L. Tiret et al., ALTERING THE SPATIAL DETERMINATIONS IN THE MOUSE EMBRYOS BY MANIPULATING THE HOX GENES, Comptes rendus de l'Academie des sciences. Serie 3, Sciences de la vie, 316(9), 1993, pp. 1017-1024
Developmental genetics in Drosophila led to the isolation of the homeo
tic genes which are involved in the cellular positional information. I
n vertebrates, homologous genes have been characterized and play simil
ar roles in the spatial determination. However, the subtle mechanisms
by which positional identity is specified by the Hox genes co-expressi
on are little known. The Hoxc-8 null mutation can induce homeosis at t
he anterior margin of Hoxc-8 expression, where the mosaicism observed
suggests that, at least in the segmented paraxial mesoderm, the number
of cells expressing a Hox gene is a determinant parameter. A combinat
orial model is also suggested by several genetic experiments where the
level of Hox genes expression is modified. Expression of some related
Hox genes in Hoxc-8 homozygous mutants is not altered, suggesting the
absence of genetic interregulations between these genes.