FIGURE 4.

Thylakoid membrane morphology as revealed by electron microscopy. Thin sections of Synechococcus sp. PCC 7002 cells from various strains were examined by transmission electron microscopy. A, thylakoid membranes were normally assembled in WT (A) and in Comp (C). Thylakoids were greatly reduced in number and area in the vipp1 mutant (B), and these cells closely resembled cells for a psaAB mutant (D). The arrows in the bottom right of B show thylakoids that clearly appear to be directly connected to the cytoplasmic membrane. Bars, 500 nm.