Fractionation of the Eye Pigments of Drosophila Melanogaster

Abstract

Optically isolating each of the sensory elements or ommatidia of the eye of the fruitfly, Drosophila mdanogaster, are groups of pigment cells. To these the eye owes its color. In the wild-type eye the cells contain granules which range in color from yellow to red or purplish red.The main body of the eye pigments can be extracted with water. The solutions exhibit characteristic color changes with pH and with oxidizing and reducing agents (cf. Schultz, 1935; Laki, 1935,36). Two groups of pigments appear to be present in the wild-type eye, designated as the red and the brown components (Mainx, 1938). The mutant scarlet, vermilion, and cinnabar eyes apparently contain only members of the red component, brown eyes only the brown component (Wright, 1932;Mainx, 1938). According to Mainx only the red component dissolves readily in water. The brown component is much more difficultly soluble; it is irreversibly decolorized and simultaneously dissolved by alkaline solutions.Some evidence exists that the red component is multiple in nature (Ephrussi, 1945), and that the red component pigments are different in sepia and wildtype eyes (Mainx, 1938). Pigments of both groups appear to contain a high proportion of nitrogen. Lederer (1940) reported 19 per cent N in a red pigment from wild-type eyes, Becket (1942) 6.79 to 17.2 per cent N in so called "ommatine" pigments of insects, which he believed include the brown component of the Drosophila eye. The latter appears to be derived from tryptophane through the intermediate formation of a-oxytryptophane and kynurenin (Beadle and Tatum, 1941;Butenandt, Weidel, and Becker, 1940 a, b;Kikkawa, 1941).The present experiments are a contribution toward the fractionation and characterization of the eye pigments of wild-type and mutant Drosophilas.They were performed in 1941-42, and were interrupted by the departure of one of us for military service. OBSERVATIONSWhole heads of flies (500 to 1500, 1 to 4 days after emergence) were extracted with distilled water after grinding in a mortar. As a control for the possible presence of pigment in head tissues other than the eye, similar numbers of heads of whiteeyed flies were extracted. They yielded negligible amounts of pigment.

Spectrophotometric and Chromatographic Adsorption Analysis of the Red Eye Pigment of Drosophila Melanogaster

“…Chromatographic adsorption analysis of extracts of wild-type and mutant flies begun by WALD and ALLEN (1946) and continued in the present study, have revealed that the red pigment consists of a number of closely related substances. The brown pigment, on the other hand, has so far resisted fractionation by this method.…”

“…-2 2 0 2 6 0 3 0 0 3 4 0 3 8 0 4 2 0 4 6 0 5 0 0 As shown by WALD and ALLEN (1946) the red and the yellow components differ markedly in their adsorption column behavior and their absorption spectra. Attempts were therefore made to separate them by means of their solubility differences.…”

“…As described by WALD and ALLEN (1946) extracts of cinnabar heads can be separated on a talc column into a t least five bands. They found that when the column is washed with water, one of these, identical with band 5 of figure 1, moves into the filtrate.…”

Phototactic Action Spectrum for Whitefly and the Question of Colour Vision

“…Excepting the optical effects of the screening pigments and of the microcomponents of ommatidial structure, and also excepting any distortions produced by the central integrative mechanisms in the case of a behavioural response, the action spectrum should correspond to the combined absorption spectra of the visual pigments. The contention that the absorption spectra of the extraretinal pigments ("eye pigments") of Drosophila coincide with phototaxy (Fingerman 1952) or with the inverse of oviposition (Volpe et al 1967) is totally fallacious as those pigments absorb at wavelengths shorter by 60-100 mp (Wald and Allen 1946;Burkhardt 1964). In fact, tbe extracted red pigments from the eyes of the vermilion mutant of Drosophila absorb maximally at 265-270 m,u and 480-490 mp (Heymann et al 1950) and resemble the ommochrome "'ommatin" in this respect (Butenandt and Schafer 1962).…”