Drosophila spoonbill encodes a dual-specificity A-kinase anchor protein essential for oogenesis.

spoonbill is a Drosophila female-sterile mutation, which interferes with normal egg patterning during oogenesis. Previous analyzes linked the mutation to a number of seemingly unrelated pathways, including GRK/EGFR and DPP, two major pathways essential for Drosophila and vertebrate development. Further work suggested that spoonbill may also function in actin polymerization and border-cell migration.

Drosophila Dynein light chain (DDLC1) binds to gurken mRNA and is required for its localization.

During oogenesis in Drosophila, mRNAs encoding determinants required for the polarization of egg and embryo become localized in the oocyte in a spatially restricted manner. The TGF-alpha like signaling molecule Gurken has a central role in the polarization of both body axes and the corresponding mRNA displays a unique localization pattern, accumulating initially at the posterior and later at the anterior-dorsal of the oocyte. Correct localization of gurken RNA requires a number of cis-acting sequence elements, a complex of trans-acting proteins, of which only several have been identified, and the motor proteins Dynein and Kinesin, traveling along polarized microtubules.

Drosophila female sterile mutation spoonbill interferes with multiple pathways in oogenesis.

spoonbill is a Drosophila female-sterile mutation, which displays a range of eggshell and egg chamber patterning defects. Previous analysis has shown that the mutation interfered with the function of two major signaling pathways, GRK/EGFR and DPP. In this report, the nature of spoonbill was further investigated to examine whether it was associated with additional pathways in oogenesis.

spoonbill, a new Drosophila female-sterile mutation, interferes with chromosome organization and dorsal-ventral patterning of the egg.

We have identified a new mutation, spoonbill (spoon), which interferes with two developmental processes during Drosophila oogenesis, nurse cell-nuclei chromatin organization and anterior-dorsal patterning of the eggshell. Here, we describe the localization patterns of key regulators of axis determination and the expression of follicle cell-specific markers involved in eggshell patterning in egg chambers from spoonbill females. Our molecular characterization of the patterning defects associated with the mutation reveals abnormalities in two major signaling pathways, the grk/Egfr and the Dpp/TGF-beta, that together control the elaborate patterning of the anterior follicular epithelium.

Gurken, a TGF-alpha-like protein involved in axis determination in Drosophila, directly binds to the EGF-receptor homolog Egfr.

The establishment of axial polarity in the Drosophila egg and embryo depends on intercellular communication between two cell types in the ovary, the germline, and the soma. The genes gurken and egfr encode two essential players of this communication pathway. Gurken protein, a TGF-alpha-like molecule, is expressed in the germline, while the EGF-receptor homolog, Egfr, is expressed in the somatic cells of the ovary.