Three novel single-nucleotide polymorphisms of the bovine LHX3 gene

Two New Insertion/Deletion Variants of the PITX2 Gene and their Effects on Growth Traits in Sheep

In China, Tong sheep (TS) and Lanzhou fat-tailed sheep (LFTS) are two closely relative endanger breeds for low meat production and low fecundity, finding some marker-assisted selected (MAS) is our first priority for improving their growth traits. For this purpose, Hu sheep (HS) and small-tailed Han sheep (STHS) were compared with two endangered breeds (TS and LFTS). Paired-liked homeodomain transcription factor 2 (PITX2) gene was the important member of PITX family, which could adjust animal growth through hypothalamic-pituitary-adrenal axis. During the past years, insertion/deletion (indel) has become increasingly popular in application as MAS. In this study, two novel indel loci were identified, and five significant differences, including chest width, hip width, chest depth, chest circumference, and body height, were found between different breeds. Interestingly, there was no DD genotype and smaller number of ID genotye. All the ID genotypes were significantly greater than II genotype, which was to say the allele of "D" was dominant variation and its frequency was lower, which demonstrated that it has huge space for selection. Briefly, the two indel were potential and useful DNA markers for selecting excellent individuals in relation to growth traits in sheep.

A novel 29 bp insertion/deletion (indel) variant of the <i>LHX3</i> gene and its influence on growth traits in four sheep breeds of various fecundity

Abstract. Belonging to the same LIM homeobox (LHX) family, LHX3 and LHX4 are key transcription factors in animal growth and reproduction. Insertion/deletion (indel) is a relatively simple and effective DNA marker. Therefore, four sheep breeds of various fecundity were used to explore the novel indel variants within the sheep LHX3 and LHX4 gene, as well as to evaluate their effects on growth traits. Herein, only one novel 29 bp indel (NC_019460.2:g.3107494-3107522delGGCCTGGACTGTGATGGGCACCCTCCGGG) within the sheep LHX3 gene was found, and three genotypes were detected. Interestingly, the increasing trends of II (insertion/insertion) genotype frequency and I allelic frequency were the same as the growth of the fertility character. Genotypic frequency and allelic frequency distributions were significantly different between the high-fecundity breeds (HS, STHS and LFTS) and low-fecundity breed (TS) based on a χ2 test (P < 0.05). Association analyses showed that body length was significantly different in female TS and STHS and that chest width was significantly different for the female TS and male STHS (P < 0.05). These findings suggested that the 29 bp indel could extend the spectrum of genetic variations of the LHX3 gene in sheep and provide a valuable theoretical basis for the marker-assisted selection (MAS) in sheep breeding and genetics.

Exploring genotype-phenotype relationships of the LHX3 gene on growth traits in beef cattle

The LIM-homeobox gene 3 (LHX3) plays an essential role in pituitary gland and nervous system development. Sequence variants (SVs) in coding and non-coding regions of LHX3 gene have an impact on LHX3 transcription and growth traits in cattle. Previously, we have identified 3 single nucleotide polymorphisms (SNPs: 1-3) in all exons and intron 2 regions of the LHX3 gene in cattle. Here, 7 novel SNPs (SNPs: 4-10) were identified by DNA sequencing and polymerase chain reaction single-stranded conformational polymorphism (PCR-SSCP) methods. In the present study, a total of 10 SNPs were assessed linkage disequilibrium (LD) in 802 cows representing four main cattle breeds from China (Nanyang, Qinchuan, Jiaxian, and Chinese Holstein). The assessment results demonstrated that 17 haplotypes and 18 diplotypes were revealed in these cattle populations. Moreover, association analysis indicated that the genotypes of SNPs 1-6 are associated with the body weight at 6, 12 and 18months of age in Nanyang cattle (P<0.01 or P<0.05), whereas no significant association was found between the 18 diplotypes and growth traits. Our results provide evidence that some SNPs in LHX3 gene may be associated with body weight at certain age, and LHX3 gene may be used as candidate gene for marker-assisted selection (MAS) in beef cattle breeding.