Marine and freshwater ecosystems are home to a bewildering assortment of microscopic organisms that possess plastids. This group, collectively known as ‘phytoplankton', includes unicellular and colonial species that may be non-motile, flagellate or amoeboid. Phytoplankton assemblages are evolutionarily diverse and include species belonging to several different kingdoms and phyla. The ancestors of many extant phytoplankton species are among the earliest diverging photosynthetic organisms that evolved via symbiosis presumably over 700 million years ago.

My students and I use traditional and molecular biological tools to investigate the phylogeny and cell biology of eukaryotic microalgae. For example, we are using nuclear- and plastid-encoded genes to examine the evolution of several groups of chlorophyll a + c -containing microalgae. Such groups include the chrysophytes, diatoms, eustigmatophytes, prymnesiophytes, synurophytes and xanthophytes among others. The morphology and biology of these tiny cells is explored using light and electron microscopy. We are also studying the systematics of the Phylum Oomycota, a taxon that includes aseptate non-photosynthetic organisms many of which are plant or animal pathogens. Recent work in my laboratory has focused on several plastid-encoded genes involved in the assembly of critically important Fe/S clusters. We are also examining members of the glutamine synthetase (GSII) gene family and are particularly interested in GSII genes that are encoded by the nucleus but function within the plastid. Real-time PCR methods are used to study how the expression of these genes differ in different organisms and to elucidate those factors responsible for up- or down-regulation of mRNA synthesis.

Research in my laboratory is supported by grants from the National Science Foundation.