Keragaman Gen Monoamine Oxidase A (MAOA) pada Sapi Pedaging

Abstract

One of the essential traits in the management of raising meat livestock is the aggressive nature of cattle, which affects livestock handling and productivity. Several genes control aggressive traits, and one that plays an important role is the monoamine oxidase A (MAOA) gene. The MAOA gene encodes the enzyme monoamine oxidase A, which plays a role in the catabolism of neurotransmitters, including dopamine, norepinephrine, and serotonin. Mutations in the MAOA gene can increase the tendency of cows to behave aggressively, which can affect neurotransmitter regulation. Studies on MAOA gene diversity in Indonesian beef cattle have yet to be carried out. Therefore, this research was conducted to identify and analyze SNP determination and MAOA gene diversity in beef cattle in Indonesia. One hundred twenty-seven blood samples from beef cattle were from Bali, Limousin, Wagyu, PO, Madura, and Balinese Wagyu crosses. Blood samples were extracted using the GeneAid kit, isolating pure DNA from beef cattle. MAOA gene diversity was analyzed using the PCR-RFLP method. Analysis results such as genotype frequencies, allele frequencies, heterozygosity values, and Hardy-Weinberg balance were calculated using Popgen32. Amplification of the MAOA gene sequence in the promoter fragment and exon 1 via PCR was successfully carried out at 57 ºC, resulting in product lengths of 548 bp and 341 bp, respectively. The results showed that the MAOA gene located in the promoter region has six SNPs that are specific to Bali cattle, namely SNP g.98 A > C, SNP g.145 G > T, SNP g.216 A > C, SNP g.340 T > G, SNP g.349 A > C, and SNP g.385 G > A. Meanwhile, the MAOA gene located in exon 1 is monomorphic. The PCR-RFLP method was used to investigate the SNP g.385 G > A MAOA gene polymorphism using the RSaI restriction enzyme. The MAOA SNP g.385 G > A gene obtained two alleles (G and A) and three genotypes: GG, GA, and AA. SNP g.385 G > A is polymorphic in Bali, PO, Madura, and Wagyu-Bali cross (F1) cattle while monomorphic in Limousin and Wagyu cattle. The allele frequency of the SNP g.385 G > A MAOA gene in Bali, PO, Madurese cattle, and Wagyu-Bali crosses (F1) is in Hardy-Weinberg equilibrium. SNP g.385 G > A of the MAOA gene can be used as a candidate aggressive genetic marker.

Salah satu sifat yang penting dalam manajemen pemeliharaan ternak daging adalah sifat agresif pada sapi yang berpengaruh pada penanganan ternak dan produktivitas. Sifat agresif dikendalikan oleh beberapa gen dan salah satu yang berperan penting adalah gen MAOA. Gen MAOA mengkodekan enzim monoamine oksidase A yang berperan dalam katabolisme neurotransmiter, termasuk dopamin, norepinefrin, dan serotonin. Mutasi pada gen MAOA dapat meningkatkan kecenderungan sapi untuk berperilaku agresif yang dapat mempengaruhi regulasi neurotransmitter. Studi keragaman gen MAOA pada sapi pedaging Indonesia belum dilakukan. Oleh karena itu, penelitian ini dilakukan untuk mengidentifikasi dan menganalisis penetuan SNP dan keragaman gen MAOA pada sapi pedaging di Indonesia. Sebanyak 127 sampel darah sapi pedaging yang terdiri dari sampel darah sapi Bali, Limousin, Wagyu, PO, Madura, dan silangan Wagyu Bali. Sampel darah diekstraksi menggunakan kit GeneAid dan menghasilkan isolasi DNA murni sapi pedaging. Keragaman gen MAOA dianalisis dengan metode PCR-RFLP. Hasil analisis seperti frekuensi genotipe, frekuensi alel, nilai heterozigositas, dan keseimbangan Hardy-Weinberg dihitung menggunakan Popgen32. Amplifikasi sekuens gen MAOA di fragmen promotor dan ekson 1 melalui PCR berhasil dilakukan pada suhu 57 ºC menghasilkan panjang produk masing-masing sebesar 548 bp dan 341 bp. Hasil penelitian menunjukkan bahwa gen MAOA yang terletak di daerah promotor memiliki enam SNP yang spesifik pada sapi Bali, yaitu SNP g.98 A > C, SNP g.145 G > T, SNP g.216 A > C, SNP g.340 T > G, SNP g.349 A > C, dan SNP g.385 G > A. Sedangkan gen MAOA yang terletak di ekson 1 bersifat monomorfik. Metode PCR-RFLP digunakan untuk menyelidiki polimorfisme gen SNP g.385 G > A MAOA menggunakan enzim restriksi RSaI. Gen MAOA SNP g.385G > A diperoleh dua alel (G dan A) dan tiga genotipe yaitu GG, GA, dan AA. SNP g.385 G > A bersifat polimorfik pada sapi Bali, PO, Madura, dan silangan Wagyu-Bali (F1), sedangkan monomorfik pada sapi Limousin dan Wagyu. Frekuensi alel SNP g.385 G > A gen MAOA pada sapi Bali, PO, Madura, dan silangan Wagyu-Bali (F1) berada dalam keseimbangan Hardy-Weinberg. SNP g.385 G > A gen MAOA dapat dijadikan sebagai kandidat penanda genetik agresif.