Comparative studies of phenol oxidase activity during pupal development of three lozenge mutants (lz8,lz,lzk) of Drosophila melanogaster.

main thrust of investigations on phenol oxidases in Drosophila has T g u s e d on pigment production and thus on color mutants since the very early experiments of GRAUBARD (1933). However, the function of the phenol oxidases may prove to be equally, or more important in cuticle formation (see KARLSON and SEKERIS 1964, for proposed pathway in Diptera). The role played by phenol oxidases in the development of fixed macromolecular structures such as cuticle may possibly be clarified in mutants which have apparently normal body pigmentation, but show decreased production of melanin precursors together with structural abnormalities of the cuticle. The lozenge pseudoalleles, first compared by GOTTSCHEWSKI (1 936), have apparently normal body color. Depending on the gene effect of the particular mutant, the more than 20 known lozenge alleles have normal claws, claws with loss of color, reduced claws o r complete absence of claws (CUMMINGS 1946; CHOVNICK, LEFKOWITZ and Fox 1956). Most of the homozygous lozenge females are infertile due to failure to complete development; presumably due to cessation of differentiation in early pupae, of the accessory sex organs, spermathecae and pars ovariae ( A”msoN 1945), associated with pathologies of the ovarian tissue (BENDER and GREEN 1962). An abnormality in development of the eye detected in the early pupal period causes partial loss or absence of the basement membrane of the eye resulting in disarrangement of the ommatidia with accompanying fusion of the facets and a corresponding decrease in the size of the eye (CLAYTON 1954). Brown pigment in the eye of the lozenge-alleles may be reduced to 25% of normal; the red pigment may be reduced to less than 1% of normal (OLIVER 1947; GREEN 1948). The most affected mutants are female sterile, have vestigial claws and sharply reduced eyes which lack facets and have a yellowish color and a dark rim; they may map to either the lst, 3rd or 4th sublocus at 27.7 on the X-chromosome. The most normal appearing mutants map to the 1st or 2nd sublocus and in compounds with the other lozenge alleles are complementary in that the heterozygote female is phenotypically similar to wild type (GREEN and GREEN 1956; GREEN 1961). Drosophila phenol oxidases have long been known to require activation in