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排序方式: 共有165条查询结果,搜索用时 31 毫秒
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R Simões WB Feitosa CM Mendes AC Nicacio FRO de Barros 《Biotechnic & histochemistry》2013,88(3):79-83
Sperm chromatin integrity is essential for accurate transmission of male genetic information, and normal sperm chromatin structure is important for fertilization. Protamine is a nuclear protein that plays a key role in sperm DNA integrity, because it is responsible for sperm DNA stability and packing until the paternal genome is delivered into the oocyte during fertilization. Our aim was to investigate protamine deficiency in sperm cells of Bos indicus bulls (Nelore) using chromomycin A3 (CMA3) staining. Frozen semen from 14 bulls were thawed, then fixed in Carnoy's solution. Smears were prepared and analyzed by microscopy. As a positive control of CMA3 staining, sperm from one bull was subjected to deprotamination of nuclei. The percentage of CMA3-positive bovine sperm did not vary among batches. Only two bulls showed a higher percentage of CMA3-positive sperm cells compared to the others. CMA3 is a simple and useful tool for detecting sperm protamine deficiency in bulls. 相似文献
44.
Timm Konold Gemma E Bone Laura J Phelan Marion M Simmons Lorenzo González Sílvia Sisó Wilfred Goldmann Saira Cawthraw Steve AC Hawkins 《BMC veterinary research》2010,6(1):13
Background
As there is limited information about the clinical signs of BSE and scrapie in goats, studies were conducted to describe the clinical progression of scrapie and BSE in goats and to evaluate a short clinical protocol for its use in detecting scrapie-affected goats in two herds with previously confirmed scrapie cases. Clinical assessments were carried out in five goats intracerebrally infected with the BSE agent as well as five reported scrapie suspects and 346 goats subject to cull from the two herds, 24 of which were retained for further monitoring. The brain and selected lymphoid tissue were examined by postmortem tests for disease confirmation. 相似文献45.
46.
J.C. Boggio T. Encinas C. Rodríguez S.E. Valtorta J.M. Ros Rodríguez M.I. San Andrés 《Biological Rhythm Research》2013,44(4):401-411
A study about the influence of administration time on pharmacokinetics of Cyproterone acetate in rabbits was performed. Thirty animals were distributed in six groups, each corresponding to a different time: 2, 6, 10, 14, 18 and 22 hours after light onset (HALO). Rabbits received a single intravenous administration of 4 mg kg-1 Cyproterone acetate. Blood samples were taken and processed by high performance liquid chromatography. Plasmatic data were fitted to a biexponential equation. Concentration at zero time (Co), concentration at zero time extrapolated from the distribution phase (A), hybrid constant for distribution phase and its half life, volume of the central compartment (Vc), volume of distribution at steady state (Vss), constants for transferring the drug from the central compartment to the exterior (K10) and from the central to the peripheral compartment presented chronobiological variations (p < 0.05) and were fitted to a cosine equation. The following parameters adjusted to circadian rhythms: Co (Acrophase: 1.72 HALO); A (Acrophase: 4.09 HALO); Vc (Acrophase: 11.92 HALO); Vss (Acrophase: 10.12 HALO) and K10 (Acrophase: 3.59 HALO). It was concluded that pharmacokinetics of intravenously injected CPA in rabbits would behave in a different, though predictable, manner according to the animal's biological clock. 相似文献
47.
Alexander N. Schmidt‐Lebuhn Matthias Müller Paola Pozo Inofuentes Francisco Encinas Viso Michael Kessler 《Biotropica》2019,51(2):99-103
Several hummingbird‐pollinated plant lineages have been demonstrated to show increased rates of diversification compared to related insect‐pollinated lineages. It has been argued that this pattern is produced by a higher degree of specialization on part of both hummingbirds and plants. We here test an alternative hypothesis: The often highly territorial hummingbirds may on average carry pollen over shorter distances than other pollinators and drive diversification by reducing gene flow distances. We present experimental data from pollen analogue tracking showing shorter dispersal distances in hummingbird‐pollinated than in bee‐pollinated species among ten Neotropical species of Justicia (Acanthaceae). Abstract in Spanish is available with online material. 相似文献
48.
Adult neurogenesis persists in the hippocampus of most mammal species during postnatal and adult life, including humans, although it declines markedly with age. The mechanisms driving the age‐dependent decline of hippocampal neurogenesis are yet not fully understood. The progressive loss of neural stem cells (NSCs) is a main factor, but the true neurogenic output depends initially on the actual number of activated NSCs in each given time point. Because the fraction of activated NSCs remains constant relative to the total population, the real number of activated NSCs declines in parallel to the total NSC pool. We investigated aging‐associated changes in NSCs and found that there are at least two distinct populations of NSCs. An alpha type, which maintains the classic type‐1 radial morphology and accounts for most of the overall NSC mitotic activity; and an omega type characterized by increased reactive‐like morphological complexity and much lower probability of division even under a pro‐activation challenge. Finally, our results suggest that alpha‐type NSCs are able to transform into omega‐type cells overtime and that this phenotypic and functional change might be facilitated by the chronic inflammation associated with aging. 相似文献
49.
Fernando Encinas Michel A Marin Juliana N Ramos Ver?nica V Vieira Ana Luiza Mattos-Guaraldi Ana Carolina P Vicente 《Memórias do Instituto Oswaldo Cruz》2015,110(6):817-819
We report the complete genome sequence and analysis of an invasive
Corynebacterium diphtheriae strain that caused endocarditis in
Rio de Janeiro, Brazil. It was selected for sequencing on the basis of the current
relevance of nontoxigenic strains for public health. The genomic information was
explored in the context of diversity, plasticity and genetic relatedness with other
contemporary strains. 相似文献
50.
Hennie G Raterman Saskia Vosslamber Sander de Ridder Michael T Nurmohamed Willem F Lems Maarten Boers Mark van de Wiel Ben AC Dijkmans Cornelis L Verweij Alexandre E Voskuyl 《Arthritis research & therapy》2012,14(2):R95