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A Xenopus laevis gastrula cDNA library has been screened in order to identify sequences that are expressed early in development. We find that the mRNA encoding translation elongation factor 1-alpha (EF-1 alpha) is synthesized in very large amounts in the early embryo. Transcription of EF-1 alpha mRNA commences at the midblastula transition (MBT), and new(More)
During the meiotic maturation of Xenopus oocytes, maternal mRNAs that lack a cytoplasmic polyadenylation element are deadenylated and translationally inactivated. In this report, we have characterized the regulation of poly(A) removal during maturation. Deadenylation in vivo is detected only after germinal vesicle breakdown and does not require de novo(More)
Ribosomal protein L5 binds specifically to 5S rRNA to form a complex that is a precursor to 60S subunit assembly in vivo. Analyses in yeast cells, mammalian cells, and Xenopus embryos have shown that the accumulation of L5 is not coordinated with the expression of other ribosomal proteins. In this study, the primary structure and developmental expression of(More)
The meiotic maturation of Xenopus oocytes initiates significant changes in the translation of a number of maternal mRNAs that coincide with alterations in their polyadenylation states. A considerable number of maternal mRNAs are deadenylated in mature oocytes, thereby reducing their translational efficiencies. In this report we demonstrate that(More)
The expression of ribosomal protein and rRNA genes during Xenopus oogenesis results in the synthesis of sufficient ribosomes to support development of the swimming tadpole. cDNA clones for ribosomal proteins L13, L15, L23, and S22 have been isolated and used as probes to examine ribosomal protein gene transcripts during oogenesis and embryogenesis. Our(More)
We have isolated and determined the nucleotide sequence of a cDNA encoding Xenopus laevis ribosomal protein S22. A synthetic S22 mRNA derived from this cDNA directs the synthesis of an in vitro translation product that is indistinguishable from S22 purified from Xenopus ovarian ribosomes. In vitro translated S22 is assembled into 40 S subunits when(More)
The transcription of 5 S RNA genes during oogenesis results in the storage of sufficient 5 S RNA in ribosomes to support subsequent embryogenesis. Xenopus oocytes of all stages synthesize oocyte-type 5 S RNA. A generalized repression of transcription occurs at meiosis and is maintained throughout early cleavage. The onset of 5 S RNA synthesis is detected at(More)
The synthesis of an endogenous ribosomal protein, L1, is selectively and efficiently inhibited by microinjection of antisense L1 RNAs into Xenopus oocytes. Repression of L1 synthesis is achieved within 12 hr and is maintained for 48 hr. RNase-protection assays reveal the formation of RNA X RNA duplexes in vivo between the endogenous L1 mRNA and injected(More)
Ribosomal protein synthesis ceases upon maturation of Xenopus oocytes. We find that this cessation results from the dissociation of ribosomal protein mRNAs from polysomes and is accompanied by the deadenylation of these transcripts. A synthetic mRNA encoding ribosomal protein L1, microinjected into stage VI oocytes, is deadenylated and released from(More)