Cytochrome P450, family 2, subfamily A, polypeptide 6 (CYP2A6) and kinesin-like protein KIF12 (KIF12) genes are predicted as candidate genes which play important roles in lamb flavour and odour. The aim of this study was to analyse the genotype polymorphism of CYP2A6 and KIF12 genes, to study association and expression of these genes with lamb flavour and odour. Identification of genes polymorphism and associations of CYP2A6 and KIF12 genes were performed using PCR-RFLP method and GLM analysis. The PCR-RFLP products of CYP2A6 and KIF12 were digested by restriction enzyme BsmAI and BfaI, respectively. The expression of CYP2A6 gene was performed using qRT-PCR. The results showed that the CYP2A6 and KIF12 genes were polymorphics. The CYP2A6 gene found to have two genotypes (TT and GT), whereas the KIF12 gene found to have three genotypes (CC, CT, and TT). The CYP2A6 and KIF12 genes were in Hardy Weinberg Equilibrium (HWE). Association analysis showed that CYP2A6 (g.49170107 G>T) was significantly (P<0.05) associated with 3-methylindole (MI) or skatole, while KIF12 (g.9617965 C>T) was not significantly associated with lamb flavour and odour. The GT genotype exhibited a greater 3-methylindole (MI) or skatole than the TT genotype (P<0.05). The mRNA expression analysis showed that CYP2A6 mRNA expression was higher (P<0.01) in animals with the TT genotype. These results will improve the understanding of the functions of the CYP2A6 in lamb flavour and odour, especially in term of 3-methylindole (MI) or skatole compound within the liver and will shed light on CYP2A6 as a candidate in the selection of sheep with low lamb flavour and odour.

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This study was aimed to identify single nucleotide polymorphism (SNP) and pathway analysis of APOA5 with fatty acids traits in sheep. A total of 47 rams consisted of 20 heads of Javanese Fat Tailed (JFT), 17 heads of Javanese Thin Tailed (JTT), and 10 heads of Garut Composite Sheep (GCS) were used in this study. Fatty acids traits were measured at the age of 12 months with the average body weight of 25-30 kg. Identification of polymorphism of APOA5 (g.26929941 C>T) gene were analyzed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The pathway analysis of APOA5 gene was performed using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The SNP of APOA5 gene were found polymorphic with three genotypes (CC, CT, and TT). The gene frequency of CC, CT, and TT were 0.83, 0.11, and 0.06, respectively. The chi square test revealed that the locus of APOA5 (g.26929941 C>T) was in Hardy-Weinberg equilibrium, except in thin tailed sheep. The chi-square values of JFT, JTT, and GCS were 0.05, 0.03, and 0.04, respectively. A SNP of APOA5 was associated (P<0.05) with polyunsaturated fatty acids including eicosapentanoic acid (C20:5n3) and docosahexanoic (C22:6n3) and saturated fatty acid lauric acid (C12:0) in combined population (JFT, JTT, and GCS). Furthermore, pathway analysis showed that APOA5 belonged to phagosome and peroxisome proliferator-activated receptors (PPAR) signaling pathway. In conclusion, this analysis has identified APOA5 and related pathway crucial for fatty acid composition and metabolism in sheep, as well as this gene provide molecular marker to select sheepmeat with high unsaturated fatty acid.

ABSTRAK Karakteristik karkas dan sifat perlemakan pada daging domba dikontrol oleh banyak gen salah satunya gen DGAT1 (Diacylglycerol Acyltransferasel 1). Penelitian ini bertujuan mengidentifikasi SNP (Single Nucleotide Polymorphism) gen DGAT1 pada titik mutasi g.8539 C>T dan asosiasinya terhadap karakteristik karkas dan sifat perlemakan pada domba Indonesia. Total sampel domba yang digunakan sebanyak 150 buah terdiri dari 35 sampel domba compass agrinak (DCA), 36 sampel domba barbados cross (DBC), 41 sampel domba komposit garut (DKG), 20 sampel domba ekor gemuk (DEG), dan 18 sampel domba ekor tipis (DET). Karakteristik karkas dan sifat perlemakan diukur dari domba jantan berumur 10-12 bulan. Identifikasi keragaman DGAT1|ALuI dianalisis dengan metode PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). Hasil keragaman gen DGAT1 bersifat polimorfik dalam DET dan DEG, sedangkan DCA, DBC, dan DKG bersifat monomorfik. Dua genotipe disebut CC dan  CT ditemukan dalam DET dan DEG. Titik mutasi gen DGAT1 berasosiasi (P<0.05) dengan karakteristik karkas, yaitu bobot dan panjang karkas. Selain itu, keragaman gen DGAT1 juga berasosiasi signifikan (P<0.05) dengan asam lemak jenuh, yaitu asam stearat (C18:0) dan asam arakidat (C20:0) dan asam lemak tak jenuh tunggal, yaitu asam oleat (C18:1n9c). Gen DGAT1 memiliki kontribusi dalam karakteristik karkas dan komposisi asam lemak pada domba.Kata Kunci: domba, gen DGAT1, karakteristik karkas, PCR-RFLP, sifat perlemakan                                                              ABSTRACT            Characteristic of carcass and fatness traits of sheep is regulated by many genes such as DGAT1 (Diacylglycerol Acyltransferasel 1) gene. The research was aimed to investigate SNP (Single Nucleotide Polymorphism) of DGAT1 and its association with characteristic of carcass and fatness traits in Indonesian sheep. A total sample of sheeps used 150 rams of 10–12 months consisted 35 samples of compas agrinak sheep (CAS), 36 of barbados cross (BCS), 41 of garut composite (GCS), 20  of javanese fat tailed (JFT), and 18 of javanese thin tailed (JTT). Identification variant of DGAT1|ALuI were performed by PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). The results of polymorphism of DGAT1 were found in JTT and JFT. However, SNP of DGAT1 in CAS, BCS and GCS were monomorfic. Two genotype namely CC and CT were found in JTT and JFT populations. A SNP of the DGAT1 was associated (P<0.05) with characteristic of carcass, including weight and length of carcass. The variant of DGAT1 was associated too with saturated fatty acids (SFA) including stearic acid (C18:0) and arachidic acid (C20:0), and mono unsaturated fatty acid (MUFA) including oleic acid (C18:1n9c). The DGAT1 gene was contribute to characteristic carcass and fatty acid composition in sheep.Keywords: DGAT1 gene, characteristic carcass, fatness traits, PCR-RFLP, sheep

Fatty acids (FA) in ruminants, especially unsaturated FA (USFA) have important impact in meat quality, nutritional value, and flavour quality of meat, and on consumer’s health. Identification of the genetic factors controlling the FA composition and metabolism is pivotal to select sheep that produce higher USFA and lower saturated (SFA) for the benefit of sheep industry and consumers. Therefore, this study was aimed to investigate the transcriptome profiling in the liver tissues collected from sheep with divergent USFA content in longissimus muscle using RNA deep-sequencing. From sheep (n = 100) population, liver tissues with higher (n = 3) and lower (n = 3) USFA content were analysed using Illumina HiSeq 2500. The total number of reads produced for each liver sample were ranged from 21.28 to 28.51 million with a median of 23.90 million. Approximately, 198 genes were differentially regulated with significance level of p-adjusted value <0.05. Among them, 100 genes were up-regulated, and 98 were down-regulated (p<0.01, FC>1.5) in the higher USFA group. A large proportion of key genes involved in FA biosynthesis, adipogenesis, fat deposition, and lipid metabolism were identified, such as APOA5, SLC25A30, GFPT1, LEPR, TGFBR2, FABP7, GSTCD, and CYP17A. Pathway analysis revealed that glycosaminoglycan biosynthesis- keratan sulfate, adipokine signaling, galactose metabolism, endocrine and other factors-regulating calcium metabolism, mineral metabolism, and PPAR signaling pathway were playing important regulatory roles in FA metabolism. Importantly, polymorphism and association analyses showed that mutation in APOA5, CFHR5, TGFBR2 and LEPR genes could be potential markers for the FA composition in sheep. These polymorphisms and transcriptome networks controlling the FA variation could be used as genetic markers for FA composition-related traits improvement. However, functional validation is required to confirm the effect of these SNPs in other sheep population in order to incorporate them in the sheep breeding program.