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

Clark, I. Q.; Orozco, C.; Cock, Ian Edwin; Clarke, Frank M.

doi:10.1530/jrf.0.1000279

Cited by 6 publications

(11 citation statements)

References 20 publications

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“…OPN/Eta-1 binds sheep red blood cell (SRBC) glycophorin and inhibits the ability of SRBC to interact with mouse Tlymphocytes that express surface receptors specific for SRBC glycophorin [11]. This rosette inhibition activity has been used as an indicator of a viable conceptus [16] and is attributed to early pregnancy factor (EPF) [17,18].…”

Section: Introductionmentioning

confidence: 99%

Ovine Osteopontin: I. Cloning and Expression of Messenger Ribonucleic Acid in the Uterus During the Periimplantation Period1

Johnson

Spencer

Burghardt

et al. 1999

Biology of Reproduction

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Trophoblast-derived interferon tau (IFNtau) acts on the endometrium to increase secretion of several proteins during the pregnancy recognition period in ruminants. One of these is a 70-kDa acidic protein that has not been identified. Our hypothesis was that the 70-kDa acidic protein is osteopontin (OPN). OPN is an acidic glycoprotein that fragments upon freezing and thawing or treatment with proteases including thrombin. OPN contains a Gly-Arg-Gly-Asp-Ser (GRGDS) sequence that binds to cell surface integrins to promote cell-cell attachment and cell spreading. Using antisera to recombinant human OPN, both 70-kDa and 45-kDa proteins were identified in uterine flushings from pregnant ewes by Western blotting. A clone containing the entire ovine OPN cDNA coding sequence was isolated by screening a Day 15 pregnant ovine endometrial cDNA library with a partial ovine OPN cDNA. In pregnant ewes, steady-state levels of OPN endometrial mRNA increased (P < 0. 01) after Day 17. In both cyclic and pregnant ewes, in situ hybridization analysis showed that OPN mRNA was localized on unidentified immune cells within the stratum compactum of the endometrium. In pregnant ewes, OPN mRNA was also expressed by the glandular epithelium. Results suggest that progesterone and/or IFNtau induce expression and secretion of OPN by uterine glands during the periimplantation period and that OPN may induce adhesion between luminal epithelium and trophectoderm to facilitate superficial implantation.

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Section: Introductionmentioning

confidence: 99%

Ovine Osteopontin: I. Cloning and Expression of Messenger Ribonucleic Acid in the Uterus During the Periimplantation Period1

Johnson

Spencer

Burghardt

et al. 1999

Biology of Reproduction

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“…Collection of sera and ammonium sulfate fractionation Sera were prepared from the blood of male mice and female mice (at days 2 and 10 of pregnancy) as described by Clark et al (1994). Individual serum samples were fractionated with 40% ammonium sulfate and the resulting supernatant and pellet fractions were extensively dialysed against PBS using nominal 8 kDa cut-off dialysis membranes.…”

Section: Methodsmentioning

confidence: 99%

“…Individual serum samples were fractionated with 40% ammonium sulfate and the resulting supernatant and pellet fractions were extensively dialysed against PBS using nominal 8 kDa cut-off dialysis membranes. The dialysis procedures were as described for Expt 1 in Clark et al, 1994, that is, each individual sample was dialysed alone in a separate container against three successive changes of 100-fold excess volumes of PBS. After the third dialysis step, the retentates were collected and stored in suitable aliquots at -30°C The extensively dialysed supernatant and pellet retentate fractions obtained from pregnancy sera (day 2 or day 10) were designated as pSr and pPr, respectively, while those from male mouse sera were designated as mSr and mPr, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Clark et al (1994) reinvestigated the effects of ammonium sulfate fraction¬ ation. Treatment of sera from pregnant mice with 40% am¬ monium sulfate was shown to liberate low molecular mass active moieties from their association with macromolecular serum components.…”

Section: Introductionmentioning

confidence: 99%

“…In combination, however, components in the dialysed pellet retentate fraction cooperate with components in the dialysed supernatant reten¬ tate fraction to allow the expression of increased rosette inhibition titres when applied to fresh spleen cells in the rosette inhibition assay. In two-step incubation protocols, a prescribed order of addition must be followed if this cooperative effect is to be observed, namely supernatant retentate fraction applied first, followed by pellet retentate fraction in the second step, but not vice versa (Clark et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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A description of the basic system of components in pregnant mice sera responsible for 'early pregnancy factor' activity

Orozco¹,

Clark²,

Cock³

et al. 1994

Reproduction

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The supernatant and pellet retentate fractions obtained from sera from pregnant mice by ammonium sulfate fractionation and extensive dialysis cannot alone induce increased rosette inhibition titres in the rosette inhibition assay. In combination, however, the mixtures can induce increased rosette inhibition titres mimicking the activity of pregnancy sera previously ascribed to the early pregnancy factor. The studies described herein demonstrated that the supernatant retentate fractions derived from sera of pregnant mice were functionally equivalent to a platelet-activating factor (PAF) or a serum stimulus because they stimulated the spleen cells used in the assay to produce active moieties and cooperated with pure thioredoxin in allowing for expression of activity. Conversely, the pellet retentate fractions obtained from sera of pregnant mice were shown to be functionally equivalent to thioredoxin in that they cooperated with a PAF stimulus to allow for the expression of increased rosette inhibition titres. The supernatant retentate fractions obtained from sera from male mice were found to be functionally equivalent to the corresponding supernatant retentate fractions obtained from sera from pregnant mice in stimulating the production of active moieties and in cooperating with thioredoxin or the pellet fractions derived from sera from pregnant mice in allowing for increased rosette inhibition titres. The pellet retentate fractions obtained from male mouse sera, however, were not functionally equivalent to either thioredoxin or the corresponding pellet retentate fractions obtained from pregnancy sera. Consideration of these data led to a basic description of the system of components in pregnancy sera which is responsible for the expression of early pregnancy factor activity.

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Research progress about nature of early Pregnancy factor

Liu

Sun

Bing

et al. 1998

Journal of Forestry Research

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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

Cited by 6 publications

References 20 publications

Ovine Osteopontin: I. Cloning and Expression of Messenger Ribonucleic Acid in the Uterus During the Periimplantation Period1

Ovine Osteopontin: I. Cloning and Expression of Messenger Ribonucleic Acid in the Uterus During the Periimplantation Period1

A description of the basic system of components in pregnant mice sera responsible for 'early pregnancy factor' activity

Research progress about nature of early Pregnancy factor

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