PERVASIVE EFFECTS OF P-ELEMENT MUTAGENESIS ON BODY-SIZE IN DROSOPHILA-MELANOGASTER

A set of Drosophila melanogaster was generated, all derived from a com mon isogenic base stock and each with a single new P element insert on the second or third chromosome. The lines were scored for their body size, measured as thorax length. P inserts were associated with highly significant effects on body size, although the genotypes of the const ruct and of the control prevented deduction of the direction of mutant effects. In addition to mutant effects on the thorax length of both s exes, there were also highly significant sex-specific effects. Pleiotr opic effects of inserts affecting body size on viability and bristle n umber, as ascertained in a separate study of these lines (Lyman ct al. , 1996), were weak. Insertional mutagenesis is potentially a powerful tool for investigating the genes involved in size-control in Drosophil a, but the technique requires fine tuning for use on polygenic and fit ness-related traits.