Influence of prion protein gene polymorphisms on performance traits in German meat sheep breeds

PrP polymorphisms influence the scrapie susceptiblility of sheep. The objective of this study was to analyse the association between performance traits and the PrP genotype in the sheep breeds German black-headed and German white-headed mutton, Bleu du Maine, German mutton merino, Leine, Texel and Suffolk from Lower Saxony and Westphalia. We analysed performance traits such as scores for muscle mass, type and wool quality and the calculated daily weight gain using linear animal models. In all seven breeds no statistically significant associations were found between performance traits and the occurrence of ARR alleles, and the ARR/ARR genotypes, respectively. All genotyped sheep of all breeds investigated showed significantly superior performance traits in comparison to the non-genotyped animals.     

Detection of prion protein gene polymorphisms in Baltic breeds of sheep

A total of 167 sheep belonging to the Estonian whiteheaded mutton, Estonian blackheaded mutton, Lithuanian coarsewool native, Lithuanian blackface and Latvian darkheaded mutton breeds, and a population of sheep kept isolated on the Estonian island of Ruhnu, were sequence-analysed for polymorphisms in the prion protein (PrP) gene, to determine their genotype and the allele frequencies of polymorphisms in PrP known to confer resistance to scrapie. A 939 base pair fragment of exon 3 from the PrP gene was amplified by pcr and analysed by direct sequencing. For animals showing polymorphism at two nucleotide positions, both haplotypes of these double-heterozygous genotypes were further verified by pcr cloning and sequence analysis. Known polymorphisms were observed at codons 136, 154 and 171, and six different haplotypes (arr, ahq, arh, ahr, arq and vrq) were determined. On the basis of these polymorphisms, the six populations of sheep possessed the resistant arr haplotype at different frequencies. The high-risk arq haplotype occurred in high frequencies in all six populations, but vrq, the haplotype carrying the highest risk, occurred at low frequencies and in only three of the populations.     

Natural scrapie in British sheep: breeds, ages and PrP gene polymorphisms.

One hundred and sixty-seven sheep of 32 breeds and crossbreeds affected by natural scrapie throughout Britain were tested for the presence of restriction fragment length polymorphisms of the PrP gene observed when their DNA was digested with EcoRI or HindIII. These polymorphisms have already been associated with different susceptibilities to experimental scrapie (controlled by alleles of the Sip gene) in a flock of Cheviot sheep. In two studies 86 to 92 per cent of the sheep were found to carry the PrP gene EcoRI fragment e1 which is associated with high susceptibility (or the sA allele of Sip) to experimental scrapie. The PrP gene HindIII genotypes of the natural scrapie sheep were not apparently associated with differences in susceptibility to scrapie. There was no link between the polymorphisms and the age or breed of the affected sheep.     

Association between IGF-I, IGF-IR and GHRH gene polymorphisms and growth and carcass traits in beef cattle

Molecular biology techniques are of help in genetic improvement since they permit the identification, mapping and analysis of polymorphisms of genes encoding proteins that act on metabolic pathways involved in economically interesting traits. The somatotrophic axis, which essentially consists of growth hormone releasing hormone (GHRH), growth hormone (GH), insulin-like growth factors I and II (IGF-I and IGF-II), and their associated binding proteins and receptors (GHRHR, GHR, IGF-IR and IGF-IIR), plays a key role in the metabolism and physiology of mammalian growth. The objectives of the present study were to estimate the allele and genotype frequencies of the IGF-I/SnaBI, IGF-IR/TaqI and GHRH/HaeIII gene polymorphisms in different genetic groups of beef cattle and to determine associations between these polymorphisms and growth and carcass traits. For this purpose, genotyping was performed on 79 Nellore animals, 30 Canchim (5/8 Charolais+3/8 Zebu) animals and 275 crossbred cattle originating from the crosses of Simmental (n=30) and Angus (n=245) sires with Nellore females. In the association studies, traits of interest were analyzed using the GLM procedure of SAS and least square means of the genotypes were compared by the Tukey test. Associations of IGF-I/SnaBI genotypes with body weight and subcutaneous backfat were significant (p<0.05), and nearly significant for longissimus dorsi area (p=0.06), with the BB genotype being favorable compared to the AB genotype. No significant associations were observed between this polymorphism and weight gain or carcass yield (P>0.05). The IGF-IR/TaqI and GHRH/HaeIII polymorphisms showed no association with production traits.     

DRD4基因多态性与鸡繁殖性状的相关性分析

旨在分析多巴胺受体4基因(dopamine receptor 4,DRD4)多态性与鸡繁殖性状的关系。对DRD4基因共设计3对引物,筛选出7个多态位点,对瑶山鸡母系60个个体进行了与繁殖性状的关联分析。结果表明:DRD4基因5365(C→T)、5747(C→T)对开产日龄存在显著影响(P0.05);5546(G→A)对首次就巢日龄、首次就巢持续时间和300日龄就巢次数存在显著影响(P0.05)。结果提示:DRD4基因5365(C→T)、5747(C→T)可作为开产日龄辅助选择标记;DRD4基因5546(G→A)可作为首次就巢日龄、首次就巢持续时间和300日龄就巢次数辅助选择标记。     

Allele frequencies of gene polymorphisms related to economic traits in Bos taurus and Bos indicus cattle breeds

Allele frequencies of 10 representative polymorphisms for beef and milk traits were investigated for a total of 240 animals from Bos taurus and Bos indicus breeds, including two Japanese groups (Japanese Black and Japanese Brown), two East Asian groups (Korean and Mongolian), three European groups (Holstein, Angus and Hereford) and a Bos indicus group in South Asia (Myanmar, Laos and Cambodia). The Japanese Black revealed unique genetic construction in GH, FASN and SREBP‐1 and the other Asian populations show intermediate frequencies between European and Japanese populations. The Bos indicus group showed low favorable allele frequencies in most of the genes. The study showed the variability and distribution of 10 genes affecting economic traits among world representative cattle breeds. The genetic information would contribute to elucidating the genetic background for worldwide cattle breeds and the possibility of improvement using the markers.     

鸡IGFBP-2基因的多态性及其与生长、繁殖性状的关系

采用PCR-SSCP方法检测京海黄鸡、AA鸡、尤溪麻鸡、边鸡等4个鸡品种胰岛素样生长因子结合蛋白2（IG-FBP-2）第3内含子部分序列、第4外显子及3′调控区的多态性,并分析其对京海黄鸡生长和繁殖性能的遗传效应。结果显示,IGFBP-2基因在P1、P3引物扩增片段中存在PCR-SSCP多态性。对于P1扩增片段,在京海黄鸡和AA鸡中都检测到EE、EF和FF这3种基因型,在尤溪麻鸡和边鸡中只检测到EE型;测序表明FF型与EE型相比有2处突变（3746T→G,3753CC→TT）;京海黄鸡3种基因型之间300日龄蛋质量、300日龄体质量、出生体质量、8周龄体质量的最小二乘均值差异显著（P〈0.05）。对于P3扩增片段,在4个鸡群体中都检测到GG、GH和HH这3种基因型;测序表明HH型与GG型相比有1处缺失（4415GCGGGAAG）;京海黄鸡3种基因型之间除出生体质量外,其他生长和繁殖性状的最小二乘均值差异均不显著（P〉0.05）。因此,推测IGFBP-2基因可能是影响鸡生长和繁殖的主效基因或与控制该性状的主效基因连锁。     

牛POU1F1-exon6多态性与生长性状的相关性研究

为了研究弗莱维赫牛和蒙贝利亚牛POU1F1-exon6多态性与体重、体尺等生长性状指标的相关性,试验采用PCR-RFLP技术分析其多态性,并采用最小二乘法拟合线性模型,对各标记基因型与部分生长性状指标差异显著性进行检验。结果表明:2个群体POU1F1-exon6基因存在2个等位基因A/G,基因频率分别为0.175 9/0.824 1,0.096 8/0.903 2;在该位点上,弗莱维赫牛处于Hardy-weinberg平衡状态(P0.05),而蒙贝利亚牛处于不平衡状态(P0.05);2个群体中AA基因型体重均值高于AG、GG基因型均值(P0.05),GG和AG基因型个体腹围均值高于AA基因型个体均值(P0.05),但在体高、体长、胸围和管围4个性状上无显著性差异(P0.05)。说明POU1F1基因的A15636G位点可以作为牛的体重和腹围指标的候选遗传标记之一。     

Prion protein genetic polymorphisms and breeding strategies in Portuguese breeds of sheep

Polymorphisms at the prion protein locus were studied in 965 animals, representative of 13 native and 3 exotic sheep breeds in Portugal. In general, ARQ was the predominant allele in most breeds, but the desirable ARR allele was present in all breeds studied. A different pattern was found in Ile de France, where ARR was predominant and VRQ had the highest frequency among the breeds analysed. In most of the breeds, especially in those of the coarse-wool type, the major hurdle in selecting for genetic resistance to clinical scrapie was the elimination of ARQ rather than VRQ alleles. Breeding schemes aiming at the creation of ARR-homozygous selection nuclei were simulated for representative breeds, and results indicate that, with intense selection, it would take between 4 years in Ile de France and 11 years in Mondegueira to obtain homozygosity in the nucleus, and the length of time needed for fixation was not affected by the type of mating (random or assortative) used. Nevertheless, intense selection for the PrP genotype alone would have undesirable consequences in terms of inbreeding, and correlated responses in production and adaptation traits should be evaluated before such a scheme is adopted.     

Unique amino acid polymorphisms of PrP genes in Mongolian sheep breeds

To characterize amino acid polymorphisms of sheep prion protein (PrP) gene, DNA from 740 sheep of nine breeds raised in Mongolia was isolated and analyzed. A total of 16 genotypes and seven allelic variants of the PrP gene at codons 112, 136, 154, and 171 were found. The MARQ/MARQ genotype associated with susceptibility to scrapie was found in 82.6% of the sheep while the MARR/MARR genotype associated with resistance to scrapie was found in 1.8% of the sheep. The polymorphisms of valine and serine at codon 127, and leucine and arginine at codon 189 were detected in eight Mongolian sheep breeds, suggesting that these polymorphisms are a common feature among Mongolian sheep breeds.     

Investigation in early growth traits, litter size, and lamb survival in two Iranian fat-tailed sheep breeds

In the present study, 1,635 lambing records of Ghezel (n?=?766) and Mehraban (n?=?869) breeds were used to evaluate the early growth traits, litter size, and lamb survival in sheep reared in Fars Province, southern Iran, during a 5-year-long period. The least squares means (± SE) of lamb birth weight for Ghezel were 5.27 (±0.22), 5.02 (±0.22), and 3.98 (±0.23) kg for single males, single females, and twin lambs, respectively; whereas, the corresponding values for Mehraban were 4.39 (±0.18), 4.18 (±0.18), and 3.50 (±0.19) kg. The least squares means of pre-weaning lamb growth (gram per day) for Ghezel were 239 (±15), 218 (±15), and 181 (±16) for single males, single females, and twin lambs, respectively, and the corresponding values for Mehraban were 204 (±12), 187 (±12), and 156 (±13). Lambs from 2 year old ewes or younger were on average lighter at birth and at weaning and had a lower average daily gain than those from older ewes (P?<?0.05). The percentage of twin births increased from 1.1 and 1.3 % for ewes aged ≤ 2 years to 19 and 12 % for those aged ≥ 6 years old in Ghezel and Mehraban, respectively (P?<?0.05). The mean pre-weaning lamb mortality was 7.1 and 4.1 % for Ghezel and Mehraban, respectively.     

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.     

Association study of polymorphisms inside the miR-1657 seed region with chicken growth and meat traits

1. Polymorphisms occurring in the seed region of microRNAs (miRNAs) could influence their target gene and lead to phenotypic variation. The purpose of the research was to explore the genetic effects of the rs14934924 (G?>?A) mutation resident in the conserved seed region of miR-1657 on growth and meat traits of the Gushi-Anka F2 resource population.

2. The NdeI polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and association analysis were used to analyse the polymorphism.

3. The mutation was associated with body weight at 8 weeks of age, shank girth at 12 weeks of age, breast bone length at 12 weeks of age, pelvis breadth at 4 weeks of age and subcutaneous fat thickness (P?P? 4. Our results will be a useful resource for a subsequent study in miRNA function, and provide a basis for molecular techniques in chicken breeding.     

PPP1CB基因多态性与西门塔尔牛肉质性状相关性分析

选用134头西门塔尔牛为试验材料,采用PCR-RFLP的方法对PPP1CB基因的第一内含子进行检测,利用SPSS软件对该基因内含子1的多态性与肉质性状进行相关性分析。分析结果表明:PPP1CB基因的第一内含子第14 434bp碱基处存在C/T基因突变,该基因多态性与屠宰率呈显著相关,对其他性状的影响差异不显著。本文首次揭示了PPP1CB基因与牛肉质性状的相关性,为西门塔尔牛利用该基因的多态性进行分子育种提供了试验依据。     

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.     

Association of single nucleotide polymorphisms in the leptin gene with carcass and meat quality traits of beef cattle

Studies with different populations are required to properly characterize the robustness of associations of polymorphisms in candidate genes with economically important traits across beef cattle populations before this sort of genetic information can be used efficiently in breeding and management decisions. The objective of this study was to evaluate the association of previously reported SNP in the bovine leptin gene with carcass and meat quality traits from a large sample of crossbred beef cattle. Five SNP (UASMS1, UASMS2, UASMS3, E2JW, and E2FB) were genotyped on 1,111 crossbred bulls, heifers, and steers. The measured traits included fat, lean, and bone yield (%) by partial rib dissection, grade fat, LM area, HCW, quality grade, LM i.m. fat, and tenderness evaluation of LM and semitendinosus muscle. Only four SNP were analyzed (UASMS1, UASMS2, E2JW, and E2FB), because UASMS1 and UASMS3 were completely linked. A uni-variate mixed-inheritance animal model was used to evaluate the association of either genotypes or haplo-types with the traits. The two leptin exon 2 SNP were associated with fat and lean yield and grade fat (E2JW, P < 0.01; E2FB, P < 0.05), and they interacted in their effect on LM tenderness (P < 0.01). The leptin promoter SNP were either not associated with any of the traits (UASMS2) or with fat yield only (UASMS1). Three haplotypes (TCAC, CCAT, TTAC) were at high frequency in the population (88%) and had similar effects on all the traits. Compared with the common haplotypes, one haplotype (CCTT) showed a significantly different effect on fat and lean yield and grade fat (P < 0.01), and one haplotype (TTTT) had a different effect on LM tenderness (P < 0.03). Therefore, important associations between SNP within the leptin gene with lean yield, fatness (fat yield and subcutaneous fat), and tenderness were detected. Results confirm some of the previously reported associations, but diverge with respect to others, showing that further efforts are required to validate some prospective associations.     

Relationship between inbreeding and milk production traits in two Italian dairy sheep breeds

The effects of inbreeding in livestock species breeds have been well documented and they have a negative impact on profitability. The objective of this study was to evaluate the levels of inbreeding in Sarda (SAR, n = 785) and Valle del Belice (VdB, n = 473) dairy sheep breeds and their impact on milk production traits. Two inbreeding coefficients (F) were estimated: using pedigree (F_PED), or runs of homozygosity (ROH; F_ROH) at different minimum ROH lengths and different ROH classes. After the quality control, 38,779 single nucleotide polymorphisms remained for further analyses. A mixed-linear model was used to evaluate the impact of inbreeding coefficients on production traits within each breed. VdB showed higher inbreeding coefficients compared to SAR, with both breeds showing lower estimates as the minimum ROH length increased. Significant inbreeding depression was found only for milk yield, with a loss of around 7 g/day (for SAR) and 9 g/day (VdB) for a 1% increase of F_ROH. The present study confirms how the use of genomic information can be used to manage intra-breed diversity and to calculate the effects of inbreeding on phenotypic traits.     

Associations of polymorphisms in the Pit-1 gene with growth and carcass traits in Angus beef cattle

The Pit-1 gene was studied as a candidate for genetic markers of growth and carcass traits. Angus beef cattle that were divergently selected for high- or low-blood serum IGF-I concentration were used in this study. The single-strand conformation polymorphism method was used to identify polymorphism in the Pit-1 gene including regions from intron 2 to exon 6. Two polymorphisms, Pit1I3H (HinfI) and Pit1I3NL (NlaIII), were detected in intron 3 of the Pit-1 gene. One polymorphism, Pit1I4N (BstNI), was found in intron 4, and a single nucleotide polymorphism, Pit1I5, was found in intron 5. The previously reported polymorphism in exon 6, Pit1E6H (HinfI), was also studied in 416 Angus beef cattle. Associations of the polymorphisms with growth traits, carcass traits, and IGF-I concentration were analyzed using a general linear model procedure. No significant associations were observed between these polymorphisms and growth and carcass traits.     

Association of ADSL gene polymorphisms with meat quality and carcass traits in domestic pigeons (Columba livia)

ABSTRACT

1. Adenylosuccinate lyase (ADSL) plays an important role in the synthesis of inosine monophosphate (IMP). In this trial, a total of 200 pigeons were sampled and slaughtered. Seven meat quality traits and 11 carcass traits were measured. DNA sequencing was used to detect nucleotide mutations, and associations between ADSL gene polymorphisms and meat quality and carcass traits were analysed.

2. Sequencing results showed that 9 nucleotide mutations were found in the exons of the ADSL gene. All the mutations were synonymous except C13065G, which caused a change in amino acids (Ser to Arg). In addition, two of the detected single nucleotide polymorphisms (SNPs) had significant associations with meat quality and carcass traits.

3. For the C13065G SNP located in exon11, the IMP content of breast muscle in AA and AB genotype was higher than in the BB genotype (P < 0.01). The SNP G10696A located in exon10 was significantly associated with carcass rate, in which AA and AB genotype were higher than the BB genotype (P < 0.01).

4. The results indicated that the ADSL gene has a close association with meat quality and carcass traits in domestic pigeons, and G10696A and C13065G SNPs could be applied as genetic markers in molecular marker-assisted breeding of pigeons.