Sterols of Soil Amoebas and Ochromonas danica: Phylogenetic Approach

SYNOPSIS. Sterols of Ochromonas danica, Mayorella palestinensis, Acanthamoeba sp. and Hartmannella rhysodes were examined by thin‐layer and gas‐liquid chromatography. The sterol patterns of O. danica and the amoebas were strikingly similar. Two of the sterols present in both groups, were identified as ergosterol and stigmasterol. This similarity is construed as evidence that “soil” amoebas evolved from phytoflagellates having sterol patterns similar to that of O. danica. An explanation is suggested for the role of ergosterol in phytoflagellates, as originally an ultra‐violet‐protective agent, then a membrane component.