尿苷酸的营养代谢与生理功能研究进展

在猪乳的5种核苷酸(尿苷酸、胞苷酸、肌苷酸、鸟苷酸以及腺苷酸)中,尿苷酸的含量最为丰富,占乳汁中总核苷酸的90%以上。与母猪乳汁相比,仔猪教槽料中尿苷酸最为缺乏,这种现象在仔猪断奶早期尤其明显,因此,尿苷酸可能对仔猪正常的生长发育起着重要的作用。尿苷酸作为一种基础的嘧啶核苷酸类化合物,具有非常重要的生理功能。本文从尿苷酸的结构、吸收代谢、生理功能、与三大营养物质代谢关系及在动物生产中的潜在应用等方面予以综述,旨在为单核苷酸在动物生产中的添加和单核苷酸营养提供参考。     

猪血清淀粉酶多态性及遗传规律研究

采集２６７头二花脸、大约克纯种猪及它们的不同杂交组合后代血样，利用水平聚丙烯酰胺凝胶电泳法，对血清中淀粉酶（Ａｍ）的遗传多态型及遗传规律进行研究，并分析了血清淀粉酶型对猪初生重的影响。结果表明猪血清症粉酶表现出多态性，有九种表现型并分别受四个共显性复等位基因控制，而其他文献大多提及Ａｍ受三个共显性复等位基因控制，并有六种表现型。Ａｍ基因型的九个交配组合后代基因型经Ｘ￣２检验，有两个交配组合（ＢＤ×ＣＤ，ＢＤ×ＡＤ）的分离比Ｘ￣２值Ｐ＜０．０１差异极显著；有两个组合（ＢＤ×ＢＣ，ＢＣ×ＣＤ）的分离比Ｘ￣２值Ｐ＜０．０５，差异显著；其他五个组合（ＢＤ×ＡＣ，ＣＤ×ＢＢ，ＣＤ×ＡＢ，ＢＤ×ＣＣ，ＢＣ×ＤＤ），分离比Ｘ￣２值Ｐ＞０．０５，差异不显著，符合孟德尔遗传规律。有些交配组合分离比与预期比不符合，是否由于某些基因型与生命力有关，还有待于进一步探讨。猪血清淀粉酶型与仔猪初生重相关关系不明显。     

Two novel intronic polymorphisms of bovine FGF21 gene are associated with body weight at 18 months in Chinese cattle

Fibroblast growth factor 21 (FGF21) is a hepatic hormone that regulates peripheral glucose tolerance, energy balance and lipid metabolism. Prior evidence suggests that FGF21 may have the potential to favorably reduce obesity. The objective of the present study was to identify single nucleotide polymorphisms (SNPs) of bovine FGF21 using 1255 animals representing the five main Chinese breeds and to investigate the effect of these SNPs on economic traits in Nanyang cattle. Four significant SNPs were identified, one was a synonymous mutation and the other three were in intronic regions. The polymorphism information content (PIC) analysis showed that four beef cattle populations (NY, JX, LX and QC) had a moderate genetic diversity at the four loci while the beef and dairy population (CRS) had a low level. Additionally, allele and genotype frequencies for the beef breeds were significantly different from CRS, implying that these mutations are possibly associated with some quantitative traits. Moreover, linkage disequilibrium analysis and haplotype frequencies were also reported. Seven different haplotypes were identified and haplotype TCCC was predominant in all five cattle breeds. Association analysis suggested that SNPs g.297C>G and g.940C>T of bovine FGF21 were associated with higher body weight at 18 months within NY cattle, which would contribute to cattle breeding and genetics through marker-assisted selection (MAS).     

A retrospective analysis of allele frequency changes of major genes during 20 years of selection in the Italian Large White pig breed

In this study, we investigated whether a selection programme based on boar genetic evaluation obtained with a classical BLUP animal model can change allele frequencies in a pig population. All Italian Large White boars born from 1992 to 2012 with estimated breeding value reliability >0.85 (n = 200) were selected among all boars of this breed. Boars were genotyped with markers in major genes (IGF2 intron3‐g.3072G>A, MC4R p.D298N, VRTN PRE1 insertion, PRKAG3 p.I199V and FTO g.276T>G). Genotyping data were analysed grouping boars in eight classes according to their year of birth. To evaluate the influence of time on allele frequencies of the genotyped markers, multinomial logistic regression models were computed. Four of five polymorphic sites (IGF2, MC4R, VRTN and FTO) showed significant (p < 0.01) changes in allele frequencies over time due to a progressive and continuous increase of one allele (associated with higher lean meat content, higher average daily gain and favourable feed: gain ratio) and, consequently, decrease of the other one, following the directional selection of the selection programme of this pig breed. The retrospective analysis that was carried out in Italian Large White boars suggests that selection based on methodologies assuming the infinitesimal model is able to modify in a quite short period of time allele frequencies in major genes, increasing the frequency of alleles explaining a relevant (non‐infinitesimal) fraction of the overall genetic variability for production traits.     

贵州地方黄牛GHR基因遗传变异、功能预测及其与生长性状的关联性分析

为探究黄牛生长激素受体（GHR）基因多态性,筛选出对贵州地方黄牛生长性状有显著影响的SNPs位点,本研究以150头贵州地方黄牛（关岭牛、思南牛、威宁牛各50头）为研究对象,以GHR为候选基因,根据GenBank收录的黄牛GHR基因外显子序列设计引物,提取贵州地方黄牛血液基因组DNA并构建混池;通过PCR扩增测序法验证GHR基因SNPs和分型,运用DNAStar、SPSS 19.0软件对GHR基因SNPs进行遗传学分析,并与贵州地方黄牛生长性状进行关联性分析,寻找各位点不同基因型间贵州地方黄牛生长性能差异,同时使用生物信息学分析GHR突变前后mRNA二级结构的变化,预测分析贵州地方黄牛GHR蛋白的结构与功能。结果显示,贵州地方黄牛GHR基因共检测出8个SNPs,分别为Exon9-C162T、Exon9-C201T、Exon9-G243C、Exon9-G383A、Exon9-A495T、Exon9-C622T、Exon9-C642T和Exon9-A650C,其中思南牛无Exon9-G243C。遗传学分析表明,除Exon9-G243C位点在威宁牛中偏离Hardy-Weinberg平衡外,其余SNPs均未偏离Hardy-Weinberg平衡。相关性分析发现,GHR基因突变位点在关岭牛和思南牛中均未检测到显著性差异,但在威宁牛中,Exon9-G243C基因型GC个体胸围显著低于GG和CC基因型（P<0.05）,Exon9-A650C基因型AA个体的体斜长、坐骨端宽均显著高于CC基因型（P<0.05）,而胸深显著低于AC和CC基因型（P<0.05）,其余6个SNPs差异均不显著（P>0.05）。生物信息学分析发现突变前后,除Exon9-G383A mRNA二级结构未发生改变外,其余SNPs mRNA二级结构均发生了改变,Exon9-G243C、Exon9-A650C会影响蛋白质二级结构的变化,但突变不影响蛋白质三级结构的变化。此外,贵州地方黄牛GHR蛋白是一种分泌蛋白,具有信号肽剪切位点且具有6个N-糖基化位点,证实该基因变异程度高。本研究提示GHR基因Exon9-G243C、Exon9-A650C这2个SNPs对贵州地方黄牛生长性状具有显著影响,可作为贵州地方黄牛生长发育的候选分子标记。     

水貂酪氨酸酶(TYR)基因克隆、SNPs筛查及其皮肤组织mRNA差异表达分析

旨在克隆和分析水貂酪氨酸酶(tyrosinase,TYR)基因编码区,揭示该基因编码区SNPs及其皮肤组织mRNA差异表达规律与水貂毛色表型的关系.本研究采集7月龄雄性金州黑水貂、名威银蓝水貂和红眼白水貂共计301个样本的血液,利用聚合酶链式反应(PCR)方法对水貂TYR基因5个外显子进行分段克隆,并拼接获得其完整编码...     

Single-nucleotide polymorphism-based epidemiological analysis of Korean Mycobacterium bovis isolates

BackgroundBovine tuberculosis (TB) is caused by Mycobacterium bovis, a well-known cause of zoonotic tuberculosis in cattle and deer, and has been investigated in many physiological and molecular studies. However, detailed genome-level studies of M. bovis have not been performed in Korea.ObjectivesTo survey whole genome-wide single-nucleotide polymorphism (SNP) variants in Korean M. bovis field isolates and to define M. bovis groups in Korea by comparing SNP typing with spoligotyping and variable number tandem repeat typing.MethodsA total of 46 M. bovis field isolates, isolated from laryngopharyngeal lymph nodes and lungs of Korean cattle, wild boar, and Korean water deer, were used to identify SNPs by performing whole-genome sequencing. SNP sites were confirmed via polymerase chain reaction using 87 primer pairs.ResultsWe identified 34 SNP sites with different frequencies across M. bovis isolates, and performed SNP typing and epidemiological analysis, which divided the 46 field isolates into 16 subtypes.ConclusionsThrough SNP analysis, detailed differences in samples with identical spoligotypes could be detected. SNP analysis is, therefore, a useful epidemiological tracing tool that could enable better management of bovine TB, thus preventing further outbreaks and reducing the impact of this disease.     

SNPs in APOBEC3 cytosine deaminases and their association with Visna/Maedi disease progression

The Apolipoprotein B mRNA-editing catalytic polypeptide-like 3 (APOBEC3) genes are able to inhibit the replication of a wide range of exogenous retroviruses, as well as endogenous retroviruses and retrotransposons.Three APOBEC3 genes, named APOBEC3Z1, APOBEC3Z2 and APOBEC3Z3, have been described in sheep.In this work the three genes have been screened in order to identify polymorphisms. No polymorphism was detected for the A3Z2 and A3Z3 genes but 16 SNPs and a 3-bp deletion were found in the A3Z1 gene. A thermoestability prediction analysis was applied to the detected amino acidic SNPs by three different programs. This analysis revealed a number of polymorphisms that could affect the protein stability. The SNPs of the 3′UTR were tested to detect alterations on the predicted microRNA target sites. Two new microRNA target sites were discovered for one of the alleles.Two SNPs were selected for association studies in relation with the retroviral disease Visna/Maedi in Latxa and Assaf sheep breeds. Although association analyses resulted unconclusive, probably due to the unsuitability of the SNP allele frequency distribution of the selected polymorphisms in the analyzed breeds, these genes remain good candidates for association studies.     

Morphological and Genomic Differences Between Cutting and Racing Lines of Quarter Horses

To investigate morphological and genomic differences between cutting and racing lines of Quarter Horses, 120 racing and 68 cutting animals of both sexes, registered at the Brazilian Association of Quarter Horse Breeders, were used. Blood samples were collected, and the following physical traits were measured: weight; height at withers; body length; length of the shank, pastern, rump, head, and neck; and chest, shank, and hoof circumference. For analysis of genomic differences, 54,602 single-nucleotide polymorphisms (SNPs) were genotyped using the Equine SNP50 BeadChip, and the quality of individual and SNP genotype data were evaluated. The fixation index, F_ST, was used to identify genome regions that were altered in the lines by selection. The results showed significant differences between the lines in all physical traits. Quality control led to the exclusion of four cutting animals with a call rate of <0.95. After filtering, 12,544, 13,815, and 13,370 SNPs were excluded for the whole population (n = 184), the 120 racing animals, and the 64 cutting animals, respectively. The number of informative polymorphisms detected in each line and in the whole population indicated that the Equine SNP50 BeadChip can be used in genetic studies of Quarter Horses. The fixation index, F_ST, identified 2,558 genome regions that may have been modified by divergent selection.