© 1977 by The Society for Integrative and Comparative Biology
Polygenic Control of Drosophila Morphogenesis During the Stages of Determination and Specification of Adult Structures
Department of Biology, Temple University Philadelphia, Pennsylvania 19122
There are three processes in the development of Drosophila which may be studied independendy but which are a manifestation of interdependent events which result in the formation of the adult phenotype. These processes are determination, specification and differentiation. The mutant phenotype Abnormal-abdomen is characterized by a loss of abdominal tergites and is controlled by a major mutant gene,A53g and a polygenic modifier system. The development of the abnormal phenotype is influenced by events in early embryogenesis and in mid-larval stages. These developmentally sensitive stages are correlated with the periods of determination and specification of the cells which constitute the larval histoblast nests and which differentiate into the adult abdominal hypoderm. Evidence for gene control at these two development stages are 1) a maternal effect of the genome correlated with changes in the efficiency of enzymes catalyzing tRNA aminoacylating reactions, 2) observations which relate histological defects of embryos at the blastoderm stage to the action of the mutant genotype, and 3) a temperature sensitive period for the expression of the abnormal phenotype which has defined limits in the late second and early third larval instars. Developmental events which take place during oogenesis, early embryogenesis, and mid-larval stages are discussed with regard to their relationship to each other and to the final differentiation of the adult phenotype.