The pteridines are associated with (GTP) and is responsible for the bright red in color of the eyes. The ommochromes associated with tryptophan is responsible for the brown pigment (Rong et al. 1998). The eye pigmentation in Drosophila is influenced by various genes, including the vermilion (v) gene that was discovered by the early experiments of Beadle, Ephrussi, Tatum and Green with their efforts to interpret the biochemical effects of genes (Shapard 1958). Their experiments involved distinguishing series of vermilion mutants with their interaction between a nonallelic X chromosome mutant (su-v). By isolating the suppressor mutants, it determines the phenotype is vermilion by distinguishing v into suppressed or unsuppressed (Shapard …show more content…
1998). Between pugD and vermilion the mutation blocks the reduction of the two pigment regulators in Drosophila, ommochrome and pteridines synthesis resulting in a red ring around the eye. The causes of pugD, relies on a gene that encodes the trifunctional enzyme methylenetetrahydrofolate dehydrogenase which is accountable for pigment defect. The mutation results in repetitive DNA segment that involves ~140 iterations of the sequence AGAGAGA. Transcription and translocation are required in which these repeats are partially responsible for the phenotype (Rong et al. 1998). Another chromosomal effect vermilion has that disturbs its phenotype