| Abstract Detail
Organelle Biology Shaver, Jeffrey M. [1], Oldenburg, Delene J. [2], Bendich, Arnold J. [2]. The structure of chloroplast DNA molecules and the effects of light on the amount of DNA per plastid during chloroplast development in Medicago truncatula. We used pulsed-field gel electrophoresis and restriction fragment mapping to analyze the structure of Medicago truncatula chloroplast DNA (cpDNA). We find most cpDNA in genome-sized linear molecules, head-to-tail genomic concatemers and complex branched forms with ends at defined sites, rather than at random sites as expected from broken circles. Our data suggest that cpDNA replication is initiated predominantly on linear DNA molecules with one of four possible ends serving as putative origins of replication. We also used 4',6-diamidino-2-phenylindole-staining of isolated plastids to determine the DNA content per plastid for seedlings grown in the dark for three days and then transferred to light before being returned to the dark. The cpDNA content increased after three hours of light, decreased with nine hours, and decreased sharply with 24 hours of light. We conclude that the absence in M. truncatula of the prominent inverted repeat cpDNA sequence found in most plant species does not lead to unusual properties with respect to plastid chromosomal structure or replication or the loss of cpDNA during light-stimulated chloroplast development.
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Related Links:
Jeff Shaver's Student Homepage
1 - University of Washington, Department of Biology, 24 Kincaid, Box 351800, Seattle, WA, 98195-1800, USA
2 - University of Washington, Department of Biology
Keywords:
chloroplast DNA
development
pulsed-field gel electrophoresis
DNA structure.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P18019
Abstract ID:802 |
