ULTRASTRUCTURE OF FLAGELLATED CHRYSOPHYTES .I. DINOBRYON

In this examination of the Chrysophycean alga Dinobryon, a consistent and in some ways unique pattern of cell fine structure has been found. Chromatophores were a prominent feature of the cytoplasm and contain thylakoids, usually of three uniformly separated bands. This is very different from other groups, viz. Euglenophyta (Gibbs 1960), and Rhodophyta (Berkoloff 1962, Bouck 1962) were the thylakoids are two to twelve banded. Why such a configuration is so consistent in the Chrysophyta and none of the other algae can only remain unanswered for the present. Also, the chromatophores were longitudinally oriented, flanking the nucleus with the thylakoids running parallel to their long axis. Additional work on other freshwater Chrysophytes would be helpful in establishing the extent of this uniformity and ultimately, what its relation is to the photosynthetic process. The chromatophore envelope consisted of three membranes. The outer membrane was smooth and continuous with the outer membrane of the nucleus; the two inner membranes limit the chromatophore proper. On the surface of the plastid, the two inner membranes divided in the region of the nucleus to allow for the presence of tubules. The exact nature of these tubules appear to be infoldings of the outer chromatophore membrane proper. The relationship of the shorter flagellum with the eyespot as reported by Conrad (1938) in Uroglena holds true for Dinobryon. No direct contact through fibrils, microtubules or extended vesicles were noted; however, the closeness of the stigma and whiplash flagellum favors some type of correlation. Cross sections of the basal body did not reveal the 9-pointed star reported in the flagella of other algal genera (Manton 1965). © 1969, Japan Mendel Society, International Society of Cytology. All rights reserved.