منابع مشابه
Graded Positional Information Interpretation for Both Fate and Guidance
Recent evidence indicates that gradients of the same extracellular molecules can act as both morphogens, specifying cell differentiation, and guidance cues, directing axon movement. We discuss how cells may use common mechanisms to convert graded information into discrete responses; and how extracellular signals provide coordinate systems that can be linked to highly diverse cellular outputs.
متن کاملPositional information, in bits.
Cells in a developing embryo have no direct way of "measuring" their physical position. Through a variety of processes, however, the expression levels of multiple genes come to be correlated with position, and these expression levels thus form a code for "positional information." We show how to measure this information, in bits, using the gap genes in the Drosophila embryo as an example. Indivi...
متن کاملQualitative Representation of Positional Information
A framework for the qualitative representation of positional information in a two-dimensional space is presented. Qualitative representations use discrete quantity spaces, where a particular distinction is introduced only if it is relevant to the context being modeled. This allows us to build a flexible framework that accommodates various levels of granularity and scales of reasoning. Knowledge...
متن کاملControl of growth and positional information by the graded vestigial expression pattern in the wing of Drosophila melanogaster.
The size and shape of organs depend on cellular processes such as cell proliferation, cell survival, and spatial arrangement of cells. In turn, all of these processes are a consequence of positional identity of individual cells in whole organs. Links of positional information with organ growth and pattern expression of genes is a little-addressed question. We show that differences in vestigial ...
متن کاملGetting the Measure of Positional Information
Understanding the mechanisms that underlie pattern formation is one of the major challenges of developmental biology. The complexity and beauty of the patterns on butterfly wings, fish scales, or bird feathers are not only remarkable products of developmental processes but puzzles that tease our intellects. If we are to understand these beautiful products of cellular activity, we need to first ...
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ژورنال
عنوان ژورنال: Cell
سال: 2003
ISSN: 0092-8674
DOI: 10.1016/s0092-8674(03)00359-3