Cytochalasin selectively inhibits synthesis of a secretory protein, cellulose, in Achlya

IN an effort to elucidate the possible relationship between cytoplasmic streaming and secretion we used the male strain E87 of the water mould Achlya ambisexualis 1 . Cellulase secreted by Achlya presumably modifies the plasticity of the cellulosic walls of this fungus during morphogenesis 2 . Synthesis of this enzyme can be induced by the steroid hormone antheridiol, by amino acids 2 , or by shake induction (mechanical agitation) as reported here. In attempts to arrest streaming we used colchicine and vinblastine, which have been employed to disrupt microtubule function, and cytochalasins, whose reversible effects include inhibition of streaming 3 , of macromolecular secretion 4 , of uptake of small molecules such as glucose 5 , and destruction of microfilaments 6 .