The biphasic expression of IMP/Vg1-RBP is conserved between vertebrates and Drosophila

The human IGF-II mRNA-binding proteins (IMPs) 1-3, and their Xenopus homolo gue Vg1 RNA-binding protein (Vg1-RBP) are RNA-binding proteins implicated i n mRNA localization and translational control in vertebrate development. We have sequenced the Drosophila homologue (dIMP) of these genes, and examine d its expression pattern in Drosophila embryos by in situ hybridization. Th e study shows that dIMP exhibits a biphasic expression pattern. In the earl y stages of development, a maternal pool of dIMP mRNA is evenly distributed in the embryo and degraded by the end of stage 4. Expression reappears in the developing central nervous system, where dIMP is expressed throughout n eurogenesis. In addition, dIMP is present in the pole cells. (C) 2000 Elsev ier Science Ireland Ltd. All rights reserved.