Choi, Chang Jae , Berges, John A. .
Contrasting features of cell death in response to oxidative stress in marine and freshwater chlorophyte algae.
Programmed cell death (PCD) is a genetically controlled self-destruction mechanism to selectively remove damaged, infected, or superfluous cells via highly coordinated pathway. PCD is well established in metazoan systems, however the molecular components in plant systems remain obscure. Data from a wide range of unicellular organisms indicate that important components of PCD and cell death pathways have ancient origins, therefore single-celled eukaryotes may provide an insight to the conserved features and mechanisms of PCD. Model organisms in the algae are challenging to find. Recently, the observation of cell death accompanied by PCD-like features has been well characterized in chlorophyte alga Dunaliella tertiolecta, although we have little physiological and molecular information for this species. Chlamydomonas reinhardtii is closely related and while we know little about cell death in this species, we have good characterization and full genome sequence. Using these two organisms, we examined the oxidative stress, ROS and RNS, as inducers of mortality. RNS treatment using sodium nitrite did not induce the cell death in D. tertiolecta but it was observed in C. reinhardtii. Hydrogen peroxide, which produces ROS showed the opposite features, which implies the involvement of different signaling and transduction mechanisms. Membrane asymmetry, a morphological hallmark of PCD, could be detected in both species with annexin V-FITC. The key enzymes involved in PCD was also examined and we identified a putative metacaspase gene in D. tertolecta using C. reinhardtii sequence. This indicates that metacaspases are conserved in unicellular green algae. The identification of a network between redox-dependent cell death and the metacaspase gene is under investigation.
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1 - University of Wisconsin at Milwaukee, Department of Biological Sciences, 3209, N. Maryland Ave, Lapham Hall, Milwaukee, WI, 53211, United States
2 - University of Wisconsin at Milwaukee, Department of Biological Sciences
Programmed Cell Death
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM