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Harmful algal blooms: mechanisms, monitoring, and prevention in a rapidly changing world
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Insights into the Multiple Roles of Programmed Cell Death Markers at Different Growth Stages and Diel Cycle in Toxic Dinoflagellate Karenia brevis
Wednesday 9th @ 1530-1550, Multifunction Hall
Yida Gao* , The University of Texas at Austin
Deana Erdner, The University of Texas at Austin
Presenter Email: yida.gao@utexas.edu |
| Historically, marine phytoplankton were presumed to replicate indefinitely by binary fission. However, drastic changes in environmental conditions have been shown to induce Programmed Cell Death (PCD) in algal cells, and may greatly affect development of phytoplankton populations. The Gulf of Mexico (GoM), a vast region with extensive shellfish resources, is subject to frequent toxic blooms of the dinoflagellate Karenia brevis. Although the formation process of K. brevis blooms have been extensively investigated, mechanisms of bloom decline and termination are not well known. Here we used established PCD markers, such as reactive oxygen species (ROS) and caspase-like activity, to define stress-related death processes at different growth stages in K. brevis under oxidative stress, and elucidate the variation of PCD markers in a diel cycle under controlled environment. ROS and caspase activity were found associated with the death process of K. brevis. Similar stress responses were observed at different growth stages, even though vulnerability to oxidative stress increased as the culture ages. In untreated cells, however, percentages of ROS and caspase fluctuated strongly, but did not correlate with cell death, which may indicate variable ROS scavenging process and quiescence preparation. The prevalence of ROS increased significantly in night phase, and could result from the activities of mitochondria generating energy for cell division at night. Our research revealed the multiple roles of PCD markers in K. brevis, highlighting the need of using cell cycle patterns to understand cellular stress responses. |
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