An electron microscope search for plastids in bleached Euglena gracilis and in Astasia longa

Abstract

Eighteen long-established strains of bleached Euglena gracilis (the products of several different bleaching techniques) and two culture-collection stocks of the naturally colorless Astasia longa were examined with electron microscope for the possible presence of plastids. Proplastid-like structures were observed in all but three of the bleached E. gracilis strains; none was seen in the A. longa stocks. None of the presumptive aplastidic strains appears capable of the extensive carotenoid synthesis seen in some of the other bleached E. gracilis stocks. There was no detectable chlorophyll(ide) in any of the several stocks examined, despite the presence of plastids.