This work analyses the effects of a high hydrostatic pressure (HHP) treatment on in vitro survival of in vitro produced (IVP) bovine embryos vitrified with the Cryologic Vitrification Method (CVM). Consequences on embryo quality in terms of cell proliferation and differentiation, and levels of embryonic Heat Shock Protein 70 (Hsp‐70) were also examined. Day 7 and 8 bovine in vitro‐produced blastocysts were submitted to an HHP treatment (60 MPa, at 32°C for 1 h) and allowed to recover for 1 or 2 h in culture medium. The HHP treatment did not improve blastocyst survival rates after vitrification/warming. Survival (24 h post‐warming) and hatching (48 h post‐warming) rates were 79.3 ± 4.9 and 51.8 ± 4.2 vs 73.9 ± 4.2 and 44.7 ± 4.1 for untreated controls and HHP‐treated embryos, respectively. Total cell numbers measured in fresh embryos were reduced after 1 h at 32°C, with or without HHP treatment, indicating that cell proliferation was stopped as a result of stress. Vitrified HHP‐treated embryos that hatched at 48 h after warming showed increased cell numbers in their ICM compared with untreated controls (50.2 ± 3.1 vs 38.8 ± 2.7), indicating higher embryo quality. Treatment of blastocysts with HHP did not alter the level of the Hsp‐70 protein. In our conditions, HHP treatment did not affect the cryoresistance of these embryos. However, combination of HHP treatment and vitrification in fibreplugs resulted in an increase in the ICM cell number of hatched embryos 48 h post‐warming. 相似文献
Pullets were fed on diets containing various concentrations of lysine and arginine from 7 to 18 or 20 weeks. Thereafter a conventional layers' diet was fed and egg productivity measured—in the first two experiments for ten, and the third for six 28‐d periods. Pullets were also fed on a standard growers' type diet on a “skip‐a‐day” or on a 20% restriction basis in the third study.
Growth and age at sexual maturation were directly related to the lysine content of the diet and to a lesser extent to the arginine content. Pullets fed on diets with the lower concentrations of lysine and arginine required less food during the growing period and matured later than those fed on a complete diet ad libitum. They also laid more eggs and required less food to produce a dozen eggs. Higher egg production was obtained in the third experiment with low concentrations of lysine and arginine than with the “skip‐a‐day” or the restricted feeding programmes. Pullets fed on the normal grower diet ad libitum produced the smallest eggs in the first and third experiments with no difference in egg size in the second experiment. Pullets maintained on the “skip‐a‐day” or the restricted feeding programme also had a larger egg size than the control group fed on the same diet on an ad libitum basis.
An ingredient effect was observed in the third experiment. Of two diets containing identical calculated values of lysine and arginine, the one containing distillers' dried grains with solubles was superior to the one with soybean meal as regards weight at 20 weeks of age, amount of food consumed during the period 6 to 18 weeks of age and percentage egg production. It is possible that the soybean meal contained a better balance of amino acids than did distillers' dried grains with solubles which resulted in a significant increase in body weight at 20 weeks of age and a subsequent lower level of egg production. These data indicate that it would be best to use ingredients with an imbalance of amino acids in the protein as sources of lysine and arginine in pullet grower diets.
There were no differences in the mortality of the birds during the laying period which could be related to dietary treatment during the pullet growing period. 相似文献
An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime. 相似文献
A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices. 相似文献
Sperm reservoirs in South American Camelids would be crucial for successful fertilization. Since ovulation occurs approximately 36 h after mating, the maintenance of the sperm viability in the oviduct waiting for the ovum is a critical reproductive event. Our study aimed at determining whether the isthmus or the utero tubal junction (UTJ) could function as a sperm reservoir in llama by means of in vivo and in vitro experiments. For the in vivo experiments, the oviducts of adult females with a dominant follicle bigger than 7 mm were examined for the presence of sperm at 6, 18, 24, 28 and 35 h after mating. The results using scanning and transmission electron microscopy showed ultrastructural differences between isthmus and UTJ with respect to (1) predominance of secretory cells in the UTJ and ciliated cells in the isthmus epithelium and (2) cytoplasmic bulbous projection of the secretory cells in the UTJ. Sperm adhered by a mucus‐like substance were seen only in the UTJ at 6, 18, 24 and 28 h post‐mating. Lack of sperm adhered to oviductal mucosa was observed around ovulation (35 h). In vitro experiments demonstrated higher ability of UTJ epithelial cell explants with respect to isthmus explants to bind sperm in a co‐cultured system. The anatomical features and the presence of a sperm bonding agent in the UTJ together with the in vitro differential binding of sperm to UTJ explants strongly suggest that both may be feasible mechanisms that facilitate sperm storage in this oviductal region in llama. 相似文献
