• Cpn 10;
  • cpn 60;
  • early pregnancy factor;
  • polymerase chain reaction;
  • rosette inhibition test

PROBLEM: The aim of this study was to investigate the expression of chaperonin (cpn) 10 and cpn 60 mRNA in oocytes or embryos, and to further explore the possibility that early pregnancy factor (EPF) is identical with cpn 10. METHOD OF STUDY: The expressions of cpn 10 and cpn 60 mRNA in oocytes and embryos at the different stages (1-cell, 2-cell, 8-cell, and morula) were examined by polymerase chain reaction techniques. The EPF activity of native rat cpn 10 isolated from rat livers was evaluated by the rosette inhibition test. RESULTS: Similar levels of mRNA of cpn 10 and cpn 60 were detected in oocytes and embryos at every stage. There were no detectable EPF activities in the native cpn 10. Immunoprecipitation using polyclonal antibodies against cpn 10 did not affect the activity of EPF in the pregnant rat serum. CONCLUSION: Our results do not support the hypothesis that cpn 10 is identical with EPF.