No abstract

In Drosophila, posterior deposition of oskar (osk) mRNA in oocytes is critical for both pole cell and abdomen formation. Exon junction complex components, translational regulation factors, and other proteins form an RNP complex that is essential for directing osk mRNA to the posterior of the oocyte. Until now, it has not been clear whether the mRNA degradation machinery is involved in regulating osk mRNA deposition. Here we show that Drosophila decapping protein 1, dDcp1, is a posterior group gene required for the transport of osk mRNA. In oocytes, dDcp1 is localized posteriorly in an osk mRNA position- and dosage-dependent manner. In nurse cells, dDcp1 colocalizes with dDcp2 and Me31B in discrete foci that may be related to processing bodies (P bodies), which are sites of active mRNA degradation. Thus, as well as being a general factor required for mRNA decay, dDcp1 is an essential component of the osk mRNP localization complex.

The establishment of dorsal-ventral asymmetry of the Drosophila embryo requires a group of genes that act maternally. None of the previously identified dorsal-ventral axis genes are known to produce asymmetrically localized gene products during oogenesis. We show that rhomboid (rho), a novel member of this group, encodes a protein that is localized on the apical surface of the dorsal-anterior follicle cells surrounding the oocyte. Loss of rho function causes ventralization of the eggshell and the embryo, whereas ectopic expression leads to dorsalization of both structures. Thus, spatially restricted rho is necessary and sufficient for dorsal-ventral axis formation. We propose, based on these observations and double mutant experiments, that the spatially restricted rho protein leads to selective activation of the epidermal growth factor receptor in the dorsal follicle cells and subsequently the specification of the dorsal follicle cells.

The production of female germline chimeras is invaluable for analyzing the tissue specificity of recessive female sterile mutations as well as detecting the maternal effect of recessive zygotic lethal mutations. Previously, we developed the “FLP-DFS” technique to efficiently generate germline clones. This technique uses the X-linked germline-dependent dominant female sterile mutation ovo  D1 as a selection for the detection of germline recombination events, and the FLP-FRT recombination system to promote site-specific chromosomal exchange. This method allows the efficient production of germline mosaics only on the X chromosome. In this paper we have built chromosomes that allow the use of this technique to the autosomes. We describe the various steps involved in the development of this technique as well as the properties of the chromosomes utilized.