Summary
InXenopus laevis embryogenesis, the synthesis of heterogeneous mRNA-like RNA starts at the cleavage stage, whereas that of low-molecular-mass RNAs and rRNA occurs at the early blastula and late blastula stages, respectively. In coenocytic fertilizedXenopus egg cells, which fail to cleave, an excess of exogenously injected DNA (pBR322) induces ‘premature’ expression of previously injected exogenous genes (yeast tRNA genes). We have carried out experiments to discover whether the injection of excess exogenous DNAs of various origins modifies the expression of endogenous genes and previously injected exogenous genes inXenopus embryogenesis. We found that injection of a relatively large amount of exogenous DNA (Xenopus rDNA clone) induces the premature expression, or enhanced expression, of previously injected bacterial chloramphenicol acetyltransferase genes in coenocytic cells. In embryos, however, the injection of exogenous DNAs of various origins did not appreciably modify the expression of either endogenous or previously injected CAT genes. The DNAs injected into fertilized eggs were not degraded and were partitioned into the nuclei of most (at least 80%) of the descendant blastomeres at least during early stages of development. Therefore, we concluded that the program of gene expression in normally developing embryos cannot easily be altered by the introduction of excess exogenous DNAs.
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References
Atsuchi Y, Tashiro K, Yamana K, Shiokawa K (1986) Level of histone H4 mRNA inXenopus laevis embryonic cells cultured in the absence of cell adhesion. J Embryol Exp Morphol 98:175–185
Bakken A, Morgan G, Sollner-Webb B, Roan J, Busby S, Reeder RH (1982) Mapping of transcription initiation and termination signals onXenopus laevis ribosomal DNA. Proc Natl Acad Sci USA 79:56–60
Brown DD, Weber CS (1968) Gene linkage by RNA-DNA hybridization I. Unique DNA sequences homologous to 4S RNA, 5S RNA and ribosomal RNA. J Mol Biol 34:661–680
Busby SJ, Reeder RH (1983) Spacer sequences regulate transcription of ribosomal gene plasmids injected intoXenopus embryos. Cell 34:989–996
Dawid IB (1965) Deoxyribonucleic acid in amphibian eggs. J Mol Biol 12:580–599
Etkin LD, Balcells S (1985) TransformedXenopus embryos as a transient expression system to analyze gene expression at the midblastula transition. Dev Biol 108:173–178
Etkin L, Pearman B (1987) Distribution, expression and germ line transmission of exogenous DNA sequences following microinjection intoXenopus laevis eggs. Development 99:15–23
Gorman CM, Moffat LF, Howard BH (1982) Recombinant genomes which express chloramphenicol acetyltransferase in mammalian cells. Mol Cell Biol 2:1044–1051
Kimelman D, Kirschner M, Scherson T (1987) The events of the midblastula transition inXenopus are regulated by changes in the cell cycle. Cell 48:399–407
Krieg PA, Melton DA (1985) Developmental regulation of a gastrula-specific gene injected into fertilizedXenopus eggs. EMBO J 4:3463–3471
Kruczek I, Doerfler W (1983) Expression of the chloramphenicol acetyltransferase gene in mammalian cells under the control of adenovirus type 12 promoters: Effect of promoter methylation on gene expression. Proc Natl Acad Sci USA 80:7586–7590
Nakakura N, Miura T, Yamana K, Ito A, Shiokawa K (1987) Synthesis of heterogeneous mRNA-like RNA and low-molecular-weight RNA before the midblastula transition in embryos ofXenopus laevis. Dev Biol 123:421–429
Newport J, Kirschner M (1982a) A major developmental transition in earlyXenopus embryos. I. Characterization and timing of cellular changes at the midblastula stage. Cell 30:675–686
Newport J, Kirschner M (1982b) A major developmental transition in earlyXenopus embryos. II. Control of the onset of transcription. Cell 30:687–696
Nieuwkoop PD, Faber J (1956) Normal table ofXenopus laevis Daudin. North-Holland, Amsterdam
Shiokawa K, Yamana K (1967) Pattern of RNA synthesis in isolated cells ofXenopus laevis embryos. Dev Biol 16:368–388
Shiokawa K, Misumi Y, Yasuda Y, Nishio Y, Kurata S, Sameshima M, Yamana K (1979) Synthesis and transport of various RNA species in developing embryos ofXenopus laevis. Dev Biol 68:503–514
Shiokawa K, Misumi Y, Yamana K (1981a) Demonstration of rRNA synthesis in pre-gastrular embryos ofXenopus laevis. Dev Growth Differ 23:579–587
Shiokawa K, Tashiro K, Misumi Y, Yamana K (1981b) Non-coordinated synthesis of RNA's in pregastrular embryos ofXenopus laevis. Dev Growth Differ 23:589–597
Shiokawa K, Takeichi T, Miyata S, Tashiro K, Matsuda K (1985) Timing of the initiation of rRNA gene expression and nucleolar formation in cleavage embryos arrested by cytochalasin B and podophyllotoxin and in cytoplasm-extracted embryos ofXenopus laevis. Cytobios 43:319–334
Shiokawa K, Sameshima M, Tashiro K, Miura T, Nakakura N, Yamana K (1986) Formation of nucleus-like structure in the cytoplasm of λ-DNA-injected fertilized eggs and its partition into blastomeres during early embryogenesis inXenopus laevis. Dev Biol 116:539–542
Shiokawa K, Tashiro K, Yamana K, Sameshima M (1987) Electron microscopic studies of giant nucleus-like structure formed by λ DNA introduced into the cytoplasm ofXenopus laevis fertilized eggs and embryos. Cell Differ 20:253–261
Shiokawa K, Tashiro K, Nakakura N, Fu Y, Atsuchi Y, Nakazato S, Tsuzaki Y, Ikenishi K (1988) A possible maternal-effect mutant ofXenopus laevis: II. Studies of RNA synthesis in dissociated embryonic cells. Cell Differ Dev 25:47–56
Shiokawa K, Yamazaki T, Fu Y, Tashiro K, Tsurugi K, Motizuki M, Ikegami Y, Araki E, Andoh T, Hosokawa K (1989) Persistence and expression of circular DNAs which code forDrosophila amylase, bacterial chloramphenicol acetyltransferase, or others inXenopus laevis embryos. Cell Struct Funct (in press)
Signoret J, Lefresne J, Vinson D, David JC (1981) Enzymes involved in DNA replication in the axolotl. I. Control of DNA ligase activity during very early development. Dev Biol 87:126–132
Tashiro K, Misumi Y, Shiokawa K, Yamana K (1983) Determination of the rate of rRNA synthesis inXenopus laevis triploid embryos produced by low-temperature treatment. J Exp Zool 225:489–495
Tashiro K, Inoue M, Sakaki Y, Shiokawa K (1986a) Preservation ofXenopus laevis rDNA-containing plasmid, pX1r101A, injected into the fertilized egg ofXenopus laevis. Cell Struct Funct 11:109–114
Tashiro K, Shiokawa K, Yamana K, Sakaki Y (1986b) Structural analysis of ribosomal DNA homologues in nucleolus-less mutant ofXenopus laevis. Gene 44:299–306
Wilson C, Cross GS, Woodland HR (1986) Tissue-specific expression of actin genes injected intoXenopus embryos. Cell 47:589–599
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Shiokawa, K., Fu, Y., Nakakura, N. et al. Effects of the injection of exogenous DNAs on gene expression in early embryos and coenocytic egg cells ofXenopus laevis . Roux's Arch Dev Biol 198, 78–84 (1989). https://doi.org/10.1007/BF02447742
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DOI: https://doi.org/10.1007/BF02447742