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991.
武陵山区蕨类植物研究 总被引:6,自引:0,他引:6
武陵山区蕨类植物资源丰富,现知有644种(包括变种),分属116属, 46科;蕨类区系属热带-亚热带山地类型;属的地理成份有12种类型,与日本、印度-马来西亚有密切关系;武陵山区蕨类区系属我国西南区系,与华中华东区关系密切,华南、华北区次之;蕨类垂直分布分四带。 相似文献
992.
993.
目前国际上的着丝粒蛋白研究工作几乎全是以酵母和高等生物为材料进行的,为了从起源与进化的角度考察着丝粒蛋白。我们以人喉癌培养细胞HepII作为对照材料,以两种ACA血清和CENP-B单抗,多抗以及CHO动粒蛋白单抗为探针,用间接免疫荧光和免疫印迹技术对嗜热四膜虫作检查,免疫荧光结果表明,HepII细胞的着丝粒抗原间期核中呈点状分布;与HepII细胞的不同,嗜热四膜虫的着丝粒抗原在间期核中的分布不规则 相似文献
994.
KPC1 (Kip1 ubiquitylation-promoting complex 1) is the catalytic subunit of the ubiquitin ligase KPC, which regulates the degradation
of the cyclin-dependent kinase inhibitor p27kip1 at the G1 phase of the cell cycle. To elucidate the expression and role of KPC1 in nervous system lesion and repair, we performed
an acute spinal cord contusion injury (SCI) model in adult rats. Western blot analysis showed a significant up-regulation
of KPC1 and a concomitant down-regulation of p27kip1 following spinal injury. Immunohistochemistry and immunofluorescence revealed wide expression of KPC1 in the spinal cord,
including expression in neurons and astrocytes. After injury, KPC1 expression was increased predominantly in astrocytes, which
highly expressed PCNA, a marker for proliferating cells. Co-immunoprecipitation demonstrated increased interactions between
p27kip1 and KPC1 4 days after injury. To understand whether KPC1 plays a role in astrocyte proliferation, we applied LPS to induce
astrocyte proliferation in vitro. Western blot analysis demonstrated that p27kip1 expression was negatively correlated with KPC1 expression following LPS stimulation. Immunofluorescence analysis showed subcellular
localizations of p27kip1 and KPC1 were also changed following the stimulation of astrocytes with LPS. These results suggest that KPC1 is related to
the down-regulation of p27kip1; this event may be involved in the proliferation of astrocytes after SCI. 相似文献
995.
X Chen L Tao J Shekiro A Mohaghaghi S Decker W Wang H Smith S Park M Tucker 《Biotechnology for biofuels》2012,5(1):60
ABSTRACT: BACKGROUND: Historically, acid pretreatment technology for the production of bio-ethanol from corn stover has required severe conditions to overcome biomass recalcitrance. However, the high usage of acid and steam at severe pretreatment conditions hinders the economic feasibility of the ethanol production from biomass. In addition, the amount of acetate and furfural produced during harsh pretreatment is in the range that strongly inhibits cell growth and impedes ethanol fermentation. The current work addresses these issues through pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. RESULTS: The results showed that deacetylation with 0.1 M NaOH before acid pretreatment improved the monomeric xylose yield in pretreatment by up to 20 % while keeping the furfural yield under 2 %. Deacetylation also improved the glucose yield by 10 % and the xylose yield by 20 % during low solids enzymatic hydrolysis. Mechanical refining using a PFI mill further improved sugar yields during both low- and high-solids enzymatic hydrolysis. Mechanical refining also allowed enzyme loadings to be reduced while maintaining high yields. Deacetylation and mechanical refining are shown to assist in achieving 90 % cellulose yield in high-solids (20 %) enzymatic hydrolysis. When fermentations were performed under pH control to evaluate the effect of deacetylation and mechanical refining on the ethanol yields, glucose and xylose utilizations over 90 % and ethanol yields over 90 % were achieved. Overall ethanol yields were calculated based on experimental results for the base case and modified cases. One modified case that integrated deacetylation, mechanical refining, and washing was estimated to produce 88 gallons of ethanol per ton of biomass. CONCLUSION: The current work developed a novel bio-ethanol process that features pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. The new process shows improved overall ethanol yields compared to traditional dilute acid pretreatment. The experimental results from this work support the techno-economic analysis and calculation of Minimum Ethanol Selling Price (MESP) detailed in our companion paper. 相似文献
996.
Monitoring vegetation recovery after China’s May 2008 Wenchuan earthquake using Landsat TM time-series data: a case study in Mao County 总被引:2,自引:0,他引:2
Tao Lu Hongcheng Zeng Yan Luo Qian Wang Fusun Shi Geng Sun Yan Wu Ning Wu 《Ecological Research》2012,27(5):955-966
The Wenchuan earthquake (Richter scale 8) on 12 May 2008 in southwestern China caused widespread ecosystem damage in the Longmenshan area. It is important to evaluate natural vegetation recovery processes and provide basic information on ecological aspects of the recovering environment after the earthquake. To circumvent the weather limits of remote sensing in the Wenchuan earthquake-hit areas, and to meet the need for regional observation analyses, three Landsat TM images pre- and post-earthquake in Mao County were used for analysis. Post-earthquake normalized difference vegetation index (NDVI) values were compared to pre-earthquake values with an NDVI-based index differencing method to determine the extent to which the vegetation was damaged in relation to the pre-earthquake pattern, and the rate of recovery was evaluated. The spatial characteristics of vegetation loss and natural recovery patterns were analyzed in relation to elevation, slope and aspect. The results indicated that severely damaged sites occurred mainly in river valleys, within a range of 1,500?C2,500?m elevation and on slopes of 25?C55°. The distance from rivers, rather than the distance from active faults, controls the damage patterns. After 1?year of natural regeneration, 36?% of the destroyed areas showed a decrease in NDVI value, 28.8?% showed very little change, 19.1?% showed an increase, and 16.1?% also increased with a recovery rate greater than 100?%. Moreover, there is a good correlation between recovery rate and both slope and elevation, but recovery patterns in the damaged area are complicated. Our results indicate that natural recovery in this arid valley is a slow process. 相似文献
997.
以回声定位蝙蝠为模式动物,采用在体动物细胞外单位记录法,研究了后掩蔽效应对下丘神经元声反应的影响。结果显示,部分神经元(38%,12/31)对测试声刺激的反应明显受到掩蔽声的抑制,其后掩蔽效应强弱与掩蔽声和测试声的相对强度差(inter-stimulus level difference,SLD),以及测试声与掩蔽声之间的间隔时间(inter-stimulus onset asynchrony,SOA)有关:当掩蔽声强度升高或测试声强度降低时,后掩蔽效应增强;而SOA的缩短,亦可见后掩蔽效应增强。另外,相当数量的神经元(52%,16/31)对测试声刺激的反应并不受掩蔽声的影响,其中有的神经元只有在特定SLD和SOA时,才表现出后掩蔽效应。而少数下丘神经元(10%,3/31)在特定SLD和SOA时,掩蔽声对测试声反应有易化作用。上述结果表明,部分下丘神经元参与了声认知活动中的后掩蔽形成过程,推测下丘神经元在定型声反应特性中,对掩蔽声诱导的兴奋前抑制性输入与测试声诱导的兴奋性输入之间的时相性动态整合起关键作用。 相似文献
998.
The Chinese egret is a globally endangered species. Here we describe a set of primer pairs to amplify its entire mtDNA. The polymerase chain reaction products (1000–2000 bp) were successfully amplified by using this primer set and were then sequenced and aligned. The contiguous mtDNA sequences of the Chinese egret were assembled to be a circular molecule (17 579 bp). This primer set was also confirmed to be useful for six other species of ardeid birds. The versatility of this primer set will provide a groundwork for further studies on the genetic structure and molecular evolution of the ardeid species. 相似文献
999.
To understand the seasonal migration of the anadromous Coilia nasus , we attempted to identify the parasites infecting C. nasus and determine their seasonal occurrence. From June 2007 to July 2008, a survey of 775 C. nasus individuals from the estuary of the Yangtze River and the coast of the East China Sea revealed more than 7,300 parasites associated with the gills and alimentary tracts of C. nasus . The following 6 helminth taxa were identified, i.e., the monogeneans Heteromazocraes lingmueni and Helciferus tenuis, the digenean Elytrophallus coiliae, the acanthocephalan Acanthosentis cheni , and larvae of the nematodes Anisakis simplex and Contracaecum sp., all of which are marine or brackish-water parasites. The absence of freshwater helminths suggested that the parasites acquired in freshwater may have been accidentally, and easily, lost by the time the fish had reached the estuary and coast. Contrary to seasonal occurrence of the parasites' life cycles, the lowest mean abundance and prevalence of H. lingmueni and A. cheni occurred in August, which suggested the immigration of C. nasus from freshwater to the Yangtze estuary, with lower parasite burdens. The highest mean abundance and prevalence of the nematodes A. simplex and Contracaecum sp. in May and June, and the lowest in August, indicated the arrival of the fish from the coast and the Yangtze River, to the estuary, respectively. These findings suggested that a majority of the fish prepared for spawning migration in the estuary in spring and early summer and returned to the estuary after spawning in the lower and middle reaches of the Yangtze River in late summer. 相似文献
1000.
Yu B Zhao Y Zhao W Chen F Liu Y Zhang J Fu W Zong Z Yu A Guan Y 《Cell biochemistry and function》2003,21(2):183-188
Bovine seminal plasma contains a group of similar proteins, namely BSP-A1, BSP-A2, BSP-A3, and BSP-30-kDa (collectively called BSP proteins), and they are secreted by the seminal vesicles. In our study, we purified the BSP-A1/-A2 through affinity chromatography and found for the first time that BSP-A1/-A2 can inhibit the activity of protein kinase C (PKC) and tyrosine protein kinase (TPK). The inhibition was dose dependent. When the PKC and TPK activities are expressed as the logarithm of percentage activity taking the activity in the absence of the BSP-A1/-A2 as 100%, there is a linear relationship between the their activities and the dose of BSP-A1/-A2. 相似文献