title: Cloning of cDNA sequences derived from poly(A)+nuclear RNA ofXenopus laevis at different developmental stages: Evidence for stage specific regulation.
abstract: Nuclear poly(A)+RNA was isolated from gastrula and early tadpole stages ofXenopus laevis, transcribed into cDNA and integrated as double stranded cDNA by the G-C joining method into the Pst cleavage site of plasmid pBR 322. After cloning inE. coli strain HB 101 the clone libraries were hybridized to32P labelled cDNA derived from nuclear poly(A)+RNA of the two different developmental stages. About 20% of the clones gave a positive hybridization signal thus representing RNA molecules of high and medium abundance. From these clones, some individual clones were identified containing sequences which are not present at the oocyte and gastrula stages but which are transcribed at the early tadpole stage of embryonic development.
authors.affiliation: Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Arnimallee 22, D-1000, Berlin 33.
authors.forename: Walter
authors.initials: W
authors.lastname: Knöchel
authors.affiliation: Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Arnimallee 22, D-1000, Berlin 33.
authors.forename: Dieter
authors.initials: D
authors.lastname: Bladauski
keywords: Poly(A)+ nuclear RNA; Stage specificity; Xenopus laevis; cDNA cloning