Charles J. O'Kelly
Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine,
The flagellar apparatus of Cafeteria roenbergensis consists of two basal bodies, three microtubular roots, of which one bears secondary cytoskeletal microtubules, and a forked rhizoplast that connects the elder, posteriorly directed basal body to the nucleus. Analysis of the three-dimentional architecture of this flagellar apparatus confirms that Cafeteria belongs to the bicosoecids and suggests that there is little variation in flagellar apparatus features among bicosoecids. Feeding apparatus architecture (the "Type I feeding basket") in bicosoecids differs from that in chromulinalean chrysophytes in several features. Nevertheless, the structures in bicosoecids and chromulinalean chrysophytes are more similar to each other than to any other stramenopiles and may share a similar mechanism based on microtubule-microtubule sliding. The feeding basket may be an ancestral motif among stramenopiles, conserved in different forms in bicosoecids and chromulinalean chrysophytes but lost from other lineages.