Purchase this article with an account.
TS Vihtelic, DR Hyde; Lens Opacity and Increased Epithelial Cell Proliferation in a Zebrafish Mutant . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3581.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Zebrafish is an established animal model for genetic studies of the vertebrate visual system. Zebrafish embryos are optically translucent and the retina and lens develops rapidly; therefore, eye morphological defects are easily assessed. Zebrafish mutants with ocular lens defects should be useful models of human disease syndromes characterized by lens malformation or cataractogenesis. Methods: Male AB line zebrafish were treated in 3 mM ENU (N-Ethyl-N-Nitrosurea). The progeny from F2 sibling pairmatings were screened at 5 and 7 days post-fertilization (dpf) for eye morphological phenotypes using a stereo microscope. Histological and immunohistochemical techniques were used to characterize the mutant eye phenotypes at 7 dpf. Thick plastic sections were stained for light microscopy to assess retinal and lens structure. Frozen sections were immunolabeled with various cell type-specific antisera to evaluate the retinal cell population and a lens-specific monoclonal antibody allowed further visualization of the developing lens structure. PCNA immunolabeling identified proliferating cells in the larval lens and retina. Finally, the lens and photoreceptor layer ultrastructure was examined by transmission electron microscopy. Results: We identified three different mutant lines possessing defects in the ocular lens. Genetic complementation analyses confirmed the mutations are in different genes. The lens opaque (lop) mutant displays lens opacity at 7 dpf, although the eye and pupil size of lop fish is indistinguishable from wild type. The lop lenses exhibit irregularly shaped cells adjacent to the lens epithelial cell layer, which sometimes extend into the anterior chamber. In addition, the mutant lenses are characterized by fiber cell disorganization. Some mutant lenses possess normal nuclear structure. Based on immunolocalization of the different opsin proteins, the lop photoreceptor layer lacks central photoreceptor cells, although opsin-expressing rod and cone cells are identified at the retinal margin. The lop photoreceptor layer abnormality is accompanied by increased numbers of PCNA-positive cells in the lens, the retinal marginal zone and the inner nuclear layer relative to wild type. Clusters of proliferating inner nuclear layer cells are occasionally observed. Conclusion: By determining the genetic basis for the phenotypes of zebrafish lens mutants, new insights into the molecular mechanisms of lens development and maintenance will be gained.
This PDF is available to Subscribers Only