Hox genes and serial homology
Article Abstract:
Hox genes are expressed in both the fore and hind limbs of tetrapod vertebrates. These were originally expressed only in the hind limb and controlled the pattern of its development. The genes were activated ectopically in the developing forelimb and imposed the morphology of the hind limb on the fore limb. When the alteration in Hox expression occurred in vertebrate evolution is uncertain. It may have happened during evolution of tetrapod limbs or it may have occurred earlier, for example, during the evolution of pectoral fins in lobe-finned fish.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Expression of Radical fringe in limb-bud ectoderm regulates apical ectodermal ridge formation
Article Abstract:
An analysis of the formation of the apical ectodermal ridge, through a study of the expression patterns of the vertebrate fringe genes in both wild-type and AER-defective chicken strains, affirms the hypothesis that the AER forms at the junction of Radical fringe-expressing and non-expressing cells. Results also found no link between the molecular control of AER formation and dorsoventral tissue specification. Findings likewise indicate that Engrailed-1 is indirectly involved in AER formation through regulation of Radical fringe expression.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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Footnote on limb evolution
Article Abstract:
Hox gene, a regulatory gene, plays an important role in morphological variation in appendage development and segmentation for both fish and land vertebrates. A comparison of the limb development in the zebrafish fin buds with tetrapod limb development indicates that the Hox genes have two distinct temporal and spatial phases. The fin buds never experience the final phase which is characteristic of foot development, contesting the theory that the tetrapod foot is an evolutionary step rather than a novelty.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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