Three SNPs within exons of INHA and ACVR2B genes are significantly associated with litter size in Dazu black goats

The aim of this study was to analyse the association between single-nucleotide polymorphisms within INHA and ACVR2B and litter size in Dazu black goats. In total, twenty-two SNPs were genotyped in 190 individuals by SNaPshot and resequencing. The results showed that three SNPs (SNP_1, SNP_12 and SNP_13 in this study) were detected to have significant additive genetic effect on the recorded goat litter size (p < .05). The SNP_1 (NC_030809.1), a non-synonymous substitution of G for T at chr2-g. 28314990 in the exon 2 of INHA gene (NM_001285606.1), resulted in homozygote 2 (HOM2) contributed 0.25 and heterozygote (HET) contributed 0.12 larger litter than homozygote 1 (HOM1). Meanwhile, SNP_12 (Chr22-g. 11721225 A > T) and SNP_13 (Chr22-g. 11721227 A > C) (NC_030829.1) simultaneously mutated at the first and third position of a triplet AAA (lysine, K) in the exon 4 of ACVR2B gene (XM_018066623.1) had estimated genetic effects of HOM1 (0.00) and HOM2 (0.03) larger than HET (−0.12). In conclusion, one SNPs (chr2-g. 28314990 T > G) within the exon 2 of INHA and two SNPs (Chr22-g. 11721225 A > T and Chr22-g. 11721227 A > C) i n the exon 4 of ACVR2B gene were highly recommended as candidate markers of litter size in Dazu black goats. A large-scale association study to assess the impact of these variants on litter size is still necessary.     

DNA polymorphism of 5' flanking region of prolactin gene and its association with litter size in sheep

A single nucleotide polymorphism of 5' flanking region of the prolactin gene was investigated in both high prolificacy breeds (Small Tail Han and Hu sheep) and low prolificacy breeds (Dorset and Suffolk sheep) using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP). The results indicated that two genotypes (AA and AB) were detected in Small Tail Han sheep (n   =   239), only one genotype (AA) was detected in Hu (n   =   40), Dorset (n   =   50) and Suffolk sheep (n   =   39). The mutant homozygous genotype (BB) was not detected in four sheep breeds. In Small Tail Han sheep (n   =   239), the frequency of genotypes AA and AB was 0.91 and 0.09, the frequency of the A and B alleles was 0.95 and 0.05, respectively. The fitness tests showed that the Small Tail Han sheep population was in Hardy–Weinberg equilibrium. Sequencing revealed a mutation (G→T) at the position 63 bp of the 5' flanking region of prolactin gene in AB genotype compared with AA genotype in Small Tail Han sheep. The Small Tail Han ewes with AB genotype had 0.83 (p < 0.05) lambs more than those with AA genotype. These results preliminarily showed that the prolactin locus is either a major gene that influences the high prolificacy in Small Tail Han sheep or is in close linkage with such a gene.     

绵羊B4GALNT2和ESR1基因多态性及其与产羔数的关联分析

为探究影响宁夏地区优质肉羊培育中多羔性状的候选位点,试验以杜泊羊、滩寒杂交羊、杂一代、杂二代和横交一代5个绵羊群体为研究对象,采用飞行质谱技术对5个绵羊群体β-1,4-N-乙酰半乳糖胺转移酶2（beta-1,4-N-acetyl-galactosaminyl transferase 2,B4GALNT2）基因g.36933082 G>A和g.36946470 G>A位点以及雌激素受体1（estrogen receptor 1,ESR1）基因g.75378892 A>T位点进行多态性检测,并与绵羊产羔数进行关联分析;应用生物信息学在线软件分析B4GALNT2和ESR1基因突变前后蛋白质的二级结构和三级结构。结果显示,B4GALNT2基因的g.36933082 G>A和g.36946470 G>A位点均存在3种基因型：AA、AG和GG,且GG基因型均为优势基因型;ESR1基因的g.75378892 A>T位点存在3种基因型：AA、TA和TT,且AA基因型为优势基因型。g.36933082 G>A和g.36946470 G>A位点在5个绵羊群体中均表现为低度多态（PIC<0.25）,g.75378892 A>T位点在5个绵羊群体中均表现为中度多态（0.25<PIC<0.5）;3个位点在5个绵羊群体中均处于哈代-温伯格平衡状态（P>0.05）。关联分析结果表明,g.36933082 G>A和g.36946470 G>A位点不同基因型在5个绵羊群体中的产羔数均无显著差异（P>0.05）;g.75378892 A>T位点在杂一代绵羊群体中TA基因型个体产羔数显著高于TT基因型（P<0.05）。生物信息学结果表明,3个位点均导致对应蛋白质的二级结构和三级结构发生变化。综上所述,B4GALNT2基因g.36933082 G>A和g.36946470 G>A位点不适用于5个绵羊群体多羔性状的选育,ESR1基因g.75378892 A>T位点可作为杂一代绵羊群体多羔性状的分子辅助标记。     

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。     

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.     

The temporal-spatial patterns,polymorphisms and association analysis with meat quality traits of FABP1 gene in domestic pigeons (Columba livia)

ABSTRACT

1. Fatty acid-binding proteins (FABP) are members of lipid-binding proteins, which participate in the metabolism and intracellular transportation of lipids. This study was designed to investigate the expression patterns, polymorphisms and associations with meat quality traits of the FABP1 gene in pigeons.

2. The temporal-spatial expression patterns showed FABP1 was widely expressed in all eleven tissues from 0–4 weeks of age, the expression level in the liver was the highest, followed by the small intestine and subcutaneous fat.

3. Five novel SNPs were found; all of them were synonymous and in Hardy-Weinberg equilibrium. Association analysis revealed that for the SNP of G161C, the AB and BB genotypes had higher (P ≤ 0.01) inosinic acid concentrations in breast muscle than the AA genotype. The BB genotype showed the highest (P < 0.01) intramuscular fat among the three genotypes, and significantly greater FABP1 mRNA levels were observed in the breast muscle of the BB genotype than in the AA and AB genotypes (P < 0.01). In the SNP C1376T, the AB and BB genotypes showed higher (P < 0.01) intramuscular fat than the AA genotype, and the relative mRNA expression level of the BB (P < 0.01) and AB (P < 0.05) genotypes was higher than that of the AA genotype in breast muscle. Correlation analysis implied that the FABP1 mRNA expression level was closely related to the inosinic acid (P < 0.05) and intramuscular fat content (P < 0.01). Oil red O staining of frozen sections of breast muscle on d 28 for SNPs G161C and C1376T also indicated that the BB genotype had the highest intramuscular fat content in both SNPs. In addition, correlation analysis implied the FABP1 mRNA expression level was closely related to inosinic acid (P < 0.05) and intramuscular fat content (P < 0.01).

4. The results suggested that FABP1 could be a potential candidate gene in marker-assisted selection for breeding pigeons with high-quality meat.