Effect of Shigella toxin on preimplantation mouse embryos in vitro

Preimplantation mouse embryos at the 4‐cell to 8‐cell stage were exposed to Shigella dysenteriae toxin at concentrations of 0.001‐100 pg/ml in vitro. The effect of the toxin was studied by morphological observation of the embryos to the blastocyst stage, by assessing protein synthesis with 14Cleucine incorporation, and by measuring embryonic adenosine triphosphate (ATP) content. Preimplantation mouse embryos were highly sensitive to the toxin. All variables investigated were adversely influenced by the toxin. After a lag period of 24 hr, 0.01 pg/ml toxin inhibited development to the blastocyst stage and protein synthesis. Toxin concentrations of 1.0 pg/ml resulted in a significant decrease in ATP content.