Ovine adipose tissue monounsaturated fat content is correlated to depot-specific expression of the stearoyl-CoA desaturase gene

The basis for the variation in fatty acid composition in different ovine ad ipose tissue depots was investigated. The proportion of stearic (C-18:0) an d oleic (C-18:0) acids vary in a site-specific fashion; abdominal depots (o mental and perirenal) contain relatively more C-18:0 than C-18:1, and carca ss depots, especially sternum, have a markedly higher proportion of C18:1 A dditionally, expression of a number of lipogenic enzyme genes (stearoyl-CoA desaturase [SCD], acetyl-CoA carboxylase-alpha [ACC-alpha], lipoprotein li pase [LPL]) and the cytoskeletal protein gene alpha-tubulin vary among depo ts, although the pattern of variation differs for each mRNA. When these exp ression data were related to the mean cell volume of adipocytes pooled from all depots, a significant pattern emerged: expression of the ACC-alpha, LP L, and alpha-tubulin genes was highly correlated with the size of adipocyte s. In contrast, when the expression of SCD mRNA was assessed as a function of mean cell volume, two populations of adipocytes emerged: no significant correlation was found between the expression of SCD mRNA per adipocyte and mean cell volume for the abdominal depots, although a highly significant co rrelation was observed between SCD gene expression and mean cell volume for the carcass and epicardial depots. Similarly, a highly significant correla tion was found for the amount of C18:1 per adipocyte and the abundance of S CD mRNA per adipocyte for the carcass and epicardial depots, whereas no sig nificant correlation was observed for these traits for the omental and peri renal depots. Thus, the SCD gene seems to be regulated in a depot-specific fashion and in a manner distinct from that of the ACC and LPL genes.