Variation in eyespot ultrastructure in <i>Chlamydomonas reinhardi</i> (ac-31)

Abstract

ABSTRACT Several morphological variations in eyespot complex fine structure were exhibited in some cells of the pale-green mutant strain ac-31 of Chlamydomonas reinhardi. The cells were grown in minimal medium supplemented with 0·2 % sodium acetate and were harvested by centrifugation and prepared for electron-microscopic examination. Microtubules were seen near the flagella, confirming previous observations. Microtubules were also seen near the eyespot complex. Although a direct connexion between the microtubules of the flagellar and eyespot region was never observed, this does not exclude the possibility that it exists and thus provides a structural and functional connexion between the two organelles. Occasionally irregular curved bodies intimately associated with the eyespot complex of some cells appeared to displace the chloroplast and cell membranes. These bodies often appeared to be nearly covered by a limiting membrane and were found near empty ‘cavities’ in the eyespot plate. Crystalline arrays of dense bodies were observed in some sections. The significance of these bodies is discussed in relation to the functional state of the carotenoid pigments making up the eyespot granules. An hypothesis for the formation of the rod-like structures is presented, based upon the observation of granules which had fused together to form a helix.