Graded changes in dose of a Xenopus activin A homologue elicit stepwise transitions in embryonic cell fate

Nature. 1990 Sep 27;347(6291):391-4. doi: 10.1038/347391a0.


The protein XTC-MIF, a Xenopus homologue of activin A and a potent mesoderm-inducing factor, can induce responding animal pole explants to form several different cell types in a dose-dependent manner, higher doses eliciting more dorso-anterior tissues. This graded response, characteristic of classically postulated morphogens, may underlie pattern formation, but the response of intact animal caps to XTC-MIF provides only a crude indication of trends. Here we report the effects of XTC-MIF on dispersed blastomeres rather than intact animal caps. Under these conditions, responding cells distinguish sharply between doses of pure XTC-MIF differing by less than 1.5-fold. Two different response thresholds have been found, defining three cell states. This suggests that XTC-MIF has an instructive effect. Notochord and muscle are both induced in the same narrow dose-range. Mixing treated with untreated cells does not seem to shift the dose thresholds, showing that at least some cells can stably record the received dose of inducing factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Activins
  • Animals
  • Blastomeres / cytology*
  • Blastomeres / drug effects
  • Cell Aggregation
  • Cell Differentiation
  • Dose-Response Relationship, Drug
  • Epidermal Cells
  • Epidermis / embryology
  • Fluorescent Antibody Technique
  • Growth Substances / administration & dosage
  • Growth Substances / pharmacology*
  • Inhibins*
  • Keratins / genetics
  • Mesoderm / cytology
  • Muscles / cytology
  • Muscles / embryology
  • Notochord / cytology
  • Notochord / embryology
  • RNA, Messenger / biosynthesis
  • Ribonucleases
  • Xenopus / embryology*
  • Xenopus / metabolism


  • Actins
  • Growth Substances
  • RNA, Messenger
  • Activins
  • Inhibins
  • Keratins
  • Ribonucleases