DINOFLAGELLATE GENOMICS

Abstract

Apt, K. E.Martek Biosciences Corp, Columbia, MD 21045 USADinoflagellates are a distinct phylum of unicellular, primarily photosynthetic microaglae, characterized by unique cellular and nuclear morphologies. Ecologically they comprise an extremely important group of primary producers, not only as free living organisms, but also as symbionts within the cells of many invertebrates. Dinoflagellates accumulate significant amounts of lipid in the form of triglyceride for carbon storage. These lipids are predominately omega‐3 polyunsaturated fatty acids, particularly EPA and DHA. Applications for these fatty acids in human nutrition, particularly for infants has developed into a significant consumer market. Elucidation of the biosynthetic pathway for these fatty acids is a major motivating force driving industry efforts for genomic research. Genome and gene structure in dinoflagellates is poorly understood. The DNA content of these organisms is extremely large for unicellular organisms, reaching an estimated 1011 Mb, which is larger than the human genome. The large genome size makes complete genome sequencing impractical, however sequencing of expressed cDNA's can be done efficiently. The limited number of nuclear encoded genes that have been characterized are present in multicopy repeats. For example, the pcp genes appear to be present in an estimated 5,000 copies. This presentation will provide an overview of both nuclear and plastid genome structure. Along with recent advancements from sequencing projects currently underway by both academic and industry efforts.