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Abstract Detail


Developmental and Structural Section

Lord, Christina [1], Dauphinee, Adrian [1], Gunawardena, Arunika [1].

Actin microfilaments: key regulators of programmed cell death (PCD) in the lace plant .

The lace plant (Aponogeton madagascariensis) is a monocotyledonous aquatic plant that forms perforations between longitudinal and transverse veins, in spaces known as areoles, over its' entire leaf surface. Perforation formation is governed via developmentally regulated programmed cell death (PCD) and in the lace plant has been divided into five stages including 1) pre perforation 2) window 3) perforation formation 4) perforation expansion and 5) mature. A single areole within a window stage leaf (where PCD is occurring) has been divided into three areas based on the progression of PCD; cells that will not undergo PCD (NPCD), cells in early stages of PCD (EPCD), and cells in late stages of PCD (LPCD). Although the mechanism(s) of PCD within plant systems are still under investigation, several key players in the cell death process have been revealed. Within other plant PCD examples the actin cytoskeleton, composed of microfilaments, has been shown to be either an activator or a target for cysteine-aspartate specific protease-like proteases (caspase-like proteases, CLPs) promoting down stream PCD processes. To divulge a link between CLP activity and microfilaments, actin was stained via Alexa Fluor 488 phalloidin and initially examined over each of the five stages of leaf development; following this, actin microfilaments were then further examined over the gradient of PCD within a single areole of a window stage leaf (NPCD-LPCD) and width and intensity were quantified. CLP activity was also quantified over three stages of leaf development (pre perforation, window and mature) utilizing a Caspase-1 Fluorometric Assay. Results illustrated that actin was visibly degraded in cells undergoing PCD over the five stages of leaf development. Within a single areole of window stage leaf, actin in NPCD cells was organized into thin filaments, often linearly arranged; actin in EPCD cells then bundled significantly, followed by depolymerization during LPCD. The completion of CLP assays over the various stages of leaf development depicted significant differences in CLP activity between leaf stages. Overall, we have shown the involvement of both actin microfilaments and CLPs during PCD in the lace plant. In order to investigate the interconnection between these two components actin and CLP inhibitor experiments are currently under investigation, following which CLP activity and microfilament dynamics will be measured.

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1 - Dalhousie University, Biology, Department Of Biology, 1355 Oxford Street, Halifax, NS, B3H 4J1, Canada

Keywords:
Programmed cell death
Lace plant (Aponogeton madagascariensis)
Caspase-like proteases (CLPs)
Actin microfilaments.

Presentation Type: Oral Paper:Papers for Sections
Session: 32
Location: Union D/Hyatt
Date: Tuesday, July 10th, 2012
Time: 11:00 AM
Number: 32003
Abstract ID:355


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