The antimorphic mode of action of lethal Abruptex alleles of the Notch locus in Drosophila melanogaster

摘要

The mode of action of lethal Abruptex alleles (Ax59b8.1, Ax59d5, and Ax75c24) of the Notch locus of Drosophila melanogaster was investigated by comparing the phenotypes of flies with different doses of the mutant alleles. The expression of the Abruptex phenotype was found to increase with increasing dose of the mutant gene, and to decrease with increasing dose of the wild type gene. It was thus concluded that the lethal Abruptex mutations are antimorphic. Different models for the explanation of antimorphic gene action are discussed. Special emphasis is laid on the “antagonistic functions” model of the Notch gene based on the assumption that the Notch locus is a regulative locus having both activator and repressor functions.