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51.
Temperature pervasively affects all cellular processes. In response to a rapid increase in temperature, all cells undergo a heat shock response, an ancient and highly conserved program of stress-inducible gene expression, to reestablish cellular homeostasis. In isolated cells, the heat shock response is initiated by the presence of misfolded proteins and therefore thought to be cell-autonomous. In contrast, we show that within the metazoan Caenorhabditis elegans, the heat shock response of somatic cells is not cell-autonomous but rather depends on the thermosensory neuron, AFD, which senses ambient temperature and regulates temperature-dependent behavior. We propose a model whereby this loss of cell autonomy serves to integrate behavioral, metabolic, and stress-related responses to establish an organismal response to environmental change.  相似文献   
52.
A new high-pressure polymorph with a modified spinel structure, beta-Mn(2)GeO(4), is stable in a pressure range intermediate between the field of the polymorph with the olivine structure and that of another high-pressure polymorph. Oxygen atoms are located approximately in cubic close packing with manganese and germanium atoms in octahedral and tetrahedral interstices, respectively, as in the spinel structure; however, germanium atoms form Ge(2)O(7) groups instead of isolated GeO(4) groups.  相似文献   
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54.
Agricultural soil is a major source of nitrous oxide (N2O), and the application of nitrogen and soil drainage are important factors affecting N2O emissions. This study tested the use of polymer-coated urea (PCU) and polymer-coated urea with the nitrification inhibitor dicyandiamide (PCUD) as potential mitigation options for N2O emissions in an imperfectly drained, upland converted paddy field. Fluxes of N2O and methane (CH4), ammonia oxidation potential, and ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) abundances were monitored after the application of PCU, PCUD, and urea to upland soil. The results showed that urea application increased the ammonia oxidation potential and AOB and AOA abundances; however, the increase rate of AOB (4.6 times) was much greater than that of AOA (1.8 times). These results suggested that both AOB and AOA contributed to ammonia oxidation after fertilizer application, but the response of AOB was greater than AOA. Although PCU and PCUD had lower ammonia oxidation potential compared to urea treatment, they were not effective in reducing N2O emissions. Large episodic N2O emissions (up to 1.59 kg N ha?1 day?1) were observed following heavy rainfall 2 months after basal fertilizer application. The episodic N2O emissions accounted for 55–80 % of total N2O emissions over the entire monitoring period. The episodic N2O emissions following heavy rainfall would be a major source of N2O in poorly drained agricultural fields. Cumulative CH4 emissions ranged from ?0.017 to ?0.07 kg CH4 ha?1, and fertilizer and nitrification inhibitor application did not affect CH4 oxidation.  相似文献   
55.
Winter cover crops increase the amount of indigenous arbuscular mycorrhizal fungi (AMF) in the soil, providing beneficial effects such as enhancement of phosphorus uptake by the subsequent crop. However, its impact on the AMF community structure is not well understood. In the present study, we aimed to reveal the effect of winter wheat cover cropping with no-till cultivation on the AMF community structures in soil and roots of the subsequent soybean. For this purpose, we conducted a field experiment consisting of two treatments, no-till soybean cultivation after winter wheat cover cropping (NTWC) and conventional soybean cultivation after winter fallow management as a control (CONT). At the flowering stage of soybean, higher AMF colonization of soybean roots was observed in the NTWC plots compared with the CONT plots. Additionally, aboveground biomass and phosphorus uptake of soybean in the NTWC plots were significantly higher than those in the CONT plots. Molecular community analyses based on PCR-denaturing gradient gel electrophoresis (DGGE) of AMF 18S rRNA genes indicated that the AMF community structures in the soil and soybean root of the NTWC plots were clearly different from those of the CONT plots. The DGGE profiles showed that the wheat cover cropping preferentially increased some phylotypes belonging to Glomeraceae and Claroideoglomeraceae. In addition, most of the phylotypes were characteristically observed in the subsequent soybean root of the NTWC plots, strongly suggesting that these phylotypes colonizing the cover crop wheat were taken over by the subsequent soybean. Our study revealed the significant effect of winter cover cropping with no-till cultivation on the structure of AMF community colonizing the subsequent soybean.  相似文献   
56.
In 1992 and 2002, investigations on the water quality and hydrology were carried out in a small agricultural catchment where swine waste was stored in earthen waste storage. The in-stream nitrogen loads and the nitrogen inputs on a sub-catchment scale were estimated and compared between 1992 and 2002. For the entire catchment, the estimated nitrogen inputs increased from 22.5 to 32.9 ton year−1 (from 406 to 594 kg ha−1 year−1), whereas the nitrate nitrogen concentration at the outlet was constant—27 mg l−1. In a sub-catchment (area C) with earthen waste storages, the nitrate nitrogen concentrations at the outlet were high, 42–51 mg l−1. In a sub-catchment (area A) with an earthen waste storage, which was not in service since 1990, although the nitrogen inputs were maintained at 390 kg year−1 (53 kg ha−1 year−1), the nitrate nitrogen concentrations at the outlet decreased from 26 to 4.9 mg l−1. With assuming that the nitrogen transport rates for sources except swine waste are equal to the rates estimated for a sub-catchment without earthen waste storage, the in-stream nitrogen loads for area A were estimated to decrease from 1,334 to 94 kg year−1 and the transport rates for area A were estimated to decrease from 3.95 to 0.73. These results suggest that the effluent from earthen waste storage has affected surface water quality two years after the storage was out of service and its effect largely decreased after a decade.  相似文献   
57.
Paddy and Water Environment - There has been a growing global interest in urban agriculture that contributes to the well-being of urban dwellers by providing various ecosystem services. Focusing on...  相似文献   
58.
We determined the analgesic effects of epidural administration of either bupivacaine at 62.5, 125, 250, and 500 micrograms/kg; buprenorphine at 5 and 10 micrograms/kg; and the combination of bupivacaine at 125 micrograms/kg and buprenorphine at 5 or 10 micrograms/kg, using the tail flick (TF) and colorectal distension (CD) tests in rats and compared the results with those obtained using morphine at 100 micrograms/kg. In both the TF and CD tests, all doses of bupivacaine alone produced potent anti-nociceptive effects, although the effect rapidly diminished after 20-30 min of administration. The administration of buprenorphine at 10 and 5 micrograms/kg produced mild to moderate anti-nociceptive effects in both the TF and CD tests, and the effects were relatively constant throughout the 2-h experimental period. Combinations of 5 or 10 micrograms/kg of buprenorphine with 125 mg/kg of bupivacaine produced a significantly higher percentage of maximum possible analgesic effect (%MPE) than that of the calculated additive effect of each drug alone in the TF and CD tests. The analgesic effect of this combination was similar to that of morphine. Minimal ataxia was observed in rats administered this combination.  相似文献   
59.
The effects of interferon (IFN)-gamma induced by virus infection on eosinophil reaction in allergic airway inflammation are not yet clear. We investigated the effects of lactic dehydrogenase virus (LDV) infection, which increases IFN -gamma production with no viral infection or replication in respiratory epithelium, on allergic airway hypersensitivity. LDV infection suppressed antigen-induced eosinophil recruitment into the airway in sensitized mice. IL -5 gene expression in bronchoalveolar lavage (BAL) cells was significantly suppressed in LDV -infected mice compared with uninfected controls. The numbers of total T cells and CD 4+ T cells were significantly reduced in LDV -infected mice compared with controls. The present results suggested that the increase in production of IFN -gamma by viral infection suppresses the eosinophil reaction, and this suppressive effect may be mediated by inhibition of the recruitment of CD 4+ T cell and IL -5 production.  相似文献   
60.
内蒙古红花尔基鸟类群落与植被类型相互关系研究   总被引:4,自引:0,他引:4  
调查了内蒙北部红花尔基夏季鸟类群落,一共记录了28种鸟类。在每个实验地取5个10m×10m的样方进行植被调查。利用线性回归方程来确定植被郁闭度和鸟类数量和鸟类密度的关系。分析结果显示鸟类数量和鸟类密度的变化及鸟类群落的形成是随着森林类型和总植物量而变化。鸟类数量和密度都随总植物量的降低而减少。鸟类群落的相似性在繁殖时期非常低,在同一分类簇中,最大相似性不超过0.65。这表明鸟类群落间种类的构成存在着显著差异。鸟类的繁殖密度与森林的生长阶段具有密切的关系,一般情况下,从稀疏的草原生态系统到顶级生态系统鸟类的密度呈现逐渐增加的趋势。图3表4参21。  相似文献   
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