A Novel Single Nucleotide Polymorphism in Exon 4 of Insulin-Like Growth Factor-1 Associated with Production Traits in Bali Cattle

Abstract

Insulin-like growth factor-1 (IGF-1) is one of the gene candidates that can be used in selection strategy by using DNA markers (marker assisted selection). Gene candidate strategy is a molecular biology techniques to identify quantitative trait loci directly, with the assumption that genetic varia-tion associated to quantitative trait variation. This study was designed to identify any new mutations in exon 4 that can cause the IGF-1 gene polymorphism and then affect the production traits on Bali cattle. Single nucleotide polymorphism (SNP) discovery was conducted by using the direct sequenc-ing technique. Genetic variation of the genes candidate was identified by using PCR-RFLP technique. The results of this study indicate the presence of a new SNP in exon 4 of IGF-1 gene caused by the T/C transition, which can be identified using Rsa1 restriction enzyme. Genotypic polymorphism of IGF-1/Rsa1 has a significant influence on birth weight, weaning weight and average daily gain of Bali cattle. CC genotype had a birth weight rate, weaning weight and average daily gain of: 15.64±1.83; 83.15±9.00, and 0.439±0.07 respectively, higher than the TT and CT genotype. IGF-1/Rsa1 can be used as a genetic marker for selection of birth weight, weaning weight, and daily body weight gain.

Insulin-like growth factor-1 (IGF-1) adalah salah satu kandidat gen dalam strategi seleksi meng-gunakan marka DNA (marker assisted selection). Strategi kandidat gen merupakan teknik biologi molekuler untuk mengidentifikasi lokus sifat kuantitatif secara langsung, dengan asumsi bahwa variasi genetik kandidat gen ini berasosiasi dengan sifat kuantitatif. Penelitian ini dirancang un-tuk mengidentifikasi adanya mutasi baru pada exon 4 yang dapat menimbulkan polimorfisme gen IGF-1 yang mempengaruhi sifat produksi pada sapi bali. Pencarian single nucleotide polymorphism (SNPs discovery) dilakukan menggunakan metode “direct sequencing”, sedangkan variasi genetik kandidat gen ini diidentifikasi menggunakan teknik “polymerase chain reaction-restriction fragment length polymorphism” (PCR-RFLP). Hasil penelitian ini menunjukkan bahwa pada exon 4 gen IGF-1 ditemukan SNPs baru, yaitu mutasi transisi T/C, yang kemudian dapat identifikasi menggunakan enzim restriksi Rsa1. Polimorfisme genotipe IGF-1/Rsa1 memiliki pengaruh yang signifikan terhadap bobot lahir, bobot sapih, dan rata-rata pertambahan bobot badan harian sapi bali. Genotipe CC me-miliki angka bobot lahir, bobot sapih, dan rata-rata pertambahan bobot badan harian berturut-turut: 15,64±1,83; 83,15±9,00; dan 0,439±0,07 yang lebih tinggi dibandingkan genotipe TT dan CT. Genotipe IGF-1/ Rsa1 dapat digunakan sebagai penciri genetik untuk seleksi bobot lahir, bobot sapih, dan pertambahan bobot badan harian