What are the mechanisms of light damage? To answer this question, I felt it was necessary to develop competence in ultrastructural techniques. In 1981, I began a series of collaborative studies with the late Prof. Stanley D. Carlson (Department of Entomology and Neuroscience Program, University of Wisconsin – Madison). These studies also initiated a long-term collaboration with The LOCI (Laboratory for Optical and Computational Instrumentation, formerly National Biophotonics Resource, formerly Integrative Microscopy Resource, formerly High Voltage Electron Microscope) in Madison. Our initial work was directed toward determining the mechanisms of retinal degeneration in the rdgB and rdgA mutants. Recent molecular approaches have kept these mutants at the forefront of Drosophila vision research and the field of signal transduction. We also characterized the photoreceptors and their visual projections in ora, of obvious interest since it is an allele of the so-called ninaE gene which codes for the predominant rhodopsin in Drosophila compound eyes. Finally, in this early work, we developed Drosophila as a model for human "eclipse blindness" by showing that intense UV and blue lights can induce degeneration in the non-mutant eye, and that this degeneration is mediated by light absorption by the visual pigments. The work on mutants and degeneration paved the way to my later focus on photoreceptor maintenance and membrane turnover, discussed below.

Calibration of light intensity is very important in my research. Clockwise from noon: Photomultiplier and power supply, thermopile, radiometer/photometer, and photodiode with batteries (used most often).

Papers on the ultrastructure of degeneration:

Stark, W.S. and Carlson, S.D. Ultrastructural pathology of the compound eye and optic neuropiles of the retinal degeneration mutant (w rdgBKS222) Drosophila melanogaster. Cell and Tissue Research, 1982, 225, 11-22. PubMed

Stark, W. S. and Carlson, S. D. Ultrastructure of the compound eye and first optic neuropile of the photorecptor mutant oraJK84 of Drosophila. Cell and Tissue Research, 1983, 233, 305-317. PubMed

Stark, W.S., Carlson, S.D. Blue and ultraviolet light induced damage to the Drosophila retina: ultrastructure. Current Eye Research l984, 3, l44l-l454. PubMed

Stark, W. S. and Carlson, S.D. Retinal degeneration in rdgA mutants of Drosophila melanogaster meigen (Diptera: Drosophilidae). International Journal of Insect Morphology and Embryology, 1985, 14, 243-254.


Stark, W.S. and Sapp, R. Ultrastructure of the retina of Drosophila melanogaster: the mutant ora (outer rhabdomeres absent) and its inhibition of degeneration in rdgB (retinal degeneration-B). Journal of Neurogenetics,1987, 4, 227-240. PubMed


Stark, W.S., Sapp, R., and Carlson, S.D. Photoreceptor maintenance and degeneration in the norpA (no receptor potential-A) mutant of Drosophila melanogaster. Journal of Neurogenetics, 1989, 5, 49-59. PubMed


Stark, W.S. and Sapp, R. Retinal degeneration and photoreceptor maintenance in Drosophila: rdgB and its interaction with outer mutants. In: Inherited and Environmentally Induced Retinal Degenerations: (ed: M.M. LaVail, R.E. Anderson and J. G. Hollyfield) New York: Alan R. Liss, Inc. 1989. pp.467-489 (Invited Chapter). PubMed


Stark, W. S., Christianson, J. S., Maier, L., Chen, D.-M. Inherited and environmentally induced retinal degenerations in Drosophila. In Retinal Degenerations. Stockholm Retinal Degenerations Satellite Symposium Proceedings Book. (eds. R. E. Anderson, J. G. Hollyfield, M. M. LaVail), Boca Raton, CRC Press, 1991, pp. 61-75


Stark, W. S., Hunnius, D., Mertz, J. Chen, D.-M. Drosophila as a model for photoreceptor dystrophies and cell death. In Degenerative Diseases of the Retina (eds. R. E. Anderson, M. M. LaVail, J. G. Hollyfield), New York, Plenum, 1995, 217-226.


A relevant research note:


Juang, J.-L., Stark, W. S., Carlson, S. D. Scanning electron microscopy of the retina of Drosophila. Drosophila Information Service 1994, 75, 104-105


UV damage (in R1-6, but not R8): High Voltage Electron Micrograph (HVEM) of proximal ommatidium of white-eyed Drosophila 1 week after UV at 19.38 log quanta per square cm; vitamin A deprivation showed that the damage was mediated through light absorption by rhodopsin (Stark and Carlson, 1984)


A low voltage scanning electron micrograph (LVSEM) of the pseudocone (and surrounding cells) and rhabdomere tips (top) and of rhabdomeric microvilli (bottom) (see Juang et al.).

Electron micrographs from Stark and Carlson (1982) showing degeneration in rdgB after one week in cyclic light of R1-6 but sparing or R8 and post-synaptic cells.

This page was last updated on July 12, 2012

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