Our research is focusing on several aspects of marine phytoplankton. First, we developed molecular methodology to study in situ growth rate of phytoplankton. Second, we study ecological adaptation using immunocytochemical techniques. Third, we study genes that are important in regulating cell division (PCNA, p34cdc2, cyclins) and photosynthesis (Rubisco). Fourth, we develop gene markers for phylogeny and species identification of dinoflagellates, particularly mitochondrial genes such as cytochrome b and cytochrome C oxidase subunit I. Fifth, we study gene expression profiles of different dinoflagellates using Expressed Sequence Tags (ESTs). One focus in our current research is growth, grazing and ecological roles of the putatively toxic dinoflagellate Pfiesteria and related heterotrophic species. We also study phytoplankton species diversity in Long Island Sound. We recently also embarked on studies of Dinoflagellate Evolution taking multi-gene approach.
- One of our efforts is identifying cell cycle and growth stage-dependent markers (PCNA, P34cdc2, cyclin B, MAPK, 14-3-3, etc.) potentially useful for growth studies for microalgae. Genes and their encoded proteins important in regulating cell division are cloned and characterized. Based on the gene sequence, DNA probes or antibodies are developed to detect expression of these genes by RT-PCR or whole cell immunofluorescence. These probes are then applied in the field to study in situ growth rate or physiological status. This method is now being used to study factors regulating dynamics of harmful algal blooms (Pfiesteria and other dinoflagellates as well as brown tide alga) and growth of biogeochemically significant species. Ecological response and adaptation to environmental stress is studied using key enzymes associated with important biological processes in attempts to elucidate mechanisms of such response or adaptation.
- Cell-environment communication is another area of interest. Recently, we have isolated several genes known to constitute a signal transduction pathway from Pfiesteria piscicida and are currently determining their expression regulation under different physiological conditions.
- Dinoflagellate chloroplasts are complex in their origin and evolution, and mitochondria are distinct in gene structure and expression. Rubisco genes are being characterized for an array of dinoflagellates in an attempt to examine evolution of photosynthesis in this taxon. We recently also discovered in P. piscicida and other dinoflagellates unusual multi-copy structure of a cytochrome b gene and its extensive transcriptional/posttranscriptional editing. Further characterization of these genes and development of cob-rRNA dual genetic marker is underway