4D.5
Programmed Cell Death in Karlodinium veneficum its induction by Environmental Factors and Potential in Bloom Management
PAPER WITHDRAWN
Gregory L. Oliver Jr., Delaware State University, Dover, DE; and D. McIntosh, D. Terlizzi, and F. Chrest
Harmful algae blooms (HABs) have devastating effects in aquaculture systems around the globe. The cosmopolitan, ichthyotoxic dinoflagellate Karlodinium veneficum, was first recognized as a threat to estuarine aquaculture following large mortality events at a striped bass culture facility, Hyrock Farm, in Princess Anne, Maryland (Terlizzi et al., 2000). HABs in aquaculture ponds can be managed using copper sulfate (CuSO4) or potassium permanganate (KMnO4), however KMnO4 can be costly and CuSO4 is known to cause cell lysis causing toxins to be released from K. veneficum cells (Deeds et al., 2002). Multiple modes of programmed cell death (PCD) including apoptosis and paraptosis are initiated at the molecular level where gene expression induces cell death signaling through the mediation of caspase enzymes that degrade DNA and other cellular components. The membrane phospholipid, phosphodylserine, inverts early in PCD and is detectable using an annexin bound fluorochrome, (Franklin et. al., 2006). Propidium iodide (PI) is able to permeate the cell membrane in necrotic cells to stain the nucleus (Franklin et. al., 2006). Flow cytometry enables detection of apoptotic PCD induction (phosphatidylserine inversion) with limited necrosis as detected by trace amounts of nuclear staining in a population of K. veneficum cells (Chrest and Terlizzi, 2008). PCD in dinoflagellates can be induced by dark treatment or CO2 (Franklin et. al., 2006; Vardi et. al., 1999). Similarly, there has been success in inducing PCD in K. veneficum through light deprivation but more study is necessary (Chrest and Terlizzi, 2008). We hypothesize that light reduction to a threshold level will induce PCD in K. veneficum. Specifically, we will be testing the ability of reduced light intensity as manipulated through the use of neutral density filters and the commercial dye, Aquashade (Applied Biochemists, Germantown, WI) to induce PCD in K. veneficum. Shaded cells will be treated with the two markers, annexin - FITC and PI to distinguish necrotic cells from cells experiencing PCD. A FACScalibur (BD Biosciences) flowcytometer will be used to detect PI and annexin- FITC fluorescence. Understanding the mechanisms of PCD induction in HAB species like K. veneficum may provide insight into management strategies.
Session 4D, Ecosystems
Friday, 13 November 2009, 10:25 AM-12:05 PM
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