...), is determined by the opposing slopes of a Dachsous/Fat gradient. We show, by altering the concentration gradients of Dachsous during development, that we can change the polarity of the denticles made by larval cells as they progress between the first and third larval instars without mitosis. ‡ Author...

... on the Drosophila eye, we proposed that a crucial step in this process is the establishment of graded expression of the cadherin Dachsous (Ds) and the Golgi-associated protein Four-jointed (Fj). These gradients were proposed to specify the direction of polarization by producing an activity gradient of the cadherin...

...)axis of the optic tectum. EphB receptors are expressed in a low to high DV gradient by retinal ganglion cells (RGCs), and ephrin-B1 is expressed in a low to high LM gradient in the tectum. RGC axons lack DV ordering along the LM tectal axis, but directionally extend interstitial branches that establish...

...., 1996 )previously suggested that epiboly contributes to extension in volcano mutants, and epiboly is underlain by an AP velocity gradient (R. J. A., D. Faruque and M. L. Concha, unpublished). We emphasize that our proposals for epiboly driving extension in the ntl mutant does not in any way argue...

... by Company of Biologists 1999 Frizzled Notch Drosophila Eye Polarity Gradients Gradients play many important roles in biology. Gradients of morphogens can specify distinct scalar outputs, such as the activation of different subsets of genes and the differentiation of distinct cell...

... as the terminal structures, are specified by two inputs: a gradient of Ras activity which emanates from the pole, and the opposing influence of more centrally deployed gap genes which repress the response to Ras. * Author for correspondence (e-mail [email protected] ) 18 09 1997 ©...

...James A. Langeland; Sherwin F. Attai; Kathy Vorwerk; Sean B. Carroll ABSTRACT We present a genetic and molecular analysis of two hairy ( h ) pair-rule stripes in order to determine how gradients of gap proteins position adjacent stripes of gene expression in the posterior of Drosophila embryos. We...

..., or it might form a concentration gradient which acts as a morphogen. We tested these hypotheses by expressing wingless ubiquitously in wingless embryos. The distribution of wingless protein in these embryos is uniform. Despite this, engrailed expression persists, is confined to the most anterior third...

...Eddy M. De Robertis; Elaine A. Morita; Ken W. Y. Cho ABSTRACT We review here old experiments that defined the existence of morphogenetic gradient fields in vertebrate embryos. The rather abstract idea of cell fields of organforming potential has become less popular among modern developmental...

...Rachel Kraut; Michael Levine The gap genes play a key role in establishing pair-rule and homeotic stripes of gene expression in the Dros-ophila embryo. There is mounting evidence that overlapping gradients of gap gene expression are crucial for this process. Here we present evidence...

... , L , O’farrell , P. & Simon , M. ( 1985 ). The engrailed locus of Drosophila: in situ localization of transcripts reveals compartment specific expression . Cell 40 , 45 – 63 . Lawrence , P. A. ( 1966 ). Gradients in the insect segment: the orientation of hairs...

... basal lamina gradients axon guidance pioneer neurones neurone substratum grasshopper embryo The embryonic grasshopper limb provides a relatively simple preparation for studying the complex problem of how neurones interact with surrounding tissues to navigate with precision to their targets...

... preconditions on this act, namely (1) sharp anterior and posterior boundaries that delimit the pattern-forming region, and (2) an axial asymmetrizing influence in the form of an anteroposterior gradient. Models for Drosophila segmentation generally rely on the gradient to provide positional information...

.... Copyright © 1985 by Company of Biologists 1985 actin a-cardiac actin a-skeletal actin cytoskeletal cytoplasmic determinant gradients induction Xenopus The experimental work summarized here is addressed to two questions concerning the developmental regulation of genes. What...

... and a little muscle). We conclude that mesoderm formation in combinations is an instructive event and propose a double gradient model to explain the complex character of the response. * Present address: Laboratory of Embryogenesis, National Institute for Medical Research, The Ridgeway, Mill Hill...