Contractile responses at the surface of an amphibian egg.

Abstract

During the course of experiments involving the application of polyelectrolytes to amoebae (Gingell, 1967 a ) it became apparent that highly charged cations are capable of affecting cellular motility. In some circumstances localized applications apparently result in contraction of the cell surface. Korohoda, Forrester, Moreman & Ambrose (1968) subsequently described a reversible charge-dependent response at the surface of isolated amoeba nuclei, which they attributed to nuclear membrane contraction and expansion. Dr Korohoda suggested to me that the surface of Xenopus laevis eggs might be expected to provide a conveniently large experimental system since any contraction would be readily visible. The localized application of cationic polyamino acid solutions close to the cell surface had a remarkable effect: the treated region coalesced into a dense black spot, blackening being due to pigment granule accumulation (Gingell, 1967 a ).