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J D Godkin

Publications and source records attributed to J D Godkin.

45 records · Page 3Linked to original sources
PubMed1984

Ovine trophoblast protein 1, an early secreted blastocyst protein, binds specifically to uterine endometrium and affects protein synthesis.

Ovine trophoblastic protein-1 (oTP-1), an early secretory protein of the sheep blastocyst, was purified after culturing day 14-16 conceptuses for 24 h in vitro. The localization of oTP-1 in the pregnant day 16 sheep uterus was determined immunocytochemically. The protein was associated with trophectoderm cells of the elongated blastocyst and with the surface and upper glandular epithelium of the maternal uterus. Receptors that bound oTP-1 with high affinity (Kd = approximately 2 X 10(-10) M) were present in crude membrane preparations derived from homogenates of endometria from day 12 nonpregnant and anestrous ewes. Uterine infusion of 125I-labeled oTP-1 into day 12 nonpregnant ewes showed that the majority of the radioactivity was retained in the uterus, and only very small amounts of intact protein appeared to enter the maternal vasculature. There was no significant association with the corpora lutea, ovaries, or other tissues tested. oTP-1 failed to compete with ovine PRL for rabbit mammary gland receptors or with hCG or bovine LH for sheep luteal cell receptors, and the oTP-1 did not stimulate progesterone production by dispersed luteal cells from day 12 cycling ewes. Incubation of endometrial explants from day 12 nonpregnant ewes with 5 micrograms/ml oTP-1 resulted in increased rates of protein release into the medium. Two-dimensional polyacrylamide gel electrophoresis revealed that the synthesis of six polypeptides was stimulated selectively by the presence of oTP-1. Together these data suggest that oTP-1 acts on the maternal endometrium. It is suggested that the interaction of oTP-1 with uterine endometrium may elicit maternal responses which contribute to the maintenance of pregnancy in the sheep.

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PubMed1984

Proteins released by cultured Day 15-16 conceptuses prolong luteal maintenance when introduced into the uterine lumen of cyclic ewes.

Experiments were performed to determine whether proteins, produced and released into the incubation medium by Day 15-16 sheep conceptuses cultured for 24-48 h, could prolong the functional lifespan of the corpus luteum (CL) when infused into the uterine lumen of cyclic ewes. Beginning on Day 12 (oestrus = Day 0) either a concentrated (2 ml) solution of total conceptus culture medium protein (2.2 mg) or diluted sheep serum (2.2 mg protein) was introduced daily via an indwelling catheter into the uterine lumen of 3 ewes for 7 days (Days 12-18). Peripheral blood samples were collected daily for 14 days (Days 12-25). On Day 25 all ewes were laparotomized and ovaries observed to determine whether CL previously marked with India ink were maintained. All controls had ovulated and formed new CL. By contrast none of the conceptus protein-treated ewes had ovulated, and their peripheral progesterone levels remained elevated. One ewe maintained a functional CL until Day 52 when she was hysterectomized. Light microscopy of histological sections prepared from the endometrium revealed glandular development comparable to that in the endometrium of cyclic animals during late dioestrus. The cells of the CL were similar to those from cyclic animals during mid- to late dioestrus. Ovine trophoblast protein ( oTP -1), a major protein secreted by the sheep conceptus between Days 13 and 21 of pregnancy, was purified from conceptus incubation medium and injected (0.2 mg protein/day) into the uterine lumen of 3 animals. Plasma progesterone concentrations indicated that oTP -1-treated animals maintained luteal function 4 days longer than did control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1984

H1 histone synthesis by implanting pig blastocysts.

Histones were isolated from pig conceptuses on Days 8-18 of pregnancy, Acid-urea polyacrylamide gel electrophoresis (PAGE) was performed on samples of total histone and on PCA-soluble histone fractions (primarily histone H1). Conceptuses were also incubated for 24 h in vitro in the presence of [3H]lysine, and the histones analysed by autofluorography after PAGE. A minimum of two H1 histone bands was resolved in stained gels by these techniques. The autofluorographs indicate that both H1 histones are synthesized throughout the developmental period analysed. No shift in H1 histone subtype, as encountered in sea urchin development, was observed. The results suggest that such a shift, if it occurs, may have been made before Day 8.

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PubMed1982

Purification and properties of a major, low molecular weight protein released by the trophoblast of sheep blastocysts at day 13-21.

Sheep blastocysts (Day 13-21) incubated in a modified Minimum Essential Medium released proteins into the medium at an approximately linear rate over a 24-h period. Single Day-16 blastocysts converted 2-8% of the radioactivity supplied (100 muCi L-[3H]leucine) into non-dialysable macromolecules which were released into the medium. Two-dimensional polyacrylamide gel electrophoresis revealed that at Day 13 there was only one major product (Protein X), consisting of three closely similar isoelectric species of (pI of denatured polypeptides about 5.5), each with molecular weights of 17 000. Between Days 14 and 21 additional proteins were detected. One of these was of high molecular weight (greater than 660 000) and did not appear on the two-dimensional gels, but Protein X continued to predominate until Day 23 when it could not be detected. Explants of chorion from Day 30 of pregnancy failed to secrete Protein X. Protein X was released in significant quantities (50-100 micrograms per 24 h) by the trophoblast but not the yolk sac of Day-14 and Day-16 conceptuses, but was present in very low amounts in the tissues. Protein X from the incubation medium of Day-14 and Day-16 conceptuses was purified by successive DEAE ion exchange and Sephacryl S-200 gel chromatography. Because Protein X and some of the other proteins are produced transiently between Days 13 and 21, it is possible that they may play a role in maternal recognition of pregnancy in sheep.

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PubMed1982

High molecular weight glycoproteins released by expanding, pre-attachment sheep, pig and cow blastocysts in culture.

Blastocysts isolated from sheep (Day 14--16), pigs (Day 16) and cows (Day 19) during the pre-attachment elongation phase were cultured for up to 30 h in a modified MEM medium in the presence of radioactive amino acids (L-[14C]leucine or L-[35S]methionine) to label protein and D-[3H]glucosamine to label complex saccharides. All the blastocysts released considerable quantities of non-dialysable radioactive material into the medium at an approximately linear rate over the course of the incubation. Ion-exchange chromatography on DEAE cellulose at pH 8.2 revealed that the major glucosamine-labelled product in the medium was a non-sulphated glycoprotein which eluted early in the salt gradient. None of the blastocysts produced any detectable glycosaminoglycan-like materials such as hyaluronic acid. The glycoprotein was purified by ion-exchange and gel filtration chromatography and had a molecular weight of greater than 660 000. Up to 100 micrograms of this material could be isolated from incubations of 2 sheep conceptuses. It was relatively resistant to protease hydrolysis and consisted of approximately 50% carbohydrate and 50% protein. The main monosaccharide constituents, as revealed by gas-liquid chromatography, were galactose and N-acetylglucosamine plus some mannose and fucose. No sialic acid was present. The linkages between the carbohydrate chains and the peptide appeared to be resistant to alkaline borohydride cleavage and were probably, therefore, N-glycosidic.

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PubMed1978

Embryonic stimulation of ovine and bovine corpora lutea.

Preimplantation embryos, recovered from sheep on Days 13-15 of pregnancy, were incubated with luteal tissue from cyclic ewes. Extracts of ovine embryos were incubated with luteal tissue from cyclic Holstein cows. Embryos and embryo extracts significantly increased progesterone production by ovine and bovine luteal tissue in vitro. The embryos themselves did not produce measurable amounts of progesterone. We suggest that the ovine preimplantation embryo produces a substance with luteotrophic properties which contributes to the maintenance of early pregnancy.

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PubMedDate not supplied

Localization of bovine trophoblast protein-1 in the cow blastocyst during implantation: an immunological cryoultrastructural study.

At implantation in ruminants the signal for maintenance of progesterone production by the corpus luteum, essential for a successful pregnancy, is an interferon-like protein (bovine, ovine or caprine trophoblast protein-1; e.g. bTP-1) produced by the blastocyst trophoblast. This quantitative immunogold cryoultrastructural study demonstrates that bTP-1 immunoreactivity is found only in the Golgi complex and associated clear vesicles in the uninucleate trophoblast cells between 18 and 23 days post insemination. The characteristic trophoblast binucleate cells (up to 20 per cent by number) show no significant label at any time. There is also some evidence for transient labelling of the fetomaternal microvillar junction at the time of maximum bTP-1 production suggesting a transfer of the molecule by exocytosis. No evidence for any labelling within the uterine epithelium was observed.

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