A. (Top) — Activities of several enzymes in Si-replete and Si-deficient C. cryptica cells. There is no significant difference in the activities of UDPglucose pyrophosphorylase, acetyl-CoA synthetase, or citrate synthase in the cells under the two conditions. However, there is a relative increase in acetyl-CoA carboxylase activity, and a decrease in chrysolaminarin synthase activity in Si-deficient cells.

B (Bottom) — Graph showing the activity of ACCase in C. cryptica cells. Exponential-phase cells were transferred into Si-free media at 0 hr. At 6 hr, (arrow), the culture was split and 1.8 mM Na2SiO3 was added to one culture. (•) Si-deficient cells; (■) Si-replete cells.

(Source: Roessler 1988a).