Today’s image is from a paper on the development of the zebrafish eye lens. As I look at the paper’s stunning images, I’m sure that these cute little eyes are following me around my room.
The eye lens is composed of two cell types called lens epithelial cells and lens fibers. During development of the eye, lens fibers are generated from dividing lens epithelial cells, and later undergo morphogenesis. During morphogenesis, these new lens fibers elongate and then migrate toward the midline of lens, with newer lens fibers displacing and compacting older fiber layers as the entire lens grows. A recent paper investigates the relationship between morphogenesis and cell interactions with the underlying extracellular matrix (ECM). Hayes and colleagues found that fibronectin1 (Fn1), an ECM component, and integrin α5, the Fn1 cellular binding partner, are both required for lens fiber morphogenesis in developing zebrafish. Mutations in either gene cause defects in lens fiber adhesion, elongation, and packing, in turn leading to cataracts. Hayes and colleagues suggest that lens fibers migrate along an Fn1-containing substrate, which in turn activates the signaling required for lens fiber morphogenesis. In the images above, Fn1 is labeled in the developing lens of control zebrafish (top) and fn1 mutants (bottom). The control lens shows Fn1 (red) at the apical side of the lens epithelium (asterisks) and in lens fibers at the posterior (arrows), while the mutant shows reduced levels of Fn1.
Hayes, J., Hartsock, A., Clark, B., Napier, H., Link, B., & Gross, J. (2012). Integrin 5/fibronectin1 and focal adhesion kinase are required for lens fiber morphogenesis in zebrafish Molecular Biology of the Cell, 23 (24), 4725-4738 DOI: 10.1091/mbc.E12-09-0672