Spectral analysis of fluorescent substances in the eyes of flies and man
No Thumbnail Available
Authors
Meeting name
Sponsors
Date
Journal Title
Format
Thesis
Subject
Abstract
"Summary. The compound eyes of flies are known to contain fluorescing substances (e.g. Franceschini 1977). Measurements of changes in fluorescence and transmission occurring in the eye while it is exposed to light were used to discover properties of photoreceptors, predominantly Rl-6. Flies receiving intense light treatment and vitamin A deprivation were used to determine which components of compound eye fluorescence are actually associated with light transducing pigments. Also microscpectrofluorometry was used to measure the emission spectra of fluorescing substances in the eyes of white-eyed Drosophila. Emission was measured using 365 nm excitation. Careful calibrations of our microspectrofluorometer were used to calculate corrected spectra. Emission measurements from the deep pseudopupil, a means of visualizing receptive elements, were taken before and after treatment with intense ultraviolet light in both normal and vitamin A deprived flies. Two emission maxima exist in the eyes of normal flies: a blue peak (max = 460 λ) and a red peak ( max = λ650 nm) (Fig. 8). The long wavelength (red) emission is absent however, in vitamin A deprived flies (Stark et al. 1979c, Fig. 8). Intense UV treatment of normal flies reduced the blue emission and eliminated the red emission (Fig. 6). UV treatment of vitamin A deprived flies caused the same reduction in blue fluorescence (Fig. 9). Since vitamin A deprivation eliminates most photopigment (e.g. Harris et al. 1977) and UV sensitizing pigment (e.g. Stark et al. 1977) this blue emission is from substances unrelated to photoreception. Excitation spectra for the >570 nm (red) fluorescence were also measured in flies before and after intense UV treatment. The excitation difference spectrum maximum was at =350 nm with a minor second peak at =514 nm (Fig. 12) providing some evidence that the red fluorescence could be from the UV sensitizing pigment. Our findings indicate that the red, photopigmentrelated, component of our emission spectra comes from metarhodopsin (Fig. 13) and/or UV sensitizing pigment (Fig. 12). Much more intense exciting light can create other fluorescing substances. Intense blue and UV light destroys photopigment and produces a red-emitting substance called metarhodopsin’ (M', e.g. Franceschini et al. 1981) (see Figs. 2-5). We have also noted a surge of yellow fluorescence accompanying exposure of red eyes to the highest intensities of blue light available (Fig. 1). The source of this yellow fluorescence remains uncertain but it depends on eye color pigments. Neither M' nor these yellow emitting fluorophores contribute to the red component of our emission spectra (Figs. 6-8) however, since the intensity of the UV exciting light was much less than that necessary to create either of them."--Page 4.
Table of Contents
DOI
PubMed ID
Degree
M.A.
Thesis Department
Rights
OpenAccess.
License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License.