Eye Pigments in Wild-Type and Eye-Color Mutant Strains of the African Malaria Vector Anopheles gambiae

Abstract

Chromatographic analysis of pigments extracted from wild-type eyes of the mosquito Anopheles gambiae reveals the presence of the ommatin precursor 3-hydroxykynurenine, its transamination derivative xanthurenic acid, and a dark, red-brown pigment spot that probably is composed of two or more low mobility xanthommatins. No colored or fluorescent pteridines are evident. Mosquitoes homozygous for an autosomal recessive mutation at the red-eye (r) locus have a brick-red eye color in larvae, pupae, and young adults, in contrast to the almost black color of the wild eye. Mosquitoes homozygous for this mutant allele have levels of ommochrome precursors that are indistinguishable from the wild-type, but the low-mobility xanthommatin spot is ochre-brown in color rather than red-brown as in the wild-type. Mosquitoes with two different mutant alleles at the X-linked pink-eye locus (p, which confers a pink eye color, and pw, which confers a white eye phenotype in homozygotes or hemizygous males) have normal levels of ommochrome precursors but no detectable xanthommatins. Mosquitoes homozygous for both the r and p mutant alleles have apricot-colored eyes and show no detectable xanthommatins. Both the pink-eye and red-eye mutations appear to involve defects in the transport into or assembly of pigments in the membrane-bound pigment granules rather then defects in ommochrome synthesis.

The ABCs of Eye Color inTribolium castaneum: Orthologs of theDrosophila white,scarlet, andbrownGenes

“…Among insects, ommochromes function as an important source of visible eye pigments (Linzen 1974). Species as diverse as mosquitoes, moths, bugs, and bees use only ommochromes for eye coloration (Dustmann 1968;Beard et al 1995;Quan et al 2002;Moraes et al 2005;Sethuraman and O'Brochta 2005), while in other species, like the grasshopper, Schistocerca gregaria (Dong and Friedrich 2005), or the fruit fly, Drosophila melanogaster (Summers et al 1982), ommochromes, together with the guanine-derived pteridines, create wild-type eye color.…”

Stable transformation of the yellow fever mosquito, Aedes aegypti , with the Hermes element from the housefly

“…Ommochrome pigments produce the deep purple color of the adult mosquito eye. Ommochromes are synthesized in a well-characterized series of enzymatically catalyzed steps from the precursor amino acid, tryptophan (10). Null mutations in two of the enzymes in this pathway, tryptophan oxygenase and kynurenine hydroxylase, result in eye color mutant phenotypes in the adults of many insects (10,11).…”

The tryptophan oxidation pathway in mosquitoes with emphasis on xanthurenic acid biosynthesis

“…Interestingly, 3-HK also is the initial precursor for the production of ommochromes that are major eye pigments in mosquitoes. Compound eye development and eye pigmentation occur mainly during the pupal and early adult stages (Beard et al, 1995;Li et al, 1999;Rasgon and Scott, 2004;Sethuraman and O'Brochta, 2005). Consequently, the 3-HK to XA pathway must be partially down-regulated in pupae and adults to allow for the accumulation of some 3-HK that then can be transported to the compound eyes for pigmentation (Li and Li, 1997;Li et al, 1999).…”