Figure 2.

Protein synthesis with an extract prepared from washed embryos. The batch system contains either 12 μl (24%) or 24 μl (48%) of extracts from washed (A) or unwashed (B) wheat embryos. Protein synthesis was measured as hot trichloroacetic acid insoluble radioactivity. Arrows show addition of substrates. C shows the polysome profiles of 15 μl of reaction mixture aliquots loaded onto a linear 10% to 45% sucrose gradient in 25 mM Tris⋅HCl (pH 7.6), 100 mM KCl, and 5 mM MgCl₂. After centrifugation, fractions were collected from the bottom of the tubes and were measured at 260 nm as described (24). Incubation times were 0 h (open circles in a), 1 h (closed circles in a), and 2 h (b) in the absence (open circles in b) or presence (closed circles in b) of 0.4 μM cycloheximide. In c, the translation system prepared from unwashed embryos was incubated for 2 h. In d and e, aliquots from the dialysis system were withdrawn after 48 and 60 h and were incubated in the presence of 0.4 μM cycloheximide for another 60 min at 26°C (closed circles). Similar analyses of the samples were carried out in the absence of mRNA (d and e, open circles) as negative controls.