Development Genes and Evolution

, Volume 214, Issue 6, pp 267–276

Organization of Iroquois genes in fish

Original Article

DOI: 10.1007/s00427-004-0402-8

Cite this article as:
Dildrop, R. & Rüther, U. Dev Genes Evol (2004) 214: 267. doi:10.1007/s00427-004-0402-8


In mammals, a total of six iroquois (Irx) genes exist, which are organized into two clusters. Here we report on the organization of all iroquois genes present in fish, using zebrafish (Danio rerio) and pufferfish (Fugu rubripes and Tetraodon nigroviridis) as examples. A total of 10 Irx genes were found in pufferfish, and 11 in zebrafish; all but one of these genes are organized into clusters (four clusters plus one isolated gene locus). The “extra” fish clusters result from chromosome duplication in the fish lineage, after its divergence from tetrapod vertebrates. Two of the four fish clusters are highly conserved to the ones in mammals, with regard to similarity of genes and cluster architecture. Irx genes within the other two clusters have diverged in sequence and cluster organization, suggesting functional divergence. These results will allow us to use the zebrafish system for functional and comparative studies of iroquois genes in vertebrate development.


Irx genesGene clusterDuplicationCluster diversification

Supplementary material

supp.pdf (317 kb)
(PDF 317 KB)

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Institute for Animal Developmental and Molecular BiologyUniversity of DüsseldorfDüsseldorfGermany