Angel Amores,
Allan Force,
Yi-Lin Yan,
Lucille Joly,
Chris Amemiya,
Andreas Fritz,
Robert K. Ho,
James Langeland,
Victoria Prince,
Yan-Ling Wang,
Monte Westerfield,
Marc Ekker,
*
John H. Postlethwait
*
HOX genes specify cell fate in the anterior-posterior
axis of animal embryos. Invertebrate chordates have one HOX
cluster, but mammals have four, suggesting that cluster duplication
facilitated the evolution of vertebrate body plans. This report shows
that zebrafish have seven hox clusters. Phylogenetic
analysis and genetic mapping suggest a chromosome doubling event,
probably by whole genome duplication, after the divergence of
ray-finned and lobe-finned fishes but before the teleost radiation.
Thus, teleosts, the most species-rich group of vertebrates, appear to
have more copies of these developmental regulatory genes than do
mammals, despite less complexity in the anterior-posterior axis.
A. Amores, A. Force, Y.-L. Yan, Y.-L. Wang, M. Westerfield,
J. H. Postlethwait, Institute of Neuroscience, University of
Oregon, Eugene, OR 97403, USA. L. Joly and M. Ekker, Loeb
Institute of Medical Research, Ottawa Civic Hospital, Ottawa, Ontario
K1Y 4E9, Canada. C. Amemiya, Center for Human Genetics, Boston
University School of Medicine, Boston, MA 02118, USA. A. Fritz,
Department of Biology, Emory University, Atlanta, GA 30322, USA.
R. K. Ho, Department of Molecular Biology, Princeton University,
Princeton, NJ 08544, USA. J. Langeland, Biology Department,
Kalamazoo College, Kalamazoo, MI 49006, USA. V. Prince, Organismal
Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
*
The experiments reported here were conducted in the laboratories of
these authors.
To whom correspondence should be addressed.
