This project will investigate the physical properties of living tissue that are important in determining the tissue curvature. The PI will quantitatively determining the number and location of defects in ordered tissues and will develop a mechanical theory of the defect distribution that can be compared with experiment. This constitutes the first quantitative study of tissue curvature as a determining factor of structural organization. Understanding of the morphology and morphogenesis of organisms has grown tremendously based on recent advances in biological and genetic research. Yet, few attempts have been undertaken to describe the development and structure of organs or tissues through quantitative mechanics. The results of this work will be equally applicable to all curved tissue layers that show a degree of order, including cancer cell acini, whose morphology is important for the development of cancer, as well as developing embryos in the morula and blastula stages. As curvature induces constraints on the degree of order, it may play a role in symmetry breaking and polarization, and thus in the earliest patterning of the embryo. Describing a direct influence of mechanical forces on cell development will be a fundamental advance towards a better understanding of morphogenesis and tissue formation in the context of both diagnostics and therapy, e.g. tissue regeneration or cancer. Data acquisition will employ the help of undergraduate students as well as outreach to high school students through the existing Bugscope project at Illinois, thus connecting with the broader public through a visually fascinating and interdisciplinary project.
This project focuses on insect eyes as a concrete example of an ordered tissue structure, because of the extreme regularity of the compound eye, the large number of individual eyes (ommatidia) in the compound eye, and the relative ease with which the structure can be quantitatively analyzed. Using both SEM imaging and confocal microscopy, the goals are to (i) determine the complete microstructure of the ommatidia and (ii) determine the macrostructure (global shape and curvature) of the eye, in order to (iii) compare the number and position of ommatidial defects with those predicted by the mechanical theory of curved patterned surfaces. The existing theory of defect placement on curved surfaces (developed for a limited number of examples from solid state physics) will be adapted to the more general shapes encountered in insect eyes. Both numerical simulations and analytical theory will be developed. While Drosophila wild-type and mutant eyes in mature and pupal stages will be the main focus, the variety of insect eye sizes and shapes in different species is an asset to this study.
