HURLEY, IA*; SCEMAMA, JL; PRINCE, VE; Organismal Biology & Anatomy, The University of Chicago; Dept. of Biology, The University of Chicago; Organismal Biology & Anatomy, The University of Chicago: The mechanism and consequences of duplicate gene preservation � a comparison of hoxb1 duplicates across teleost fish

Vertebrate evolution is characterized by gene/genome duplication events, and there is strong evidence that a whole genome duplication occurred in the lineage leading to the teleost fishes. We have focused on the teleost hoxb1 duplicate genes as a paradigm to investigate the mechanism and consequences of duplicate gene preservation. Previous analysis of the zebrafish hoxb1 genes found good evidence that the duplicates were preserved via subfunctionalization (McClintock et al., 2002). The combined expression patterns of the two zebrafish hoxb1 genes together resemble the expression pattern of the single HoxB1 gene of tetrapods, possibly due to degenerative changes in complementary cis-regulatory elements of the duplicates. We have tested the hypothesis that preservation of hoxb1 duplicates via subfunctionalization is a synapomorphy of the teleost fishes. Consistent with this theory, analysis of hoxb1 genes from divergent teleosts shows that upstream hoxb1a cis-regulatory elements are highly conserved, whereas equivalent hoxb1b elements show significant variation. We have compared hoxb1 expression patterns in zebrafish, medaka and striped bass, and used transient transgenic analysis to test directly whether degenerative changes in cis-regulatory elements underlie subfunctionalization in these species. It has also been demonstrated that zebrafish hoxb1 duplicates have evolved different functional capacities (McClintock et al. 2001). We have used a gain-of-function approach to compare the functions of hoxb1 duplicates from zebrafish, medaka and striped bass in order to uncover the consequences of duplicate gene preservation across the teleost group.