Abstract
Purpose: :
The zebrafish is a promising model for studying lens development and structure. Unlike mammalian lens development, the zebrafish lens delaminates from surface ectoderm rather than forming a lens vesicle. Detailed 3-D imaging in vivo of zebrafish lens development to characterize the stages of development and delamination for correlation with protein expression in the normal adult zebrafish lens will provide insight into similarities with the mammalian lens.
Methods: :
Transgenic zebrafish embryos which expressed cyan fluorescent protein in lens cell membranes were injected at the 1-cell stage with a plasmid containing yellow fluorescent protein to achieve mosaic YFP expression. Multiphoton microscopy was performed in vivo on anesthetized transgenic zebrafish embryos from 1-3dpf using an Olympus FluoView FV1000 microscope with a 25X or 60X water immersion lens. Trypsin digested protein from freshly dissected adult zebrafish lenses were sequenced by Linear Trap Quadripole Fourier Transform (LTQ-FT) LC/MS/MS and used to identify the intact proteins present in lens.
Results: :
Time lapse multiphoton imaging of the developing zebrafish lens from the lens placode stage through delamination of the lens from the cornea (approximately 16-24hpf) demonstrated the close relationship between cells of the developing lens and cornea. Prior to complete separation between the lens and cornea, lens cells elongated and began to take on the appearance of secondary fibers. After delamination, lens fibers continued to proliferate, migrate, and elongate from the bow region which was located more posterior than the bow region in mammals. Mass spectrometry of proteins expressed in the wild-type adult zebrafish lens determined commonalities with proteins expressed in the mammalian lens, which included crystallins and cytoskeletal proteins.
Conclusions: :
Real-time in vivo 3-D imaging of lens development in the zebrafish identified a coordinated, symmetric pattern of growth and differentiation of the lens cells as they remained connected to the developing cornea. Similarities in the protein composition of the lens in the adult zebrafish and mouse were identified. On the basis of the close relationship between developing cells of the lens and cornea in the zebrafish, it can be hypothesized that protein expression in the lens and cornea are similar.
Keywords: development • imaging/image analysis: non-clinical • protein purification and characterization