The serendipity alpha gene encodes a membrane-associated protein required for the cellularization of the Drosophila embryo

Abstract

The Drosophila serendipity alpha (sry α) gene is specifically transcribed at the blastoderm stage, from nuclear cycle 11 to the onset of gastrulation, in all somatic nuclei. This pattern of transcription and a zygotic cellularization defect observed in embryos homozygous for Df(3R)X3F, a deficiency covering the sry locus, suggest that sry α plays a role in the cellularization of the syncytial blastoderm embryo. P-element rescue experiments show that one copy of the sry α gene rescues the defective cellularization phenotype associated with Df(3R)X3F. Lack of sry α activity results in erratic disruptions of the cytoskeleton at the beginning of the interphase of mitotic cycle 14. Multinucleate cells form during plasma membrane invagination. Immunodetection of the sry α protein using anti-sry α polyclonal antibodies indicates that the 58-kD sry α protein accumulates transiently at the blastoderm stage. The sry α protein is associated with the invaginating plasma membrane and colocalizes with F-actin. We propose that sry α is involved in the localization of membrane furrows within the syncytial blastoderm.