Vermilion mutant

DNA base sequence changes were analysed in 31 transmissible vermilion mutants recovered from Drosophila melanogaster, the male germ cells of which had been treated with diethyl sulfate. There were 93% base-pair substitutions and 7% deletions. The most frequent base-pair changes were GC—>AT transitions (73%) and AT—>TA transversions (10%) (Sierra et al., 1993). 

This very elegant hypothesis requires further proof. Mischke et al. (1975) could not induce tryptophane pyrrolase activity in fresh homogenates of the vermilion mutant of D, melanogaster and D. hydei, although the treatment was done in exactly the same manner as by Jacobson (1971). At the same time, enzyme activity could be induced almost to the wild-type level by homogenation of vermilion flies in the presence of 0.02M EDTA, the standard component in mixtures of ribonu-clease. The authors suggested that the tryptophane pyrrolase activity, stimulated by EDTA, is possibly derived from another enzyme (peroxidase, for instance), but not from the tryptophane pyrrolase molecule. 

In Drosophila the existence of a suppressor locus, su(s)-1.00 (Lindsley and Grell, 1967), is known. Mutants at this locus acted as recessive suppressors of the vermilion mutation and partially reinstated the normal phenotype. 

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