Respiratory properties of mitochondria from the calcareous sponge Clathrina clathrus (Schmidt) and phylogenetic implications

1. 1. A mitochondria-enriched fraction, containing coupled mitochondria, was obtained from Clathrina clathrus. Substrate preferences, respiratory control index, ADP/O ratio, and the effect of various respiratory inhibitors were polarographically studied. 2. 2. Oxygen consumption and reaggregation of dissociated sponge cells were also tested in the presence respiratory inhibitors or uncoupler. 3. 3. Results suggest that the enzymatic systems and cytochrome characters of sponge respiratory chain are more similar to those described for high metazoa, rather than to those found in lower bilateral metazoa. Phylogenetic implications are briefly discussed.