Ancient and recent duplications of the rainbow trout Wilms' tumor gene

The Wilms' tumor suppressor (WT1) gene plays an important role in the devel opment and functioning of the genitourinary system, and mutations in this g ene are associated with nephroblastoma formation in humans. Rainbow trout ( Oncorhynchus mykiss) is one of the rare animal models that readily form nep hroblastomas, yet trout express three distinct WT1 genes, one of which is d uplicated and inherited tetrasomically. Sequence analyses suggest an ancien t gene duplication in the common ancestor of bony fishes resulted in the fo rmation of two WT1 gene families, that conserve the splicing variations of tetrapod WT1, and a second duplication event occurred in the trout lineage. The WT1 genes of one family map to linkage groups 6 and 27 in the trout ge nome map. Reverse transcribed polymerase chain reaction (RT-PCR) expression analysis demonstrated little difference in WT1 tissue expression pattern b etween genes.