Analysis of renal function with isolated pronephros of Xenopus frog.

To understand integrative renal functions in vertebrates, we explored and characterized genes expressing in pronephros of amphibian tadpole and mesonephros of teleost. We constructed the GFP expression vector linked 5'-upstream promoter of Na^+, K^+-ATPase, marker protein of renal tubule, and succeeded in isolating a living pronephric tubule by using transgenic technique. Furthermore, we explored genes associated with polycystic kidney disease (PKD) by a PCR-based subtractive hybridization method using pc mutant, a PKD model of medaka. As a result, we identified 2 genes (vasotocin type-2 receptor and aquaporin-8) reduced markedly in the kidney of pc mutant. Currently, we explore genes expressing in pronephros by global analysis and then characterize 2 genes found as candidate gene associated with teleost PKD.