THE EFFECTS OF CERAMIDE AND ITS ANALOGS ON THE SECRETION OF THE MUCOCYST CONTENT OF TETRAHYMENA

Monoclonal antibody to Geodia lectin is bound by the mucocyst content of Tetrahymena. By using this (fluorescent-labelled) antibody and conf ocal microscopy, the actual state of the mucocyst (position, resting, filling or extruding) can be studied. Treatment with Cp ceramide and n on-hydroxy fatty acid caused a rapid depletion of mucocyst material. A nother ceramide analogue, psychosine caused fusion of mucocysts. Tn th ese cases -in contrast to the controls- the contractile vacuole was fi lled with mucocyst material and this was seen in the tubules in contac t with the contractile vacuoles. Hydroxy fatty acid ceramide, sphingom yelin and sphingasine-1-phosphate were ineffective. As the former mate rials influence also the cytoskeleton, while the latter do not, the cy toskeleton is presumed to have a mediatory effect. Neither the connect ion of contractile vacuoles with tubular structures nor mucocyst fusio n have been described before.