【作者】 张雄；

【导师】 张勇；

【作者基本信息】 贵州大学 ， 动物遗传育种与繁殖， 2017， 硕士

【摘要】 (1)为探索从江香猪肌内脂肪含量的超声活体预测方法,选取110头从江香猪育肥猪开展活体测定,测定性状包括体重、背膘厚和眼肌深度,以第10~11肋间,距背中线5cm处,大小为50*50像素区域的超声波图像为分析对象,利用Matlab R2015b图像分析软件提取灰度梯度及4个方向灰度共生矩阵共31个图像纹理特征参数。以实际测定肌内脂肪含量为因变量,体重、背膘厚、眼肌深度和图像特征参数为自变量,通过逐步回归分析法构建IMF含量预测模型,再将此模型应用于42头从江香猪,根据实测肌内脂肪含量与预测肌内脂肪含量的相关分析进行模型验证。构建回归拟合方程如下:预测肌内脂肪含量(PIMF)=6.443+0.064×背膘厚+0.031×灰度平均-7.421×梯度熵(F=14.826,P<0.001)。逐步回归分析结果表明:背膘厚、灰度平均和梯度熵3个参数指标达到显著水平(P<0.05),回归预测模型确定性系数(R2)为0.369,经相关分析得出PIMF与IMF的皮尔逊积矩相关系数和斯皮尔曼相关系数分别为0.592和0.640(P<0.001)。结果提示,本试验所构建的拟合回归模型可用于从江香猪IMF活体预测。(2)为探究LPL基因的调控功能,揭示其对从江香猪肉质性状的影响,以从江香猪为试验动物,利用RT-PCR技术克隆从江香猪LPL基因CDS区,生物信息学软件预测蛋白理化性质及结构特征,通过PCR-RFLP方法对从江香猪LPL基因第5内含子AfaⅠ、第6内含SmaⅠ位点进行群体遗传效应及关联性分析,运用qRT-PCR技术分析不同月龄阶段从江香猪背最长肌组织中LPL m RNA表达发育规律,并研究其与肌内脂肪含量相关性。结果表明:从江香猪LPL基因CDS区全序列长1437 bp,共编码478个氨基酸,构成具有PLAT/LH2结构域的稳定亲水性蛋白。不同品种猪间氨基酸序列的同源性很高,其中从江香猪与挪威长白猪和陆川猪氨基酸序列的同源性高达99.8%,与贵州白香猪同源性最低,为99.2%。PCR-RFLP分析结果显示,AfaⅠ位点中CG为优势基因型,等位基因C和G频率分别为35.05%和64.95%,CC基因型的皮厚显著高于CG型(P<0.05);SmaⅠ位点中AG为优势基因型,等位基因A和G频率分别为44.29%和55.71%,GG基因型的背膘厚、眼肌深度指标均显著高于AA和AG型(P<0.05)。时序表达谱显示,不同月龄阶段从江香猪背最长肌组织中LPL mRNA表达水平呈现出先降低后升高的趋势,LPL mRNA表达量与IMF含量呈显著正相关(P<0.05)。结果提示,LPL基因可作为影响从江香猪脂肪沉积的关键候选基因之一,试验结果为提高从江香猪肌内脂肪含量提供分子选育手段。更多还原

【Abstract】 (1)The study about ultrasound predict intramuseular fat of Congjiang pigs have been progressed in this test.Three traits of 110 Congjiang pigs containing body weight,backfat thickness and loin muscle deepness between 10 th to 11 th ribs were measured.The real-time ultrasound images with a size of 50*50 pixel were collected across the 10 th to 11 th ribs and 5cm off-midline of back were used as the object of study.A total of 31 candidate image parameters of Gray gradient and the four direction graylevel cooccurrence matrix within a defined region(50*50 pixel region placed the 10 th to 11 th rib)for each ultrasound image were obtained using image analysis software(Matlab R2015b).The model for predicting IMF was developed using linear regression analysis with IMF measured as dependent variables and body weight,backfat thickness,loin muscle deepness and image texture parameters as independent variables.The other 42 Congjiang pigs were chosen for model validation by correlation analysis of IMF and predicted IMF.The regression model was as follows:PIMF=6.443+0.064*Backfat thickness+0.031*Average gray value-7.421*Gradient entropy(F=14.826,P<0.001).The result of regression analysis indicated that three independent variables which contained backfat thickness and two image parameters were significant in last model(P<0.05).The coefficient of determination for the prediction model were 0.369.Correlation analysis showed that the Pearson Correlation Coefficients and Spearman Correlation Coefficients were 0.592 and 0.640(P<0.001),respectively.The results suggested the regression model constructed in this study could be used to predict the living body of Congjiang pigs.(2)In order to understand the function of gene LPL and reveal its effects on meat quality traits in Congjiang pigs.In this study,the CDS region of LPL gene was cloned by RT-PCR from Congjiang pigs,the physical and chemical properties as well as structure characteristics of LPL protein was predicted using bioinformatics softwares.The genotype of AfaⅠlocus of intron5 and SmaⅠlocus of intron6 in Congjiang pigs was tested by PCR-RFLP.Meanwhile,the expression profile of LPL gene was investigated by q RT-PCR and their association with content of intramuscular fat in dorsal muscles of different stages Congjiang pigs were analyzed.The results showed that the CDS of LPL gene was 1437 bp encoding a stable,hydrophilic protein with478 amino acids and a PLAT/LH2 domain.There was high amino acid homology of LPL among different breeds of pig,the amino acid sequence of LPL of Congjiang pigs had similarity of 99.8% with Norwegian Landrace and Luchuan pigs,the lowest homology with Guizhou baixiang pigs was 99.2%.PCR-RFLP results showed that the AfaⅠlocus of the LPL gene have three genotypes in Congjiang pigs,the CG was dominant genotype.The allele frequencies of C and G at AfaⅠlocus were 0.3505 and0.6495,repectively.The skin thickness of CC genotype was significantly higher than that of CG genotype(P<0.05).The SmaⅠlocus of the LPL gene have three genotypes in Congjiang pigs,the AG was dominant genotype.The allele frequencies of A and G at AfaⅠlocus were 0.4429 and 0.5571,repectively.The backfat thickness and lion eye depth of GG were higer than those of other genotypes(P<0.05).q RT-PCR results suggested that the expression level of LPL gene in the dorsal muscles of Congjiang pigs at different stages was decreased first and then increased,the correlation analysis indicated that there was a significant correlation between LPL m RNA expression and intramuscular fat content(P<0.05).In conclusion,the LPL gene might play an important role in the IMF deposition of Congjiang pigs,the results of this study provide marker-assist selection for improving the intramuscular fat content of Congjiang pigs.更多还原