Kazuei Ito

Study of Early Pregnancy Factor (EPF) in Equine (Equus caballus)

PROBLEM: Early pregnancy factor (EPF) is an immunosuppressive protein detected in the early pregnancy serum. We have already reported that we developed the rosette inhibition test for mare EPF and detected EPF in thoroughbreds. The aim of this study was to determine whether or not our method could be used clinically.
 METHODS OF STUDY: The rosette inhibition test for equine EPF was carried out on serum from six nonpregnant and six pregnant Shetland ponies, a female and a male Chinese pony, and four nonpregnant and 13 pregnant thoroughbred mares. In the thoroughbreds, sera were collected during the pregnancy period. Furthermore, we measured progesterone and detected pregnant mare serum gonadotrophin (PMSG) in order to confirm pregnancy of the Chinese pony 3 and 6 months after mating.
 RESULTS: In the nonpregnant Shetland ponies, the rosette inhibition titre (RIT) was 6.0±1.0 and EPF was negative. In contrast, in the pregnant ponies, the RIT was 9.2±0.4 and EPF was positive. Based on these results, we diagnosed pregnancy of the Chinese pony. The RIT of the female Chinese pony (3 months after mating) was above 10 and EPF was positive. Furthermore, we detected PMSG and progesterone in the serum of this pony. EPF appeared in the maternal blood circulation at 24–72 hr after mating, it was detected until the second trimester, and after that it disappeared from the maternal serum.
 CONCLUSIONS: The ponys EPF was detected by using the same rosette inhibition test as in the thoroughbred and was present from 24 to 72 hr after mating until the second trimester. The results indicated that our method was useful for pregnancy diagnosis of Equine.

Partial Purification of Mare Early Pregnancy Factor

Problem:  Early pregnancy factor (EPF) is an immunosuppressive protein detected in the serum in early pregnancy. We have already reported the development of the rosette inhibition test for mare EPF and have detected EPF in thoroughbreds and ponies. Here, we attempted to purify equine EPF from pregnant mare serum.

Chaperonin 10 in the Rat Oocytes and Early Embryos: its Expression and Activity for Early Pregnancy Factor

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.

Supplementation effect of early pregnancy factor-positive serum into bovine in vitro fertilization culture medium.

PROBLEM: Early pregnancy factor (EPF) has been detected in pregnant bovine serum, and its activity appeared from 24 to 48 hr after insemination. However, in bovine in vitro fertilization (IVF), an EPF‐like substance(s) had been detected in the culture medium of fertilized ovum. Therefore, we think that EPF and EPF‐like substance(s) are very important materials for the development of the embryo. In this study, we examined the development of the embryo when fertilized bovine ova were cultured with IVF culture medium supplemented with EPF‐positive or ‐negative serum.