The consequence of inhibition of sterol biosynthesis on the photosynthetic activity and apparatus of N. oceanica. (A) Effect of CLO (20 mg l-1), and TBF (2.5 mg l-1) on the maximum photosynthetic efficiency of PSII. (B) Transcript levels of RBCL gene of N. oceanica induced by CLO (20 mg l-1) or TBF (2.5 mg l-1). (C) Levels of sterols, chlorophylls, and carotenoids in the presence of CLO and TBF. Values were normalized (100% for mock control). (D-F) Transmission electron microscopy analysis of algal cells cultured with DMSO control (D), CLO (E), and TBF (F). (G-H) Scanning electron microscopy analysis of algal cells treated with DMSO control (G) or TBF (H). Algal cells were grown in medium containing CLO, TBF, or an equivalent amount of DMSO (control) for 96 h under 50 μmol photons m-2 s-1 light. Scale bars represent 0.5 μm. Asterisks (*) indicate P values < 0.05.