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排序方式: 共有127条查询结果,搜索用时 234 毫秒
121.
The aims of this study were to test (i) the effect of time of tissue and RNA extracts storage on ice and (ii) the effect of repeated freeze–thaw cycles on RNA integrity and gene expression of bovine reproductive tissues. Fragments of endometrium (ENDO), corpus luteum (CL) and ampulla (AMP) were subdivided and incubated for 0, 1, 3, 6, 12 or 24 h on ice. RNA extracts were incubated on ice for 0, 3, 12 or 24 h, or exposed to 1, 2, 4 or 6 freeze–thaw cycles. RNA integrity number (RIN) was estimated. Expression of progesterone receptor (PGR) and cyclophilin genes from RNA extracts stored on ice for 0 or 24 h, and 1 or 6 freeze–thaw cycles was measured by qPCR. Tissue and RNA extract incubation on ice, and repeated freeze–thaw cycles did not affect RIN values of RNA from ENDO, CL or AMP. Storage on ice or exposure to freeze–thaw cycles did not affect Cq values for PGR or cyclophilin genes . In conclusion, neither generalized RNA degradation nor specific RNA degradation was affected by storage of tissue or RNA extracts on ice for up to 24 h, or by up to 6 freeze–thaw cycles of RNA extracts obtained from bovine ENDO, CL and AMP. 相似文献
122.
L Krakowski J Obara A Wąchocka T Piech P Bartoszek K Kostro MR Tatara 《Reproduction in domestic animals》2013,48(5):826-832
The objective of the study was to assess apoptosis and DNA defragmentation in equine semen diluted and chilled to +4°C. Semen was collected from nine fertile stallions, including four Arabian thoroughbreds and five coldbloods. Examinations were carried out immediately after semen collection (0) and at five storage times (24, 48, 72, 96 and 120 h). The basic semen evaluation was performed in terms of volume, sperm concentration, viable sperm percentage, progressive motility and morphology. Using flow cytometry, DNA defragmentation and cell membrane integrity of spermatozoa were determined. The results of basic tests did not demonstrate significant differences amongst stallions, except for progressive sperm motility, which was significantly higher (p < 0.05) in the semen of Arabian stallions. In the semen of the same stallions, a significant decrease in the percentage of alive spermatozoa was observed at 72, 96 and 120 h of storage, whereas a significant increase in the number of spermatozoa with DNA defragmentation was found after 24 h storage. In the semen of coldblood stallions, significantly reduced live spermatozoa percentage was observed at 96 and 120 h, while increased DNA defragmentation was observed at 48 h. These findings demonstrated that the semen of Arabian stallions chilled to +4°C retained original characteristics until 24 h of storage, whereas in coldbloods, these were preserved up to 48 h of storage. 相似文献
123.
When Bill Manktelow died at his home in his 74th year on the 3rd of May, the veterinary profession lost a major figure whose work over 50 years has influenced many people in all branches of the profession. 相似文献
124.
TC Johnson CA Scholz MR Talbot K Kelts RD Ricketts G Ngobi K Beuning I Ssemmanda JW McGill 《Science (New York, N.Y.)》1996,273(5278):1091-1093
Lake Victoria is the largest lake in Africa and harbors more than 300 endemic species of haplochromine cichlid fish. Seismic reflection profiles and piston cores show that the lake not only was at a low stand but dried up completely during the Late Pleistocene, before 12,400 carbon-14 years before the present. These results imply that the rate of speciation of cichlid fish in this tropical lake has been extremely rapid. 相似文献
125.
MR Andrews CG Townsend H Miesner DS Durfee DM Kurn W Ketterle 《Science (New York, N.Y.)》1997,275(5300):637-641
Interference between two freely expanding Bose-Einstein condensates has been observed. Two condensates separated by approximately 40 micrometers were created by evaporatively cooling sodium atoms in a double-well potential formed by magnetic and optical forces. High-contrast matter-wave interference fringes with a period of approximately 15 micrometers were observed after switching off the potential and letting the condensates expand for 40 milliseconds and overlap. This demonstrates that Bose condensed atoms are "laser-like"; that is, they are coherent and show long-range correlations. These results have direct implications for the atom laser and the Josephson effect for atoms. 相似文献
126.
Recent work suggests a discernible human influence on climate. This finding is supported, with less restrictive assumptions than those used in earlier studies, by a 1961 through 1995 data set of radiosonde observations and by ensembles of coupled atmosphere-ocean simulations forced with changes in greenhouse gases, tropospheric sulfate aerosols, and stratospheric ozone. On balance, agreement between the simulations and observations is best for a combination of greenhouse gas, aerosol, and ozone forcing. The uncertainties remaining are due to imperfect knowledge of radiative forcing, natural climate variability, and errors in observations and model response. 相似文献
127.
The magnitude of damage to buffalo spermatozoa during incubation with different levels of H2O2 was assessed. A total number of 24 ejaculates from four Murrah buffalo bulls were analysed in the study. Each ejaculate was split into two parts (part I and II). Part I was extended in Tris–egg yolk–citrate extender (20% egg yolk:7% glycerol), equilibrated (4 h at 5°C) and cryopreserved in 0.5‐ml French straws and stored in liquid nitrogen. The other part was utilized for fresh semen studies. The sperm in fresh, equilibrated and frozen–thawed semen was separated by centrifugation (1500 g ; 15 min) and were washed with sperm TALP. The sperm cells were re‐suspended in incubation TALP at the rate of 108 sperm cells per millilitre and incubated with 0, 10, 25, and 50 μm H2O2 per ml at 37°C. Sperm motility, viability and intact acrosome percentages were assessed at 15‐min intervals up to 60 min of incubation. Lipid peroxidation levels of sperm were assessed at 0 and 60 min of incubation. The results of the experiment revealed that sperm motility decreased drastically during incubation with H2O2. Among the different levels of H2O2, the 50‐μm H2O2‐incorporated group had significantly (p < 0.05) higher malonaldehyde (MDA) level than the other groups. In the 50‐μm H2O2‐incorporated group, the MDA levels in fresh, equilibrated and frozen–thawed semen after incubation for 60 min were 961.6 ± 12.7, 991.8 ± 10.3 and 1234.9 ± 9.6 nm per 109 spermatozoa respectively. An inverse relationship was observed between sperm motility, viability, intact acrosome percentages and concentration of H2O2 and duration of incubation. The decrease in sperm functions with duration of incubation and concentration of H2O2 was significantly (p < 0.05) higher in frozen–thawed than fresh and equilibrated spermatozoa. 相似文献