[The effect of cytochalasin A on the composition of subcellular fractions of hyphae in the growth of Mucor mucedo L. I. Composition of the plasmalemma].

The plasma membrane of young hyphae of Mucor mucedo L. growing in presence or absence of cytochalasine A was isolated by continuous density gradient centrifugation using Percoll at 10% or on discontinuous sucrose density gradient. Isolated membranes were characterized by enzymatic markers and cytochemical reactions, using electron microscopy. Lipid composition and protein content were determined. From the enzymatic point of view, the cytochalasine A induced a decrease (60%) in ATPase activity and with regard to the chemical composition of the membrane, a decrease in sterol content and in the sterol-phospholipid ratio as well as a decrease in protein content and an increase in the proportion of cysteine relative to other amino acids.