In cell culture, themain source of fatty acids to support cell proliferation
is the FBS in the culture medium (Tocher et al., 1988). In Fig. 4A,
the SBT-E1 cells were cultured with or without various PUFAs in the
presence of 5% (v/v) FBS. Addition of the PUFAs to the culture medium
significantly reduced the expression of Δ6 Fads but not Elovl5. In
Fig. 4b, the SBT-E1 cells were cultured either in the presence of 10%
(v/v) FBS or with or without various PUFAs in the presence of 2% (v/v)
FBS. In this case, reducing the FBS concentration from 10% to 2% (v/v)
significantly increased the expression of Δ6 Fads and supplementation
of the culture medium with the various PUFAs in the presence of 2%
FBS returned the expression of Δ6 Fads to the lowlevel seen in the presence
of 10% (v/v) FBS. Thus, fatty acid deprivation (i.e. reduction of the
FBS concentration from 10% to 2% (v/v)) increased the expression of
Δ6 Fads but this was reversed when the cells were supplied with various
PUFAs. Similarly, Elovl5 gene expression appeared to be higher in
cells cultured in 2% (v/v) FBS compared to 10% (v/v) FBS but there
were no significant differences between the different treatments in
the case of Elovl5. In Fig. 4C, the absolute expression (gene of interest
transcript copy number relative to β-actin transcript copy number) of
Δ6 Fads is compared with that of Elovl5. Interestingly, expression of
theΔ6 Fads genewasmore than 2 orders ofmagnitude greater than that
of the Elovl5 gene