Identification of complete linkage disequilibrium in the DSG4 gene and its association with wool length and crimp in Chinese indigenous sheep.

The desmoglein 4 (DSG4) gene is a potential candidate in the search for genes that may affect wool traits, because of its function. This study aimed to screen for polymorphisms in partial exon 16 and 3ꞌUTR of the sheep desmoglein 4 DSG4 gene, and to test its possible association with wool length and crimp associated with fur. Overall, 326 sheep were scanned via single-strand conformational polymorphism assay, through three pairs of primers. The breeds included Tan, Han, and TanxHan from China, Polled Dorset from Australia, and Suffolk from Britain genotypes AA, BB, and AB for primer2 and genotypes DD, EE, and DE for primer3 were detected in native breeds. Six SNPs and 3-bp insertion/deletions were found in exon 16, of which 4 lead to amino acid substitutions. In addition, 1 SNP was found in 3ꞌUTR. The DSG4 genotype was found to be strongly associated with all wool traits that were considered in this study (P < 0.01). Sheep with the genotype MM had a higher least square mean compared to sheep with the genotype WW or WM with respect to birth scapular wool length (P < 0.01), crimp number of birth scapular wool crimp (P < 0.01), crimp number of weaning scapular wool crimp (P < 0.01), and crimp number of weaning rump wool crimp (P < 0.01, P < 0.05). In conclusion, our study is the first to demonstrate that the DSG4 gene may be a candidate, or major gene, which influences important wool traits.

Characterization of microRNAs from goat (Capra hircus) by Solexa deep-sequencing technology.

MicroRNAs (miRNAs) are an important class of small noncoding RNAs that are highly conserved in plants and animals. Many miRNAs are known to mediate a myriad of cell processes, including proliferation and differentiation, via the regulation of some transcription and signaling factors, which are closely related to muscle development and disease. In this study, small RNA cDNA libraries of Boer goats were constructed. In addition, we obtained the goat muscle miRNAs by using Solexa deep-sequencing technology and analyzed these miRNA characteristics by combining it with the bioinformatics technology. Based on Solexa sequencing and bioinformatics analysis, 562 species-conserved and 5 goat genome-specific miRNAs were identified, 322 of which exceeded 100 in the expression levels. The results of real-time quantitative polymerase chain reaction from 8 randomly selected miRNAs showed that the 8 miRNAs were expressed in goat muscle, and the expression patterns were consistent with the Solexa sequencing results. The identification and characterization of miRNAs in goat muscle provide important information on the role of miRNA regulation in muscle growth and development. These data will help to facilitate studies on the regulatory roles played by miRNAs during goat growth and development.

Polymorphisms of the myostatin gene (MSTN) and its relationship with growth traits in goat breeds.

Mutations in the myostatin (MSTN) gene can inactivate its expression and result in a non-functional protein, which leads to dramatic muscularity and a "double-muscling" phenomenon in many species. Using gene sequencing and polymerase chain reaction-single-strand conformation polymorphism methods, polymorphisms of the MSTN gene were investigated as a candidate marker for growth in 288 goats. The results showed 2 novel single nucleotide polymorphisms: DQ167575 g.197G>A and 345A>T. Three potential genotypes (AA, AB, and BB) of substitution 197G>A in the 5'-untranslated region were detected in the 2 breeds. The polymorphism (CC and CD) of substitution 345A>T in exon I was segregated. The genetic diversity analysis revealed that Boer goat and Anhui white goat possessed intermediate genetic diversity in the P1 and P3 loci. Significant associations between the genotypes of the P3 locus and body weight, body length, and body height were observed in Boer goat and Anhui white goat (P < 0.05). It could be inferred that the MSTN gene may be a major gene or linked to the major gene affecting the goat growth traits. The polymorphic site could be a molecular marker-assisted selection program for body weight.