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A Najafi MH Najafi Z Zanganeh M Sharafi F Martinez‐Pastor H Adeldust 《Reproduction in domestic animals》2014,49(6):934-940
A soybean lecithin‐based extender supplemented with hyaluronic acid (HA) was assayed for effectiveness to improve the quality of frozen–thawed ram semen. HA has not been tested yet in an extender containing soybean lecithin for freezing ram semen. Thus, the aim of this study was to analyse the effects of soybean lecithin at 1% or 1.5% along with HA at 0, 0.5 and 1 mg ml‐1 in a Tris‐based extender on the motion characteristics, membrane integrity (HOST), viability, GSH peroxidase (GSH‐PX) activity, lipid peroxidation and acrosomal status after freezing–thawing. Semen was collected from four Mehraban rams during the breeding season and frozen in the six lecithin×HA extenders. The extender containing 1.5% lecithin supplemented with no HA yielded higher total motility (52.5%±1.6), viability (55.8%±1.6) and membrane integrity (44.5%±1.7), but the effects of the lecithin concentration did not reach signification. Linearity‐related parameters, ALH, BCF, lipid peroxidation, GSH‐PX activity, morphology and acrosomal status were not affected by the extender composition. In general, adding HA significantly decreased sperm velocity (1 mg ml‐1 HA), total motility (only with 1.5% lecithin), viability (1 mg ml‐1 HA for 1% lecithin; both concentrations for 1.5% lecithin) and membrane integrity. In conclusion, adding HA to the freezing extender supplemented with soybean lecithin failed to improve quality‐related variables in ram semen. Increasing the lecithin content could have a positive effect, but further studies are needed. 相似文献
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JI Yun HJ Park MH Park MS Kim JH Choi E Lee SP Gong JM Lim ST Lee 《Reproduction in domestic animals》2014,49(5):705-710
Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats. 相似文献
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The preparation of suitably large protein single crystals is essentially the rate-determining step of protein x-ray structure determinations. Attempts to produce single crystals with two model compounds-beta-galactosidase and lysozyme-under conditions of microgravity were successful. Crystals formed by salting out from solutions kept free of convection were 27 and 1000 times larger in volume, respectively, than those produced in the same apparatus but exposed to terrestrial gravitation. 相似文献
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van Putten MH 《Science (New York, N.Y.)》1999,284(5411):115-118
The coalescence of a neutron star and a black hole in a binary system is believed to form a torus around a Kerr black hole. A similarly shaped magnetosphere then results from the remnant magnetic field of the neutron star. In the strong-field case, it contains a cavity for plasma waves located between the barrier of the gravitational potential and the surrounding torus. This cavity may be unstable to superradiance of electromagnetic waves. Superradiant amplification of such waves, initially excited by turbulence in the torus, should inflate into a bubble in a time as short as approximately 0.75 (1 percent/&cjs3539;epsilon&cjs3539;2)(M/7M middle dot in circle) seconds approximately 0.15 to 1.5 seconds, assuming an efficiency &cjs3539;epsilon&cjs3539;2 = 0.5 to 5 percent and a mass M = 7M middle dot in circle. These bubbles may burst and repeat, of possible relevance to intermittency in cosmological gamma-ray bursts. The model predicts gamma-ray bursts to be anticorrelated with their gravitational wave emissions. 相似文献
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Background, Goal and Scope A large share of anthropogenic contamination of the coastal zone is a result of riverine contributions. Accordingly, the pollution
of North Sea estuaries and coastal areas by organic xenobiotics is dominantly characterized by land-derived contamination.
In a previous study, we identified a high number of organic contaminants in sediments of the German Bight emitted by industrial
and municipal sources, primarily as a result of riverine contributions. Furthermore, a group of contaminants was identified
representing Elbe-specific marker compounds.
However, quantitative analyses are more adequate to describe the source specificity via the spatial distribution as compared
to qualitative analyses. Hence, in the present investigation, the determination of various anthropogenic contaminants has
been performed in order to evaluate the proposed Elbe-specific marker compounds.
Methods Numerous anthropogenic contaminants were quantified in seven surface sediment samples from the German Bight by means of gas
chromatographic — mass spectrometric analyses. The analytical procedure includes extraction, reI moval of sulphur, fractionation,
concentration and addition of internal standard.
Results and Discussion Two groups of Elbe-derived contaminants were differentiated. Substances of the first group appear only at sampling locations
directly influenced by the Elbe river and include hexachlorobutadiene and alkylsulfonic acid phenyl esters. The second group
consists of compounds, which occur additionally in minor concentrations at sites situated at a greater distance from the coastal
area, which are therefore only influenced to a minor-degree by the Elbe river. However, their spatial and quantitative distribution
characterizes them clearly as Elbe river-derived components. Compounds of the second group are tetra- to hexachlorinated benzenes,
mono- and disubstituted chloronaphthalenes, tetrabutyltin, 4,4’-dichlorodiphenylsulfide and DDT related compounds
In order to discern the discussed Elbe marker compounds from non-marker substances, several nonspecific contaminants were
analyzed additionally. These contaminants include galaxolide, tonalide, tri-n-butylphosphate, 2,4,4-trimethylpentane-l,3-dioldi-iso-butyrate and 2,2,4,4,6,8,8-heptamethylnonane. No significant accumulation of these compounds was observed at sampling locations
mainly influenced by either the Elbe river, or the Ems and Weser rivers.
Conclusions For the evaluation of the proposed Elbe marker compounds, the quantitative and spatial distribution was investigated and successfully
discussed as the most important criterion to define their source specificity. Generally, these results illustrate how quantitative
data on source-specific organic contaminants and the corresponding spatial distribution can be used to trace individual riverine
contributions to the pollution of coastal areas. This approach might be especially useful to differentiate the contribution
of several rivers discharging close together into the marine environment. Fingerprinting, the individual riverine contribution
additionally allows one to quantify the individual, river-derived contamination. Subsequently, the level of coastal zone contaminations
can be reduced more effectively.
Further comprehensive analyses on numerous coastal and estuarine areas have to be done to support this approach. 相似文献
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The current investigations were undertaken to study the mechanism of the adverse effect of phytoestrogens on the function of bovine granulosa (follicles >1< cm in diameter) and luteal cells from day 1–5, 6–10, 11–15, 16–19 of the oestrous cycle. The cells were incubated with genistein, daidzein or coumestrol (each at the dose of 1 × 10?6 m ). The viability and secretion of estradiol (E2), progesterone (P4) and oxytocin (OT) were measured after 72 h of incubation. Moreover, the expression of mRNA for neurophysin‐I/OT (NP‐I/OT; precursor of OT) and peptidyl‐glycine‐α‐amidating monooxygenase (PGA, an enzyme responsible for post‐translational OT synthesis) was determined after 8 h of treatment. None of the phytoestrogens used affected the viability of cells except for coumestrol. The increased secretion of E2 and P4 was only obtained by coumestrol (p < 0.05) from granulosa cells from follicles <1 cm in diameter and decreased from luteal cells on days 11–15 of the oestrous cycle, respectively. All three phytoestrogens stimulated (p < 0.05) OT secretion from granulosa and luteal cells in all stages of the oestrous cycle and the expression of NP‐I/OT mRNA in the both types of cells. The expression of mRNA for PGA was stimulated (p < 0.05) by daidzein and coumestrol in granulosa cells, and by genistein and coumestrol in luteal cells. In conclusion, our results demonstrate that these phytoestrogens can impair the ovary function in cattle by adversely affecting the synthesis of OT in follicles and in corpus luteum. However, their influence on the ovarian steroids secretion was less evident. 相似文献
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