Changes in the patterns of RNA synthesis in early embryogenesis of Xenopus laevis

Shiokawa, K.; Misumi, Yuko; Tashiro, Kosuke; Nakakura, Norihiko; Yamana, K.; Oh-uchida, Mamoru

doi:10.1016/0922-3371(89)90019-1

Cited by 28 publications

(20 citation statements)

References 30 publications

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“…Although it is generally believed that minimal transcription occurs prior to MBT, detection of high molecular weight RNA synthesized prior to MBT in dissociated or cleavage-arrested embryos has been reported (Kimelman et al, 1987;Nakakura et al, 1987;Shiokawa et al, 1989). However, this RNA had not been shown to be polyadenylated, a feature of most mRNAs, and had not been described in intact embryos.…”

Section: Transcription Of Heterogeneous Polyadenylated Rnas In Intactmentioning

confidence: 99%

“…Because of this, work on pre-MBT embryonic development has focused primarily on posttranscriptional control mechanisms. Low-level transcription has been detected before MBT in Xenopus and Drosophila (Edgar and Schubiger, 1986;Kimelman et al, 1987;Nakakura et al, 1987;Shiokawa et al, 1989;Yasuda and Schubiger, 1992), but the significance of this early transcription is not known. Nevertheless, regulated transcription of specific mRNAs has not been described in vertebrate embryos and, except for Drosophila engrailed (discussed below) (Karr et al, 1989), little attention has been given to zygotic transcription as a regulatory mechanism in the pre-MBT embryo.…”

Section: Introductionmentioning

confidence: 99%

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β-Catenin/Tcf-regulated transcription prior to the midblastula transition

et al. 2002

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Following fertilization, the zygotic genome in many organisms is quiescent until the midblastula transition (MBT), when large-scale transcription begins. In Xenopus embryos, for example, transcription is believed to be repressed until the twelfth cell division. Thus, although dorsal-ventral patterning begins during the first cell cycle, little attention has been given to transcriptional regulation in pre-MBT development. We present evidence that regulated transcription begins during early cleavage stages and that the β-catenin-Tcf complex is required for the transcription of the Xenopus nodal genes Xnr5 and Xnr6 as early as the 256-cell stage. Moreover, inhibition of β-catenin/Tcf function can block dorsal development, but only if the inhibition begins early and is maintained throughout pre-MBT stages. Dorsal development can be rescued in ventralized embryos if Tcf-dependent transcription is activated prior to MBT, but activation of Tcf after MBT cannot rescue ventralized embryos, suggesting that β-catenin/Tcf-dependent transcription is required prior to MBT for dorsal-ventral patterning in Xenopus.

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Section: Transcription Of Heterogeneous Polyadenylated Rnas In Intactmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

β-Catenin/Tcf-regulated transcription prior to the midblastula transition

et al. 2002

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“…In Xenopus laevis, EGA initiates with the activation of class II genes (mRNA), followed by class III genes (tRNA) and finally class I genes (rRNA; Shiokawa et al 1989Shiokawa et al , 1994. In eukaryotes, RNA Pol II is responsible for transcription of mRNAs and of most of the small nuclear RNAs.…”

Section: Rna Pol IImentioning

confidence: 99%

“…In mammals, the fact that transcriptional activation of class I genes (rRNA) depends on the previous activation of class II genes (mRNA; Shiokawa et al 1989Shiokawa et al , 1994 Bovine NT embryo (A1) and pig-bovine iSCNT embryo (C1) were counterstained with DAPI (A and C) at 96 h after activation. DAPI highlighted the presence of (A) homogenously stained nuclei in NT embryo and (C) chromatin condensation in the nuclei of iSCNT embryo.…”

Section: Rna Pol I Activation and Nucleolar Maturationmentioning

confidence: 99%

Development, embryonic genome activity and mitochondrial characteristics of bovine–pig inter-family nuclear transfer embryos

Lagutina¹,

Fulka²,

Brevini³

et al. 2010

Reproduction

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The best results of inter-species somatic cell nuclear transfer (iSCNT) in mammals were obtained using closely related species that can hybridise naturally. However, in the last years, many reports describing blastocyst development following iSCNT between species with distant taxonomical relations (inter-classes, inter-order and inter-family) have been published. This indicates that embryonic genome activation (EGA) in xeno-cytoplasm is possible, albeit very rarely. Using a bovine-pig (inter-family) iSCNT model, we studied the basic characteristics of EGA: expression and activity of RNA polymerase II (RNA Pol II), formation of nucleoli (as an indicator of RNA polymerase I (RNA Pol I) activity), expression of the key pluripotency gene NANOG and alteration of mitochondrial mass. In control embryos (obtained by IVF or iSCNT), EGA was characterised by RNA Pol II accumulation and massive production of poly-adenylated transcripts (detected with oligo dT probes) in blastomere nuclei, and formation of nucleoli as a result of RNA Pol I activity. Conversely, iSCNT embryos were characterised by the absence of accumulation and low activity of RNA Pol II and inability to form active mature nucleoli. Moreover, in iSCNT embryos, NANOG was not expressed, and mitochondria mass was significantly lower than in intra-species embryos. Finally, the complete developmental block at the 16-25-cell stage for pig-bovine iSCNT embryos and at the four-cell stage for bovine-pig iSCNT embryos strongly suggests that EGA is not taking place in iSCNT embryos. Thus, our experiments clearly demonstrate poor nucleus-cytoplasm compatibility between these animal species.

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“…In Xenopus laevis, it was found that major embryonic genome activation (EGA) initiated with activation of class II genes (mRNA), followed by class III genes (tRNA), and finally class I genes (rRNA; Shiokawa et al 1989Shiokawa et al , 1994. In mammals, this was confirmed by the demonstration that RNA polymerase I as well as other key nucleolar proteins, upstream binding factor (UBF) and topoisomerase I, engaged in transcription of the rDNA, and fibrillarin , which is involved in early processing of rRNA, appeared in embryos at the time of EGA (Maddox-Hyttel et al 2007.…”

Section: Introductionmentioning

confidence: 99%

Formation of nucleoli in interspecies nuclear transfer embryos derived from bovine, porcine, and rabbit oocytes and nuclear donor cells of various species

Lagutina

Zakhartchenko²,

Fulka³

et al. 2011

Reproduction

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The most successful development of interspecies somatic cell nuclear transfer (iSCNT) embryos has been achieved in closely related species. The analyses of embryonic gene activity in iSCNT embryos of different species combinations have revealed the existence of significant aberrations in expression of housekeeping genes and genes dependent on the major embryonic genome activation (EGA). However, there are many studies with successful blastocyst (BL) development of iSCNT embryos derived from donor cells and oocytes of animal species with distant taxonomical relations (inter-family/inter-class) that should indicate proper EGA at least in terms of RNA polymerase I activation, nucleoli formation, and activation of genes engaged in morula and BL formation. We investigated the ability of bovine, porcine, and rabbit oocytes to activate embryonic nucleoli formation in the nuclei of somatic cells of different mammalian species. In iSCNT embryos, nucleoli precursor bodies originate from the oocyte, while most proteins engaged in the formation of mature nucleoli should be transcribed from genes de novo in the donor nucleus at the time of EGA. Thus, the success of nucleoli formation depends on species compatibility of many components of this complex process. We demonstrate that the time and cell stage of nucleoli formation are under the control of recipient ooplasm. Oocytes of the studied species possess different abilities to support nucleoli formation. Formation of nucleoli, which is a complex but small part of the whole process of EGA, is essential but not absolutely sufficient for the development of iSCNT embryos to the morula and BL stages.

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Changes in the patterns of RNA synthesis in early embryogenesis of Xenopus laevis

Cited by 28 publications

References 30 publications

β-Catenin/Tcf-regulated transcription prior to the midblastula transition

β-Catenin/Tcf-regulated transcription prior to the midblastula transition

Development, embryonic genome activity and mitochondrial characteristics of bovine–pig inter-family nuclear transfer embryos

Formation of nucleoli in interspecies nuclear transfer embryos derived from bovine, porcine, and rabbit oocytes and nuclear donor cells of various species

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