Possible tributyltin-calmodulin interaction in morphofunctional alterations of ascidian phagocytes

This paper addresses studies on the rearrangement of cytoskeletal component s occurring in phagocytes of the colonial ascidian Botryllus schlosseri dur ing phagocytosis and their alteration induced by sublethal concentrations o f the immunotoxic tributyltin (TBT). Incubation with TBT leads to changes i n phagocyte morphology due to depolymerisation of microfilaments and microt ubules. Calmodulin is able to restore amoeboid shape, microtubule and micro filament polymerisation, and activity of the membrane-bond Ca2+-ATPase, but never the phagocytosis index. A direct TBT-calmodulin interaction establis hing intracellular Ca2+ homeostasis, following a pattern of saturation, is suggested, even though other interactions with cytoskeletal components cann ot be excluded.