CHLOROPLAST DEVELOPMENT AND ULTRASTRUCTURE IN THE FRESHWATER RED ALGA BATRACHOSPERMUM.

Chloroplast development and ultraslructure of the freshzoater red alga Batrachospermum moniliforme are described. Chloroplasts develop from proplastids which have a double-membraned chloroplast envelope and a parallel double-membraned outer photosynthetic lamella. Of these 2 double-membraned structures of the proplastid, only the outermost photosynthetic lamella functions in production of further lamellae. The mature chloroplast consists of 2 or more concentric lamellae and a variable number of nonconcentric lamellae. These lamellae are not dense uninterrupted sheets as described for other red algae, but are largely constructed of tubules, lying side by side, that form interrupied lamellar sheets. The possible physiological significance of lamellar interruptions in providing pathways for movement of materials in the chloroplast stroma is discussed. [ABSTRACT FROM AUTHOR]