FIG. 5.

Heterocyst-specific glycolipids and secreted proteins in hgdD mutants. (A) Thin-layer chromatography of lipids of the wild-type Anabaena sp. strain (wt) (lanes 1, 3, 5, and 8), mutant NMΔ-alr2887 (Δ) (lanes 2, 4, 6, and 9), and mutant DR181 (DR) (lanes 7 and 10). Lipids were extracted from filaments grown in BG11 medium (lanes 1 and 2), from filaments 3 days after transfer to BG11₀ medium (lanes 3 and 4), from isolated heterocysts (Het) (lanes 5, 6, and 7), or from isolated heterocyst cell walls (CW) (lanes 8, 9, and 10). The lipids of the cell wall fractions show a slightly altered migration behavior due to edge effects of the thin-layer chromatography plate. The HGL lipids are indicated by arrows (open arrows, HGL1; gray arrows, HGL2). In lanes 9 and 10 the area where HGL2 would be expected is also indicated. (B) Proteins secreted from the wild type or NMΔ-alr2887 mutant 9 h after nitrogen step-down were concentrated and subjected to SDS-PAGE, followed by silver staining. The positions of molecular weight standards (MW) are indicated on the right, and proteins not secreted from the mutant are indicated by arrows.