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Brief Communication |
Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4 Canada
ABSTRACT
We developed an improved cytological protocol for producing high quality, light microscope images of plant meiotic chromosomes. Because the technique works on species with small genomes and thick microsporocyte cell walls, it should be useful for studying the wild relatives of Arabidopsis and other eudicots with small genomes. Combining this improved fixation protocol with our new analysis of associated substages in floral buds, we can unambiguously assign individual meiotic cells to particular substages of prophase I in Arabidopsis thaliana, even for difficult distinctions such as that between late zygotene or early diplotene. In this report we provide the first estimate of the individual duration of the zygotene and pachytene substages (4.8 h and 10.0 h, respectively) in A. thaliana. We also have examined the diffuse substage of prophase I and report that during this post-pachytene substage, nuclei retain the association of homologous nucleolus organizer regions and homologous centromeres, despite the generally diffuse chromatin and generally unpaired chromosome regions. Additionally, we have observed that centromeric regions of the chromosomes of diffuse-stage nuclei are highly condensed, more so than those of any other substage of prophase I.
Key Words: Arabidopsis thaliana (Brassicaceae) diffuse stage duration pachytene duration zygotene floral bud substage-association staging improved cytology meiosis
Received for publication April 12, 2007. Accepted for publication October 25, 2007.
FOOTNOTES
1 The authors acknowledge support from The National Science and Engineering Research Council of Canada to C.A.H. and the University of Toronto School of Graduate Studies to P.E.S.
2 Author for correspondence (e-mail: hasenkampf{at}utsc.utoronto.ca )
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