Mesosome-like Structures in a Blue-green Alga, Phormidium Luridum

Abstract

The invagination of the plasma membrane (plasmalemma) to form vesicular or lamellar structures, usually called mesosomes (l) or plasmalemmosomes (2), has been extensively documented in bacteria (3) and more recently also in lower eucaryotes (e.g., the fungi, 4). Such structures have “been implicated in septum formation (i.e., cell division of gram-positive bacteria), in respiratory reactions, and in DNA replication.In photosynthetic bacteria, such as Rhodospirilium rubrum, vesicular structures derived from the plasma membrane were shown by Drews and Giesbrecht (5) to give rise to thylakoids (photosynthetic vesicles or chromatophores). Continuation between the plasma and thylakoidal membranes is readily seen in R. rubrum (6).