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Dev Biol 2004 Apr 01;2681:207-19. doi: 10.1016/j.ydbio.2003.12.022.
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Timed interactions between the Hox expressing non-organiser mesoderm and the Spemann organiser generate positional information during vertebrate gastrulation.

Wacker SA , Jansen HJ , McNulty CL , Houtzager E , Durston AJ .

We report a novel developmental mechanism. Anterior-posterior positional information for the vertebrate trunk is generated by sequential interactions between a timer in the early non-organiser mesoderm and the organiser. The timer is characterised by temporally colinear activation of a series of Hox genes in the early ventral and lateral mesoderm (i.e., the non-organiser mesoderm) of the Xenopus gastrula. This early Hox gene expression is transient, unless it is stabilised by signals from the Spemann organiser. The non-organiser mesoderm and the Spemann organiser undergo timed interactions during gastrulation which lead to the formation of an anterior-posterior axis and stable Hox gene expression. When separated from each other, neither non-organiser mesoderm nor the Spemann organiser is able to induce anterior-posterior pattern formation of the trunk. We present a model describing that convergence and extension continually bring new cells from the non-organiser mesoderm within the range of organiser signals and thereby create patterned axial structures. In doing so, the age of the non-organiser mesoderm, but not the age of the organiser, defines positional values along the anterior-posterior axis. We postulate that the temporal information from the non-organiser mesoderm is linked to mesodermal Hox expression.

PubMed ID: 15031117
Article link: Dev Biol

Species referenced: Xenopus
Genes referenced: egr2 en2 hoxa7 hoxb4 hoxb9 hoxc6 hoxc9-like hoxd1 hoxd13 nog nrp1 tbx2 tbxt

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