Kajian Polimorfisme Nukleotida Tunggal (SNP) dalam Gen Prolaktin (PRL) pada Lembu Tenusu di Pahang dan Melaka

Study of Single Nucleotide Polymorphism (SNP) in Prolactin (PRL) Gene in Dairy Cattle in Pahang and Melaka

Abstract

Susu merupakan makanan kompleks yang penting dalam pemakanan manusia iaitu membantu dalam tumbesaran. Pengeluaran susu lembu yang dihasilkan di Malaysia adalah kurang dari permintaan dan menyebabkan susu terpaksa diimport dari luar negara. Penghasilan susu dalam lembu tenusu dipengaruhi oleh banyak gen dan salah satunya ialah gen Prolaktin (PRL). Kehadiran polimorfisme nukleotida tunggal (SNP) dalam gen PRL didapati mempunyai kaitan dengan penghasilan dan kualiti susu. Oleh itu, kajian ini bertujuan untuk menyaring SNP dalam gen PRL pada lembu tenusu di Melaka dan Pahang yang boleh digunakan sebagai penanda genetik untuk pembiakbakaan. Sebanyak 20 sampel darah lembu tenusu yang diperoleh dari baka Australian Friesian Sahiwal, Jersey dan baka campuran telah berjaya diekstrak. Kaedah tindakbalas berantai polimerase (PCR) telah berjaya mengamplifikasi ekson 4 menggunakan pencetus ke hadapan PRLex4F dan pencetus ke belakang PRLex4R untuk menghasilkan produk PCR bersaiz 294 pb. Produk PCR telah dijujuk dan hasil jujukan disunting menggunakan perisian Sequencher dan MEGA-11. Jujukan DNA telah disaring dan didapati terdapat dua SNP iaitu SNP#120 dan SNP#141. Hasil saringan SNP #120 menunjukkan terdapat 13 sampel yang menunjukkan kehadiran bes C, dua sampel menunjukkan kehadiran bes G dan lima sampel menunjukkan kehadiran bes C/G. Bagi SNP #141, terdapat 13 sampel yang menunjukkan kehadiran bes G, dua sampel menunjukkan kehadiran bes A dan lima sampel menunjukkan kehadiran bes G/A. Frekuensi alel C pada SNP #120 bagi sampel dari negeri Pahang menunjukkan nilai yang lebih tinggi iaitu 0.7 berbanding alel G (0.2) dan frekuensi alel C pada SNP #120 bagi sampel dari negeri Melaka adalah lebih tinggi iaitu 0.75 berbanding alel G (0.25). Frekuensi alel G pada SNP #141 bagi sampel dari negeri Pahang menunjukkan nilai yang lebih tinggi iaitu 0.8 berbanding alel A (0.2) dan frekuensi alel G pada SNP #141 bagi sampel dari negeri Melaka adalah lebih tinggi iaitu 0.75 berbanding alel A (0.25). Hasil ini dapat diaplikasikan sebagai penanda genetik untuk pembiakbakaan dan dapat membantu penternak memilih lembu yang menghasilkan susu yang berkualiti dan lebih banyak.

Milk is an important complex food in human nutrition that aids in growth. The production of cow’s milk produced in Malaysia is less than the demand and the milk must be imported from abroad. Milk production in dairy cows is influenced by many genes and one of them is the Prolactin (PRL) genes. The presence of single nucleotide polymorphisms (SNP) in the PRL gene has been found to be associated with milk production and quality. Therefore, this study aims to screen SNPs in PRL genes in dairy cows in Melaka and Pahang which can be used as genetic markers for breeding. A total of 20 dairy cow blood samples obtained from Australian Friesian Sahiwal, Jersey and mixed breeds were successfully extracted. The polymerase chain reaction (PCR) method has successfully amplified exon 4 using PRLex4F forward primer and PRLex4R reverse primer to produce a 294 bp PCR product. The PCR products were sequenced, and the sequences were edited using Sequencher and MEGA-11 software. The DNA sequences were screened, and it was found that there were two SNPs, namely SNP #120 and SNP #141. The results of SNP #120 screening showed that there were 13 samples showing the presence of base C, two samples showing presence of base G and five samples showing the presence of base C/G. For SNP #141, there were 13 samples showing the presence of base G, two samples showing the presence of base A and five samples showing the presence of base G/A. The frequency of the C allele in SNP #120 for the sample from Pahang showed a higher value of 0.7 compared to the G allele (0.2) and the frequency of the C allele in SNP #120 for the sample from Melaka was higher at 0.75 compared to the G allele (0.25). The frequency of the G allele in SNP #141 for the sample from Pahang showed a higher value of 0.8 compared to the A allele (0.2) and the frequency of the G allele in SNP #141 for the sample from Melaka was higher at 0.75 compared to the A allele (0.25). These results can be applied as genetic markers for breeding and can help breeders choose cows that produce better quality and more milk.