Expression patterns of threespine stickleback Hox genes and insights into the evolution of the vertebrate body axis

Authors
Citation
Dg. Ahn et G. Gibson, Expression patterns of threespine stickleback Hox genes and insights into the evolution of the vertebrate body axis, DEV GENES E, 209(8), 1999, pp. 482-494
Citations number
61
Categorie Soggetti
Cell & Developmental Biology
Journal title
DEVELOPMENT GENES AND EVOLUTION
ISSN journal
0949944X → ACNP
Volume
209
Issue
8
Year of publication
1999
Pages
482 - 494
Database
ISI
SICI code
0949-944X(199908)209:8<482:EPOTSH>2.0.ZU;2-A
Abstract
Understanding the patterning mechanisms that operate to promote differentia tion of individual segments along the main body axis is an important goal o f both developmental and evolutionary biology. In order to gain a better in sight into the role of Hox genes in generating diversity of axial plans see n in vertebrates, we have cloned 11 homeobox sequences from an acanthoptery gian teleost, the threespine stickleback, and analyzed the expression of 7 of thee during embryogenesis. Transcripts are observed in a variety of tiss ues including thp neural tube paraxial mesoderm, lateral plate mesoderm, pe ctoral fins, pronephric ducts, as well as some neural crest-derived structu res. Anterior limits of expression in the central nervous system and paraxi al mesoderm exhibited both similarities and differences to those of mouse a nd zebrafish homologs. In both stickleback and zebrafish embryos expression limits within the paraxial mesoderm were detected only within the trunk re gion in which ribs are attached to all vertebrae. The finding of this patte rn in two divergent teleosts as well as in various tetrapod species support s the hypothesis that a Hox precede was present prior to the divergence of ray-finned and lobe-finned fishes and was subsequently used to generate dif ferent types of vertebrae in tetrapods. We also describe a dynamic pattern of expression of several stickleback Hox genes associated with the developm ent of the caudal paraxial mesoderm, which suggests uncoupling of the proce ss of segmentation from segmental identity determination. We propose that i n fishes the patterning of the tail region is under the control of a separa te mechanism from the trunk, which utilizes Hox genes in a different manner .