Schistosoma mansoni: stage-dependent formation and repair of membrane pores induced by a cytotoxin from Pseudomonas aeruginosa.

Various stages of Schistosoma mansoni were treated with a cytotoxin from Pseudomonas aeruginosa and their response to the damaging effect was studied in detail. Marker release and membrane potential measurements showed that the cytotoxin formed stable pores in all developmental stages. However, in juvenile 27-day-old worms, which are refractory to the killing effect of the cytotoxin, the pores had a smaller functional diameter as compared to other stages including 31-day-old worms. Furthermore, these resistant 27-day-old worms, but not susceptible older juvenile worms were able to repair the membrane lesions as shown by restoration of the resting membrane potential. In contrast, older juvenile and adult parasites were unable to cope with the breakdown of the resting potential induced by the cytotoxin. The results demonstrate the existence in 27-day-old schistosomes of effective repair mechanisms dealing with damage to the surface membrane.