Partial characterisation of early pregnancy factor in the sheep

Identification of a putative inhibitor of early pregnancy factor in mice

“…The earlier studies of Clarke et al (1980), which showed that 40% saturated ammonium sulphate could apparently split EPF activity in early pregnancy serum into two components, were repeated but tested over an extensive range of dilutions, as shown in Fig. 1(a) Since the original studies indicated that "EPF-A" was produced by the oviduct during oestrus as well as early pregnancy (Morton et ai, 1980), the present studies were extended to include serum from mice in oestrus and dioestrus.…”

The 'early pregnancy factor' revisited: the effect of ammonium sulfate on the capacity of pregnant mouse sera to express activity in the rosette inhibition assay

“…While the first mentioned phenomenon is addressed in a later paper, the present report re-examines the latter phenomenon. Clarke et al (1980) reported that when pregnancy sera were treated with 40% ammonium sulfate, and the resulting supernatant and pellet fractions were collected and extensively dialysed and then tested in the rosette inhibition assay, neither pellet, nor supernatant fraction, could induce increased rosette inhibition titres. However, when these dialysed fractions were recom¬ bined the combination induced increased inhibition titres, mimicking the action of the unfractionated sera.…”

Isolation and Purification of Early Pregnancy Factor (EPF) in Rat Serum.

“…It has been shown that EPF from serum 1 to 7 days after gestation is separated to EPF-A and EPF-B by 40% ammonium sulfate fractionation [4,9]. EPF-A (soluble in 40% ammonium sulfate) is produced by the oviduct during estrus and pregnancy, and EPF-B (insoluble in 40% ammonium sulfate) is produced by the ovary only during pregnancy.…”

“…In sheep, the purified EPF active material had a M. W. of 20 KD from sera 24 h after insemination [4] and of 20 KD and 67 KD from sera at 3 to 8 weeks of gestation [13]. Clarke and Wilson [14] reported that the major rosette inhibition test active form was characterized as a protein with a M. W. of 20 KD, possessed internal disulphide loop(s), and had a tendency to aggregate into oligomers.…”