Mix.1, a homeobox mRNA inducible by mesoderm inducers, is expressed mostly in the presumptive endodermal cells of Xenopus embryos.
In frogs, mesoderm presumably derives from presumptive ectoderm by induction under the control of diffusible substances produced by the endoderm. To analyze the early phase of mesoderm induction, I have isolated cDNA copies of mRNAs induced in presumptive ectoderm by mesoderm inducing factor secreted by the XTC cell line. One of the inducible mRNAs encodes a homeodomain-containing protein that is likely to play a regulatory role in development. Mix.1 behaves as an immediate early response to induction, and its kinetics of expression suggest a major role for MBT in the control of inducible gene expression. Unexpectedly, Mix.1 is expressed mostly in the future endoderm, suggesting that endoderm may be formed by induction in a similar way as mesoderm.
Rosa
F M
FM
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004627:Embryonic Induction; D004707:Endoderm / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D005801:Genes, Homeobox; D006133:Growth Substances / Q000494:pharmacology; D008648:Mesoderm / Q000502:physiology*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D014018:Tissue Distribution; D014982:Xenopus laevis / Q000196:embryology*
D006133:Growth Substances; D012333:RNA, Messenger; D004247:DNA