Karakterisasi Gen CYP2E1 dan HSD17β13 sebagai Kandidat Gen untuk Perbaikan Kualitas Daging Domba Indonesia

Abstract

Gen CYP2E1 dan HSD17β13 merupakan salah satu kandidat gen yang diduga berperan dalam mengontrol kualitas daging domba. Penelitian ini bertujuan melakukan karakterisasi gen CYP2E1 dan HSD17β13 dengan tujuan untuk perbaikan kualitas daging tujuh jenis domba Indonesia, yaitu domba compass agrinak (DCA), domba barbados cross (DBC), domba komposit garut (DKG), domba garut (DG), domba ekor gemuk (DEG), domba ekor tipis (DET), dan domba jonggol (DJ). Karakterisasi gen dilakukan dengan tiga tahapan, yaitu melakukan identifikasi keragaman gen CYP2E1 (g 50.657.948 T>G) dan HSD17β13 (g 101.689.913 C>T) dengan menggunakan metode Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP), melakukan asosiasi gen CYP2E1 dan HSD17β13 dengan kualitas daging menggunakan uji T-test, serta menganalisis ekspresi gen CYP2E1 dan HSD17β13 dengan menggunakan Quantitative Real Time PCR (qRT-PCR). Hasil penelitian menunjukkan bahwa gen CYP2E1 dan HSD17β13 bersifat polimorfik yang ditandai dengan adanya tiga macam genotipe pada gen CYP2E1 (GG, GT, dan TT) dan HSD17β13 (CC, CT, dan TT). Keragaman genotipe gen CYP2E1 dan HSD17β13 tidak berada dalam kesetimbangan Hardy-Weinberg. Hasil analisis menunjukkan bahwa gen CYP2E1 (g 50.657.948 T>G) secara nyata berasosiasi (P<0,05) dengan kualitas daging seperti pH, keempukan daging, komposisi asam lemak (asam lemak tak jenuh tunggal seperti asam elaidik (C18:1n9t) dan asam lemak tak jenuh ganda seperti asam linoleat (C18:2n6c)), serta kandungan flavor dan odor, yaitu 3-methylindole (skatole). Domba dengan genotipe GG memiliki nilai kualitas daging yang lebih baik dibandingkan genotipe GT dan TT untuk sifat fisik daging dan komposisi asam lemak. Gen HSD17β13 (g 101.689.913 C>T) berasosiasi (P<0,05) dengan komposisi asam lemak, seperti asam lemak jenuh (asam arakidat (C20:0), asam henekosanoat (C21:0)), asam lemak tak jenuh, yaitu asam lemak tak jenuh tunggal (MUFA) seperti asam lemak ginkgoleat (C17:1) dan asam lemak tak jenuh ganda (PUFA) yaitu asam eikosedienoat (C20:2). Daging domba dengan genotipe CT memiliki nilai asam lemak tak jenuh yang lebih tinggi dibandingkan genotipe lainnya. Analisis ekspresi gen CYP2E1 menunjukkan adanya perbedaan yang nyata (P<0,05) antar genotipe. Genotipe GG memiliki tingkat ekspresi tertinggi di antara genotipe lainnya. Di lain pihak gen HSD17β13 tidak menunjukkan level ekspresi yang berbeda (P>0,05) antar genotipenya. Hasil penelitian ini menunjukkan bahwa gen CYP2E1 dan HSD17β13 dapat dijadikan sebagai kandidat marker dalam program seleksi domba untuk memperbaiki kualitas daging.

CYP2E1 and HSD17β13 genes are candidate genes that play important role in controlling the lamb quality. This study aims to characterize the CYP2E1 and HSD17β13 genes in order to improve the quality of lamb of seven Indonesian sheep, namely compass agrinak sheep (DCA), barbados cross sheep (DBC), garut composite sheep (DKG), garut sheep (DG), fat tailed sheep (DEG), thin-tailed sheep (DET), and jonggol sheep (DJ). Gene characterization was carried out in three stages, namely identifying the diversity of CYP2E1 (g 50.657.948 T>G) and HSD17β13 (g 101.689.913 C>T) genes using the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method, associated CYP2E1 and HSD17β13 genes with meat quality using the T-test, and analyzed the expression of CYP2E1 and HSD17β13 genes using Quantitative Real Time PCR (qRT-PCR). The results showed that the CYP2E1 and HSD17β13 genes were polymorphic which was indicated by the presence of three genotypes in the CYP2E1 (GG, GT, and TT) and HSD17β13 (CC, CT, and TT) genes. The genotypic diversity of the CYP2E1 and HSD17β13 alleles was not in Hardy-Weinberg equilibrium. The result showed that the CYP2E1 gene (g 50.657.948 T>G) was significantly associated (P<0,05) with meat quality such as pH, meat tenderness, fatty acid composition (monounsaturated fatty acids such as elaidic acid (C18: 1n9t) and polyunsaturated fatty acids such as linoleic acid (C18:2n6c)), as well as flavor and odor content, namely 3-methylindole (skatole). Lamb with the GG genotype had better meat quality values than those of the GT and TT genotypes for the physical characteristics of the meat and the fatty acid composition. The HSD17β13 gene (g 101.689.913 C>T) was significantly (P<0,05) association with the composition of fatty acids, such as saturated fatty acids (arachidic acid (C20:0), henekosanoic acid (C21:0)), unsaturated fatty acids, namely monounsaturated fatty acids (MUFA) such as ginkgoleic fatty acids (C17:1) and polyunsaturated fatty acids (PUFA), namely eicosedienoic acid (C20:2). Lamb with the CT genotype had a higher unsaturated fatty acid value than the other genotypes. Analysis of CYP2E1 gene expression showed a significant difference (P<0,05) between genotypes. The GG genotype has the highest expression level among other genotypes. On the other hand, the HSD17β13 gene was not show different expression levels (P>0,05) between genotypes. The results of this study indicated that the CYP2E1 and HSD17β13 genes can be used as candidate markers in the sheep selection program to improve meat quality.