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排序方式: 共有868条查询结果,搜索用时 15 毫秒
1.
Tropospheric ozone concentrations (O3) are continuously increasing with harmful effects on vegetation. Ozone uptake triggers oxidative stress that may promote adverse changes in various plant physiological processes. The aim of this study was to evaluate the relationship between meteorological conditions and O3 exposure in foliar injuries, gas exchanges and antioxidant enzyme activity in Psidium guajava Paluma. Saplings of Paluma were exposed in a site contaminated by O3. Foliar injuries, gas exchanges, and the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were evaluated weekly. Results were analyzed by multivariate analysis. The O3 exposure reduced carbon assimilation and induced the onset of foliar injuries. The enzymatic activities were more related to meteorological conditions than to O3 exposure, indicating that these enzymes are not this species’ first line of defense. However, our finding indicates that Paluma may be considered a response indicator, given its presentation of foliar injuries even at low O3 concentrations. 相似文献
2.
Release of N-Acetylaspartylglutamate from Slices of Rat Cerebellum, Striatum, and Spinal Cord, and the Effect of Climbing Fiber Deprivation 总被引:1,自引:1,他引:0
M. Zollinger J. Brauchli-Theotokis U. Gutteck-Amsler K. Q. Do P. Streit M. Cuénod 《Journal of neurochemistry》1994,63(3):1133-1142
Abstract: The release of endogenous N -acetylaspartylglutamate (NAAG) from slices of rat cerebellum, striatum, and spinal cord upon depolarization with 50 m M K+ was investigated. NAAG in superfusates was prepurified using an ion exchanger, esterified, and then quantified by gas chromatography-mass spectrometry. Deuterated NAAG was used as internal standard. A depolarization-induced release of NAAG was found in all three regions. The release was Ca2+ dependent to over 85% in cerebellum and striatum, but only to approximately 70% in spinal cord. In addition, the effect of lesions of the olivocerebellar pathway on the K+ -induced release of NAAG was studied: Treatment of the animals with 3-acetylpyridine reduced the release of NAAG from cerebellar hemispheres significantly, by about 40% compared with controls. These results suggest that part of the NAAG released from cerebellar slices on depolarization is related to climbing fibers. Implications of these findings concerning possible physiological roles of NAAG in the three CNS regions are discussed. 相似文献
3.
Mutations were induced in tissue-cultured wasabi (Wasabia japonica Matsumura) by treating in vitro-derived shoot tips with either γ-rays or X-rays at 0, 10, 20, 40 or 80 Gy. Doses of up to 40 Gy of either γ- or X-ray treatments
resulted in a survival rate of more than 60% in culture after 3 mo. The use of γ- or X-rays at doses between 10 Gy and 40 Gy
to induce mutation in W. japonica resulted in an alteration of the growth and allyl isothiocyanate (AITC) content of multiple shoots after 3 mo. in culture
on Murashige and Skoog medium containing 5 μM N6-benzyladenine (BA). Putative mutants from the 40 Gy treatments of either γ- or X-rays exhibited a reduction in shoot weight,
number, and height, whereas treatments of either γ-rays or X-rays at 10 Gy and 20 Gy doses showed no significant differences
in shoot growth. All shoots treated with 80 Gy were either necrotic or irregenerable, while those treated with 40 Gy produced
deformed leaves, from both types of ionizing radiation. Concentrations of AITC were measured by the use of gas chromatography-mass
spectrometry (GC-MS). The accumulation of AITC was shown to decrease when doses increased in both γ- and X-ray treatments,
compared with the controls. Positive responses were solely occurred at 18 mo. after transfer of in vitro rooted shoots to the shade house. The survival rate, rhizome weight and AITC content of plants derived from shoots treated
with 20 Gy or 40 Gy of either γ-rays or X-rays were significantly greater than those of the controls. 相似文献
4.
The mass distribution regularity in substrate of solid-state fermentation (SSF) has rarely been reported due to the heterogeneity of solid medium and the lack of suitable instrument and method, which limited the comprehensive analysis and enhancement of the SSF performance. In this work, the distributions of water, biomass, and fermentation product in different medium depths of SSF were determined using near-infrared spectroscopy (NIRS) and the developed models. Based on the mass distribution regularity, the effects of gas double-dynamic on heat transfer, microbial growth and metabolism, and product distribution gradient were systematically investigated. Results indicated that the maximum temperature of substrate and the maximum carbon dioxide evolution rate (CER) were 39.5 °C and 2.48 mg/(h g) under static aeration solid-state fermentation (SASSF) and 33.9 °C and 5.38 mg/(h g) under gas double-dynamic solid-state fermentation (GDSSF), respectively, with the environmental temperature for fermentation of 30 ± 1 °C. The fermentation production (cellulase activity) ratios of the upper, middle, and lower levels were 1:0.90:0.78 at seventh day under SASSF and 1:0.95:0.89 at fifth day under GDSSF. Therefore, combined with NIRS analysis, gas double-dynamic could effectively strengthen the solid-state fermentation performance due to the enhancement of heat transfer, the stimulation of microbial metabolism and the increase of the homogeneity of fermentation products. 相似文献
5.
Identification and Determination of 1-Methylimidazole-4-Acetic Acid in Human Cerebrospinal Fluid by Gas Chromatography-Mass Spectrometry 总被引:2,自引:2,他引:0
Abstract: A method for the quantification of 1-methylimidazole-4-acetic acid in human CSF was developed. Methylimidazole-acetic acid was identified and quantitated in CSF. The method involves concentration of the compound on a cation exchanger, extraction of the methyl ester with ethyl acetate, and preparation of a heptafluorobutyryl derivate of the methyl ester, which is finally purified by chromatography on silica gel and quantitated by gas chromatography-mass spectrometry with the deuterated analogue as internal standard. The coefficient of variation at 1 ng/ml was 13%. The limit of sensitivity was about 0.2 ng/ml. The concentration of methylimidazole-acetic acid in lumbar CSF from healthy volunteers was below 1 ng/ml. Ventricular CSF contained higher concentrations than lumbar fluid. The existence of a rostrocaudal concentration gradient was established. There was a correlation between the concentration of methylimidazole-acetic acid and tele-methylhistamine in CSF. The concentration of methylimidazole-acetic acid in lumbar CSF from schizophrenic patients, patients with subarachnoidal haemorrhage, or patients with rheumatic disease was in the range of that in healthy volunteers. 相似文献
6.
《Animal : an international journal of animal bioscience》2022,16(11):100659
Using agricultural by-products such as dehydrated orange pulp (DOP) in animal feeds is of interest to increase pig sector sustainability. With this aim, an assay was carried out to assess the effects of increasing inclusion levels of DOP in pig diets regarding animal performance, carcass quality, and environmental impact. Four experimental diets were designed, a control diet (T1) and three more diets with increasing levels of DOP with 80, 160, and 240 g/kg of DOP for diets T2, T3, and T4, respectively. One hundred and sixty growing pigs were used in the experiment. Growth performance (average daily gain, ADG; average daily feed intake, ADFI and feed conversion ratio, FCR) and in vivo backfat thickness (BF) and loin depth (LD) gain were recorded during the finishing phase (from 70 to 130 kg BW). Faecal samples were incubated for bacteria enumeration. At slaughter, carcass characteristics and meat quality traits were measured, and subcutaneous fat was sampled to analyse the fatty acid (FA) profile. Additionally, the slurry excreted by the animals was measured, characterised and subjected to a gaseous emission assay during its storage. The final BW and overall ADFI, ADG and FCR were similar among treatments. In vivo final LD and BF gain decreased (P ≤ 0.10) as the inclusion level of DOP increased. No differences were observed in carcass characteristics with the inclusion of DOP, except carcass weight that decreased linearly (P = 0.05) with DOP. Regarding the FA profile of the subcutaneous fat, the ratio of total monounsaturated to saturated FA increased with the inclusion level of DOP. Neither slurry excretion and characterisation nor bacterial counts from faeces showed any significant difference among treatments. The inclusion of DOP led to greater CH4 emissions in mg per L of slurry and hour, whereas these differences disappeared when expressed in mg per animal and day. In all, it has been demonstrated that the inclusion of DOP up to 240 mg/kg in pig diets had minor effects on growth performance, carcass quality traits or gaseous emissions from slurry, favouring the circular economy strategy and pig sector sustainability. 相似文献
7.
目的:研究华法令对大鼠体内主动脉的钙化作用。方法:采用华法令(3 mg/g饲料)的饲料喂养诱导大鼠体内动脉钙化。实验分3组(n=6),对照组、6 W钙化组、12 W钙化组。Von Kossa染色观察钙结节形成,邻甲酚酞络合酮比色法定量测定钙沉积含量。采用TUNEL染色法检测大鼠主动脉组织内血管平滑肌细胞(Vascular Smooth Muscle Cell,VSMC)凋亡。Western blot法检测大鼠主动脉组织中生长抑制特异蛋白6(Growth Arrest Specific Gene 6 Protein,Gas 6)蛋白表达水平。结果:钙化组钙结节、钙沉积含量及VSMC凋亡均高于对照组(P0.01)有显著差异。钙化形成与凋亡表达呈显著正相关(R2=0.8853,P0.0001);钙化组Gas 6蛋白表达量较对照组下调(P0.01)有显著差异。结论:华法令通过下调Gas 6蛋白诱导大鼠体内主动脉钙化形成。 相似文献
8.
Nathachit Limjunyawong Jonathan Fallica Amritha Ramakrishnan Kausik Datta Matthew Gabrielson Maureen Horton Wayne Mitzner 《Journal of visualized experiments : JoVE》2015,(95)
The mouse is now the primary animal used to model a variety of lung diseases. To study the mechanisms that underlie such pathologies, phenotypic methods are needed that can quantify the pathologic changes. Furthermore, to provide translational relevance to the mouse models, such measurements should be tests that can easily be done in both humans and mice. Unfortunately, in the present literature few phenotypic measurements of lung function have direct application to humans. One exception is the diffusing capacity for carbon monoxide, which is a measurement that is routinely done in humans. In the present report, we describe a means to quickly and simply measure this diffusing capacity in mice. The procedure involves brief lung inflation with tracer gases in an anesthetized mouse, followed by a 1 min gas analysis time. We have tested the ability of this method to detect several lung pathologies, including emphysema, fibrosis, acute lung injury, and influenza and fungal lung infections, as well as monitoring lung maturation in young pups. Results show significant decreases in all the lung pathologies, as well as an increase in the diffusing capacity with lung maturation. This measurement of lung diffusing capacity thus provides a pulmonary function test that has broad application with its ability to detect phenotypic structural changes with most of the existing pathologic lung models. 相似文献
9.
目的 探讨高原低氧对大鼠大脑皮质生长休止蛋白7(Gas7)表达的影响.方法 36只大鼠随机分为正常对照组和模拟高原低氧组,模拟高原低氧组大鼠进行6周缺氧,复制慢性高原低氧动物模型.实验结束后,所有动物采用免疫组织化学和免疫印迹技术检测大鼠大脑皮质中Gas7的表达.结果 与对照组相比,Gas7在模拟高原低氧组大鼠大脑皮质的表达明显增强.结论 Gas7可能参与了高原低氧对大鼠大脑皮质神经元结构和功能的影响. 相似文献
10.
目的探讨生长休止蛋白7(Gas7)在成年大鼠关节软骨中的表达及意义。方法雄性SD大鼠(3个月、12个月)各12只。取膝关节和股骨上端关节部分,经脱钙石蜡包埋并切片,采用HE染色和免疫组化SABC法检测。检测各关节软骨组织中Gas7的表达及其定位。结果关节软骨切线层与移行层Gas7的表达呈现强阳性,而在辐射层及软骨钙化层则弱阳性或阴性。结论Gas7在成年大鼠关节软骨各层细胞的表达不同,可能与各层软骨细胞的生长发育及代谢状况有关 相似文献