The levels of PHA-E expression and accumulation were quantified byimmunological assay (Western blotting after analysis of total protein by SDS-PAGE) using rabbit polyclonal antibodies raised against PHA-E as the primary antibody, with HRP-conjugated goat anti-rabbit IgG (BioRad) as the secondary antibody. The protein was visualised using ECL detection system (Amersham) as previously described (Gatehouse et al., 1997). Stability of transgene expression in line 35 was monitored over threesuccessive generations (T1–T3). In all cases plants were grown in con- trolled environment in rooms with identical conditions (30 ?C; 16 h of light).The final concentration of the PHA-E in the animal diet was alsodetermined by immunoassay and was estimated as 1.5% of the total soluble protein content of the diet.