Expression pattern of insulin receptor mRNA during Xenopus laevis embryogenesis

We have identified a member of the insulin receptor (InsR)/insulin-like gro wth factor-1 receptor (IGF-1R) family. The Xenopus insulin receptor (Xe-Ins R) is present as a maternal 6.6 kb transcript. Northern blot analysis revea ls the presence of this transcript until the midblastula transition (MBT), when levels decrease. At neurulation, two distinct transcripts of 6.6 and 7 .7 kb are detected, both of which persist throughout embryogenesis. In situ hybridization analysis shows that InsR expression is restricted to regions of ectodermal and mesodermal origin, notably the encephalon, otic vesicles , optic vesicles, gills, somites and the pronephros. (C) 1999 Elsevier Scie nce Ireland Ltd. All rights reserved.