THE CYTOPLASMIC FINE-STRUCTURE OF THE DIATOM HASLEA-OSTREARIA (BACILLARIOPHYCEAE) IN RELATION TO MARENNINE PRODUCTION

The fine structure of Haslea ostrearia Simonsen, a diatom that is able to synthesize a blue pigment (marennine), is described. Ultrastructur ally, this microalga has a typical naviculoid organization, but marked changes occur depending on the stage of cell blueing by accumulation of marennine. A comparison of the ultrastructure of blue and nonblue p igmented cells shows modifications of the thylakoid organization in ch loroplasts of the blue-pigmented cells. The blueing stage is also char acterized by the presence of a vesicular complex that is particularly obvious at the ends of the cells. Image analysis of marennine distribu tion in living blue cells observed by light microscopy supports the re sults of electron microscopy. These observations suggest a cytoplasmic pathway in the synthesis of blue pigment and a role by the vesicular complex in the synthesis or storage of marennine.