Bacteria-like cytoplasmic symbionts in a natural population of the green alga Desmatractum bipyramidatum (chlorococcales)

During routine ultrastructural research on the morphological features of Desmatractum bipyramidatum (Chodat) Pascher (1930), thirteen cells were selected by light microscope in a flat embedded heterogenous sample of algae from a Dutch moorland pool complex (Kouwets 1980) and sectioned for transmission electron microscopy (TEM) (Reymond & Kouwets 1981). In addition to the presence of the usual organelles, several bacteria-like structures assumed to be endosymbionts were found in three cells and their spatial position was reconstructed through serial sections. None of the symbionts observed in the cytoplasm of the three cells seemed to be preferentially related to specific organelles.