ANALYSIS OF THE GOOSEBERRY LOCUS IN DROSOPHILA EMBRYOS - GOOSEBERRY DETERMINES THE CUTICULAR PATTERN AND ACTIVATES GOOSEBERRY-NEURO

The segment-polarity class of segmentation genes in Drosophila are pri marily involved in the specification of sub-segmental units. In additi on, some of the segment-polarity genes have been shown to specify cell fates within the central nervous system. One of these loci, gooseberr y, consists of two divergently transcribed genes, gooseberry and goose berry neuro, which share a paired box as well as a paired-type homeobo x. Here, the expression patterns of the two gooseberry gene products a re described in detail. The gooseberry protein appears in a characteri stic segment-polarity pattern of stripes at gastrulation and persists until head involution. It is initially restricted to the ectodermal an d neuroectodermal germ layer, but is later detected in mesodermal and neuronal cells as well. The gooseberry neuro protein first appears dur ing germ band extension in cells of the central nervous system and als o, much later, in epidermal stripes and in a small Dumber of muscle ce lls. P-element-mediated transformation with the gooseberry gene has be en used to demonstrate that gooseberry transactivates gooseberry neuro and is sufficient to rescue the gooseberry cuticular phenotype in the absence of gooseberry neuro.