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1.
Holstein heifers (n = 29) were used to determine whether thermal stress during the first 7 d of embryonic development may increase the incidence of embryonic abnormalities in dairy cattle. Heifers were acclimated to environmental chambers at 20 degrees C for 9 d and superovulated with follicle stimulating hormone-pituitary (FSH-P; 40 mg total), beginning on Days 9 to 11 of the estrous cycle. Prostaglandin F(2)alpha (Lutalyse; 50 mg total) was administered on Day 3 of FSH-P. Heifers were inseminated artificially at estrus and then maintained at either thermal neutrality (20 degrees C) or under hyperthermic conditions (daily exposure up to 16 h at 30 degrees C and 8 h at 42 degrees C) for 7 d beginning at 30 h after the onset of estrus. On Day 7 post estrus, embryos were recovered nonsurgically and evaluated morphologically for stage of development and quality. The distribution of embryos classified as normal, abnormal, retarded or as unfertilized ova, differed (P<0.001) between heat stress and thermoneutral treatments. Only 20.7% of 82 embryos recovered from stressed heifers were normal compared with 51.5% of 68 embryos from thermoneutral animals. Stressed heifers had a higher incidence of abnormal and retarded embryos with degenerate nonviable blastomeres. Responses indicated that thermal stress from 30 h after the onset of estrus to Day 7 post estrus increases the incidence of abnormal and retarded embryos in superovulated heifers. 相似文献
2.
F W Bazer W W Thatcher F Martinat-Botte M Terqui 《Journal of reproduction and fertility》1988,84(1):37-42
Large White (LW) and Meishan (MS) gilts were killed on Days 8, 10, 11, 12, 14 and 30 of gestation. Mean diameters (mm) for MS and LW conceptuses, respectively, were: Day 8, 0.45 and 0.69; Day 10, 2.7 and 1.9; Day 11, 5.3 and 2.7, with the differences among days being affected by breed (P less than 0.01). Variation in diameter among conceptuses from LW gilts was greater (P less than 0.01) than that for MS gilts on Days 8-11, respectively: Day 8, 20 and 46%; Day 10, 29 and 38%; and Day 11, 22 and 44%. Conceptuses had elongated in 3 of 5 MS and 1 of 4 LW gilts on Day 11, 6 and 6 MS and 2 of 4 LW gilts on Day 12 and all gilts of both breeds on Day 14. These results indicate that conceptuses of MS gilts develop more rapidly and more uniformly between Days 8 and 14 of gestation. Overall, embryonic survival for Days 8-12 for gilts not having elongated conceptuses was 90.2% for MS and 73.2% for LW gilts (P less than 0.01). On Day 30 of gestation, embryonic survival was also higher (P less than 0.01) for MS (89%) than LW (55%) gilts. However, embryonic weight, crown-rump length, placental length, allantoic fluid volume, amniotic fluid volume, as well as total glucose, fructose and protein in allantoic fluid were not affected by breed. Placental weight was greater (P less than 0.01) for LW gilts. Uterine development at Day 30 of gestation, based on total length and weight of uterine horns, width of uterine horns, total endometrial surface area and total endometrial weight was greater (P less than 0.01) for LW gilts.(ABSTRACT TRUNCATED AT 250 WORDS) 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.
Proteins secreted by day-16 to -18 bovine conceptuses extend corpus luteum function in cows 总被引:1,自引:0,他引:1
J J Knickerbocker W W Thatcher F W Bazer M Drost D H Barron K B Fincher R M Roberts 《Journal of reproduction and fertility》1986,77(2):381-391
Corpus luteum function, interoestrous interval and spontaneous uterine PGF-2 alpha (PGF) production were evaluated in 9 cyclic Holstein cows (3/group) after intrauterine injections of pooled conceptus secretory proteins, 5 beta-pregnan-3 alpha-ol-20-one, or homologous serum proteins on Days 15.5 through 21 after oestrus. A significant extension of corpus luteum lifespan and interoestrous interval were detected in cows treated with conceptus secretory proteins compared to the other 2 groups. CL lifespan and interoestrous interval were not different (P greater than 0.25) between 5 beta-pregnan-3 alpha-ol-20-one and control groups. Evaluation of spontaneous PGF responses suggested that proteins synthesized and secreted by the bovine conceptus accommodate luteal maintenance during early gestation via an attenuation of endometrial PGF production. 相似文献
5.
Human interleukin-2 (IL-2) has 3 cysteine residues; cysteines 58 and 105 form an intramolecular disulfide bridge, whereas cysteine 125 has a free sulfhydryl group. In this study, site-specific mutagenesis has been used to modify the cysteine residues of recombinant Escherichia coli-derived IL-2 (rIL-2) to evaluate the functional structure of IL-2. Substitution or deletion of cysteine 105 disrupted the disulfide bridge and yielded a mutant protein which was 8-10 times less active than wild type rIL-2. A similar modification at position 58, however, reduced the activity of rIL-2 by more than 250-fold. Although substitution of serine for cysteine 125 did not affect IL-2 activity, deletion of cysteine 125 or deletion of amino acids in the vicinity of this cysteine yielded mutant proteins with little, if any, activity. These results indicate that the protein structure in the vicinity of both positions 58 and 125 is more critical than that close to position 105. These findings may provide a clue to the understanding of the functional structure of human IL-2. 相似文献
6.
S M Liang B Allet K Rose M Hirschi C M Liang D R Thatcher 《The Biochemical journal》1985,229(2):429-439
Interleukin 2 isolated from Escherichia coli cells expressing the human interleukin gene has been characterized. The observed properties of the protein have been compared with those properties which can be deduced from the DNA sequence alone and the published properties of natural human interleukin 2. The purified E. coli-derived interleukin 2 is a monomeric protein of Mr 15 000 with a sedimentation velocity of 1.86S. The amino acid composition of the protein and isoelectric point (7.7) are consistent with that part of the translated DNA sequence of the gene corresponding to the mature protein. A single disulphide bridge was identified between Cys-58 and Cys-105. C.d. suggested that interleukin 2 is predominantly alpha-helical in secondary structure. The E. coli-derived protein differed from natural interleukin 2 in the presence of N-terminal methionine and also in the absence of a carbohydrate moiety. Removal of the coding region for the first three amino acids of the natural interleukin 2 protein sequence (Ala-Pro-Thr) by site-specific mutagenesis resulted in a protein with N-terminal serine. The possibility that the specificity of the E. coli ribosomal methionine aminopeptidase may not recognize the sequence NH2-Met-Xaa-Pro is discussed (where Xaa is any amino acid residue). 相似文献
7.
The effect of bovine conceptus secretory proteins (CSP) on uterine prostaglandin (PG)-F2 alpha production was evaluated in dairy cattle following injection of estradiol-17 beta. Intrauterine injections of dialyzed serum proteins (Control, n = 5) or CSP (n = 5) were administered from days 15 through 18 post-estrus. Following intrauterine treatments on day 18, all cows were injected with E2 (3 mg) to stimulate uterine PGF2 alpha production. Plasma concentrations of progesterone (P4) and 15-keto-13,14-dihydro-PGF2 alpha (PGFM) were determined by RIA. The PGFM responses following E2 challenge were decreased (p less than 0.01) for cows receiving CSP versus serum proteins into the uterine lumen. Individual PGFM, P4 and cycle length responses are discussed. Data suggest that proteins secreted by the bovine conceptus suppress uterine PGF2 alpha production during pregnancy recognition in the cow. 相似文献
8.
On day 17 postestrus or postmating, heifers were given intrauterine injections of saline (2 pregnant, 2 non-pregnant) or 200 micrograms PGF2 alpha (7 pregnant, 6 nonpregnant) through cannulae installed surgically into the uterine horn ipsilateral to the corpus luteum bearing ovary. Jugular blood samples were collected prior to the laparotomy at which the cannulae were installed during surgery, and for 90 min following the intrauterine injection. Plasma was assayed for progesterone and 13,14-dihydro-15-keto-PGF2 alpha (PGFM). Laparotomies were reopened to confirm proper cannula placement and to determine if blastocysts were present in mated heifers. Concentrations of PGFM were higher in pregnant compared to nonpregnant heifers during the presurgery (68 +/- 26 vs 24 +/- 26 pg/ml; P less than .025) and surgery (186 +/- 47 vs 65 +/- 17 pg/ml; P less than .05) periods. Pregnancy status did not alter the mean concentrations of PGFM (pregnant, 554 +/- 70 pg/ml; nonpregnant, 422 +/- 81 pg/ml) or the half-life of its decline in concentration (18 min) following intrauterine injection of PGF2 alpha. Pregnancy at 17 days in cattle does not appear to influence PGF2 alpha transport from the uterine lumen or its metabolism in the uterus or elsewhere in response to an acute intrauterine injection. 相似文献
9.
Marilyn Frank Fuller W. Bazer W.W. Thatcher C.J. Wilcox 《Prostaglandins & other lipid mediators》1977,14(6):1183-1196
Polyvinyl catheters were placed into the right and left utero-ovarian veins and saphenous vein and artery of three control (C) and four estradiol valerate (EV) treated gilts on Day 9 after onset of estrus. The EV treated gilts received 5mg EV/day on Days 11 through 15 after onset of estrus. On Days 12 through 17 utero-ovarian vein blood samples were collected at 15 min intervals from 0700 to 1000 hr and 1900 to 2200 hr and single samples were taken at 1100 and 2300 hr. Peripheral blood samples (saphenous vein or artery) were taken at 0700, 1100, 1900 and 2300 hr from Day 12 until the control gilts returned to estrus or until Day 25 for EV treated gilts and used to measure plasma steroid hormone concentrations. Utero-ovarian vein prostaglandin F (PGF) concentrations (ng/ml, n=1,177) were measured by RIA. Status (control
EV treated gilts) by day interactions were detected (P=.10). Curvilinear day trends were detected for plasma PGF concentrations in control (P<.01) but not EV treated gilts. PGF concentrations (
) for control and EV treated gilts were 1.20 ± 2.08 and .26 ± .84 ng/ml, respectively. PGF peaks (concentrations greater than
+ 2 S.D.) occured with greater frequency in control gilts (X2 = 4.87; P<.05). The interestrus interval (
) for control and treated gilts was 19.0 ± .6 and 146.5 ± 74.8 days, respectively. Data indicate that estradiol valerate may exert its luteotrophic effect by preventing PGF release from the uterus. 相似文献
10.
The Escherichia coli D-galactose and D-glucose receptor, an aqueous periplasmic receptor that triggers sugar sensing and transport, possesses a single Ca2+ binding site similar in structure and specificity to the EF-hand class of sites found in eukaryotic Ca2+ signaling proteins including calmodulin and its homologues. A universal feature of these sites is the use of a pentagonal bipyramidal array of seven oxygens to coordinate bound Ca2+. Here we investigate the mechanisms used by this coordinating array to control ion specificity. To vary the cavity size and charge of the array, we have replaced axial glutamine 142 in the prokaryotic site with asparagine, glutamate, and aspartate. The ion selectivities of the resulting engineered sites have been quantitated by measuring dissociation constants for a series of spherical metal ions, differing in increments of radius and charge, from groups Ia, IIa, and IIIa and the lanthanides. Dramatic specificity changes are observed: sites containing an engineered smaller side chain (Asn or Asp) bind the largest cations up to 50-fold more tightly than the native site; and sites containing an engineered negative side chain (Glu or Asp) exhibit preferences for trivalent over divalent cations up to 1900-fold higher than the native site. The results indicate that the cavity size and negative charge of the coordination array play key roles in selective Ca2+ binding and that the array can be engineered to preferentially bind other cations. 相似文献