BMPR-IB基因多态性与河北肉用绵羊产羔数及羔羊生长发育的相关性研究

为了研究BMPR-IB基因单核苷酸多态性及其对绵羊产羔数和羔羊生长发育的影响,试验采用PCR-RFLP方法对小尾寒羊、杜泊、德克赛尔及河北肉用绵羊的BMPR-IB基因单核苷酸多态性进行了测定,并对BMPR-IB基因多态性与河北肉用绵羊产羔数和生长发育的关系进行了研究。结果表明:基因型频率在各品种间分布极不平衡,BB基因型河北肉用绵羊群体的总体平均产羔数显著高于B+基因型(P<0.05),极显著高于++基因型群体(P<0.01);90日龄时,++基因型河北肉用绵羊的胸宽和腰角宽显著高于B+基因型群体(P<0.05)。说明BMPR-IB基因的基因型对河北肉用绵羊羔羊的生长发育有一定影响。     

Indel variants within the PRL and GHR genes associated with sheep litter size

Growth hormone and prolactin belong to the class of peptide hormones that have a wide range of regulatory functions. In this study, polymorphisms of growth hormone receptor (GHR) and prolactin (PRL) genes were analysed as candidate genes, which are responsible for the litter size in Australian White (AUW) sheep. According to the statistical analyses results, the polymorphism information content (PIC) values of the PRL-P1-ins-23 bp, GHR-P2-del-23 bp and GHR-P8-del-23 bp were 0.371, 0.366 and 0.375, respectively, which indicates the high genetic polymorphism in AUW sheep. Moreover, all indel loci are not conformed to the HWE (p < .05). Further, our findings revealed that the PRL-P1-ins-23 bp polymorphism in the ovine PRL gene was significantly related to the first parity litter size (p = .001) and the DD genotype displaying the highest genotypic mean. Meanwhile, the GHR-P2-del-23 bp and GHR-P8-23 bp indels in the ovine GHR gene were significantly correlated with first parity litter size (p < .05), and the individuals with the genotype II showed significantly higher litter size than others. Collectively, these results demonstrated that our findings could be useful for future sheep breeding strategies based on the molecular-assisted selection (MAS).     

Association between novel variants in BMPR1B gene and litter size in Mongolia and Ujimqin sheep breeds

Prolificacy is an important trait of animals, specifically for sheep. The Bone morphogenetic protein receptor 1B (BMPR1B) is a major gene affecting the litter size of many sheep breeds. The well-known FecB mutation (Q249R) was associated fully with the hyper prolific phenotype of Booroola Merino. However, the identification of variation in all exonic regions of BMPR1B was rare. In this study, we sequenced all exonic regions of BMPR1B gene of Mongolia sheep breed, and ten novel variants were detected by direct sequencing. Among them, the litter size of the Mongolia ewes with the CC genotype was significantly higher (0.34 additional lambs, p < .05) than those with the TT genotype of the g.29346567C>T single nucleotide polymorphism (SNP). The litter size of the Mongolia ewes with the TT genotype was significantly higher (0.19 additional lambs, p < .05 and .31 additional lambs, p < .01, respectively) than those with the GT and GG genotypes of the c.1470G>T SNP. The silent c.1470G>T mutation is predicted to increase the stability of the mRNA secondary structure through reducing minimum free energy and is predicted to change the mRNA secondary structure of BMPR1B. Our findings may give potentially useful genetic markers for increasing litter size in sheep.     

Polymorphisms of the melatonin receptor 1A gene that affects the reproductive seasonality and litter size in Small Tail Han sheep

Previous researches have shown that MTNR1A plays an essential role in sheep reproduction. However, most researches focused more on the reproductive seasonality of sheep, and few scientists had studied the association of polymorphisms of the MTNR1A gene with ovine litter size and reproductive seasonality. Therefore, we chose MTNR1A gene to detect its novel sequence polymorphisms and population genetics and analyse their association with seasonal reproduction and litter size in ewes. The mRNA expression level in hypothalamus, pituitary and ovary was also detected. In this study, five polymorphisms (g.15118664G > T, g.15118683C > T, g.15118756C > T, g.15118774C > T and g.15118951G > A) were identified in exon 2. Most importantly, the g.15118683C > T and g.15118951G > A were significant difference between year‐round oestrous sheep and seasonal oestrous sheep (p < .01), and g.15118756C > T had a great effect on litter size of Small Tail Han sheep (p < .05). In addition, the mRNA expression level of MTNR1A in the hypothalamus of polytocous Small Tail Han sheep was significantly higher than that in monotocous Small Tail Han sheep (p < .01) and the expression of MTNR1A in the hypothalamus of year‐round oestrous sheep was significantly higher than that in seasonal oestrous sheep (p < .01). Polymorphisms in exon 2 may regulate the reproductive seasonality and litter size of ewes by influencing gene expression to regulate the reproductive seasonality and litter size of ewes. Our studies provided useful guidance in marker‐assisted selection of the litter size in Small Tail Han sheep.     

小尾寒羊、无角道赛特及其杂交后代BMPR-IB基因多态性研究

为了检测骨骼形态发生蛋白IB型受体(BMPR-IB)基因在小尾寒羊母羊、无角道赛特公羊、道×寒F1和F2代杂交公羊及道×寒F2横交固定所产种公羊中的多态性,分析小尾寒羊基因型与产羔数的相关性,试验采用PCR-RFLP法对BMPR-IB基因进行分型。结果表明:在无角道赛特公羊中只有1种基因型,即野生型(++);在小尾寒羊母羊中检测到2种基因型(BB和B+),基因型频率分别为0.35,0.65;在道×寒F1和F2代杂交公羊中检测到2种基因型(B+和++),F1代基因型频率分别为0.75,0.25,F2代基因型频率分别为0.30,0.70。小尾寒羊的2种基因型产羔数差异极显著(P<0.01),BMPR-IB基因的遗传方式符合孟德尔遗传定律。     

TGIF1 and SF1 polymorphisms are associated with litter size in Small Tail Han sheep

TGF-β induced factor homeobox 1 (TGIF1) and splicing factor 1 (SF1) are important for mammalian reproduction; however, the effects of these genes on litter size in sheep remain unexplored. In this study, we genotyped 768 ewes from seven sheep breeds at two loci: g.37871539C>T, a synonymous mutation of TGIF1; and g.42314637T>C, a 3′UTR variant of SF1. Our analysis of polymorphism revealed only two genotypes at locus g.37871539C>T in TGIF1, with most sheep populations being moderately polymorphic (0.25 < PIC < 0.5) at this site. In contrast, most breeds exhibited low polymorphism (PIC ≤0.25) at the SF1 locus g.42314637T>C. The association analysis revealed that a synonymous mutation at g.37871539C>T in TGIF1 was highly associated with litter size in Small Tail Han sheep, in which it causes a significant decrease in litter size. Conversely, while the SF1 3′UTR variant g.42314637T>C was also highly associated with litter size in sheep, it causes a significant increase in the number of litter size. Combined, these data provide valuable information regarding candidate genetic markers for sheep breeding programs.     

Identification of polymorphisms in the oocyte-derived growth differentiation growth factor 9 (GDF9) gene associated with litter size in New Zealand sheep (Ovis aries) breeds

Having the ability to control litter size is important for sheep farmers and breeders worldwide. However, making genetic gain in key livestock traits like reproductive performance needs typically a lot of time, and both the fecundity and fertility traits have a great economic importance. Attention has therefore turned to better understanding the genes that control reproductive performance. Of these genes, research has focussed on the growth differentiation growth factor 9 (GDF9) gene (GDF9). In this study, a PCR-single strand conformation polymorphism (PCR-SSCP) approach was used to investigate variation in this gene in separate groups of purebred Finnish Landrace sheep, Finnish Landrace × Texel-cross sheep and composite sheep of undefined breed background, but based on New Zealand Romney-type genetics. Three GDF9 variants (named A, B and C) were found, and upon DNA sequencing, the nucleotide substitutions c.978A>G, c.994G>A and c.1111G>A were revealed. The frequency of variant A (containing nucleotides c.978A, c.994G and c.1111G) in the Finnish Landrace, Finnish Landrace × Texel-cross and composite sheep was 0.86, 0.78 and 0.76, respectively. In these three sheep groups, the frequency of B (defined by the presence of nucleotides c.978G and c.994A) was 0.01, 0.03 and 0.23 and for C (containing c.1111A) was 0.13, 0.18 and 0.01, respectively. An animal model was used to estimate the additive effect of fertility data for Finnish Landrace × Texel-cross sheep and revealed an association between litter size and the c.1111G>A variation (p = .036), but this was not observed for the Finnish Landrace sheep (p = .27) or the composite sheep (p = .17). When all the sheep were analysed together, the presence of c.1111A was associated (p < .05) with increased litter size, when compared to ewes that had c.1111G. Litter size did not differ between sheep with and without c.994A in all three groups of sheep investigated. This study suggests that c.1111A could be a useful genetic marker for improving fecundity in New Zealand sheep breeds and that it could be introgressed into other breeds, but analysis of more sheep will be required to confirm the associations that have been observed here.     

Parity and litter size effects on maternal behavior of Small Tail Han sheep in China

The effects of parity and litter size on maternal behavior of Small Tail Han sheep was investigated at Linyi University, China. Sixty‐eight ewes were observed from parturition to weaning. Continuous focal animal sampling was used to quantify the duration of maternal behaviors. Ewe feces were collected every 2 days and estradiol concentration was measured with an enzyme immunoassay kit. All lambs were weighed 24 h after parturition and again at 35 days of age. Parity increased sucking, following, grooming, low‐pitched bleat, head‐up and udder‐refusal behavior and decreased aggressive behavior (P < 0.01, P < 0.01, P < 0.05, P < 0.05, P < 0.05, P < 0.05, P < 0.01, respectively), and litter size showed significant effect on sucking, following and low‐pitched bleat behavior (P < 0.05, P < 0.01, P < 0.05, respectively). The lambs of multiparous ewes were significantly heavier than primiparous ewes at birth (P < 0.01) and were significantly heavier at weaning age (P < 0.01). Similar results were founded for birth weight and weaning weight gain in litter size (P < 0.01, P < 0.01, respectively). Estradiol concentration in feces was higher in multiparous ewes than primiparous ewes. Parity and litter size may have effects on maternal behavior during lactation. Ewes that have 2–3 lambs may be more suitable for production of Small Tail Han sheep in China.     

猪催乳素受体基因第8内含子多态性及其对产仔性能的影响

采用PCR-SSCP技术检测了大白猪、长白猪、杜洛克猪、马身猪、山西黑猪和山西白猪等6个品种364头个体催乳素受体基因(prolactin,PRLR)第8内含子的多态性,并分析了多态位点对猪头胎产仔性能的影响。结果表明,猪PRLR基因第8内含子存在多态性,共检测到A、B、C 3个等位基因和AA、AB、AC、BB、BC和CC 6种基因型。在杜洛克猪、长白猪、山西黑猪和山西白猪群体中,A等位基因的频率最高,分别为0.8276、0.5439、0.5345和0.7669;而在大白猪和马身猪群体中,B等位基因的频率最高,分别为0.6894和0.7000;仅在大白猪、山西黑猪和山西白猪中检测到C等位基因,且频率较低,在0.0379~0.1385之间。PRLR基因型对母猪头胎产仔数有显著影响(P<0.05),对产活仔数的影响未达显著水平。AC基因型母猪的头胎产仔数和产活仔数显著高于BC基因型个体,而与AA、AB和BB基因型个体差异不显著。含有A等位基因的母猪的产仔性能优于不带有A等位基因的个体,表明A等位基因是有利于母猪产仔性能提高的等位基因,可应用于标记辅助选择来提高母猪的繁殖性能。     

乌骨绵羊MC1R基因多态性研究

酪氨酸酶(TYR)、酪氨酸酶相关蛋白1(TYRP1)和酪氨酸酶相关蛋白2(TYRP2)是动物黑色素生物合成过程的重要酶,黑素皮质素1受体(MC1R)一旦与配体α-促黑素细胞激素(α-MSH)结合,对TYR、TYRP1和TYRP2酶活性的表达水平均有重要影响,因此认为MC1R是黑素合成模式的控制点。本研究以MC1R基因为候选基因,对乌骨绵羊MC1R基因多态性进行了研究,希望揭示MC1R基因与乌骨绵羊乌质性状之间的关系。结果表明,乌骨绵羊MC1R基因存在2个多态位点,分别为A12G和G144C。翻译表明这2处突变都为同义突变,对应的氨基酸分别是丝氨酸(Ser)和亮氨酸(Leu)。PCR-RFLP分析发现绵羊MC1R存在2个等位基因,即MC1R*1和MC1R*2,对应11型、22型和12型3种基因型。乌骨绵羊和兰坪本地绵羊MC1R等位基因的频率差异不显著,而与罗姆尼羊差异显著,推测MC1R基因可能不是控制乌骨绵羊乌质性状的主效基因。     

Polymorphism of inhibin βB gene and its relationship with litter size in sheep

The inhibin β_B (INHBB) gene was studied as a candidate gene for the prolificacy of Small Tail Han and Hu sheep. According to the sequence of exon 1 and 2 of bovine INHBB gene, six pairs of primers were designed to detect single nucleotide polymorphisms of exon 1 and 2 of INHBB gene in both high (Small Tail Han and Hu sheep) and low prolificacy breeds (Dorset, Texel and German Mutton Merino sheep) by polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP). Three pairs of primers (primers 1‐1, 1‐2 and 1‐3) were used to amplify the exon 1, and others (primers 2‐1, 2‐2 and 2‐3) to the exon 2. Only the products amplified by primer 2‐3 displayed polymorphism. For primer 2‐3, three genotypes (AA, AB and BB) were detected in Hu sheep and only AA genotype in other breeds. In Hu sheep, frequency of AA, AB and BB genotypes was 0.636, 0.046 and 0.318, respectively. Sequencing revealed 276A > G mutation (based on the amplification region of primer 2‐3) which did not cause any amino acid change because it lay in the 3′ untranslated region. The ewes with genotype BB had 0.58 (P < 0.01) lambs more than those with AA in Hu sheep.     

DNA polymorphism of insulin-like growth factor-binding protein-3 gene and its association with birth weight and body weight in cattle

Insulin‐like growth factor‐binding protein‐3 (IGFBP‐3) is a protein that binds the majority of insulin‐like growth factors in circulation for regulation of its action on growth and metabolism of the animals. Animals belonging to Hariana, Holstein‐Friesian (HF) and their crossbreds (HF × Hariana) were studied using polymerase chain reaction‐restriction fragment length polymorphism and nucleotide sequencing of the IGFBP‐3 gene. A 651‐bp fragment of the IGFBP‐3 gene spanning over a part of exon 2, complete intron 2, exon 3 and a part of intron 3 was amplified and digested with HaeIII restriction enzyme. Three patterns of restriction fragments were observed in HF and crossbred cattle revealing polymorphism in both the populations. The frequency of AA, AB and BB genotypes was 0.65, 0.32 and 0.03 in crossbreds and 0.29, 0.65 and 0.06 in HF respectively. The allelic frequency of the A and B allele was 0.81 and 0.19 in crossbreds and 0.62 and 0.38 in HF cattle respectively. Only one restriction pattern (AA genotype) was observed in all the animals of Hariana breed of Bos indicus showing the absence of polymorphism. Nucleotide sequencing revealed a C → A mutation in the intron 2 region of the IGFBP‐3 gene as the cause of the polymorphism. Least squares analysis revealed a significant effect (p < 0.05) of genotypes on birth weight and body weight (weight at 12, 18 and 24 months of age) of the animals. Animals of AB genotype showed higher birth weight and body weight than the animals possessing AA genotype.     

绵羊催乳素受体基因外显子10多态性及其与产羔数相关分析

采用PCR-SSCP技术检测催乳素受体(PRLR)基因外显子10在湖羊、小尾寒羊、洼地羊和阿勒泰羊中的单核苷酸多态性,研究该基因与湖羊高繁殖力的关联性。结果表明:4个绵羊品种在P2引物扩增区域均符合Hardy-Wenberg平衡,但P3引物只有阿勒泰羊符合Hardy-Wenberg平衡。P2扩增片段的不同基因型分布频率在4个品种间差异不显著(P0.05);而除阿勒泰羊P3扩增片段的基因型分布与其余3个品种间存在极显著差异(P0.01)外,其余各品种间基因型分布差异不显著(P0.05)。4个绵羊品种间产羔数存在极显著差异(P0.01),但不同基因型间产羔数差异不显著(P0.05);湖羊不同引物不同基因型产羔数的差异亦均不显著(P0.05)。本研究表明,PRLR基因不能作为湖羊高繁殖力的候选基因。     

山羊乳中上皮黏蛋白MUC1遗传多态性与产羔数的相关性研究

采用SDS-PAGE法分析9个山羊群体乳中上皮黏蛋白MUC1遗传多态性,并通过构建的线性模型,采用最小二乘法分析乳MUC1位点遗传多态性与产羔数的相关性。结果表明:(1)9个山羊群体中,乳MUC1在SDS-PAGE上均呈现出了丰富的遗传多态性,表现为1条或2条迁移率不同的区带,317个个体共检测到7个不同分子质量的MUC1区带,分别代表A、B、C、D、E、F、G7个等位基因,共有17种基因型。(2)乳MUC1位点对山羊产羔数的影响达到显著水平(P<0.05);基因型为CC、EE和FF的个体产羔数的最小二乘均值显著大于基因型为BB、BD和CF的个体最小二乘均值(P<0.05)。因此,说明山羊乳MUC1遗传多态性有望作为产羔数的有效遗传标记。     

A substitution within erythropoietin receptor gene D1 domain associated with litter size in Beijing Black pig,Sus scrofa

Studies of uterine capacity and litter size in swine have suggested that erythropoietin receptor (EPOR) plays an important role in fetal survival through maturation of red blood cells. In this study, we screened the porcine EPOR gene for mutations and identified three single nucleotide polymorphisms (SNPs): two missense mutations and one synonymous mutation. We then genotyped 272 Beijing Black sows, Sus scrofa, and compared this data with litter sizes from a total of 1523 parities among the sows. The G allele of the nonsynonymous SNP, EPOR c.434A>G, was associated with greater litter size at both first parity (P < 0.05) and at later parities (P < 0.01). This SNP causes His92Arg adjacent to the fourth conserved cysteine residue in the mature protein and is in the D1 domain of the protein. Additionally, we determined the allele frequencies for this SNP among six Chinese indigenous pig breeds (Bamei, Erhualian, Laiwu Black, Mashen, Meishan and Min) and three Western commercial pig breeds (Duroc, Landrace and Large White). The c.434G allele was significantly more common among the more prolific Chinese breeds than the Western breeds, implying that EPOR c.434A>G could be a useful genetic marker to improve litter size in swine.     

Detection of novel single-nucleotide polymorphisms (SNPs) in the CYP21 gene and association analysis of two SNPs for CYP21 and ESR2 with litter size in a commercial sow population

Altogether 129 F₁ sows from a commercial sow farm with at least four litters were genotyped for the oestrogen receptor 2 gene (ESR2) and cytochrome P450 hydroxylase 21 gene (CYP21) and investigated for associations on the litter‐size parameters: total number born and number born alive. Five novel polymorphisms were found in the 3′‐untranslated region for the CYP21 gene. Genotype and allele frequencies for the CYP21 (position 3462G > A) single‐nucleotide polymorphism (SNP) were 0.434 (GG), 0.504 (AG), 0.062 (AA) and 0.69 (G):0.31 (A), respectively. No association was found between this polymorphism and litter‐size parameters. For the ESR2 gene, the SNP in exon 5 associated with an amino acid substitution MET (allele A) > VAL (allele G) was investigated. Only two genotypes were found leading to allele frequencies of 0.34 (A):0.66 (G). Only number born alive piglets were significantly increased for the AG genotype (p = 0.034) with 11.64 piglets per sow and litter in comparison with the GG genotype, leading to only 10.96 piglets per sow and litter. From these data, it can be concluded that the investigated SNP of the ESR2 gene is associated with the number of liveborn piglets in the commercial population considered, and hence could be useful in selection for litter size. Therefore, this gene should be investigated in additional populations.     

绵羊mtDNA变异与产羔数关联分析

旨在分析线粒体DNA变异与产羔数性状的关系,寻找影响绵羊繁殖性能的分子遗传标记,为高繁殖力绵羊的选育提供理论依据和方法.本研究以有产羔记录的健康小尾寒羊多羔母羊(multiple Small tailed han sheep,XM)、湖羊多羔母羊(multiple Hu sheep,HM)、蒙古羊双羔母羊(twins ...