Ultrastructure of the zoospores of Entophlyctis confervae-glomeratae, Rhizophydium patellarium and Catenaria anguillulae

Abstract

The fine structure of zoospores of Entophlyctis confervae-glomeratae, Rhizophydium patellarium, and Catenaria anguillulae has been described and compared. The zoospores of E. confervae-glomeratae contain many posteriorly located mitochondria in a petal-like arrangement. On the inner (proximal) side of a kinetosome are two electron-dense, slightly curved bands with the convex side directed inward towards the eccentrically located nucleus. Microtubules radiate from the convex side of the bands. Two or three lipid bodies are seen usually in the anterior region of the zoospore with microbodies often associated with them. Ribosomes are scattered throughout the cytoplasm. The zoospores of R. patellarium contain a single, bowl-shaped mitochondrion in the posterior region and a centrally located nucleus. Ribosomes are mainly clustered between the mitochondrion and the nucleus and are partially enclosed by a double-membrane envelope. No microtubules are seen associating with the kinetosome and the non-functional centriole lies parallel to the kinetosome. In the anterior region there is a single lipid body as well as two types of microbodies: very electron-dense microbodies un-associated with any other organelle, and a finely granular microbody associated closely with the lipid body. The zoospores of C. anguillulae contain a single basal mitochondrion with the associated side-body complex. From the proximal region of the kinetosome, a set of 27 microtubules radiate anteriorly and surround the base of the cone-shaped nucleus. Ribosomes are enclosed within a distinct nuclear cap. Gamma bodies are present in the cytoplasm. Taxonomic implications resulting from this study are discussed.