Cory Dashiell
Senior | Biology

Biology and systematics of the Eustigmatophyceae 

"One line of investigation in our lab focuses on the eustigmatophytes, a poorly known class of algae that includes freshwater and marine representatives.  Most of these organisms are tiny (5-20mm) and take the form of walled, free-living, (non-colonial) single cells.  Until recently eustigmatophytes were considered “rare” or “occasional” members of phytoplankton communities, but our efforts suggest otherwise.  Because they are so easily overlooked most aspects of the biology of eustigmatophyte species remain unexplored.  For example, the subcellular organization and wall architecture of most eustigmaophytes is unknown and current knowledge of their life histories is based on scant evidence collected from a handful of species.  In addition, their relationship to other phytoplankton groups – in particular those chlorophyll a and c-containing taxa referred to as ‘heterokont algae’ – are nebulous.  We have brought into laboratory culture 10 new eustigmatophyte isolates from freshwater environments.  We are in the process of examining these organisms using a suite of techniques including brightfield, scanning and transmission electron microscopy.  These methods provide valuable information on the cells’ morphology and subcellular architecture.  We are also generating DNA sequence data for nuclear- and chloroplast-encoded genes that will be used to reassess the evolutionary history of these species and their relatives.  Our studies have already produced data that will fundamentally alter how the eustigmatophytes are perceived in terms of their biodiversity, life cycles, taxonomy, and abundance and ecology in aquatic habitats.  The mysteries of eustigmatophyte evolution at grander scales of inquiry – When did eustigmatophytes evolve?  To which other eukaryotic taxon are they most closely related?  What is the function of the apparently unique organelles they possess? – are the subject of on-going investigation".