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991.
In this study, Dendrobium officinale polysaccharide (named DOPS-1) was isolated from the stems of Dendrobium officinale by hot-water extraction and purified by using Sephadex G-150 column chromatography. The structural characterization, antioxidant and cytotoxic activity were carried out. Based on the results of HPLC, GC, Congo red experiment, together with periodate oxidation, Smith degradation, SEM, FT-IR, and NMR spectral analysis, it expressed that DOPS-1 was largely composed of mannose, glucose and galacturonic acid in a molar ratio of 3.2 : 1.3 : 1. The molecular weight of DOPS-1 was 1530 kDa and the main chain was composed of (1→4)-β-D-Glcp, (1→4)-β-D-Manp and 2-O-acetyl-(1→4)-β-D-Manp. The measurement results of antioxidant activity showed that DOPS-1 had the strong scavenging activities on hydroxyl radicals, DPPH radicals and superoxide radicals and the high reducing ability in vitro. Moreover, DOPS-1 was cytotoxic to all three human cancer cells of MDA-MB-231, A549 and HepG2. 相似文献
992.
Rui-Fang Li Xin-Xin Wang Liu Wu Li Huang Qi-Jian Qin Jia-Li Yao Guang-Tao Lu Ji-Liang Tang 《Molecular Plant Pathology》2020,21(3):360-375
Xanthomonas campestris pv. campestris (Xcc) controls virulence and plant infection mechanisms via the activity of the sensor kinase and response regulator pair HpaS/hypersensitive response and pathogenicity G (HrpG). Detailed analysis of the regulatory role of HpaS has suggested the occurrence of further regulators besides HrpG. Here we used in vitro and in vivo approaches to identify the orphan response regulator VemR as another partner of HpaS and to characterize relevant interactions between components of this signalling system. Bacterial two-hybrid and protein pull-down assays revealed that HpaS physically interacts with VemR. Phos-tag SDS-PAGE analysis showed that mutation in hpaS reduced markedly the phosphorylation of VemR in vivo. Mutation analysis reveals that HpaS and VemR contribute to the regulation of motility and this relationship appears to be epistatic. Additionally, we show that VemR control of Xcc motility is due in part to its ability to interact and bind to the flagellum rotor protein FliM. Taken together, the findings describe the unrecognized regulatory role of sensor kinase HpaS and orphan response regulator VemR in the control of motility in Xcc and contribute to the understanding of the complex regulatory mechanisms used by Xcc during plant infection. 相似文献
993.
994.
Schmidgen H 《Journal of the history of biology》2004,37(3):477-513
This paper addresses the visual culture of late-19th-century experimental physiology. Taking the case of Johann Nepomuk Czermak (1828–1873) as a key example, it argues that images played a crucial role in acquiring experimental physiological skills. Czermak, Emil Du Bois-Reymond (1818–1896) and other late-19th-century physiologists sought to present the achievements and perspective of their discipline by way of immediate visual perception (unmittelbare Anschauung). However, the images they produced and presented for this purpose were strongly mediated. By means of specifically designed instruments, such as the cardioscope, the contraction telegraph, and the frog pistol, and of specifically constructed rooms, so-called spectatoriums, physiologists trained and controlled the perception of their students before allowing them to conduct experiments on their own. Studying the material culture of physiological image production reveals that technological resources such as telegraphy, photography, and even railways contributed to making physiological facts anschaulich. At the same time, it shows that the more traditional image techniques of anatomy played an important role in physiological lecture halls, especially when it came to displaying the details of vivisection experiments to the public. Thus, the images of late 19th century physiology stood half-way between machines and organisms, between books and instruments.This paper was written in the context of ten project, The Experimentalizaiton of Life: Configurations of Life Sciences, Art, and Technology (1830–1930). The project is based at the Max Planck Institute for the History of Science (Dept. III: Hans-Jörg Rheinberger), Berlin, and receives funding from the Volkswagen Stiftung, Hannover. A first draft of this paper was presented, accompanied by Sven Dierig on the Virtual Laboratory, at the Institute of Theater Sciences, Free university Berlin, in December 2000. I would like to thank Sven Dierig and the other members of the project as well as Nick Hopwood, Skúli Sigurdsson and the anonymous referees and the editors of this journal for their helpful comments on an earlier version of this paper. Thanks also to Laurie McLaughlin and Nancy Anderson for helping me with the English version of the text. 相似文献
995.
Objective
To examine the role of miR-124a in LPS-induced septic cardiac insufficiency where underlying mechanism is unclear.Results
Expression of miR-124a was decreased in myocardium of LPS-induced septic cardiac dysfunction model. miR-124a antagomiR or agomiR were injected via tail vein to induce miR-124a-dysregulated model. miR-124a antagomiR aggravated LPS-induced cardiac dysfunction and apoptosis, while miR-124a agomiR had the opposite effect. Syntaxin-2 (STX2) was indicated as a candidate target gene by bioinformatic software. Further experiments confirmed that STX2 was downregulated in miR-124a agomiR-treated rats but upregulated in miR-124a antagomiR-treated rats, and STX2 inhibition could strongly block the miR-124a antagomiR-associated increase in cell apoptosis. Luciferase reporter activity assay indicated that STX2 was a direct target of miR-124a. Serological detection reveled that miR-124a was down-regulated in the plasma of septic cardiac dysfunction rats.Conclusions
miR-124a aggravates LPS-induced cardiac dysfunction and the miR-124a/STX2 pathway might serve as the potential diagnostic and therapeutic targets for septic cardiac dysfunction.996.
Mark C. Ball Laura Finnegan Micheline Manseau Paul Wilson 《Conservation Genetics》2010,11(6):2131-2143
Individual-based clustering (IBC) methods have become increasingly popular for the characterization and delineation of genetic
population units for numerous species. These methods delineate populations based on the genetic assumptions of a breeding
unit which may provide a better representation of the behaviour of the species. The increasing use of IBC has resulted in
the development of several analytical models all of which vary in their theoretical assumptions to infer genetic population
structure. In this paper, we report a comparative strategy utilizing three IBC methods to characterize the spatial genetic
structure of the boreal population of woodland caribou (Rangifer tarandus caribou) in central Canada. In addition, we implement both tests for isolation-by-distance (IBD) and frequency-based assignment tests
to validate the consensus genetic clusters as defined by IBC. We also compare indirect metrics of genetic diversity and gene
flow using both a priori defined herds and the IBC defined populations. Although our results show some concordance between both pre-defined herds
and IBC derived genetic clusters, the IBC analyses identified a cluster that was cryptic to observation-based caribou herds
and found no difference between several adjacent herds. By comparing multiple IBC methods and integrating both IBD and indirect
genetic diversity metrics a posteriori, our strategy provides an effective means to delineate wildlife population structure and accurately assess genetic diversity
and connectivity. 相似文献
997.
998.
Derived amino acid sequence and identification of active site residues of Escherichia coli beta-hydroxydecanoyl thioester dehydrase 总被引:9,自引:0,他引:9
J E Cronan W B Li R Coleman M Narasimhan D de Mendoza J M Schwab 《The Journal of biological chemistry》1988,263(10):4641-4646
The nucleotide sequence of the fabA gene encoding beta-hydroxydecanoyl thioester dehydrase, a key enzyme of the unsaturated fatty acid synthesis pathway of Escherichia coli, has been determined by the dideoxynucleotide sequencing technique. Most of the sequence was obtained by sequencing intragenic insertions of the transposon, Tn1000, isolated in vivo. A synthetic primer complementary to a portion of the inverted repeat sequences at the ends of the transposon was used to prime DNA synthesis into the flanking fabA sequences. The gene is composed of 516 nucleotides (171 amino acid residues) encoding a protein with a molecular weight of 18,800. Approximately half of the derived amino acid sequence was confirmed by automated Edman sequencing of peptides obtained by cyanogen bromide cleavage. The active site histidine residue (His-70) has been identified by analysis of the peptides labeled by reaction with 14C-labeled 3-decynoyl-N-acetylcysteamine, a specific mechanism-activated inhibitor. A cysteine residue (Cys-69) adjacent to the active site histidine may play the role in catalysis previously assigned to a tyrosine residue. We also report a simplified purification process for the dehydrase beginning with extracts of a brain which greatly overproduces the enzyme. 相似文献
999.
1000.
Moso bamboo (Phyllostachys pubescens) is widely distributed in the acid soil region of Southern China, where great potential of aluminum (Al) toxicity exists.
To evaluate the Al tolerance of Moso bamboo, seed germination and root elongation were compared with two rice cultivars, and
physical and physiological damages were examined under various levels of Al stress. Results showed that Moso bamboo seed germination
was inhibited when Al concentration increased to 500 μM, and the median lethal concentration was 2,000 μM. Comparatively,
the rice seed germination was not inhibited even at a concentration of 2,000 μM Al. Aluminum accumulated mainly in the cell
wall of root apices, and entered into protoplasts as treating time prolonged and/or Al concentration increased, which resulted
in apoptosis. The bamboo root epidermis degraded significantly in the presence of 2,000 μM Al. In conclusion, Moso bamboo
is moderately weak in Al tolerance. 相似文献