DEVELOPMENTAL BIOLOGY 85, 39-54 (1981) Mutations Causing Pattern Deficiencies and Duplications in the lmaginal Wing Disk of Drosophila melanogasfer ANTHONY A. JAMES’ AND PETER J. BRYANT Developmental Biology Center and Department of Developmental and Cell Biology, University of California, Irvine, California 92717 Received December 15, 1979; accepted in revised form January 2, 1981 Pattern deficiencies and duplications are produced in derivatives of the imaginal wing disk by the mutations sdUC’, vg, tet, and wg’ in Drosophila melanogaster. In sdocr and vg the majority of adults show a simple wing emargination pheno- type, but some of them show almost complete wing deficiency accompanied by duplication of the remaining thoracic struc- tures. In tet and wg’ the latter class of phenotype is seen in some of the animals, but the remainder are normal and the simple deficiency phenotype is not observed. Serial sections of sduC’and vg disks revealed extensive cell death throughout the third larval instar in locations corresponding to presumptive wing blade. A small amount of scattered cell death was also found in early third instar wild-type disks, and it is suggested that the mutations sdL’C’ and vg affect wing shape by exaggerating the extent of normal cell death. The types of duplications seen in sdac’ and vg mutant adults are consistent with the known regulative behavior of cultured fragments of imaginal wing disks, and we therefore propose that the dupli- cations are a secondary response to degeneration of a large part of the disk. Little cell death was seen in tet and wg’ during the third larval instar, so these mutations may cause pattern duplication by a different mechanism. INTRODUCTION Pattern duplications can be induced in Drosophila in a number of different ways. Irradiation of larvae with X or gamma rays (Wadding-ton, 1942; Villee, 1942; Postle- thwait and Schneiderman, 1973; Postlethwait, 1975; Wieschaus and Gehring, 1976) at certain embryonic or early larval stages can produce duplications in the adult derivatives of the imaginal disks and histoblasts. Bisec- tion of wing or leg disks in situ sometimes results in du- plications (Bryant, 1971) and fragments of imaginal disks cultured in adult hosts and subsequently reimplanted into larvae often show pattern duplications after meta- morphosis (for review, see Bryant, 1978). Furthermore, many mutations are known to cause duplications (see Bryant, 1978) and in some casesit appears that the dupli- cations arise as secondary effects of mutant genes whose initial action is to cause cell death in the developing imaginal disks. The mutations eyeless (Sang and Burnet, 1963) and vestigial (Waddington, 1953) cause antenna1 and thoracic duplications, respectively, and both were shown by Fristrom (1968, 1969) to cause cell death in the respective imaginal disks. Temperature-sensitive cell-le- thal mutations also produce duplications after pulses of the restrictive temperature, probably as a result of local- ized patches of cell death in the affected disks (Russell, 1 Current address: Division of Cancer Genetics, Sidney Farber Can- cer Institute, Charles A. Dana Cancer Center, 44 Binney Street, Bos- ton, Mass. 02115. 1974; Arking, 1975; Simpson and Schneiderman, 1975; Clark and Russell, 1977). Because of the association of duplications with cell death in some mutant strains, we investigated four mu- tations, scallopeducl, vestigial, tetraltera, and wingless’, all of which cause duplications of the thorax, to deter- mine whether cell death plays a role in the production of their phenotypes. We also studied the range of struc- tures duplicated and the exact localization of dying cells in the developing wing disks of these mutants and of the wild type. MATERIALS AND METHODS Wild-type flies of either the Oregon-R or Oregon-RC strain were used as controls. The mutation scallopeduci is a new allele of the scalloped locus (Vyse and James, 1972) and was marked with yellow and white and kept balanced over the Muller-5 chromosome. Two strains of vestigial, vg, and vg bw were used. The tetraltera stock was kept as ass; tet because ass is necessary for tet ex- pression (Lindsley and Grell, 1968). The wingless’ stock (Sharma and Chopra, 1976) was kindly provided by Dr. R. P. Sharma. See Lindsley and Grell(1968) for further details and descriptions. All stocks were maintained on a yeasted corn meal, corn syrup, and agar medium at 25°C using standard Drosophila techniques. Preparations of adult structures were made by dehy- drating whole or parts of flies in ethanol and mounting the specimens in Euparal between coverslips. The prepa- 39 0012-1606/81/090039-16$02.00/O Copyright 0 1981 by Academic Press, Inc. All rights of reproduction in any form reserved.