zyxin基因外显子7(exon 7)SNP位点与京海黄鸡屠宰及肉品质性能的相关性

以京海黄鸡为试验材料,采用PCR-SSCP技术检测斑联蛋白(zyxin)基因第7外显子SNP,探讨zyxin基因该位点多态性与京海黄鸡屠宰性能以及肉品质之间的关系.结果发现该位点存在1个SNP突变位点,表现为3种基因型,分别为AA、AB和BB.统计分析表明公鸡的肝质量、屠宰率,BB基因型显著高于AA型(P＜0.05);腹脂质量、胸肌率、腿肌率,AA型显著高于BB型(P＜0.05).母鸡群体中,只有爪质量AA型显著高于BB型(P＜0.05).3种基因型对内品质的影响均不显著(P＞0.05).     

松辽黑猪IGF-Ⅰ基因的单核苷酸多态性(SNP)及其与生长和胴体性状的关联性

采用PCR-SSCP技术分析了IGF-Ⅰ基因的5’UTR、外显子4在松辽黑猪群体中的遗传多态性。结果在所扩增的IGF-Ⅰ基因的5’UTR中的2个目的片段均未发现PCR-SSCP遗传多态;在第4外显子中发现PCR-SSCP多态,有2种等位基因A和B,有3种基因型AA型、AB型、BB型。对多态片段的测序分析表明:在IGF-Ⅰ基因第4外显子中存在有1碱基A→G突变。适合性卡方检验表明,该位点的不同基因型频率处于Hardy-Weinberg平衡。用最小二乘法分析IGF-Ⅰ基因第4外显子不同基因型与松辽黑猪生长和胴体性状的相关性,发现IGF-Ⅰ不同基因型对断奶后日增重有显著影响,AA型显著高于AB型和BB型(P<0.01)。AA型猪的瘦肉率显著低于AB型和BB型(P<0.01),而AA型猪的平均背膘厚显著高于AB型和BB型(P<0.01),对其他性状的影响差异不显著。结果表明,松辽黑猪IGF-Ⅰ基因应是影响生长和胴体性状的一个主效基因或与影响这些性状的主效基因紧密连锁。     

Heritabilities for duration of fertility traits in Brown Tsaiya female ducks (anas platyrhynchos) by artificial insemination with pooled muscovy (cairina moschata) semen

1. Fertility traits in 348 Brown Tsaiya female ducks were analysed following intergeneric crossbreeding by artificial insemination (AI) with pooled Muscovy semen. The females descended from 18 sires and 107 dams. At 50 weeks of age, the ducks were intra‐vaginally inseminated once with 0.03 ml of pooled Muscovy semen. Subsequently eggs were collected for 15 d and set for incubation up to candling 10 d later.

2. Average fertility decreased from 87% at day 2 after AI to 53% at day 6 and less than 7% from day 10 onwards.

3. The best criterion of selection for duration of fertility seems to be the number of fertile eggs from 2nd day up to the 15th day after AI. Heritability estimates for this trait were A² = 0.29 ± 0.18., h² _D = 0.38 ± 0.22.     

Crossbreeding effects on reproductive traits in two strains of duck (Anas platyrhynchos): Brown Tsaiya and Pekin

1. The reproductive performances of 211 domestic duck females (Anas platyrhynchos) from the pure breeds Brown Tsaiya (Ts) and Pekin (Pk) and their two reciprocal crossbreds were analysed.

2. Differences in the 4 genotypes, additive direct and maternal crossbreeding effects and heterosis were estimated on the following traits: age at first egg, egg production to the ages of 30, 35, 40 and 52 weeks of age, egg weight at 30 weeks of age, and (egg) fertility by artificial insemination with Muscovy drakes’ pooled semen.

3. Egg production up to 52 weeks of age was higher in Ts than in Pk (respectively 214 ± 7 and 150 ± 8 eggs), but not statistically different from that of the reciprocal crossbreds. The ratio of settable eggs to total eggs was nearly 90%, without any difference between genotypes.

4. Average egg weight at the age of 30 weeks was 75 ± 0.9 g for Pk, which was higher than the corresponding values for Ts (62 ± 0.8 g), but not significantly different from the crossbreds.

5. An effect of genotype was found on egg fertility: the Pk strain exhibited the lowest value, 71.3 ±3.1% compared with 75.9 ±2.1% for Ts, 80.6 ± 2.6% for Ts × Pk and 74.6 ± 1.9% for Pk × Ts.

6. Crossbreeding genetic variables showed favourable direct genetic effects for egg production and (egg) fertility in Ts, while Pk had favourable direct genetic effects on egg weight. The Pk genotype had a favourable maternal effect on fertility. Direct heterosis was 34% and 10% for egg production up to 30 and 52 weeks of age respectively, 8.8% for egg weight and 5.4% for (egg) fertility.

7. Crossing Ts with Pk seems profitable for the production of mule ducklings.     

郏县红牛TAFA1基因多态性及其与生长性状的关联分析

本研究旨在探讨TAFA趋化素样家族成员1（TAFA1）基因多态性与郏县红牛生长的关联性。试验共采集了79头郏县红牛成年母牛的血样并提取基因组DNA,利用直接测序法对TAFA1基因上的错义突变SNP rs137516577进行基因型分型,并与郏县红牛体高、体长、胸围、腰角宽、坐骨端宽、尻长、十字部高、荐高、胸深、胸宽、体重等11个生长和体尺性状进行关联分析。同时根据“Animal Omics Datebase”数据库对TAFA1基因的组织表达情况进行分析。结果发现该SNP与体长、腰角宽、坐骨端宽、尻长和体重等性状显著相关（P<0.05）,且GC型个体体长、腰角宽、坐骨端宽、尻长和体重均显著高于GG型（P<0.05）。TAFA1基因在牛大脑组织中表达量最高。结果表明,TAFA1基因上错义突变SNP rs137516577与郏县红牛生长性状相关,可作为郏县红牛生长性状的分子标记。     

The incidence of genotypes at codon 171 of the prion protein gene (PRNP) in five breeds of sheep and production traits of ewes associated with those genotypes

Scrapie is one of several transmissible spongiform encephalopathies of livestock. Disease susceptibility is linked to polymorphisms in the normal prion protein gene that encodes the mammalian prion precursor. Codon 171 of this gene is a major determinant of scrapie susceptibility. Selection for arginine (R) at codon 171 is encouraged by the USDA to decrease the incidence of scrapie. Objectives of this study were to determine the frequency of R allele variants at codon 171 in a sample of sheep from five breeds (Columbia, Hampshire, Rambouillet, Suffolk, and Targhee) and western white-faced commercial ewes and to determine whether the R allele is associated with ewe and lamb production traits. Genotyping was performed on 532 ewes and 901 lambs from the University of Wyoming flock, in addition to 820 rams from 52 sheep producers from Wyoming and surrounding areas, using a DNA mismatch assay that discriminated the R allele from others at codon 171. Genotyping was performed by DNA sequencing on 127 rams representing all breeds, except Hampshire from the USDA Sheep Experiment Station at Dubois, ID. The 171R allele was found in all five breeds and in the commercial western white-faced ewes. Genotype frequencies varied (P < 0.001) by breed in ewe and ram populations. Influence of R-allele frequency on ewe lambing records and individual lamb records was analyzed for Columbia (62, 161, 121), Hampshire (89, 193, 162), Rambouillet (87, 179, 133), Suffolk (67, 178, 161), and commercial sheep (227, 463, 324) for numbers of ewes, total number of ewe production records, and individual lamb records, respectively. Suffolk ewes without the R allele (non-R/non-R) gave birth to more (P or= 0.08) by ewe genotype. Lamb birth and weaning weights were not influenced (P >or= 0.12) by lamb genotype in any of the breeds or in the commercial flock. In this population, ultimate lamb production was only influenced by genotype at codon 171 in the Suffolk flock.     

Inheritance of reproductive traits of female common ducks (Anas platyrhynchos) in pure breeding and in inter-generic crossbreeding with muscovy ducks (Cairina moschata)

1. Genetic parameters of reproductive traits were estimated in a population of common duck, in purebreeding and crossbreeding (with Muscovies) insemination systems. A total of 989 females were studied over three generations as well as 4025 purebred offspring and 4,125 male mule offspring. 2. Traits studied were age at first egg, total number of eggs laid until the age of 48 weeks, fertility and hatchability rates in pure and crossbreds, weight at 6 and 30 weeks of age, average egg weight and body weight of the male mule ducks at 6 weeks of age. 3. Heritability estimates were found to be medium range for reproductive traits (0.15 to 0.47). Heritability value for fertility or hatchability in crossbreds was twice as high as in purebreds (0.32 vs 0.15 for fertility; 0.36 vs 0.16 for hatchability). 4. Fertility in purebreeding and in crossbreeding were two different traits (r(g) = 0.49) while hatchability displayed a high genetic correlation between breeding systems (r(g) = 0.88). 5. Genetic correlations with number of hatched mule ducks were medium or high and favourable. Genetic correlations between reproductive traits and weights were low (< 0.36), the most related trait being the body weight of the male mule duck at 6 weeks of age.     

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.     

The relationship between leptin gene polymorphisms and reproductive traits in Jersey cows

The aim of the study was to analyse the relationship between three leptin gene polymorphisms, and indices of reproductive performance--age at first calving, days open, calving interval, number of inseminations per conception, and gestation length in Jersey cattle. A total of 219 cows were tested for the R4C, A59V and C(-963)T mutations using the PCR-RFLP technique. The following allele frequencies were found: R4C--0.80 (C) and 0.20 (T), A59V--0.67 (C) and 0.33 (T), C(-963)T--0.83 (C) and 0.17 (T). The statistically significant correlation (P < or = 0.05) was found only for the A59V mutation. Cows with the TT genotype were characterized by shorter calving interval and time of days open than animals with CT and CC genotype. Also, the number of inseminations per conception was lower in A59V--TT homozygotes compared with two other genotypes. The association analysis did not reveal any significant correlations for both R4C and C(-963)T polymorphisms.     

Relationship of the bovine growth hormone gene to carcass traits in Japanese black cattle.

The bovine growth hormone gene (bGH) possesses three haplotypes, A, B and C, that differ by amino acid mutations at positions 127 and 172 in the fifth exon: (leucine 127, threonine 172), (valine 127, threonine 172) and (valine 127, methionine 172) respectively. The correlation between meat quality or carcass weight and these haplotypes was investigated in Japanese black cattle. Altogether, 940 bGH haplotypes were compared with respect to six carcass traits: carcass weight, longissimus muscle area, rib thickness, subcutaneous fat thickness, beef marbling score and beef colour. The frequency of the B haplotype was higher (0.421) than that of A (0.269) and C (0.311). High carcass weight and low beef marbling were associated with haplotype A (p < 0.05 and p < 0.01 respectively), whereas beef marbling was increased by haplotype C (p < 0.05). Estimated regression coefficient of the A haplotype substitution effect for carcass weight and beef marbling score were 5.55 (13.1% of the phenotypic SD) and -0.31 (17.0%) respectively. That of the C haplotype for beef marbling score was 0.20 (11.0%). The other traits showed no relationship to the haplotypes examined. The results of this investigation suggest that information pertaining to bGH polymorphisms in Japanese black cattle could be used to improve the selection of meat traits.     

Genetic evaluation of Atlantic salmon for growth traits incorporating SNP markers

Genetic evaluations of individual fish were calculated for growth traits in North American Atlantic salmon with and without inclusion of genetic markers. The number of SNP markers was reduced to 6,000 and further to 270 in order to reduce the problem of overparameterization. SNP genotypes were predicted for all ungenotyped animals in the pedigree. Analysis of traits used a model with polygenic effects and SNP markers together. Polygenic effects refer to the additive genetic effects that remain after accounting for SNP genotypes. SNP marker genotypes were included as covariates to evaluate fish for growth traits (weight and length) in different environments (freshwater and seawater) with genders separated. Including regressions on SNP marker genotypes reduced the sum of squares of residuals by 2.7%–12.5% and increased the variability of Mendelian sampling effects (i.e., within‐family variation) compared to traditional animal model evaluations. Genetic evaluations may be carried out with a few hundred markers which may be more affordable for genotyping large numbers of fish.     

Single nucleotide polymorphism (SNP) at the GHR gene and its associations with chicken growth and fat deposition traits

1. The growth hormone receptor (GHR) plays crucial roles on chicken growth and metabolism. 2. The full cDNA of the chicken GHR gene was scanned for single nucleotide polymorphisms (SNP) by means of denaturing high-performance liquid chromatography (DHPLC). Three SNP, C6540334T, C6542011T and G6631778A, were genotyped in a F(2) designed full-sib resource population to analyse their associations with chicken growth and fat deposition traits. 3. Fifty-five SNP and two other variations were identified in the 8908 bp region of the GHR gene. Among the 55 SNP, 10 were located in coding exons (6 resulted in changes of amino acids) and 45 were in non-coding regions (introns, 5'UTR and 3'UTR). The nucleotide diversity (theta), corrected for sample size of chicken GHR gene, is 1.45 x 10(-3). Fourteen PCR-RFLP markers were developed in the chicken GHR gene. 4. The G6631778A was associated with body weight at 63 d (BW63), dressed weight (DW) and subcutaneous fat thickness (SFT), BW35 and BW49 (P < 0.01) as well as hatch weight (HW) and BW42 in the male population. However, G6631778A was only associated with BW28 in the female population. G rather than A was dominant for chicken growth and fat deposition. Haplotypes based on the three SNP were associated with BW21, BW70, BW77 and SFT, BW7, BW35, BW42, BW49 and BW56 in males, and associated with BW7 and BW14 in females. For growth in males, the H2 and H6 haplotypes had positive and negative effects, respectively; meanwhile H6 was predominant for fat deposition.     

Associations between maternal milk protein genotypes with preweaning calf growth traits in beef cattle

The objectives of this study were to investigate milk casein polymorphisms in dams and to determine the impacts of maternal casein genotypes on growth traits of their sucking calves. Milk samples from 433 dams of the breeds German Angus (GA) and German Simmental (GS) were typed at the milk protein loci α _s1-casein (α_s1-CN), β-casein (β-CN), α _s2-casein (α_s2-CN), and κ-casein (κ-CN) via isoelectric focusing. Associations between casein genotypes in maternal milk with growth traits of their 1,872 calves were analyzed until the age of weaning using linear mixed models, considering either genotypes of individual casein loci (model 1) or composite α _s1-β-α _s2-κ-CN genotypes within the casein cluster (model 2). Besides environmental effects such as sex, age of the dam, and calving year-season, genetic effects (breed group and maternal and paternal effects) were considered in statistical models. The composite casein genotype BBǀA2A2ǀAAǀAB (order of genes on bovine chromosome 6: α _s1-ǀβ-ǀα _s2-ǀκ-CN) was associated with greater average daily weight gains (ADG) and heavier age-adjusted weaning weights (WW) of calves (P < 0.05). The effects of composite genotypes on birth weight of calves were similar (P > 0.05; model 2). With regard to individual casein loci, greater ADG and WW were observed for calves from dams with the genotypes κ-CN BB and α _s1-CN BB, respectively (P < 0.05; model 1). Age-adjusted WW was largest for calves from dams carrying the κ-CN genotype BB (215 kg) compared with calves representing the maternal AB and AA genotypes (both 204 kg). Results from the present study suggested selectable casein genotypes due to their nutritional value of milk (value in terms of offspring performances), offering new perspectives for breeding strategies in beef cattle to improve preweaning calf performance.     

Association of SNP variants of MHC Class II DRB gene with thermo-physiological traits in tropical goats

Host defense in vertebrates depend on many secreted regulatory proteins such as major histocompatibility complex (MHC) class II which provide important regulatory and effector functions of T cells. Gene polymorphism in the second exon of Capra-DRB gene in three major Nigerian goat breeds [West African Dwarf (WAD), Red Sokoto (RS), and Sahel (SH)] was analyzed by restriction fragment length polymorphisms (RFLP). Four restriction enzymes, BsaHI, AluI, HaeIII, and SacII, were utilized. The association between the polymorphic sites and some heat tolerance traits were also investigated in a total of 70 WAD, 90 RS, and 50 SH goats. Fourteen different types of alleles identified in the Nigerian goats, four of which were found in the peptide coding region (A57G, Q89R, G104D, and T112I), indicate a high degree of polymorphism at the DRB locus in this species. An obvious excess (P?<?0.01) of non-synonymous substitutions than synonymous (dN/dS) in this locus is a reflection of adaptive evolution and positive selection. The phylogenetic trees revealed largely species-wise clustering in DRB gene. BsaHI, AluI, HaeIII, and SacII genotype frequencies were in Hardy-Weinberg equilibrium (P?>?0.05), except AluI in RS goats and HaeIII in WAD goats (P?<?0.05). The expected heterozygosity (H), which is a measure of gene diversity in the goat populations, ranged from 0.16 to 0.50. Genotypes AA (BsaHI), GG, GC and CC (AluI) and GG, GA, AA (HaeIII) appeared better in terms of heat tolerance. The heat-tolerant ability of SH and RS goats to the hot and humid tropical environment of Nigeria seemed better than that of the WAD goats. Sex effect (P?<?0.05) was mainly on pulse rate and heat stress index, while there were varying interaction effects on heat tolerance. Variation at the DRB locus may prove to be important in possible selection and breeding for genetic resistance to heat stress in the tropics.     

Polymorphisms of the prolactin gene and their association with egg production traits in two Chinese domestic ducks

1. Prolactin (PRL) as a polypeptide hormone which plays a crucial role in egg production traits.

2. Polymorphisms of the PRL gene were analysed with DNA sequencing and polymerase chain reaction-single-strand conformation polymorphism methods in two Chinese domestic laying duck breeds (Jinding, n = 400, Youxian, n = 400, respectively).

3. The results showed that one polymorphism was detected (A-412G) in intron 1 of the PRL gene, with three genotypes: AA, AG and GG. Association analysis showed that the ducks with the GG genotype had significantly greater egg production and egg weight than those with AG and AA genotype (p < 0.05). Hence, the 412A > G polymorphism of the PRL gene in intron 1 is a potentially valuable genetic marker for laying duck breeding programmes.     

Genetic correlations between growth and reproductive traits in Zandi sheep

For the first time, the current study reports the genetic and phenotypic correlations between growth and reproductive traits in Zandi sheep. The data were comprised of 4,309 records of lamb growth traits from 1,378 dams and 273 sires plus 2,588 records of reproductive traits from 577 ewes. These data were extracted from available performance records at Khojir Breeding Station of Zandi sheep in Tehran, Iran, from 1993 to 2008. Correlations were estimated from two animal models in a bivariate analysis using restricted maximum likelihood procedure between lamb growth traits [birth weight (BW), weaning weight at 3 months of age (WW), as well as six-month weight (6 MW)] and ewe reproductive traits [litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth (TLWB), and total litter weight at weaning (TLWW)]. The genetic correlations between BW and reproductive traits varied from low to high ranges from 0.10 for BW–LSB to 0.86 for BW–TLWB. WW was moderately (0.37) to highly (0.96) correlated with all the reproductive traits. Moreover, the genetic correlations were observed between 6 MW and reproductive traits, varied from 0.19 to 0.95. Relationships between growth and reproductive traits ranged from 0.01 for BW–LSW to 0.28 for BW–TLWB in phenotypic effects. Results indicated that selection to improve WW would have high effect on genetic response in TLWW, and also, these results could be effective for all of the reproductive traits in Zandi sheep.     

Association of a novel SNP in exon 10 of the IGF2 gene with growth traits in Egyptian water buffalo (Bubalus bubalis)

Insulin-like growth factor 2 (IGF2) plays an important role in muscle growth and it might be used as a marker for the growth traits selection strategies in farm animals. The objectives of this study were to detect polymorphisms in exon 10 of IGF2 and to determine associations between these polymorphisms and growth traits in Egyptian water buffalo. PCR-single-strand conformation polymorphism (SSCP) and DNA sequencing methods were used to detect any prospective polymorphism. A novel single nucleotide polymorphism (SNP), C287A, was detected. It was a non-synonymous mutation and led to replacement of glutamine (Q) amino acid (aa) by histidine (H) aa. Three different SSCP patterns were observed: AA, AC, and CC, with frequencies of 0.540, 0.325, and 0.135, respectively. Association analyses revealed that the AA individuals had a higher average daily gain (ADG) than other individuals (CC and AC) from birth to 9 months of age. We conclude that the AA genotype in C287A SNP in the exon 10 of the IGF2 gene is associated with the ADG during the age from birth to 9 months and could be used as a potential genetic marker for selection of growth traits in Egyptian buffalo.     

DECR1 and ME1 genotypes are associated with lipid composition traits in Duroc pigs

Variation at the porcine DECR1 and ME1 genes has been associated with meat quality traits and backfat thickness in Landrace pigs, respectively. However, it has not been investigated yet whether DECR1 and ME1 genotypes influence lipid composition. With this aim, we have genotyped two missense DECR1 substitutions (c.160G>C and c.437G>C) and one silent ME1 (c.576C>T) polymorphism in 361 Duroc barrows distributed in five half‐sib families and phenotyped for serum lipid concentrations and intramuscular fat content and composition traits. At the whole‐population level, relevant associations, that is, with a posterior probability of the allele substitution effect to be over or below zero (PPN0) > 0.90, were observed between DECR1 genotype and serum cholesterol (CHOL) (PPN0 = 0.932) and LDL concentrations (PPN0 = 0.945) at 190 days, as well as between ME1 genotype and longissimus dorsi saturated fatty acid content (PPN0 = 0.924). At the within‐family level, we found relevant associations between DECR1 and ME1 genotypes and diverse lipid composition traits, but most of them were family‐specific. Discrepancies in allele substitution effects estimated in half‐sib families might be produced by many factors such as number of individuals, marker allele frequencies and informativeness in each family, unaccounted random genetic and environmental effects, epistasis and family‐specific differences in the linkage phase or amount of linkage disequilibrium between causal and marker mutations. This lack of consistency across families, combined with the fact that the ME1 mutation is synonymous and that the two DECR1 polymorphisms are conservative, suggests that the associations found are not causative.