Early embryonic induction in C. elegans can be inhibited with polysulfated hydrocarbon dyes.

During embryogenesis of Caenorhabditis elegans cellular interactions are necessary to determine the fate of blastomeres. In one of these interactions, taking place in the 4-cell stage, the germline cell P2 induces longitudinal orientation of the cleavage spindle in the neighboring EMS cell, its asymmetric division, and the establishment of a gut lineage. Application of several polysulfated hydrocarbon dyes (e.g., trypan blue, TB) in the 1- to 4-cell stages inhibits induction of the gut precursor cell. However, dye application from the late 4-cell stage onward does not interfere with gut induction, supporting the earlier finding of a short time window for this interaction. We also tested the effect of TB on the induction of pharyngeal muscle cells by the MS blastomere, which appears to involve a surface receptor-ligand interaction. We found that this process is inhibited as well. These and additional data indicate that polysulfated hydrocarbon dyes are suitable tools to generally interfere with cell-cell interactions in the nematode embryo.