Drosophila, eye pigments

Diamino-, 4-amino-2-methylthio-, and 2-amino-4-alkoxy-pteridines react similarly <86MI 718-05, 88HCA531). Deoxysepiapterin (120), one of the two yellow Drosophila eye-pigments, could be... 

The Drosophila eye pigments sepiapterin and drosopterins (Figs. 15-17 and 25-19) arise from 6-pyruvoyltefrahydropferin. " Reduced glutathione appears to be the reducing agent needed to convert the... 

Silica gel plates also have been used for the separation of 16 different eye pigments of Drosophila melanogaster using two-dimensional development in nonpolar solvent systems [55]. Although not very common, two-dimensional development may be nsed in preparative scale on thick-layered plates for further analysis. 

First isolated from human urine, biopterin (Fig. 15-17) is present in liver and other tissues where it functions in a reduced form as a hydroxylation coenzyme (see Chapter 18).338 It is also present in nitric oxide synthase (Chapter 18).341/342 Other functions in oxidative reactions, in regulation of electron transport, and in photosynthesis have been proposed.343 Neopterin, found in honeybee larvae, resembles biopterin but has a D-erythro configuration in the side chain. The red eye pigments of Drosophila, called drosopterins, are complex dimeric pterins containing fused 7-membered rings (Fig. 15-17).344 345... 

In 1935, George Wells Beadle before collaborating with Edward Lawrie Tatum (Columbia, New York) began studying the development of eye pigment in Drosophila with Boris Ephrussi. 

C,H,N502, Mr 221.22. An eye pigment of the fruit fly Drosophila melanogaster, occurs also in the cyanobacterium Anacystis nidulans. 

The eye pigment drosopterin 107 and its enantiomer isodrosopterin are the major components isolated from the head of Drosophila melanogaster, whereas aurodrosopterin 108 is the minor pigment in wild-type flies. The chemical stmcture consists of a pentacyclic ring system containing a pyrimidodiazepine portion, a pteridine portion, and a pyrrole ring (Figure 7.30). 

There is no clear genetic relation in Drosophila eyes of the water-insoluble ommachrome pigments (derived from kynurenine) and the water-soluble yellow and red pterins (Hadorn, 1956 Hadom and Schwinck, 1956). 

Entirely independent experiments on Drosphila in two different laboratories bolster belief in this parallel action. Knowing that xanthine oxidase from cream converted 2-NHj-4-hydroxypterin to isoxanthopterin, Forrest et d. (1956) identified xanthine oxidase in the pupae of the wild type by the ability of supemates of ground pupae to oxidize this compound to isoxanthopterin, xanthopterin to leucopterin, and xanthine to uric acid. The eye-color mutants (maroon and maroon-like) lacked the enzyme. It becomes apparent why xanthine oxidase should cause parallel changes in pterin eye pigments of Drosophila, and their purines. The rosy mutants of Drosophila are deficient in isoxanthopterin (Hadom, 1956 Hadom and Schwinck, 1956) they should be deficient in xanthine oxidase. As pected, the substrates of the missing enzyme accumulate hypoxanthine and 2-NH2-4-hydroxypteridine in maroon (Glassman et d., 1968), which is also devoid of uric acid, and exactly the same accumulation of hypoxanthine and complete absence of uric acid and isoxanthopterin (Morita, 1968). 

In other Drosophila mutants, deficiency of pterin eye pigments appears to result from lack of substrate, not lack of xanthine oxidase. White-apricot larvae which normally contain very small amounts of 2-NHfe-4-hydroxy-pteridine and isoxanthopterin, produced isoxanthopterin when fed the hy-droxypteridine (Forrest et d., 1956). 

Butenandt has similarly shown that the ommochrome eye pigments found in Drosophila species were not formed in some mutants imless kynurenine (24) or 3-hydroxykynurenine (88) was provided in the diet. In addition xanthommatin (84), rhodommatin and ommatin C, ommochromes synthesised by the blowfly Callio-phora erythrocephala, were demonstrated to possess radioactivity after injection of either d L-3-[ C]-tryptophan or D l-5-[ C]-kynurenine . Based on these observations Butenandt proposed that xanthommatin (84) was biosynthesised by an oxidative condensation of two molecules of 3-hydroxykynurenine (88) and a biogenetically patterned synthesis of (84) was achieved by treatment of 3-hydroxykynurenine (88) with potassium ferri-cyanide. The synthesis proceeds probably by oxidation to the... 

Fu, W. and Noll, M (1997) The Pax2 homolog sparkling is required for development of cone and pigment cells in the Drosophila eye . Genes and Development, 11, 2066-78. 

Fig. 22. Metabolism of tryptophan and the formation of brown eye pigment in Drosophila. (After Baillie and Chovnick, 1971)...

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