Temperature-sensitive mutations in Drosophila melanogaster: XIII. Temperature-sensitive periods of the lethal and morphological phenotypes of selected combinations of notch-locus mutations

Abstract

Temperature-shift experiments were performed on five Notch-locus genotypes with temperature-sensitive phenotypes. The results show that temperature-sensitive periods (TSPs) for lethality may occur at any developmental stage: (1) N g11 N g11 ; Dp 51 b7 having a short embryonic TSP for lethality, (2) Ax 16172 N −40 having a second-instar TSP for lethality, and (3) N −103 fa no with a long, possibly polyphasic, TSP, beginning in the embryonic stage and ending in the pupal stage. On the other hand, TSPs for adult morphological phenotypes appear to be restricted to the third larval instar: (1) Ax 16172 N −40 having third-instar TSPs for wing vein gapping and ocellar bristle loss, and (2) N −103 spl having third-instar TSPs for eye facet disarray, wing notching, bristle number variation, and fusion of tarsal segments. The significance of these results is discussed in terms of the role of the Notch locus in development.