Analysis on DNA sequence of KiSS-1 gene and its association with litter size in goats

Three pairs of primers were designed to clone the goat KiSS-1 and scan polymorphisms and four pairs to detect polymorphisms in sexual precocious and sexual late-maturing goat breeds. A 4118 bp DNA fragment was obtained, which contains an ORF of 408 bp and encodes 135 amino acids, having a high homology with other mammals. The protein was predicted containing a signal peptide of 17 amino acids. There are two mutations (G3433A [A86T] and C3688A) in exon 3, three mutations (G296C, G454T and T505A) in intron 1 and a 18 bp deletion (-)/insertion (+) (1960-1977) in intron 2 and no mutations in exon 2. The genotype distribution didn't show obvious difference between sexual precocious and sexual late-maturing goat breeds and no consistency within the sexual late-maturing breeds. For the 296 locus, the Jining Grey goats with genotype CC had 0.80 (P < 0.01) or 0.77 (P < 0.01) kids more than those with genotype GG or GC, respectively. No significant difference (P > 0.05) was found in litter size between GG and GC. For the 1960-1977 locus, the Jining Grey goat does with genotype -/- had 0.77 (P < 0.01) or 0.73 (P < 0.01) kids more than those with +/+ or +/-, respectively. No significant difference (P > 0.05) was found in litter size between +/+ and +/- genotypes. For the other four loci, no significant difference (P > 0.05) was found in litter size between different genotypes in Jining Grey goats. The present study preliminarily indicated an association between allele C of the 296 locus and allele (-) of the 1960-1977 locus in KiSS-1 and high litter size in Jining Grey goats.