Fait également perceptible dans la petitesse du nombre de gènes Hox.
Heu… n=39 pour les Hox, c’est petit ?
Dev Growth Differ. 2007 May;49(4):265-75
Iimura T, Pourquié O.
Vertebrae display distinct morphological features at different levels of the body axis. Links between collinear Hox gene activation and the progressive mode of body axis elongation have provided a fascinating blueprint of the mechanisms for establishing these morphological identities. In this review, we first discuss the regulation and possible role of collinear Hox gene activation during body formation and then highlight the direct role of Hox genes in controlling cellular movements during gastrulation, therefore contributing to body formation. Additional related research aspects, such as imaging of chromatin regulation, roles of micro RNAs and evolutional findings are also discussed.
Fig. 3. Hox genes control the timing of mesoderm formation. Two expression constructs of Hoxb1 with DsRed express and Hoxb9 with ZsGreen were electroporated in the epiblast layer of the left and right sides of the anterior primitive streak region, respectively, at Stage 5HH of a chick embryo. Fluorescent images were taken by a confocal microscope 6 h after reincubation. Some Hoxb1-expressing red cells had already ingressed into the mesodermal layer and migrated anteriorly to the Hensen’s node, while Hoxb9-expressing green cells remained in the anterior streak region, most of them still maintained their epithelial structure (Iimura & Pourquié 2006). The oval circle and dotted lines indicate the position of Hensen’s node and the primitive streak, respectively. HN: Hensen’s node. Confocal scanning image, dorsal view, anterior to the top.