Disruption of actin filament organization by cytochalasin D inhibits rhabdom synthesis in the compound eye of the crab Hemigrapsus sanguineus

Abstract.

This paper demonstrates that the actin filaments in the photoreceptor cell body of the crab Hemigrapsus sanguineus are involved in the transport of the smooth endoplasmic reticulum in the process of rhab- dom synthesis. In isolated eyes, the transverse sectional area of a rhabdom increased at dusk. The increase was inhibited by disrupting the actin filaments with cytochalasin D. In the photoreceptor cell body of cytochalasin D-treated eyes, rhodamine-conjugated phalloidin labeled some spots, which appeared to be the aggregates of short filaments as revealed by electron microscopy. The photoreceptor cell bodies in cytochalasin D-treated eyes contained more vesicular smooth endoplasmic reticulum than those in the control eye. These results indicate that the disruption of actin organization with cytochalasin D resulted in the accumulation of smooth endoplasmic reticulum. Microtubules do not play a direct role in the rhabdom synthesis because colchicine failed to stop the rhabdom increase.