We use laser hole drilling to assess the mechanics of an embryonic epithelium during development-in vivo and with subcellular resolution. We ablate a subcellular cylindrical hole clean through the epithelium and track the subsequent recoil of adjacent cells (on ms time scales). We investigate dorsal closure in the fruit fly with emphasis on apical constriction of amnioserosa cells. The mechanic...

Dorsal closure (DC) in the Drosophila embryo requires the coordinated interaction of two different functional domains of the epidermal cell layer-the leading edge (LE) and the lateral epidermis. In response to activation of a conserved c-Jun amino-terminal kinase (JNK) signaling module, the dorsal-most layer of cells, which constitute the LE of the stretching epithelial sheet, secrete Dpp, a me...

Morphogenesis is a complex set of processes in which a number of cellular functions such as signal transduction, cell movements, rearrangements and shape changes, are involved. It is desirable to employ model systems for the investigation of such complex processes. Dorsal closure is a morphogenetic event that takes place during the late stages of embryogenesis in Drosophila melanogaster. Halfwa...

We report the isolation and characterization of a putative angiotensin converting enzyme (ACE) in Drosophila, called Race. General interest in mammalian ACE stems from its association with high blood pressure; ACE has also been implicated in a variety of other physiological processes including the processing of neuropeptides and gut peristalsis. Mammalian ACE is a membrane associated zinc bindi...

During Drosophila embryogenesis the process of dorsal closure (DC) results in continuity of the embryonic epidermis, and DC is well recognized as a model system for the analysis of epithelial morphogenesis as well as wound healing. During DC the flanking lateral epidermal sheets stretch, align, and fuse along the dorsal midline, thereby sealing a hole in the epidermis occupied by an extra-embry...

Throughout development, tissues exhibit dynamic cell deformation, which is characterized by the integration of cell boundary contraction and/or elongation. Such changes ultimately establish tissue morphology and function [1-5]. In comparison to cell boundary contraction, which is predominantly driven by non-muscle myosin II (MyoII)-dependent contraction [6-9], the mechanisms of cell boundary el...

Most insect embryos develop from a monolayer of cells around the yolk, but only part of this blastoderm forms the embryonic rudiment. Another part forms extra-embryonic serosa. Size and position of the serosa anlage vary between species, and previous work raises the issue of whether such differences co-evolve with the mechanisms that establish anteroposterior (AP) polarity of the embryo. AP pol...

Genetic evidence suggests that the Drosophila ectoderm is patterned by a spatial gradient of bone morphogenetic protein (BMP). Here we compare patterns of two related cellular responses, both signal-dependent phosphorylation of the BMP-regulated R-SMAD, MAD, and signal-dependent changes in levels and sub-cellular distribution of the co-SMAD Medea. Our data demonstrate that nuclear accumulation ...

Innate behaviors have their origins in the specification of neural fates during development. Within Drosophila, BTB (Bric-a-brac,Tramtrack, Broad) domain proteins such as Fruitless are known to play key roles in the neural differentiation underlying such responses. We previously identified a gene, which we have termed jim lovell (lov), encoding a BTB protein with a role in gravity responses. To...

Single and collective cellular oscillations involving the actomyosin cytoskeleton have been observed in numerous biological systems. We show here that a generic model of a contractile material, which is turning over and contracts against an elastic element, exhibits spontaneous oscillations. Such a model can thus account for shape oscillations observed in amnioserosa cells during dorsal closure...