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Development, Vol 117, Issue 4 1385-1396, Copyright © 1993 by Company of Biologists
JOURNAL ARTICLES |
S Roth
Department of Molecular Biology, Princeton University, NJ 08544.
The establishment of the dorsal-ventral pattern in Drosophila embryos depends on a signal transduction process: a putative extracellular ligand released into the perivitelline space surrounding the embryo binds to the Toll receptor. Toll activation triggers the formation of the nuclear gradient of dorsal protein, the morphogen of the dorsal-ventral axis. Here, I analyse the dorsal protein distribution and the expression of zygotic dorsal-ventral genes in Toll- embryos that have been injected with wild-type cytoplasm under a variety of different injection conditions. Injections into two positions within a single embryo lead to the formation of two dorsal-ventral patterns in one embryo, allowing the analysis of interactions between pattern-forming processes. The results of single and double injections suggest that the spatial information for the embryonic dorsal-ventral axis is largely derived from spatial cues present in the extraembryonic compartment, which restrict the release of the putative Toll ligand. They argue against a Toll-dependent pattern-formation process employing local self-enhancement and lateral inhibition to enhance a weak initial asymmetry. The putative Toll ligand appears to originate from a ventrally restricted zone which extends along the entire anterior-posterior axis. Ligand diffusion or its graded release are required to determine the slope of the nuclear dorsal protein gradient. Both the Toll receptor and the putative ligand of Toll are in excess in wild-type embryos. Since spatial information for the embryonic dorsal-ventral axis is already present in the vitelline membrane or the perivitelline space, it is most likely generated during oogenesis. Oogenic pattern formation is also responsible for the perpendicular orientation the dorsal-ventral axis maintains with respect to the anterior-posterior axis.
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  S Roth, P Jordan, and R Karess Binuclear Drosophila oocytes: consequences and implications for dorsal-ventral patterning in oogenesis and embryogenesis Development, January 2, 1999; 126(5): 927 - 934. [Abstract] [PDF]
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 A. M. Huang, J. Rusch, and M. Levine An anteroposterior Dorsal gradient in the Drosophila embryo Genes & Dev., August 1, 1997; 11(15): 1963 - 1973. [Abstract] [Full Text] [PDF]
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R P Ray and T Schupbach Intercellular signaling and the polarization of body axes during Drosophila oogenesis. Genes & Dev., July 15, 1996; 10(14): 1711 - 1723. [PDF]
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C. Smith, H Giordano, M Schwartz, and R DeLotto Spatial regulation of Drosophila snake protease activity in the generation of dorsal-ventral polarity Development, January 12, 1995; 121(12): 4127 - 4135. [Abstract] [PDF]
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S Roth and T Schupbach The relationship between ovarian and embryonic dorsoventral patterning in Drosophila Development, January 8, 1994; 120(8): 2245 - 2257. [Abstract] [PDF]
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M Leptin and S Roth Autonomy and non-autonomy in Drosophila mesoderm determination and morphogenesis Development, January 4, 1994; 120(4): 853 - 859. [Abstract] [PDF]
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