DIFFERENTIAL EXPRESSION OF XENOPUS RIBOSOMAL-PROTEIN GENE XLRPS1C

Components of the translational machinery of the cell, including ribos omal proteins, are generally considered to be clear examples of housek eeping genes with a spatially ubiquitous distribution of messenger RNA during embryonic development. Here we present data based upon in situ hybridization experiments as well as RNase protection assays, demonst rating that Xenopus ribosomal protein gene S1 is differentially expres sed in a complex and spatially distinct pattern during embryogenesis. We observed dramatically high levels of expression in some tissues, su ch as the branchial arches, otic vesicles. optic vesicles and somites and virtually no expression in other tissues, such as the cement gland , epidermis and notochord. Moreover, ribosomal protein genes S22, L1, and L5 display expression patterns nearly identical to S1. Our data is consistent with a model of ribosomal gene expression according to whi ch ribosomal protein genes (or perhaps a subset of ribosomal protein g enes) may be expressed at low levels in all tissues, but are abundantl y expressed in other cell types reflecting a dynamic and complex patte rn of transcriptional control throughout embryonic development. (C) 19 97 Elsevier Science B.V.