组相比,小尾寒羊放栓第14天雌激素(E_(2))浓度和同期妊娠率均显著升高(P<0.05),蒙古羊放栓第14天FSH浓度、同期受胎率和同期妊娠率均极显著下降(P<0.01)。综上可见,试验Ⅱ组(FGA+撤栓前24 h注射PMSG+LHRH-A_(3))对于提高蒙古羊春季繁殖力效果较好,试验Ⅲ组(FGA+撤栓前24 h注射PMSG+LHRH-A_(3)+OXT)对于提高小尾寒羊繁殖力效果较好。

加味补中益气散对小尾寒羊肉品质及免疫功能的影响

试验旨在探究加味补中益气散对羊的肉品质及免疫功能的影响。选取2月龄小尾寒羊公羊羔60只,随机分为5组,每组3个重复,每个重复4只。试验组分别在基础日粮中添加1%、2%和3%的加味补中益气散,商品对照组在基础日粮中添加2%的四胃动力散,空白对照组饲喂基础日粮。预试期9 d,正式试验期107 d。结果显示,1%剂量组羊肉总脂肪酸的含量显著高于其他组(P<0.05)。与空白对照组相比,2%剂量组羊肉中风味氨基酸和正庚醛含量显著升高(P<0.05),正己醛和正壬醛的含量显著降低(P<0.05);3%剂量组羊肉中必需氨基酸、总氨基酸和1-辛烯-3-醇的含量显著提高(P<0.05),癸酸、硬脂酸含量显著降低(P<0.05)。5月龄和6月龄时,各剂量组羊血清中小反刍兽疫抗体水平显著升高(P<0.05)。研究表明,加味补中益气散可能通过影响小尾寒羊机体脂肪酸与风味氨基酸代谢来调控羊肉中膻味物质和挥发性风味物质的合成,进而改善羊肉风味,同时在一定程度上增强了肉羊的免疫力。

不同蛋白质水平饲粮对舍饲小尾寒羊公羔羊生长性能和肉品质的影响

试验为研究不同蛋白水平饲粮对舍饲小尾寒羊公羔羊生长性能和肉品质的影响,选择75只约90日龄的小尾寒羊公羔羊,随机分为试验Ⅰ组(低蛋白组,12.16%)、Ⅱ组(中蛋白组,14.04%)、Ⅲ组(高蛋白组,15.70%),每组5个重复,每个重复5只公羔羊。预试期10 d,正式试验期90 d。结果表明:试验Ⅱ组和试验Ⅲ组平均增重和平均日增重均极显著高于试验Ⅰ组(P<0.01),料重比显著低于试验Ⅰ组(P<0.05)。试验Ⅰ组的胴体重、背膘厚度显著低于试验Ⅱ组和试验Ⅲ组(P<0.05),蒸煮损失、滴水损失、亮度值和黄度值显著高于试验Ⅱ组和试验Ⅲ组(P<0.05)。试验Ⅱ组羔羊平均日收益2.47元/d,比试验Ⅰ组和试验Ⅲ组分别高0.74元/d和0.39元/d。研究表明,代谢能水平为11.52~11.57 MJ/kg时,提高饲粮蛋白质水平可以提高舍饲小尾寒羊公羔羊的生长性能,并对羊肉品质具有改善作用,以粗蛋白质水平为14.04%时经济效益最高。

豆粕减量替代日粮对育肥小尾寒羊生长性能、肉用性能及经济效益的影响

试验旨在研究豆粕减量替代日粮对育肥小尾寒羊生长性能、肉用性能及经济效益的影响。试验选择75只体重(41.64±1.19) kg相近的180 d左右小尾寒羊育成公羊,随机分成对照组和试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组,其中对照组粗饲料全部为揉丝豆秸,试验组日粮中豆粕减量、粗饲料为不同比例的花生秧代替豆秸,全程保持日粮精粗比60∶40不变、各组日粮的消化能和蛋白质水平相近。试验开始和结束时测定小尾寒羊空腹体重和体尺指标,试验结束测定肉用性能指标,计算经济效益。结果表明:(1)与对照组比较,试验各组平均日增重显著提高(P<0.01),以试验Ⅰ组、试验Ⅱ组、试验Ⅲ组的增重效果较好,而各组的体尺指标无显著差异(P>0.05);(2)与对照组比较,试验各组背脂厚和GR值均显著提高(P<0.05),屠宰率、净肉率、眼肌面积无显著差异(P>0.05);(3)与试验各组相比,对照组羊肉的滴水损失和黄度值最大,均显著高于试验各组(P<0.05);(4)试验各组的经济效益均极显著高于对照组(P<0.01)。说明豆粕减量替代日粮对育肥小尾寒羊生长性能、肉用性能和经济效益均有不同程度的影响,以试验Ⅰ、Ⅱ、Ⅲ组的效果较好,经济效益较高。

复方中药制剂对小尾寒羊生长性能、血清生化指标、抗氧化指标、粪便评分的影响

为探讨复方中药制剂对小尾寒羊生长性能、血清生化指标、抗氧化指标、粪便形态的影响及驱虫效果,试验选取3月龄左右小尾寒羊母羊100只,随机分为4组,每组5个重复,每个重复5只羊,分别为对照组、试验Ⅰ、Ⅱ、Ⅲ组,试验期42 d,测定并统计小尾寒羊的生长性能、血清生化指标、抗氧化指标及粪便评分。结果表明:与对照组相比,试验Ⅱ、Ⅲ组终末重量显著升高(P<0.05);试验Ⅰ、Ⅱ、Ⅲ组增重和平均日增重显著升高(P<0.05);试验Ⅱ、Ⅲ组血清总蛋白(TP)含量显著升高(P<0.05);试验Ⅱ、Ⅲ组血清白蛋白(ALB)含量显著升高(P<0.05);试验Ⅱ、Ⅲ组血清丙二醛(MDA)含量显著降低(P<0.05);试验第28、42天,试验Ⅱ、Ⅲ组粪便评分显著降低(P<0.05)。综上,日粮中添加复方中药制剂可以提高幼年小尾寒羊的生长性能,改善血清生化指标,提高抗氧化能力,改善粪便形态,适合应用于临床,适合的添加剂量为1%。

Construction of SMART cDNA Library of Sheep Ovary and Identification of Candidate Gene by Homologous Cloning

The cDNA library of an ovary from Small Tail Han sheep before estrus was constructed by switching mechanism at 5＇ end of RNA transcript （SMART） approach. This library had a plaque titer of 1 x 109 pfu mL-1 and a 96% recombinant ratio of which the fragment length of inserted average cDNA sequences was 1.0 kb. Based on bioinformatics analysis of the sequences, we obtained 338 expressed sequence tags （ESTs） from 380 cDNA clones which indicated 191 contigs. These contigs consist of 89 unmatched ESTs, 9 homologous known genes in sheep, and 93 homologous sequences in species of mouse, bovine, and human beings, including 19 sequences expressed in the ovary or follicle and 14 unknown sequences. Several candidate genes associated with sheep reproduction trait such as epidermal growth factor （EGF）, estrogen receptor （ESR）, Inhibin, follicle stimulating hormone receptor （FSHR）, prostaglandin （PG）, and transforming growth factor-β （TGF-β） were identified and the homologous were cloned from this library, which will contribute to compile expression profiles and find the major genes of prolificacy of Small Tail Han sheep.

Improving the Local Sheep in Gansu via Crossing with Introduced Sheep Breeds Dorset and Borderdale

In order to improve the meat performance of local sheep in Gansu Province,Dorset and Borderdale were introduced to crossbreed with local sheep which were Tan sheep,Small-tail Han sheep and Mongolia sheep. The offspring under different crossbreeding combinations were sampled randomly at the different growing stage to measure their growth traits so as to select optimize the crossbreeding mode. The results indicated that,for the same crossbreeding mode,the growth rate of progeny was in order F3】 F2】 F1; for the F3 progeny,the combinations Dorset- Borderdale- Small tail Han sheep and Dorset- Borderdale- Mongolia sheep gave a higher growth rate,with a body weight of 1. 57%,3. 17%,8. 23%,1. 15% higher in male and female individuals than the counterparts of Dorset and Tan sheep and Small tail Han sheep; for the F2 progeny,the combinations Dorset- Borderdale- Small tail Han sheep and Dorset- Borderdale- Mongolia sheep also gave a higher growth rate,with a body weight of 2. 15%,4. 53%,9. 21% and 2. 75% higher in male and female individuals than the counterparts of Dorset and Tan sheep and Small tail Han sheep; for the F1 progeny,the combination Borderdale and Small tail Han sheep assumed a higher growth rate,with a body weight of 3. 23%,6. 07%,7. 42% and 8. 66% higher in male and female individuals than the counterparts of Borderdale- Mongolia sheep and Tan sheep- Small tail Han sheep,respectively. Therefore,in the Small-tail Han sheep and Mongolia sheep producing regions,the F2 or F3progeny bred by using Dorset or Borderdale sheep as male parent to cross with local breeds,or the hybrid lambs of Small-tail Han sheep and Borderdale sheep as highly qualified commodity,would produce significant economic benefit. Moreover,the novel breeds obtained by crossing were the valuable genetic resource for breeding meat sheep.

小麦低聚肽对小尾寒羊屠宰性能、肉品质及瘤胃菌群结构的影响

本试验旨在研究饲粮添加小麦低聚肽对小尾寒羊屠宰性能、肉品质及瘤胃菌群结构的影响。选取平均体重为35 kg左右、4月龄的健康小尾寒羊公羔羊30只,随机分为2组,即对照组(饲喂基础饲粮)和试验组(饲喂基础饲粮+0.3%小麦低聚肽)。试验期共75 d,包括预试期15 d,正试期60 d。结果表明:1)与对照组相比,饲粮中添加小麦低聚肽显著提高了肉羊背膘厚度(P<0.05),对肉羊胴体重、屠宰率、眼肌面积无显著影响(P>0.05)。2)与对照组相比,试验组肉羊背最长肌的pH_(45 min)、pH_(24 h)以及肉色中的亮度(L^(*))和红度(a^(*))值没有显著变化(P>0.05),而肉色中的黄度(b^(*))值显著提高(P<0.05),剪切力和失水率显著降低(P<0.05),蒸煮损失有降低的趋势(P=0.09)。3)与对照组相比,饲粮中添加小麦低聚肽对肉羊瘤胃菌群的alpha多样性无显著影响(P>0.05);在门水平上,与对照组相比,试验组拟杆菌门相对丰度有增加的趋势(P=0.08)。本试验结果提示,小麦低聚肽能够增加羊肉的嫩度和保水能力,同时具有调节小尾寒羊瘤胃菌群结构的潜力。

高精料添加鞣花酸后绵羊瘤胃发酵及微生物的特征

本试验旨在在绵羊高精料饲粮(精粗比为65꞉35)中添加鞣花酸以观察其对瘤胃发酵和微生物多样性的影响,为鞣花酸的应用提供参考。选取5只健康、平均体重为40 kg左右、安装有永久性瘤胃瘘管的空怀小尾寒羊母羊作为试验动物,采用自身对照试验设计,试验分为两期,对照期饲喂基础饲粮,试验期每天每只在基础饲粮中添加鞣花酸10 g。每期适应12 d后连续采集瘤胃内容物3 d,用于分析瘤胃发酵参数;通过16S rDNA测序分析瘤胃细菌、产甲烷古菌和真菌的多样性和相对丰度。结果表明,添加鞣花酸对绵羊采食量以及瘤胃液pH、预测甲烷、NH_(3)-N、微生物蛋白和原虫数均无显著影响(P>0.05)。添加鞣花酸后总挥发性脂肪酸显著下降(P<0.05),对乙酸、异丁酸的摩尔比无显著影响(P>0.05),丙酸、异戊酸摩尔比显著下降,丁酸、戊酸的摩尔比和乙酸/丙酸显著升高(P<0.05)。通过高通量测序发现,鞣花酸对瘤胃细菌、真菌和产甲烷古菌的多样性指数无显著影响(P>0.05),但细菌中小杆菌属、瘤胃球菌2属、互营球菌属和Solobacterium属的相对丰度增加(P<0.05),而产乙酸糖发酵菌属和瘤胃球菌1属的相对丰度降低(P<0.05)。鞣花酸对绵羊瘤胃中的真菌和古菌相对丰度无显著影响(P>0.05)。由此可见,鞣花酸主要作用于瘤胃细菌厚壁菌门,使菌群结构发生变化,改变挥发性脂肪酸的比例关系,并减少总挥发性脂肪酸。

新吉细毛羊和小尾寒羊差异表达miRNAs筛选与调控网络分析

【目的】筛选新吉细毛羊和小尾寒羊体内差异微小RNAs(microRNAs,miRNAs),研究miRNAs和靶基因对羊毛纤维机制表达的调控模式。【方法】选取两种毛细度存在显著差异的新吉细毛羊(XFWS)和小尾寒羊(SXW),采集血浆中外泌体进行转录组测序,构建文库并鉴定miRNAs,使用edgeR包对miRNAs进行差异表达分析,使用miRanda和Targetscan软件预测miRNAs的靶基因,对靶基因进行GO功能和KEGG通路富集分析,对差异miRNAs靶基因进行miRNAs-mRNA互作调控网络分析,使用实时荧光定量PCR对转录组数据中miRNAs进行验证。【结果】新吉细毛羊和小尾寒羊血浆外泌体中存在1019个miRNAs,其中已知miRNAs 112个,新预测miRNAs 907个,经筛选存在差异表达miRNAs 364个,其中与羊毛细度呈正相关性基因62个,呈负相关性基因302个。经多数据库比对获得靶基因的注释信息18996个,GO功能富集分析显示,17193个注释靶基因富集到6608个条目中;KEGG通路分析显示其富集在276个通路之中,经蛋白互作分析找到与羊毛纤维机制表达相关miRNAs 5个及靶基因42个。实时荧光定量PCR验证差异miRNAs结果显示,oar-miR-218a、oar-miR-370-3p、oar-miR-133、oar-miR-29a、oar-miR-27a、oar-miR-485-3p、oar-miR-22-3p、oar-miR-23a、oar-miR-148a、oar-miR-412-3p在新吉细毛羊体内表达量均显著高于小尾寒羊(P<0.05),oar-miR-26a、oar-miR-29b、oar-miR-329b-3p、oar-miR-409-3p、oar-miR-30a-3p在小尾寒羊体内表达量均显著高于新吉细毛羊(P<0.05),与转录组测序结果一致。【结论】新吉细毛羊和小尾寒羊体内存在oar-miR-218a、oar-miR-370-3p、oar-miR-133等364个差异miRNAs,其中oar-miR-133、oar-miR-150、oar-miR-127、oar-miR-23a、oar-miR-370-3p与其42个靶基因共同参与羊毛纤维机制表达,FGFR2、NOTCH1、SHH参与多通路调节,在联级调节中起重要作用。

丁酸梭菌对小尾寒羊宰后成熟过程中挥发性风味物质的影响及机理研究

为探究丁酸梭菌对小尾寒羊宰后成熟过程中挥发性风味物质的影响及其可能机制,以6月龄小尾寒羊为研究对象,取其背最长肌进行宰后成熟(4℃),然后分别在第0、1、2、3、4、5天对羊肉中的挥发性风味物质和腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、乙酰辅酶A羧化酶(acetyl CoA carboxylase,ACC)和肉毒碱脂酰转移酶1(carnitine palmitoyltransferase,CPT1)等脂肪代谢相关酶活性进行测定。电子鼻测定结果显示,丁酸梭菌组小尾寒羊肉中的烷类、氢过氧化物和氮氧化合物的含量更加丰富;结合气相色谱-质谱联用技术测定结果可知,丁酸梭菌组小尾寒羊肉中醛、醇及酮类化合物的种类较为丰富,而脂肪氧化产物如辛醛、壬醛、癸醛、庚醛的含量均明显降低;利用相对气味活度值法筛选了宰后成熟过程中两组小尾寒羊肉中共有的关键风味物质,包括辛醛、壬醛、反-2-癸烯醛和1-辛烯-3-醇,其中癸醛对羊肉风味的贡献最大。与对照组相比,丁酸梭菌组小尾寒羊肉中AMPK和CPT1的含量在宰后成熟过程中均显著降低(P<0.05),而丁酸梭菌组小尾寒羊肉中ACC含量在宰后成熟第0、1、3、5天显著高于对照组(P<0.05);相关性分析结果表明,AMPK和CPT1与壬醛均呈极显著正相关(P<0.001),而ACC与壬醛和癸醛呈极显著负相关(P<0.001)。综上,日粮添加丁酸梭菌可能通过调控AMPK-ACC-CPT1通路进而影响小尾寒羊宰后成熟过程中的挥发性风味物质。