Ruthenium red and violet. III. Fine structure of the plasma membrane and extraneous coats in amoebae (A. proteus and chaos chaos)

Abstract

Ruthenium violet, closely related to ruthenium red, supplements the ultrastructural knowledge of the plasma membrane complex. Amoebae throughout were handled individually with braking pipettes and were exposed to ruthenium violet alive, during fixation with acrolein and O_SO₄, or during dehydration. Ruthenium violet was less toxic than ruthenium red but still killed the amoebae. Conventional methods reveal a filamentous layer 2000 Å thick, an amorphous layer 150 Å thick, and a typical trilaminar plasma membrane (48 Å center‐to‐center). Ruthenium violet binds to the plasma membrane, and to the extraneous coats revealing globules in the filamentous layer. The diameter of the globules decreased according to the stage of processing at which the amoebae first encountered ruthenium violet; they were 1200 Å in diameter when amoebae were alive, 600 Å in acrolein and 300 Å in dehydration. The appearance of the filamentous layer varied when ruthenium violet was replaced by very pure ruthenium red or red containing ruthenium brown (typical of commercial ruthenium red). The globules could be demonstrated without using ruthenium dyes when amoebae were treated after fixation with uranyl acetate or phosphotungstic acid. The relationship of extraneous coats of amoebae is compared with the coats and laminae of animal tissue cells.