Transcriptome Analysis of Liver for Meat Odour and Flavour in Javanese Fat-Tailed By Using RNA Deep Sequencing

Unpleasant flavour or odour of the sheepmeat occurs due to high level accumulation of Branched Chain Fatty acid (BCFA: including 4-methylnonanoic (MNA)), 4-metylphenol acid (MP), and Skatole (3-methylindole (MI) in adipose tissue. It is crucial to understand the genomics of sheepmeat odour and flavour to select sheep for lower MNA, MP, and MI thus reduce sheepmeat odour. The aim of this study is to investigate trancriptome profilling in liver tissue with divergent MNA, MP and MI levels using RNA deep sequencing. The total number of reads produced for each liver sample ranged from 21.37 to 25.37 million. Approximately 136 genes were differentially regulated (P<0.01, FC>1.5). Among them, 75 genes were up regulated in higher off-flvaoured group, whereas 61 were down-regulated. Several genes relevant to fat metabolism in adipose tissues were identified including two top genes with the highest fold change (JAML1 and GSTM1). Differentially regulated genes in the liver samples collected from sheep with high unpleasant odour and flavour were enriched in metabolic processes such as heme binding, sodium channel activity and iron ion binding. Pathway analysis identified the adrenergic signaling in cardiomyocytes, chemical carciogenesis, protein digestion and absorption, and metabolism of xenobiotics by chytochrome P450 pathways which may play important roles in higher sheepmeat odour and flavour metabolism. This work highlighted potential genes and gene networks that affect sheepmeat odour and flavour and fat deposition in sheep.

Keyword: RNA deep sequencing, odour, flavour, sheep