COELOMOCYTE AGGREGATION IN CUCUMARIA FRONDOSA: EFFECT OF ETHYLENEDIAMINETETRAACETATE, ADENOSINE, AND ADENOSINE NUCLEOTIDES

¹ Institute for Cell Studies, Faculty of Medicine, and the Marine Sciences Research Laboratory, Memorial University of Newfoundland, St. John's, Newfoundland

Cells found within the coelomic cavity of the sea cucumber. Cucumaria frondosa, aggregated rapidly upon removal from the body. This cell aggregation is normally characterized by a morphological change in the bladder amoebocyte which becomes a filiform cell. A method has been devised whereby the effects of EDTA, adenosine, and adenosine nucleotides could be observed upon coelomocyte aggregation. It was found that EDTA at pH 6.0 in ASW (Ca⁺⁺ and Mg⁺⁺ free) prevented the morphological change from bladder to filiform amoebocyte as well as cell aggregation. EDTA at pH 7.8 in ASW (Ca⁺⁺ and Mg⁺⁺ free) did not prevent the morphological change although it did prevent cell aggregation. Based on the different chelating affinities of EDTA for calcium ions at these two different pH values, it is suggested that coelomocyte aggregation has two components: (1) the morphological change, which is Ca⁺⁺ independent and possibly requires the removal of some other cation or is a direct effect of EDTA upon some cellular component, and (2) the cell aggregation itself which appears to be Ca⁺⁺ dependent.

Adenosine and adenosine nucleotides in general did not appear to influence coelomcyte aggregation. These results raise the question as to whether or not the mechanism of coelomocyte aggregation is similar to and can be described in the same terms as the mechanism currently used to explain avian and mammalian cell aggregation.