Ubiquitous MyoD transcription at the midblastula transition precedes induction-dependent MyoD expression in presumptive mesoderm of X. laevis.
We have used a quantitative reverse transcription-polymerase chain reaction assay to detect MyoD mRNA during early embryonic development of Xenopus laevis. We find that during a short period of time following the midblastula transition MyoD becomes transcriptionally activated at a low level ubiquitously throughout the embryo. Restriction of MyoD expression to muscle precursor cells appears as a subsequent event, in which the process of mesoderm induction stabilizes transcription only in the marginal zone of the embryo, the presumptive mesoderm.
Department of Genetics, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
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D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D004268:DNA-Binding Proteins / Q000235:genetics; D004627:Embryonic Induction; D015870:Gene Expression; D005801:Genes, Homeobox; D008648:Mesoderm / Q000502:physiology; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D017570:MyoD Protein; D009841:Oligonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic; D014982:Xenopus laevis / Q000196:embryology*
D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D017570:MyoD Protein; D009841:Oligonucleotides; D012333:RNA, Messenger