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Cell death in normal and rough eye mutants of Drosophila
1Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47906.
Abstract:
The regular, reiterated cellular pattern of the Drosophila compound eye makes it a sensitive amplifier of defects in cell death. Quantitative and histological methods reveal a phase of cell death between 35 and 50 h of development which removes between 2 and 3 surplus cells per ommatidium. The timing of this epoch is consistent with cell death as the last fate to be specified in the progressive sequence of cell fates that build the ommatidium. An ultrastructural survey of cell death suggests dying cells in the fly eye have similarities as well as differences with standard descriptions of programmed cell death. A failure of cell death to remove surplus cells disorganizes the retinal lattice. A screen of rough eye mutants identifies two genes, roughest and echinus, required for the normal elimination of cells from the retinal epithelium. The use of an enhancer trap as a cell lineage marker shows that the cone cells, like other retinal cells, are not clonally related to each other or to their neighbors.
Insights
Drosophila eye development involves programmed cell death to remove surplus cells. Mutations in roughest and echinus genes disrupt this essential cell elimination process, impacting retinal organization.
Area of Science:
- Developmental biology
- Cell biology
- Genetics
Background:
- The Drosophila compound eye provides a model system for studying cellular development and programmed cell death.
- Understanding cell elimination is crucial for normal tissue patterning and organogenesis.
Purpose of the Study:
- To investigate the role and timing of cell death in Drosophila eye development.
- To identify genes involved in the removal of surplus cells during ommatidium formation.
- To characterize the nature of cell death in the developing fly retina.
Main Methods:
- Quantitative and histological analyses of developing Drosophila eyes.
- Ultrastructural examination of dying cells.
- Genetic screening of rough eye mutants.
- Utilizing enhancer traps for cell lineage tracing.
Main Results:
- A specific phase of cell death occurs between 35-50 hours of development, eliminating 2-3 surplus cells per ommatidium.
- Dying cells in the fly eye exhibit characteristics both similar to and distinct from typical programmed cell death.
- Disruption of cell death leads to disorganized retinal lattice.
- Mutations in roughest and echinus genes are identified as critical for normal cell elimination.
- Cone cells are shown not to be clonally related to neighboring retinal cells.
Conclusions:
- Programmed cell death is a critical, timed event in Drosophila eye development, ensuring proper retinal architecture.
- The genes roughest and echinus are essential for regulating surplus cell removal.
- Further investigation into the ultrastructure of fly eye cell death is warranted.