A homeo domain protein reveals the metameric nature of the developing chick hindbrain.
The segmented embryonic hindbrain of vertebrates develops by sequential constriction of the neural tube into eight metameric units known as rhombomeres. The cellular and molecular basis of this segmentation process is largely unknown. Using an antibody, we analyzed the expression pattern of the chick homeo domain-containing protein Ghox-lab in the developing chick hindbrain. At the neural plate stage, prior to the appearance of rhombomeres, Ghox-lab is expressed within a single domain that extends anteriorly up to the site where rhombomere 4 will later form. After rhombomere 4 has appeared and as hindbrain segmentation progresses, the level of Ghox-lab protein increases significantly within the fourth rhombomere. This intensification, accompanied by the elimination of Ghox-lab protein in rhombomeres 5 and 6, eventually results in the formation of a distinct island of expression in rhombomere 4. All cells in the newly formed rhombomere 4 express Ghox-lab, except for the cells of the floor plate. In addition, neural crest cells migrating from the fourth rhombomere are also Ghox-lab-positive. These data raise the possibility that Ghox-lab protein might be one of the factors involved in the specification of the metameric pattern of the vertebrate hindbrain.
Sundin
O H
OH
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.
Eichele
G
G
D000818:Animals; D030161:Avian Proteins; D002642:Chick Embryo; D004475:Ectoderm / Q000378:metabolism; D005326:Fetal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics*; D009432:Neural Crest / Q000166:cytology / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D009928:Organ Specificity / Q000235:genetics; D012249:Rhombencephalon / Q000196:embryology* / Q000378:metabolism
D030161:Avian Proteins; D005326:Fetal Proteins; C066380:Ghox-lab protein, chicken; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins