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. Ultrastructurally, 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 pigmented cells shows modifications of the thylakoid organization in chloroplasts of the blue-pigmented cells. The blueing stage is also characterized by the presence of a vesicular complex that is particularly obvious at the ends of the cells. Image analysis of marennine distribution in living blue cells observed by light microscopy supports the results 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.