On the Molecular Basis of Transvection Effects and the Regulation of Transcription

Abstract

Since the original cloning of sequences from the white locus of Drosophila (Bingham et al. 1981), white has been subjected to extensive molecular analysis (Bingham et al. 1982; Rubin et al. 1982; Zachar and Bingham 1982; O'Hare et al. 1983; Levis et al. 1984; Pirrotta and Brockl 1984; Bingham and Zachar 1985; Davison et al. 1985). We describe here selected portions of our study at the white locus of a class of phenomena referred to as transvection effects. Our results suggest that a single, tissue-specific enhancer is ultimately responsible for all the superficially distinct transvection effects at white. On the basis of our analysis, we propose a new, general model for the molecular basis of transvection effects. We discuss the relevance of this proposal to the detailed mechanistic basis of enhancer function and transvection. We further discuss selected technical and evolutionary implications of our model.