The results for the desaturation/elongation of incorporated
[1-14C]-labelled PUFAs by the SBT-E1 cells are shown in Table 5.
Cells supplied with [1-14C]18:3n−3 converted 12.8% of this substrate
to desaturation/elongation products. The majority of this conversionwas
to the C2 elongation product 20:3n−3 (9.4%) but therewas
also some Δ6 desaturation to yield 18:4n−3 (2.2%) and a small amount
of Δ6 desaturation plus C2 elongation to yield 20:4n−3 (1.2%). In
contrast, the cells supplemented with [1-14C]18:2n−6 showedapproximately
equal amounts of either C2 elongation (2.8%) or Δ6 desaturation
(2.5%) but no detectable Δ6 desaturation plus C2 elongation and
the total amount of substrate conversion (5.3%) was significantly less
than for 18:3n−3. In contrast to the above, the cells supplied
[1-14C]20:5n−3 showed substantial C2 elongation (16.8% substrate
conversion). Thus, the cells exhibited appreciable fatty acyl elongase
activity but only very limited Δ6 Fads activity.