Suppressive Insertion-Induced Mutations in Drosphila

This chapter provides a review of the basic elements of the origin and behavior of transposons and their relationship to their cellular hosts. It focuses on one specific aspect of the analysis of transposons in Drosophila: the molecular genetic analyses of suppressor/enhancer loci. In this case, the objective is to develop a new, detailed proposal for the role of suppressor/enhancer loci. Transposons carry on a life-style requiring very complex behaviors and decisions. In spite of this, transposons are very small (typically 3 to 10 kb in size), with limited amounts of genetic information. This paradoxical juxtaposition of genetic simplicity and a complex life-style is achieved by extensive parasitism of information produced by the cellular host. Equivalently, transposons carry only a tiny fraction of the genetic information necessary to their existence. This tiny fraction consists of a few functions idiosyncratic to transposition and whatever information is necessary to organize parasitized host functions and information. This latter “organizational” function is incompletely understood but certainly consists of cis-acting regulatory elements responsive to host regulatory information.