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排序方式: 共有78条查询结果,搜索用时 15 毫秒
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Effect of Oil Overlay on Inhibition Potential of Roscovitine in Sheep Cumulus‐Oocyte Complexes 下载免费PDF全文
LF Crocomo WC Marques Filho CMV Ulian NS Branchini DT Silva CL Ackermann FC Landim‐Alvarenga SD Bicudo 《Reproduction in domestic animals》2015,50(3):410-416
Inhibitors of cyclin‐dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus‐oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor‐free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (?) at 38.5°C and 5% CO2. At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/?) exhibited total expansion while in both Rosco groups (+/?) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p < 0.05). This meiotic arrest was reversible, and proper meiosis progression also occurred in the Control groups (+/?). So, the culture system without oil overlay improved the meiotic inhibition promoted by roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression. 相似文献
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AM Batista WA Gomes CCD Carvalho PLJ Monteiro Jr FLM Silva FC Almeida PC Soares GF Carneiro MMP Guerra 《Reproduction in domestic animals》2014,49(3):476-480
The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E2) and progesterone (P4) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E2 concentrations on day of oestrus (r = 0.562; p < 0.01) and P4 concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats. 相似文献
4.
OHO Eckhardt SMMK Martins ME Pinese FC Horta AC Rosseto MA Torres AFC De Andrade BBD Muro CT Marino PHM Rodrigues AS Moretti 《Reproduction in domestic animals》2014,49(6):964-969
The aim of this study was to evaluate the reproductive performance of three parities of gilts treated or not treated with gonadotropin to induce puberty. Sixty gilts received 600 IU of equine chorionic gonadotropin (eCG) followed by 2.5 mg of porcine luteinizing hormone (LH) 72 h later. Fifty‐nine other gilts were exposed only to a mature boar for 15 min twice daily. Artificial insemination (AI) was performed at 0, 12 and 24 h after the detection of oestrus, and gestation was confirmed by ultrasound after 35 days. Sows were inseminated at the first post‐weaning oestrus. The total numbers of piglets born, piglets born alive, stillborn, mummified foetuses, as well as pregnancy and farrowing rates were evaluated for each of the three parities. Culling rates, farrowing intervals and weaning‐to‐oestrous intervals (WEI) were also analysed. Mean age at puberty and oestrous manifestation were not significantly different between treatments (p = 0.0639; 179.20 ± 17.52 compared with 173.96 ± 16.94, 91.66% compared with 94.92%) across the experimental period. However, females that underwent puberty induction showed modest increases both in the number of total pigs born and in the number of piglets born alive. In conclusion, puberty induction through exogenous gonadotropin administration in field conditions did not induce a more concentrated first oestrous manifestation, but trended to a modest increase in the number of pigs born alive in the first parity and a reduced culling rate during the first gestation. 相似文献
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Use of ultrasonic Doppler waveforms to estimate changes in uterine artery blood flow and vessel compliance 总被引:2,自引:0,他引:2
Previous data from our laboratory have demonstrated that uterine blood flow (UBF) and uterine arterial smooth muscle tone vary regularly during the estrous cycle of the cow. Uterine blood flow is highest and uterine arterial tone is lowest at estrus, whereas UBF is lowest and uterine arterial tone is highest during the luteal phase of the cycle. Blood flow through arteries is highly pulsatile; changes in arterial wall properties affect shape of the velocity waveform. This study was conducted to evaluate changes in uterine arterial velocity waveforms throughout the estrous cycle of the cow and to relate these changes to fluctuations in UBF and concentrations of estrogen and(or) progesterone in systemic blood. Pulsatile velocity waveforms were obtained daily from pulsed-wave ultrasonic probes placed surgically on the middle uterine artery of five beef cows exhibiting estrous cycles of normal duration (d 0 = day of estrus). Velocity waveforms varied regularly during the estrous cycle of each cow in association with changes in UBF and steroid concentrations. Further, two distinct velocity waveform shapes were observed during the estrous cycle. The first waveform shape, which was observed during periods of high UBF (d -4 to +4 of the estrous cycle), was characteristic of a highly compliant vessel and was associated with a high estrogen:progesterone ratio. The second waveform shape, which was observed from d 7 to 14 of the estrous cycle, was characteristic of a less compliant vessel and was associated with a depressed estrogen:progesterone ratio. These data suggest that compliance of the uterine artery changes during the estrous cycle in association with the changing estrogen:progesterone ratio in blood. 相似文献
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The Extreme Ultraviolet Explorer (EUVE) satellite conducted extensive observations of the jovian system before, during, and after the impact of the fragments of comet Shoemaker-Levy 9 in July 1994. About 2 to 4 hours after the impacts of several of the larger fragments, the brightness of the neutral helium (He I) resonance line at 58.4 nanometers temporarily increased by a factor of about 10. The transient 58.4-nanometer brightenings are most simply explained by resonant scattering of sunlight from the widespread high-altitude remnants of the larger impact plumes. Other possible sources of emission, such as electron impact excitation of He or radiative recombination of He(+), may contribute to the observed signal. 相似文献
9.
Lichtenegger HC Schöberl T Bartl MH Waite H Stucky GD 《Science (New York, N.Y.)》2002,298(5592):389-392
Biominerals are widely exploited to harden or stiffen tissues in living organisms, with calcium-, silicon-, and iron-based minerals being most common. In notable contrast, the jaws of the marine bloodworm Glycera dibranchiata contain the copper-based biomineral atacamite [Cu2(OH)3Cl]. Polycrystalline fibers are oriented with the outer contour of the jaw. Using nanoindentation, we show that the mineral has a structural role and enhances hardness and stiffness. Despite the low degree of mineralization, bloodworm jaws exhibit an extraordinary resistance to abrasion, significantly exceeding that of vertebrate dentin and approaching that of tooth enamel. 相似文献
10.
Waite JH Cravens TE Ip WH Kasprzak WT Luhmann JG McNutt RL Niemann HB Yelle RV Mueller-Wodarg I Ledvina SA Scherer S 《Science (New York, N.Y.)》2005,307(5713):1260-1262
Ions were detected in the vicinity of Saturn's A ring by the Ion and Neutral Mass Spectrometer (INMS) instrument onboard the Cassini Orbiter during the spacecraft's passage over the rings. The INMS saw signatures of molecular and atomic oxygen ions and of protons, thus demonstrating the existence of an ionosphere associated with the A ring. A likely explanation for these ions is photoionization by solar ultraviolet radiation of neutral O2 molecules associated with a tenuous ring atmosphere. INMS neutral measurements made during the ring encounter are dominated by a background signal. 相似文献