Analysis of PrP genotypes in relation to reproductive and production traits in Chios sheep

The study describes the changes with time in gene and genotype frequencies of a closed Chios herd. Genomic DNA was isolated and purified from peripheral blood leucocytes using standard procedures. The identification of the allelic variants present in the DNA samples, was performed in a simple multiplex PCR reaction and melting curve analysis of the PrP gene. Only ARR/ARR female genotypes were kept for breeding, and only males of the same genotype were used following year 2 of the study. As a result of planned individual matings and selection, the susceptible ARQ/ARQ genotype was eliminated from the flock in 4 years. The gene frequency of the R allele from a low 0.056 at year 1 reached a high 0.911 at year 6 of the study. Data from first lactation ewes of known genotypes were used to examine possible associations between PrP genotypes and ewe reproductive (litter size at birth and at weaning) and production traits (litter weight at birth and at weaning and 60-day milk yield after weaning). No effects of the sire genotype (ARR/ARR and ARR/ARQ) were found for any of the traits studied. The ewe genotype was associated with performance for reproductive traits but not with total weight of lamb output at birth or at weaning. ARR/ARR ewes had a higher litter size at birth (2.09) compared to ARQ/ARQ ewes (1.79) and higher litter size at weaning (1.84) compared to ARR/ARQ ewes (1.59). 60-day milk yield after weaning was not influenced by genotype (114.8, 105.8 and 114.8 kg for ARR/ARR, ARR/ARQ and ARQ/ARQ genotypes, respectively). Birth weight and 98-day weight were not influenced by the lamb genotype. ARQ/ARQ lambs were slightly heavier (P < 0.05) than ARR/ARR lambs at weaning as a result of faster pre-weaning growth. Post weaning growth was similar for the homozygous genotypes.     

Testing the equivalence of different ovine PrP genotypes for estimated breeding values

In this study we applied equivalence testing methods to prove the absence of differences in genetic values of ewes with different PrP genotypes. In particular, the milk production genetic value equivalence of ARR ovine prion protein (PrP) genotypes was analysed. There is no scientific evidence implying that the performances and genetic values of different PrP genotypes will be different, but it is interesting to confirm that the performance of one genotype is indistinguishable from another before starting a genetic scrapie control programme. Genotyping was performed on 204 ewes from a Spanish population of Lacaune breed. Ewes were sampled from the lower and upper tails for the distribution of estimated breeding value (EBV) for standardized lactation. The conditional probability that the number of ARR alleles contained in the group of higher EBV was larger than that found in the group of lower EBV was found to be in the interval between the true value (1/2) and two different pre-specified bounds (0.1 and 0.2). The results evidence the equivalence of ARR PrP genotypes for milk production EBV, and lead to the conclusion that the average genetic values for milk production of Lacaune flocks considered will not be affected by the selection of ewe carriers of resistance scrapie alleles (p<0.05).     

Association analyses between the prion protein locus and reproductive and lamb weight traits in Ripollesa sheep

The objective of this study was to analyze the association between the haplotypes of the prion protein (PrP) locus and several reproductive and lamb weight traits in Ripollesa sheep. Prion protein genotypes were available for a total of 310 sheep (7 rams, 114 ewes, and 189 lambs), all of them belonging to the purebred Ripollesa flock of the Universitat Autònoma of Barcelona, for which all sheep had a known pedigree. In addition, the genotype of 24 historical descendants of the previously genotyped adult individuals was reconstructed, provided that both parents were homozygous for PrP haplotypes. Only 3 haplotypes (ARR, ARQ, and ARH) were observed in the PrP locus of the sheep sampled. Reproductive traits included conception rate and litter size, whereas birth BW and 90-d BW were the lamb weight traits studied. The additive effect of PrP haplotypes was analyzed through Bayesian animal threshold and linear models, for reproduction and weight traits, respectively. Ewe reproductive data belonged to 89 ewes that gave 492 conception rate records and 440 litter size records. Analyses of BW at birth and at 90 d of age were made on 323 and 164 lamb records, respectively. No associations between PrP haplotypes and conception rate and BW traits were observed. For litter size, the effect of the ARH haplotype was greater than that of the ARQ haplotype. Differences between ARH and ARR haplotypes also suggested an advantage for the ARH. As a whole, our results indicated that the selection favorable to increase litter size in Ripollesa ewes may also increase the ARH haplotype frequency, which contradicts the recommendations of the current European Union legislation aiming to increase the genetic resistance to scrapie. As a consequence, scrapie genotyping needs to be included as a new selection criterion in the breed.     

Associations of polymorphisms of the ovine prion protein gene with growth, carcass, and computerized tomography traits in Scottish Blackface lambs

The objective of this study was to investigate and estimate the associations of the ovine prion protein (PrP) genotypes with a wide range of performance traits in Scottish Blackface lambs. Performance records of up to 7,138 sheep of known PrP genotypes born from 1999 to 2004 in 2 experimental farms were utilized. Performance traits studied were BW at birth, marking (when the sheep were identified with permanent ear tags at an average age of 52 d), and weaning (average age of 107 d); slaughter traits (BW at slaughter, slaughter age, carcass weight, and carcass conformation); ultrasonic muscle and fat depths; and computerized tomography-predicted carcass composition and carcass yield at weaning. Different linear mixed models, including random, direct animal effect, and up to 3 maternal effects (genetic, permanent, and temporary environmental) were used for the different traits. The PrP genotype was included in the model as a fixed effect, along with other fixed factors with significant effects (P < 0.05). Five separate analyses were carried out for each trait, differing in the method of PrP genotypic classification. The first analysis was based on classifying the sheep into categories according to all 9 available PrP genotypes. In the other 4 analyses, sheep were categorized according to the number of each PrP allele carried. Results showed that there were no significant differences between PrP genotypes for any of the performance traits studied when all 9 genotypes were compared (first analysis). Similarly, performance of the lambs did not significantly differ between genotypes with different numbers of ARR copies. However, there were significant variations in a few traits with respect to the number of ARQ, AHQ, and VRQ alleles carried. Heterozygous lambs for the AHQ or the ARQ allele were significantly heavier at some ages than lambs of the other genotypes. Lambs carrying the VRQ allele required approximately 10 d longer finishing time (P = 0.01) and yielded carcasses approximately 0.5 kg heavier (P = 0.03) compared with noncarriers. The few significant associations found do not have a negative influence on performance when selecting against the most susceptible PrP allele (VRQ) or in favor of the most resistant one (ARR). Overall, there were no major associations of PrP genotypes with most lamb performance traits in Scottish Blackface sheep.     

Clinical signs, histopathology and genetics of experimental transmission of BSE and natural scrapie to sheep and goats

This paper compares the dinical signs, histopathology, detection of PrPSc protein and PrP genetics of the transmission of BSE to sheep and goats, with the effects of the transmission of natural scrapie from a brain homogenate from a single sheep. After intracerebral and oral inoculations there were similarities in the clinical signs due to the two sources of infection, but there were differences in pathology at the end stage of disease and in the genotypes of the sheep which succumbed to the challenges. The incubation period of BSE was associated with the sheep PrP codon 171 genotype, but the natural scrapie source, despite inducing disease only in known susceptible genotypes, showed no clear association with PrP genotype.     

鲁中肉羊SMAD1和ESR2基因多态性与产羔数关联分析

为探究SMAD1、ESR2基因多态性与鲁中肉羊产羔数之间的关系,采用Sequenom MassARRAY誖SNP技术检测鲁中肉羊SMAD1、ESR2基因单核苷酸多态性,并与产羔数进行关联分析。结果表明:SMAD1基因g.12485895A>G存在AA、AG和GG基因型,基因型频率分别为0.05、0.45和0.50;ESR2基因g.73324006C>T存在CC和CT基因型,基因型频率分别为0.98和0.02。g.12485895A>G位点在鲁中肉羊表现为中度多态(0.25T位点为低度多态(PIC<0.25);卡方适合性检验表明,g.12485895A>G位点在鲁中肉羊处于哈代温伯格不平衡状态(P<0.05),g. 73324006C>T位点处于哈代温伯格平衡状态(P>0.05)。g.12485895A>G位点多态性与鲁中肉羊产羔数没有显著关联(P>0.05), g.73324006C>T位点多态性与鲁中肉羊产羔数显著关联(P<0.05)。综上可知,SMAD1基因g.12485895A>G位点和鲁中肉羊产羔数性状没有显著关联(P>0.05),ESR2基因g.73324006C>T位点对鲁中肉羊产羔数性状选育具有一定的指导意义。     

Quantifying diversity losses due to selection for scrapie resistance in three endangered Spanish sheep breeds using microsatellite information

The effect of selection for scrapie resistance on genetic variability in three endangered Spanish sheep breeds (Colmenareña, Mallorquina and Rubia de El Molar) was studied using two different criteria for quantifying contributions to genetic variability: (a) molecular coancestry or genetic identity; and (b) average number of alleles per locus or allelic richness. A total of 236 (81 Colmenareña, 76 Mallorquina and 79 Rubia de El Molar) individuals were genotyped for the PrP gene and for 22 microsatellite markers. The analyses assumed a selective policy aimed at the elimination of the VRQ allele and the reduction of the frequency of the ARQ/ARQ genotype. These goals are approached by rejecting for breeding those individuals with the highest susceptibility for scrapie (risk groups R4 and R5) in a genetic scenario with no previous selection programmes considering the PrP gene polymorphism carried out. When all the individuals classified into risk groups R4 and R5 were removed from the dataset, the total molecular coancestry slightly increased in the Colmenareña breed illustrating that the carriers of undesirable PrP genotypes are not essential to maintain its overall gene diversity. When the allelic richness was considered, the removal of the R4 and R5 individuals gave high losses in the Rubia de El Molar breed. The analyses carried out considering the sex of the individuals informed that most increases in genetic identity in the Colmenareña breed resulted from the removal of the R4 and R5 males while in the Mallorquina breed resulted from the removal of the undesirable females. Losses of diversity in the Rubia de El Molar breed were basically independent of the sex of the individuals due to the balanced contributions to diversity of both sexes. As a general recommendation, not all the individuals of undesirable risk groups should be rejected for reproduction at the same time to avoid irretrievable loses of genetic diversity but according to the sex of the individuals.     

绵羊生物钟基因Cry多态性与产羔数的关联分析

为探究绵羊Cry1基因g.175355119T>C、g.175357583C>T位点与Cry2基因g.74126865C>T位点多态性与绵羊产羔数之间的关系,本实验利用全基因组重测序结合Sequenom MassARRAY?SNP技术对常年发情绵羊品种(小尾寒羊、湖羊和策勒黑羊)和季节性发情绵羊品种(滩羊、苏尼特羊和草原型藏羊)Cry1基因与Cry2基因共3个多态位点多态性进行检测,并与小尾寒羊产羔数进行关联分析。结果表明:Cry1基因g.175355119T>C位点存在CC、CT和TT 3种基因型,g.175357583C>T位点存在TT、TC和CC 3种基因型;Cry2基因g.74126865C>T位点存在CC、CT和TT 3种基因型。群体遗传学分析表明,Cry1基因g.175355119T>C位点与Cry2基因g.74126865C>T位点的基因型频率和等位基因频率在2种发情模式绵羊品种间的差异均达到极显著水平。在6个绵羊品种中,Cry1基因g.175355119T>C位点与g.175357583C>T位点均表现为中度多态(0.25T位点均表现为低度多态(PIC<0.25)。卡方适合性检验表明,Cry1基因g.175355119T>C位点在6个绵羊品种中均处于哈代温伯格平衡状态(P>0.05),g.175357583C>T位点在苏尼特羊中处于哈代温伯格不平衡状态(P<0.05),Cry2基因g.74126865C>T位点在滩羊和草原型藏羊中处于哈代温伯格不平衡状态(P<0.05)。关联分析表明,3个多态位点与小尾寒羊第1、第2以及第3胎产羔数均无显著关联(P>0.05)。综上,Cry1基因g.175355119T>C、g.175357583C>T位点与Cry2基因g.74126865C>T位点均不适用于小尾寒羊产羔数选育。     

PrP genotype frequencies in German breeding sheep and the potential to breed for resistance to scrapie

Genetic susceptibility to scrapie is associated with polymorphisms in three different codons of the ovine prion protein (PrP) gene (136, 154, 171). Studies of PrP genotypes linked to scrapie have revealed the resistance of homozygous PrPARR/PrPARR animals and the high risk of PrPVRQ/PrPVRQ and PrPvRQ/PrPARQ animals in scrapie-affected flocks. The selection of PrPARR/PrPARR genotypes may therefore provide a strategy for controlling clinical scrapie. The genotypes of 1361 German breeding sheep from 15 different breeds in northern Germany were determined. Apart from the wildtype allele PrPARQ, at least four mutually exclusive allelic variants were found. The greatest variability within the PrP gene was encountered in texel sheep, in which 14 PrP genotypes were found. In the important meat breeds, Suffolk, German whiteheaded mutton and German blackheaded mutton, the PrPARR allele was predominant, and in these breeds the breeding of scrapie-resistant pedigree flocks within four generations seems to be a feasible option. In the texel sheep, the German merino, the German milk and the German land sheep breeds, the frequency of the PrPARR allele was much lower, and in several breeds no homozygous rams were available for breeding purposes. In these breeds the breeding strategy would depend on the number of heterozygous rams available, but resistant pedigree flocks could be achieved within nine generations.     

中国荷斯坦奶牛EEF1D基因的SNPs检测及其与产奶性状的关联分析

试验旨在研究中国荷斯坦奶牛真核生物翻译延伸因子1D（eukaryotic translation elongation factor 1 delta,EEF1D）基因的多态性及其与产奶性状的相关性。利用Sequenom MassARRAY SNP分型技术对宁夏地区1 252头中国荷斯坦奶牛EEF1D基因的多态性进行了检测,并对其多态位点不同基因型和组合基因型与产奶性状进行了关联分析。结果显示,EEF1D基因的5'侧翼区存在2个SNPs位点,即EEF1D-1和EEF1D-3;经检测发现,EEF1D-1存在2种基因型,EEF1D-3存在3种基因型。χ²检验表明,中国荷斯坦奶牛在EEF1D-1位点偏离Hardy-Weinberg平衡状态（P < 0.05）,在EEF1D-3位点未偏离Hardy-Weinberg平衡状态（P > 0.05）;EEF1D-1和EEF1D-3位点多态信息含量（PIC）分别为0.10和0.28,分别呈现低度多态和中度多态。在试验群体中,EEF1D-1位点对乳脂率和乳蛋白率性状的效应均达到极显著水平（P<0.01）,对305 d产奶量性状的效应达到显著水平（P<0.05）;EEF1D-3位点对305 d产奶量、乳脂率和乳蛋白率性状的效应均达到极显著水平（P<0.01）;EEF1D基因的优势基因型组合GG-AG和GG-GG个体乳脂率均显著高于GG-AA组合个体（P<0.05）。说明EEF1D基因可以作为影响中国荷斯坦奶牛产奶性状的候选基因用于标记辅助选择。     

Frequencies of PrP genotypes in meat breeds of Japanese sheep and trail of selective breeding in experimental sheep flock

The selection of sheep with scrapie-resistant PrP genotypes is one of the control measures for transmissible spongiform encephalopathies in ruminants. In this study, we investigated the frequencies of PrP genotypes in meat breeds in Japan. The nationwide surveillance revealed that nearly half of the Suffolk sheep, a major meat breed in Japan, carried scrapie-susceptible AQ/AQ and AQ/VQ genotypes. In addition, the VQ haplotype, which confers high susceptibility to scrapie within sheep, was also found in Poll Dorset sheep. A trial of selective breeding using sires with scrapie-resistant PrP genotypes AQ/AR and AR/AR could raise the ratio of scrapie-resistant sheep from less than 50% to 80% within 3 years. However, the use of sires with the AR/AR genotype and the selection of ewes would be required to achieve a higher ratio of scrapie-resistant sheep.     

绵羊FSTL3基因g.40674542C>T位点多态性与产羔数的关联分析

文章旨在探究绵羊FSTL3基因g.40674542C>T位点多态性与绵羊产羔数之间的关系,以期为绵羊高繁殖力分子育种提供新的遗传标记。利用全基因组重测序结合Sequenom MassARRAY~SNP技术对常年发情绵羊品种(小尾寒羊、策勒黑羊和湖羊)和季节性发情绵羊品种(滩羊、苏尼特羊和草原型藏羊)FSTL3基因g.40674542C>T位点多态性进行了检测,并与小尾寒羊产羔数进行了关联分析。结果表明:FSTL3基因g.40674542C>T位点存在CC、TC和TT三种基因型,基因型频率和等位基因频率在两种发情模式绵羊品种间差异均不显著(P>0.05);g.40674542C>T位点在6个绵羊品种中均表现为低度多态(PIC<0.25),经卡方适合性检验,该位点在小尾寒羊、湖羊和草原型藏羊中处于哈代温伯格平衡状态(P>0.05),在其余3个绵羊品种中处于哈代温伯格不平衡状态;g.40674542C>T位点不同基因型与小尾寒羊第一、第二以及第三胎产羔数均无显著关联(P>0.05)。说明FSTL3基因g.40674542C>T位点不适合用于小尾寒羊产羔数选育。     

澳系进口荷斯坦奶牛CXCR1基因遗传多态性与泌乳性状及体细胞评分的关联性分析

采用聚合酶链式反应-单链构象多态性（PCR—SSCP）技术对以海丰奶牛场588头澳系进口荷斯坦牛牛趋化因子受体1（Chemokine receptor1,CXCR1）基因的遗传多态性进行分析;采用混合动物模型分析CXCRl基因2个突变位点与测定日产奶量、乳脂率、乳蛋白率、305d产奶量、305d乳脂量、305d乳蛋白量及体细胞评分7个性状的相关性,寻找可用于生产实际的分子标记。结果显示,CXCR1基因5’侧翼区-1830位点发生了A—G的突变,检测到AA、AG和GG3种基因型,频率分别为0．684、0．289和0．027,等位基因A和G的频率分别为0．828和0．172;GG基因型奶牛的日产奶量、SCS和305d产奶量均板显著高于AA基因型（P〈0．01）,而其乳脂率和乳蛋白率却显著低于AA基因型奶牛（P〈0．05）。编码区783位点仅发现AA和AC2种基因型,基因型频率分别为0．886和0．114,等住基因A和c的频率分别为0．943和0．057。AA型的个体的日产奶量、305d脂肪产量和305d蛋白产量极显著高于AC型个体,而其乳脂率、乳蛋白率和SCS却极显著低于AC型个体（P〈O．01）。结果表明,CXCR1基因遗传突变对澳系进口荷斯坦牛泌乳性状和乳房炎抗性有较大的遗传效应,可用于澳系进口荷斯坦牛的分子标记辅助选择。     

Genetic diversity loss due to selection for scrapie resistance in the rare Spanish Xalda sheep breed

The effect of selection for scrapie resistance on genetic variability in the rare Xalda sheep breed was studied. Pedigree information comprised 1851 animals (1444 alive) at the moment of sampling. A total of 304 reproductive (or selected for reproduction) Xalda individuals were sampled and genotyped for 14 microsatellites. Genetic variability was assessed using: gene diversity (1 − average kinship, GD), mean average relatedness (AR) and self-coancestry (c_i) at the genealogical level; and expected heterozygosity (H_e), molecular mean kinship (Mk), molecular self-coancestry (s_i) and rarefacted average number of alleles per locus (A) at the molecular level. Two breeding strategies were evaluated: a) use of only young rams with genotype ARR/ARR and young ewes with low to moderate risk (risk groups R1 to R3); b) breeding without selection for PrP genotypes. The major cause of losses of genetic variability in the Xalda breed is the drift that occurs when a new group of reproductive individuals is selected. The loss of genetic variability is small in females compared to the males, where it is considerable. However, losses at the molecular level for young females with respect to adult females were above 5%. Young male individuals also retained most of the genetic variability assessed in adult rams. Selection against susceptibility to scrapie produced additional losses of more than 2% for H_e and A when rYF individuals are considered. As regards males, the situation becomes critical because of the scant number of available ARR/ARR young rams. The consequences for the management of the Xalda breed are discussed.     

IGFBP-3基因PCR-RFLP多态性与中国荷斯坦牛泌乳性状的相关分析

以胰岛素样生长因子结合蛋白3(IGFBP-3)基因作为中国荷斯坦牛部分泌乳性状的候选基因,在对61头中国荷斯坦牛进行PC R-R FLP分析的基础上,对中国荷斯坦牛群体中IGFBP-3基因座多态性与泌乳性状进行相关分析。结果表明:IGFBP-3基因座对产奶量、乳蛋白率和体细胞评分的影响显著(P<0.05),IGFBP-3 BB型个体的305 d产乳量显著(P<0.05)高于AA型和AB型,BB型个体的乳蛋白率和体细胞评分显著(P<0.05)低于AB型。     

绵羊MKRN3基因多态性与产羔数的关联分析

本实验旨在探究绵羊MKRN3基因g.275981C>T与g.276999C>T位点多态性与绵羊产羔数之间的关系,以期为绵羊高繁殖力分子育种提供新的遗传标记。利用全基因组重测序结合Sequenom MassARRAY~?SNP技术对常年发情绵羊品种(小尾寒羊、策勒黑羊和湖羊)和季节性发情绵羊品种(滩羊、苏尼特羊和草原型藏羊)MKRN3基因2个多态位点多态性进行检测,并与小尾寒羊产羔数进行关联分析。结果表明:MKRN3基因g.275981C>T位点与g.276999C>T位点均存在3种基因型;g.276999C>T位点基因型频率和等位基因频率在2种发情模式绵羊品种间差异均达到极显著水平(P<0.01);g.275981C>T位点在6个绵羊品种中均表现为低度多态(PIC<0.25),g.276999C>T位点在6个绵羊品种中均表现为中度多态(0.25T位点在苏尼特羊和策勒黑羊中均处于哈代温伯格平衡状态(P>0.05),g.276999C>T位点在6个绵羊品种中均处于哈代温伯格平衡状态;关联分析表明,g.275981C>T和g.276999C>T位点不同基因型与小尾寒羊第1、2、3胎产羔数均无显著关联。可见,MKRN3基因2个多态位点均不适合用于小尾寒羊产羔数选育。     

The evidence of associations between prion protein genotype and production, reproduction, and health traits in sheep

The EU Commission issued a regulation in 2003, which requires all member states to implement a breeding programme for resistance to transmissible spongiform encephalopathies in sheep by selecting for specific alleles of the prion protein (PrP) gene. A key concern with regard to this regulation was that the intensive selection programmes, designed to increase resistance to scrapie, may have a negative impact on a range of other economically important production, reproduction, and disease traits in sheep. Such problems could arise for a number of reasons. Firstly, a number of breeds have a low frequency of the resistant PrP allele. Secondly, there may be a negative association between the resistant allele and animal performance. Thirdly, selection for scrapie resistance may reduce the rate of improvement towards current breeding goals. The evidence concerning the relationship between PrP genotype and reproduction, production, and disease traits is the subject of this review. We conclude that there is no evidence for a negative association between PrP genotype and reproduction traits (e.g. litter size), lamb performance traits (e.g. growth rate, conformation, carcass composition) or milk production. There is, however, a distinct paucity of information on the relationship between the PrP gene and disease traits. In this context it is noted that there are a number of genes located on chromosome 13, in close proximity to the PrP gene, that are involved in intracellular cell signalling, apoptosis, phagocytosis, and immune function. Thus further direct studies of key disease traits associated with sheep production systems are warranted.     

Derivation of a scrapie-free sheep flock from the progeny of a flock affected by scrapie

The Cheviot flock at the Institute for Animal Health's Neuropathogenesis Unit (npu) has endemic scrapie, which affects primarily vrq/vrq sheep and at high frequency. A new flock with a full range of PrP genotypes, including the highly susceptible vrq/vrq, has been produced on a separate site, from animals in the npu breeding flock, and it remains scrapie-free after eight years. In contrast, in a parallel flock at the npu farm, scrapie has reappeared after five years, although the animals were kept in separate accommodation from the scrapie-affected sheep. During this time the npu breeding flock continued to have scrapie cases. Although it is known that highly susceptible sheep can remain free of infection in a clean environment, this is the first report of the infection being removed successfully from the bloodlines of scrapie-affected sheep. The results confirm that scrapie is not a genetic disease dependent only on the PrP gene sequence, but requires both genetic susceptibility and an infectious agent.     

鲁中肉羊GTF2A1基因多态性及其与产羔数的关联分析

该研究旨在分析绵羊GTF2A1基因g.89505005G>A位点多态性与产羔数之间的关系,以期寻找与绵羊产羔数有关的分子标记。针对前期利用基因组选择信号分析获得的候选基因GTF2A1及其g.89505005G>A位点,采用Sequenom MassARRAY SNP技术对产羔数存在差异的鲁中肉羊群体进行该位点的多态性检测,并与产羔数进行关联分析。结果表明:鲁中肉羊GTF2A1基因g.89505005G>A位点存在AA、AG和GG三种基因型,且以GG基因型为主;g.89505005G>A位点多态性与鲁中肉羊第1胎、第2胎以及第3胎产羔数均存在显著关联(P<0.05),AA型各胎产羔数均高于GG型(P<0.05)。综上,g.89505005G>A位点A等位基因可能是提高绵羊产羔数的一个潜在有效的DNA标记。     

中国荷斯坦牛RPL23A和ACACB基因对产奶性状的遗传效应分析

作者所在团队前期通过奶牛乳腺上皮组织转录组测序及荷斯坦公牛全基因组重测序研究发现RPL23A和ACACB基因是奶牛乳蛋白和乳脂性状的候选功能基因,本研究旨在探究这两个基因是否对奶牛产奶性状具有显著遗传效应。以北京地区7个牧场的1059头中国荷斯坦母牛为试验群体,采集尾根静脉血并提取基因组DNA,通过飞行时间质谱方法检测SNP位点基因型,利用SAS9.4软件的MIXED过程进行关联分析。结果表明,RPL23A基因的SNP位点g.20146771C>T与第1泌乳期5个产奶性状达到显著或极显著关联(P=0.0001~0.0416),其优势等位基因为T;ACACB基因的g.63878254T>C位点与第1泌乳期产奶量、乳脂量和乳蛋白量呈极显著关联(P<0.01),其优势等位基因为C;g.63962768G>A位点与第1泌乳期产奶量、乳脂量、乳脂率和乳蛋白率关联显著或极显著(P=0.0001~0.0391),其优势等位基因为A。综上,RPL23A基因主要影响中国荷斯坦牛产奶量和乳蛋白,ACACB基因对产奶量和乳脂具有显著遗传效应,3个SNP位点可考虑作为遗传标记用于标记辅助选择培育奶牛高乳蛋白乳脂新品系和选育提高。