The Biochemistry of Imaginal Disk Development

Abstract

The extensive developmental studies conducted by Ernst Hadorn, his students and his colleagues, and reviewed in this volume, have made imaginal disks of Drosophila one of the most extensively characterized embryonic tissues known. Through numerous investigations on determination, trans determination and differentiation imaginal disks have emerged as not only convenient tissues for biological studies, but also for molecular studies. Many important requirements for molecular biological investigations on development are met by disks. First, Drosophila melanogaster is by far the best genetically characterized multicellular organism and therefore the important advantages supplied by genetic techniques are available. Furthermore, most of the known mutants of Drosophila affect disks or structures derived from disks. Thus, mutants are available which affect viability of specific cells within disks (Fristrom, 1969a; Spreij, 1971), the viability of all disks (El Shatoury and Waddington, 1957; Stewart et al. , 1972), the developmental fate of disks (Lewis, 1964; Gehring, 1966; Ouweneel, 1969 a, b), growth of disks (Gateff and Schneiderman, 1969; Stewart et al., 1972), and possibly the capacity of disks to differentiate at metamorphosis (Stewart et al., 1972). Additionally the systematic recovery and use of temperature sensitive mutants (Suzuki, 1970) offers an important tool both to the developmental and the molecular biologist. The characteristics of imaginal disk differentiation during the prepupal period (which we call “disk metamorphosis” in this monograph) are also noteworthy.