Ricin A chain can be used to arrest cell metabolism as it inhibits translation by targeting rRNA. Unlike DNase I, injection of ricin A chain does not require such a high level of precision as DNase I. Over-dosage of DNase I leads to cell lysis, and this often causes serious problems in embryo culture. It is more desirable that the ablated cell become arrested, and ricin A chain can do this in a broad range of working concentration.

For injection, we adjust the final concentration of ricin A chain (Sigma L4022, supplied in buffered glycerol solution) to ~ 0.1 mg/ml by diluting the ricin A chain stock solution with a 1:1 mixture of 100 mg/ml fluorescent dextran lineage tracer and 4% Fast Green (both in 0.2 M KCl).