In Drosophila, the dorsal-ventral polarity of the egg chamber depends on the localization of the oocyte nucleus and the gurken RNA to the dorsal-anterior corner of the oocyte. Gurken protein presumably acts as a ligand for the Drosophila EGF receptor (torpedo/DER) expressed in the somatic follicle cells surrounding the oocyte. cornichon is a gene required in the germline for dorsal-ventral sign...

Specification of the anteroposterior (AP) axis in Drosophila oocytes requires proper organization of the microtubule and actin cytoskeleton. The establishment and regulation of cytoskeletal polarity remain poorly understood, however. Here, we show important roles for the tumor suppressor Lethal (2) giant larvae (Lgl) and atypical protein kinase C (aPKC) in regulating microtubule polarity and se...

Much is known about determinative events in early amphibian embryos, perhaps more than any other animal group. However, as yet, little attention has been focused on the cytoarchitecture of the oocyte, and the way in which this could regulate asymmetries in the egg, which in turn could lead to developmentally important interactions. The changing cytoarchitecture of the Xenopus oocyte is describe...

Pattern formation in early insect development is dominated by coordination of the germ lines polarity with the polarity of the follicle cell layer. The production of an elaborate protective chorion, covering the ovulated oocyte, has made establishing parallel polarity of germ line and soma absolutely essential. Genetics and molecular biology, particularly on Drosophila melanogaster, have identi...

Establishment of anterior-posterior polarity in one-cell stage Caenorhabditis elegans embryos depends in part on astral microtubules. As the zygote enters mitosis, these microtubules promote the establishment of a posterior pole by binding to and protecting a cytoplasmic pool of the posterior polarity protein PAR-2 from phosphorylation by the cortically localized anterior polarity protein PKC-3...

Owing to its large size, rich ultrastructure and amenability to genetic analysis, the Drosophila oocyte has been extensively studied as a model system for understanding mechanisms that generate and maintain cell polarity. The polarity of the oocyte has been best described in terms of the asymmetric distribution of mRNAs and proteins that play key instructive roles in patterning the future embry...

The Drosophila gene nudel may encode a spatially restricted serine protease involved in producing the ligand for the receptor Toll and linking dorsal-ventral polarity in the egg chamber to the developing embryonic axis. One of the important insights to have emerged from the study of early pattern formation in the Drosophila embryo is that the basic embryonic axes have their origins in the polar...

Specification of the anterior-posterior axis in Drosophila oocytes requires proper communication between the germ-line cells and the somatically derived follicular epithelial cells. Multiple signaling pathways, including Notch, contribute to oocyte polarity formation by controlling the temporal and spatial pattern of follicle cell differentiation and proliferation. Here we show that the newly i...

Recent work on Drosophila oogenesis has uncovered connections between cell-cycle checkpoints and pattern formation. Genes of the spindle class, which encode double-strand break repair enzymes and RNA helicases, affect oocyte polarity and the decision whether to differentiate as an oocyte or a nurse cell.