Expression of mRNAs of the aquaporin family in mouse oocytes and embryos

The molecular basis of water and cryoprotectant permeability in mammalian o ocytes and embryos is poorly understood. Therefore, we investigated the exp ression of mRNAs of water channel proteins (aquaporins) in mouse oocytes an d embryos by RT-PCR. The total RNA of mouse oocytes at metaphase II and emb ryos at the 4-cell, morula, and blastocyst stages was isolated, reverse-tra nscribed, and subjected to nested PCR amplification. Aquaporins were expres sed in both oocytes and embryos, but the types were different among the dev elopmental stages: aquaporins 3 and 7 were expressed in oocytes and embryos at all stages examined, but aquaporins 8 and 9 were expressed only in blas tocysts. On the other hand, aquaporins 1, 2, 4, 5, and 6 were not detected in any of the stages examined. The present study shows for the first time t hat aquaporins are expressed in mammalian oocytes and embryos. These aquapo rins may play a role in water transport and conceivably also in cryoprotect ant transport across the plasma membrane in these cells. (C) 2000 Academic Press.