Cellular patterns during leaf development

Sanchez-Corrales, Yara (2013) Cellular patterns during leaf development. Doctoral thesis, University of East Anglia.

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A major problem in developmental biology is to understand how the behaviour of individual cells creates reproducible biological shapes. Moreover, the reproducibility of form also happens at the cellular level and cellular patterns are evident in the temporal as well as the spatial scales. Understanding the principles underlying these cellular patterns will contribute to linking the individual cell dynamics to the collective phenomenon of morphogenesis.

The relatively flat shape, the absence of cell migration and apoptosis makes the leaf of Arabidopsis thaliana an excellent system to study morphogenesis at the cellular level. However the information about the cellular dynamics that is available has only been inferred indirectly or restricted to few cells.

In this thesis, I present some methods that permitted the characterisation of cellular dynamics over long time periods at the organ level. I present the Lobe Contribution Elliptical Fourier Analysis (LOCO-EFA), that enabled the quantification of complex cell geometries and provided a shape profile to evaluate populations of cells. In turn, the shape profile of individual cells was used to develop a tracking algorithm that, integrated with a segmentation algorithm, resulted in a powerful tool to recognize cells in a succession of images and extract cell shape, cell area, cell position and cell lineages.

The synergy between in vivo imaging and computational tools permitted the study of cellular patterns at unprecedented resolution. Interestingly, the dynamics of cell growth and cell shape are highly influenced by the cell age and to a limited extend, by their position. Moreover, direct measurement of cell division shows that the division zone is restricted towards the base of the leaf, but is not constant in length and that the frequency of divisions decreases over time in a rather gradual fashion.

At single cell level, new events of lobe formation were identified, suggesting that the intracellular patterning underlying the multi-polar pavement cell shape is dynamic and lobes are newly formed rather than being specified at a single time point.

The cellular dynamics of growth, shape and divisions using long time-lapse and imaging enabled me to revisit previous hypothesis and propose new ones about the regulation of cellular behaviour during leaf morphogenesis.

(The CD-ROM referred to in the thesis contains Movies in AVI format. However these were submitted as separate files which could not be uploaded to the repository. Please contact the author for more information.)

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 21 Jul 2014 14:55
Last Modified: 22 Jul 2014 14:42
URI: https://ueaeprints.uea.ac.uk/id/eprint/49709

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