Microinjection of alpha-toxin from Clostridium novyi type A promotes meiotic maturation in Xenopus laevis oocytes.

Microinjection of purified alpha-toxin into Xenopus laevis oocytes induced meiotic maturation provided insulin was present in the medium. Induction of maturation as indicated by breakdown of the germinal vesicle depended on the amount of intracellular alpha-toxin (with a detection limit of 2 ng/oocyte) and on the concentration of insulin. The hormone concentrations used were inactive when given alone and so was alpha-toxin (1 micrograms/ml) applied from the outside. The results demonstrate an intracellular target for alpha-toxin whereas an extracellular target is apparently lacking in oocytes.