Search results for "Gradient theory"
showing 2 items of 2 documents
Spatial distribution of two maternal messengers encoding two sea urchin cell surface proteins
1993
We have localized, byin situ hybridization, two messengers, called bepl and bep4 (butanol extracted proteins), coding for cell surface proteins, involved in cell interaction, in sections of eggs of the sea urchinP. lividus. These maternal RNAs are spatially distributed in a gradient with a maximum at one pole of the egg. These results represent the first demonstration of the existence of a gradient of informational molecules in the sea urchin egg,i.e., the biological material for which the gradient theory was first proposed.
A model explaining some bryozoan colonies
2008
AbstractAlthough the colonialism surely developed independently in Graptolithoidea and Bryozoa, both groups share similar patterns of astogeny. One of the common features is the presence of morphological gradients. Many attempts at its explanation were made for more than a half of the century. This paper discusses a new model of the late astogeny in some bryozoan colonies, showing a cyclic reappearance of secondary zones of astogenetic change and astogenetic repetition that cannot be explained by the single morphogen gradient theory.