title: Time-dependent responses to glp-1-mediated inductions in early C. elegans embryos.
abstract: In an embryo of the nematode Caenorhabditis elegans, two blastomeres at the 4-cell stage, ABa and ABp, are born with equivalent developmental potential. Subsequently, interactions with the P2 blastomere at the 4-cell stage and the MS blastomere at the 12-cell stage generate differences in developmental fate among descendants of ABa and ABp. We have reproduced these inductions in vitro using embryonic blastomeres isolated in cell-culture medium. We show that during these inductions only the responding AB descendants require the activity of the glp-1 gene, which is similar in sequence to Drosophila Notch, supporting models in which GLP-1 protein acts as a receptor for both the P2 and MS signals. We also show that P2 signaling requires the activity of the apx-1 gene, similar in sequence to Drosophila Delta, and that MS signaling requires the putative transcription factor SKN-1. We present evidence that the primary factor determining the different responses to these two signals is the age of the AB descendants, not the identity of the signaling cell or ligand. Therefore, we suggest that time-dependent changes in factors within AB descendants are responsible for their different responses to inductive signals that use a common receptor.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Shelton
authors.forename: B
authors.initials: B
authors.lastname: Bowerman
mesh_terms: D000375:Aging; D000818:Animals; D001757:Blastomeres / Q000502:physiology; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins; D018929:Cell Culture Techniques; D002678:Chimera / Q000502:physiology; D004268:DNA-Binding Proteins; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D015801:Helminth Proteins / Q000235:genetics* / Q000502:physiology; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000502:physiology; D009130:Muscle, Smooth / Q000196:embryology; D010614:Pharynx / Q000196:embryology; D051880:Receptors, Notch; D015398:Signal Transduction / Q000235:genetics*; D015222:Sodium Channels; D013997:Time Factors; D014157:Transcription Factors
chemical_list: D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; C060620:Glp-1 protein, C elegans; D015801:Helminth Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D051880:Receptors, Notch; D015222:Sodium Channels; D014157:Transcription Factors; C489774:apx-1 protein, C elegans; C073702:skn-1 protein, C elegans