Genomics of HAB Dinoflagellates: Identification of Molecular Mechanisms Regulating Blooms
Project Status: This project began in October 2005 and is projected to be completed in September 2015
We are working to identify key genes and processes encoded in the dinoflagellate genome that are responsible for regulating the growth, maintenance, and termination of toxic dinoflagellate blooms. Analogous to cancer research, once key mechanisms are identified, we can use them to develop molecular tools for monitoring the status of blooms, forecasting their impacts, and possibly manipulating their demise. Our current focus is on the Florida red tide dinoflagellate, Karenia brevis.
Why We Care
Harmful algal blooms (HABs) cost an estimated 75 million dollars annually due to the closure of economically vital shellfish resources, dieoffs of fish and protected marine species, human health consequences, and lost tourism revenue. HABs develop when optimal environmental conditions such as temperature, nutrients, and oceanographic upwelling coincide to favor the growth of a particular HAB species over competing phytoplankton. We are working to address the lack of fundamental knowledge of the cellular processes in any dinoflagellate species that tip the scales toward HAB species in this competition. Defining genes controlling the development of HABs will provide the information to develop applied tools to monitor for bloom growth, toxicity, and cell death, and a new source of information for improving the accuracy of predictive models of bloom impacts.
What We Have Learned
Through high production sequencing of K. brevis DNA copies (cDNA), we have established a publicly available database of K. brevis expressed genes. From this, we developed a DNA microarray (screening process) to study gene expression. Through these gene expression studies we found that:
Dinoflagellates use an unusual process of trans-splicing in the maturation of their RNA;
This trans-splicing enables them to have very stable RNA and rely mainly on changes in protein levels to regulate their cellular responses;
Many genes are present in very high copy number, which partly explains their large genome size;
The genes responsible for toxin biosynthesis have an unprecedented structure;
Their cell cycle is under circadian rhythm control, but is regulated by proteins that are present in all eukaryotes; and
Dinoflagellates undergo programmed cell death.
We are currently adapting proteins important to cell cycle regulation and proteins important in cell death to develop field-usable biomarkers for bloom growth and termination. These assays for growth and death will be used on a flow cytometry–based platform and will be transitioned to end-users involved in red tide monitoring and modeling.
Related Regions of Study: Gulf of Mexico, Florida
Primary Contact: Fran VanDolah
Harmful Algal Blooms
Related NCCOS Center: CCEHBR
- Johnson, Jillian G., Michael G. Janech, and Frances M. Van Dolah. 2014. Caspase-like activity during aging and cell death in the toxic dinoflagellate Karenia brevis. Harmful Algae 31:41–53.
- Morey, Jeanine S. and Frances M. Van Dolah. 2013. Global analysis of mRNA half-lives and de novo transcription in a dinoflagellate, Karenia brevis. PLoS ONE 8(6):e66347
- Morey, Jeanine. S., Emily A. Monroe, Amanda L. Kinney, Marion Beal, Jillian G. Johnson, Gary L. Hitchcock, and Frances M. Van Dolah. 2011. Transcriptomic response of the Florida red tide dinoflagellate, Karenia brevis, to nitrogen and phosphorus depletion and addition. BMC Genomics 12:346.
- Brunelle S.A. and F.M. Van Dolah. 2011. Post-transcriptional regulation of S-phase genes in the dinoflagellate, Karenia brevis. Journal of Eukaryotic Microbiology 58(4):373–382.
- Monroe, Emily A., Jillian G. Johnson, Zhihong Wang, Richard K. Pirece, and Frances M. Van Dolah. 2010. Characterization and expression of nuclear encoded polyketide synthases in the brevetoxin-producing dinoflagellate Karenia brevis. Journal of Phycology 46(3):541–552.
- Van Dolah, Frances M., Kristy B. Lidie, Emily A. Monroe, Debashish Bhattacharya, Lisa Campbell, Gregory J. Doucette, and Daniel Kamykowski. 2009. The Florida red tide dinoflagellate Karenia brevis: New insights into cellular and molecular processes underlying bloom dynalmic. Harmful Algae 8(4):562–572.
- Van Dolah, Frances M., Kristy B. Lidie, Jeanine S. Morey, Stephanie A. Brunelle, James C. Ryan, Emily A. Monroe, and Bennie L. Haynes. 2007. Microarray analysis of diurnal- and circadian-regulated genes in the Florida red tide dinoflagellate, Karenia brevis (Dinophyceae). Journal of Phycology 43(4):741–752.
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