su(f)¹²/su(f)¹⁹ females shifted to the restrictive temperature as embryos die as first instar larvae. The number of metaphase mitotic figures in the brains of su(f)¹²/su(f)¹⁹ third instar larvae shifted to 29^oC for 4 to 14 hours is double that of wild type.

Homozygotes are phenotypically wild type at 18^oC.

Homozygotes die at 29^oC, show moderate enhancement of the w^a phenotype at 25^oC, and stronger enhancement at 21^oC. Homozygotes show strong suppression of f¹ penetrance at 25^oC and weak suppression at 21^oC. Enhances the lz³⁷ phenotype and suppresses the lz¹ phenotype.

Homozygous larvae maintained at 29^oC develop into adults with a range of abnormalities, including large eye or head deficiencies, extra structures in the gena, fusion of the first pair of legs, distal duplication of the legs, and large deficiencies of the scutum. The overall frequency of abnormalities is reduced if larvae are treated with 32^oC pulses, and negligible after 35^oC pulses.

temperature-sensitive lethal cell autonomous Selected as a cell-autonomous, temperature-sensitive lethal. Relative survival is 85% at 22^oC, 75% at 25^oC and 1% at 29^oC; temperature-sensitive period from first larval instar to early pupa. Homozygous females become sterile after two days at 29^oC, whereas males so treated remain fertile. 23% of eggs laid at 29^oC fail to hatch; surviving larvae grow at subnormal rate and survive for up to twelve days, reaching the third instar; imaginal discs reduced greatly in size. 48-h pulses of 30^oC during late second and third instars results in considerable cell death in imaginal discs with a consequent deletion of some pattern elements and duplications of others in the head and legs; head duplications occur only in association with deficiencies; leg duplications seen as simply and complexly branched appendages involving variable numbers of joints. Pulses applied to early pupae lead to failure of histoblast differentiation and applied later to the lack of chaetae (Russell, Girton and Morgan, 1977). Extensive use made of leg duplications induced in su(f)¹² in investigations of pattern formation (Tiong, Girton, Hayes and Russell, 1977; Postlethwait, 1978; Girton and Russell, 1980; Girton, 1981; Girton and Russell, 1981). Enhances RpS17, as indicated by reduced viability of su(f)¹² versus su(f)⁺ sibs that are RpS17/+ (Girton, Langner and Cejka, 1986). temperature-sensitive lethal

su(f)¹² is an enhancer of phenotype of lz³⁷

su(f)¹² is an enhancer of phenotype of w^a