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1.
Establishment of pregnancy in cattle has been proposed to depend on production of a conceptus protein, bovine trophoblast protein-1 (bTP-1), which has a high degree of sequence homology with bovine interferon-alpha (bIFN-alpha), especially the alpha II subfamily. A preparation of bovine conceptus secretory proteins enriched for bTP-1 has antiviral and physico-chemical properties similar to other bIFN-alpha. Antiviral activity is initially detectable in uterine flushings on Day 14 of pregnancy, when the conceptus measures 4-5 mm in length, and increases as the conceptus elongates through Day 18. Day 17 conceptuses produce more than 10(6) U antiviral activity during 24 h of culture. All IFNs induce the enzyme 2',5'-oligoadenylate synthetase, which catalyzes production of 2',5'-oligo(A), which in turn is involved in antiviral and growth inhibitory effects of IFNs. This enzyme activity is induced in Madin-Darby bovine kidney cells by the partially purified bTP-1 preparation similarly to IFN-alpha, -beta, and -gamma. Likewise, the partially purified bTP-1 and bIFN-alpha 1 induce 2',5'-oligo(A) synthetase activity in monolayers of endometrial epithelial and stromal cells. Compared to epithelial cells, stromal cells have higher baseline activity of 2'-5'-oligo(A) synthetase activity (p less than 0.01) and show a greater degree of induction in the presence of either the partially purified bTP-1 or bIFN-alpha 1 (p less than 0.01). Also, 2',5'-oligo(A) synthetase of endometrial stromal cells is induced to a greater degree by our enriched bTP-1 preparation than by bIFN-alpha 1 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
2.
Galactose-1-phosphate uridylyltransferase (uridine diphosphoglucose: α-d-galactose-1-phosphate uridylyltransferase, EC 2.7.7.12) has been purified 4000-fold from human placenta in four chromatographic steps using DEAE-cellulose, hydrocylapatite, ethyliminohexylagarose, and Sephacryl S-200. The specific activity of the homogeneous enzyme was 56 units/mg protein. The placental enzyme consists of two similar subunits, each of molecular weight about 48,000. The placental enzyme was similar to published results for the red cell enzyme (V. P. Williams, Arch. Biochem. Biophys., 1978, 191, 182–191) with respect to subunit molecular weight, electrophoretic migration, and immunological properties. The more purified fractions of the placental enzyme invariably contained a glycoprotein which was removed in the gel filtration step. After this glycoprotein was removed, the enzyme was very labile and only about 20% of the catalytic activity was recovered. 相似文献
3.
T S Gross C Plante W W Thatcher P J Hansen S D Helmer D J Putney 《Biology of reproduction》1988,39(4):977-987
The conceptus is believed to produce factors that regulate endometrial function and prevent luteolysis during early pregnancy. Endometrial tissues were collected from cyclic (n = 8) and pregnant (n = 2) cows at Day 17 post-estrus and cultured for 24 and 48 h with bovine conceptus secretory proteins (bCSP) (0%, 10%, 100%), where the amount of protein produced by a bovine conceptus during 24 h of culture is 100%. Incorporation of [3H]leucine into secreted proteins was determined and examined qualitatively by trichloroacetic acid precipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography. Levels of an intracellular endometrial inhibitor of prostaglandin synthesis were determined with a cotyledonary microsomal test system. Treatment with 10% and 100% bCSP reduced incorporation of [3H]leucine into secreted proteins. However, bCSP selectively induced two secreted proteins (13 and 10 kDa) from endometrium of cyclic cows. Prostaglandin F (PGF) secretion was decreased by bCSP treatment while prostaglandin E2 secretion was unaltered. An intracellular endometrial inhibitor of prostaglandin synthesis was induced by bCSP; synthesis of PGF by the cotyledonary prostaglandin-generating system was decreased when incubated with cytosol of endometrium treated with bCSP, but unaltered by cytosol from control tissues. In conclusion, products produced by the bovine conceptus are capable of regulating endometrial protein and prostaglandin biosynthesis in a fashion that could act to prevent luteolysis in vivo and provide endometrial secretory products for embryonic development. 相似文献
4.
Aluminum geochemistry in peatland waters 总被引:4,自引:4,他引:0
The chemical speciation of aluminum was examined in surface water samples from Sphagnum peatlands in north-central Minnesota, from peatlands along the Canadian east coast, and from bogs in the Pennine Mountain area of England. In highly organic ([DOC] 50 mg L–1 ), low pH waters, 80–90% of total dissolved Al was complexed with organic matter (OM), while in waters with low DOC ([DOC] 5 mg L–1) 54–86% of total dissolved Al existed as Al+3 or other inorganic Al species. Batch titrations of OM with Al revealed a high Al binding capacity, 1.4–2.8 mol (mg DOC)–1, that generally was unsaturated with Al. Titrations of OM with Al in conjunction with a continuous distribution model were used to determine Al-OM conditional stability constants. Binding capacity (mol Al (mg DOC)–1) and strength (formation constant) increased from pH 3 to 5 but decreased above pH 5 due to formation of AI-hydroxy species including A1(OH)3 (s). The high binding capacity of OM in bog waters facilitates metal mobility, especially in low pH (< 5) wetlands where metal solubility is high and OM concentrations are highest. Results showed that the relative degree of organic matter saturation with metal ions was important in modeling AI speciation in bog waters. 相似文献
5.
The conserved ninth C-terminal heptad in thyroid hormone and retinoic acid receptors mediates diverse responses by affecting heterodimer but not homodimer formation. 总被引:18,自引:11,他引:7 下载免费PDF全文
M Au-Fliegner E Helmer J Casanova B M Raaka H H Samuels 《Molecular and cellular biology》1993,13(9):5725-5737
6.
Human galactose-1-phosphate uridylyltrsferase: purification and comparison of the red blood cell and placental enzymes 总被引:1,自引:0,他引:1
Galactose-1-phosphate Uridylyltransferase (uridine diphosphoglucose: α-d-galactose-1-phosphate Uridylyltransferase, EC 2.7.7.12) has been purified from human red blood cells and placental tissue. The placental enzyme was obtained as a homogeneous protein with a specific activity of about 100 units/mg of protein by a combination of previously published methods (G. R. Helmer, Jr., and V. P. Williams, 1981,Arch. Biochem. Biophys.210, 573–580) and concanavalin A-Sepharose chromatography. The properties of the two enzyme forms have been examined with respect to subunit size, electrophoretic properties, isozyme distribution, kinetic patterns, and immunological properties. 相似文献
7.
Genetic analysis of potassium transport loci in Escherichia coli: evidence for three constitutive systems mediating uptake potassium. 总被引:14,自引:9,他引:5 下载免费PDF全文
D C Dosch G L Helmer S H Sutton F F Salvacion W Epstein 《Journal of bacteriology》1991,173(2):687-696
The analysis of mutants of Escherichia coli that require elevated concentrations of K+ for growth has revealed two new genes, trkG, near minute 30 within the cryptic rac prophage, and trkH, near minute 87, the products of which affect constitutive K+ transport. The analysis of these and other trk mutations suggests that high rates of transport, previously considered to represent the activity of a single system, named TrkA, appear to be the sum of two systems, here named TrkG and TrkH. Each of these two is absolutely dependent on the product of the trkA gene, a cytoplasmic protein associated with the inner membrane (D. Bossemeyer, A. Borchard, D. C. Dosch, G. C. Helmer, W. Epstein, I. R. Booth, and E. P. Bakker, J. Biol. Chem. 264:16403-16410, 1989). The TrkH system is also dependent on the products of the trkH and trkE genes, while the TrkG system is also dependent on the product of the trkG gene and partially dependent on the product of the trkE gene. It is suggested that the trkH and trkG products are membrane proteins that form the transmembrane path for the K+ movement of the respective systems. Two mutations altering the trkA product reduce the affinity for K+ of both TrkG and TrkH, indicating that changes in peripheral protein can alter the conformation of the sites at which K+ is bound prior to transport. The TrkD system has a relatively modest rate of transport, is dependent solely on the product of the trkD gene, and is the sole saturable system for Cs+ uptake in this species (D. Bossemeyer, A. Schl?sser, and E. P. Bakker, J. Bacteriol. 171:2219-2221, 1989). 相似文献
8.
A R Fuchs H Helmer O Behrens H C Liu L Antonian S M Chang M J Fields 《Biology of reproduction》1992,47(6):937-944
Oxytocin receptors were measured in myometrium and intercaruncular endometrium of cows during pregnancy and parturition. Concentrations of estradiol-17 beta, estrone, and progesterone in peripheral blood were also measured. Receptor concentrations in the endometrium rose almost 200-fold from Day 20 to term (p < 0.0001, ANOVA), from 40 +/- 11 to 7300 +/- 1430 fmol/mg protein. Myometrial receptor concentrations increased 10-fold from 180 +/- 36 fmol/mg on Day 20 to 1850 +/- 360 fmol/mg protein at term (p < 0.0001, ANOVA). During labor, endometrial receptors (6600 +/- 1300 fmol/mg) remained at prelabor values, whereas myometrial receptor concentrations had decreased to 1190 +/- 316 fmol/mg (not significant) and declined further postpartum. Plasma concentrations of progesterone declined from 4-5 ng/ml to about 2 ng/ml between Days 250 and 282 and dropped to < 0.2 ng/ml shortly before delivery. Plasma concentrations of estrone and estradiol-17 beta were below 10-20 pg/ml until Day 230. Estrone concentrations were significantly (p < 0.05) increased by Day 250 and estradiol-17 beta by Day 270, and then both rose rapidly. During labor, plasma estrone was 1135 +/- 245 pg/ml and plasma estradiol-17 beta was 226 +/- 131 pg/ml. The molar ratio of estrone and estradiol-17 beta to progesterone rose from less than 0.01 to 4.4 during labor, and was correlated with oxytocin receptor concentrations in endometrium (r = 0.5160, p < 0.001), but not those in myometrium (r = 0.0122). The regulation of oxytocin receptors by ovarian hormones in the two tissues may therefore differ.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
Functional evidence for ligand-dependent dissociation of thyroid hormone and retinoic acid receptors from an inhibitory cellular factor. 总被引:9,自引:10,他引:9 下载免费PDF全文
10.
Jean Kaboré Marie Metzger Catherine Helmer Claudine Berr Christophe Tzourio Ziad A. Massy Bénédicte Stengel 《PloS one》2016,11(1)