Fig. 1. The nature and properties of original mutations in AS-C. (A) Schematic presentation of the yellow/ac/sc region. Small arrowheads show insertions of the P elements associated with certain mutations. Thick horizontal arrows show the direction of transcription of the yellow, ac and sc genes. The arrows in boxes indicate the orientation of the P elements. The structure of the sc^ls1, sc^ls2 and sc^ls3 alleles was described previously (Golovnin et al., 1999). (B) Phenotypes of the indicated sc bristle mutations in males. The standard nomenclature for each bristle is indicated as follows (Lindsley and Zimm, 1992): HU, humeral; AOR, anterior orbital; PS, presutural; ASA, anterior supra-alar; OC, ocellar; PV, postvertical; ANP, anterior notopleural; SC, scutellar. Only the bristles affected in sc mutations are shown. Empty boxes indicate that the corresponding bristles are present (wild-type phenotype). In all but the scutellar, one quarter black, half black and fully black boxes mean that the corresponding bristle(s) was (were) absent in over 10%, 50% or 90% of the flies, respectively. For scutellars, quarter black, half black and fully black boxes mean that 3-4, 2-3 or 0-1 scutellar bristles, respectively, were present. Number of bristles is the mean of about 100 scored flies. The phenotypes of sc^ls1, sc^ls2 and sc^ls3 flies were taken from Golovnin et al. (Golovnin et al., 1999). The su(Hw)^v/su(Hw)^f and su(Hw)^v/su(Hw)² transheterozygous lines had similar effect on the sc^ms1 and sc^ms2 mutations.