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Presents a study to clarify the temporal and causal relationships between mitogen-activated protein (MAP) kinase and maturation-promoting factor (MPF) during meiotic maturation, particularly during the resumption of meiosis. Use of pig oocytes matured synchronously in culture; Analysis of kinase activities; Demonstration that MAP kinase is activated simultaneously with MFP at germinal vesicle breakdown; Indication that its activation is not essential for the activation of MPF nor for the resumption of the first meiosis in pig oocytes.

In several transformed cell lines, the growth factors IGF-I and epidermal growth factor (EGF) activate second messenger systems that cause the phosphorylation of the estrogen receptor (ER). One kinase catalysing receptor phosphorylation is mitogen activated protein (MAP) kinase, and the result of phosphorylation is an increase in receptor transactivation function. EGF and IGF-I, secreted locally and systemically, are involved in uterine–conceptus interactions in early pregnancy, and therefore it is of interest to determine whether these growth factors affect ER function in the uterus. An estrogen response element, chloramphenicol acetyl transferase reporter gene construct (CATERE) was transfected into bovine endometrial epithelial and stromal cells in vitro, and CAT measured during transient expression. Growth factors were added at various times following transfection, and MAP kinase phosphorylation was monitored by western blotting of p42 and p44. The MEK inhibitor U 0126 was used to determine whether the effect of IGF-I on CATERE expression was mediated through MAP kinase, and the anti-estrogen ICI 182780 was used to identify effects involving the ER. In stromal cells, reporter gene activity was increased in a dose dependent manner by IGF-I or hEGF in the presence or absence of estradiol-17β. In the absence of estradiol the effect of IGF-I was not inhibited by ICI 182780. The effect of IGF-I occurred within an hour, before any detectable increase in cell proliferation, and the activation of CAT expression in response to IGF-I or EGF was blocked by U 0126. In contrast to their effects in stromal cells, neither IGF-I nor EGF affected CAT expression in bovine endometrial epithelial cells. Measurement of phosphorylated MAP kinases p42/p44 by western blotting showed that EGF but not IGF-I activated MAP kinase phosphorylation in both epithelial and stromal cells. In stromal cells, the fact that U 0126 blocked the CAT responses to IGF-I and EGF indicates the involvement of a MAP kinase. But since IGF-I did not activate p42/p44, a different MAP kinase, not detected by the antibody used here, is implicated. As the response was not blocked by ICI 182780, we conclude this effect is independent of ER activation. Therefore in bovine uterine cells in culture effects on MAP kinases p42/p44 can be dissociated from those on ERE-dependent gene expression, and reporter gene expression may be independent of ER activation. [Copyright &y& Elsevier]

Ovine interferon tau (oIFN-τ) is an embryonic protein of critical importance in the establishment of pregnancy in the sheep. We have produced recombinant (r) oIFN-τ using a baculovirus expression system and demonstrated the biological activity of the protein produced. Bombyx mori larvae were infected with B. mori nuclear polyhedrosis virus (BmNPV), modified by inserting a cDNA coding for oIFN-τ downstream of the strong polyhedron promoter. Following infection, antiviral activity of the haemolymph rose to a maximum of 3.6 x 108 u/mL (equivalent to 3 mg roIFN-τ/mL) by day 5, when haemolymph was collected and stored frozen. Control haemolymph, collected from uninfected insects at an equivalent time, contained no antiviral activity. The roIFN-τ was partially purified by gel filtration column chromatography and the presence of roIFN-τ confirmed by western blotting. The biological activity of the partially purified roIFN-τ was tested in ewes. Treatment with roIFN-τ caused a significant delay in luteolysis confirming biological potency. The results demonstrate that this system can be successfully used to produce large quantities of roIFN-τ. [ABSTRACT FROM AUTHOR]

Examines the rapid increase in plasma prostaglandin concentrations after vaginal examinations and amniotomy in Great Britain. Measurement of peripheral plasma concentrations; Analysis on the result of the study; Explanation on the influence of amniotomy and vaginal examination on labor.