排序方式: 共有65条查询结果,搜索用时 15 毫秒
31.
Zongkui Kou Tingting Wang Qilin Gu Mo Xiong Lirong Zheng Xin Li Zhenghui Pan Hao Chen Francis Verpoort Anthony K. Cheetham Shichun Mu John Wang 《Liver Transplantation》2019,9(16)
Due to integrated advantages in electrochemical functionalities for energy conversion, 2D nonlayered heterostructure nanosheets offer new and fascinating opportunities for electrocatalysis but their fabrication is challenging when compared with the widely studied 2D layered heterostructure. Herein, a bottom‐up approach is established for facile synthesis of holey 2D transition metal carbide/nitride heterostructure nanosheets (h‐TMCN) with regulated hole sizes by controlled thermal annealing of the Mo/Zn bimetallic imidazolate frameworks (Mo/Zn BIFs). Ex situ phase and structural identifications disclose that the Mo/Zn BIFs precursor experiences interconnected three steps of transformation to produce h‐TMCN. Especially, the slow successive solid‐state diffusion of nitrogen and carbon into immediate noncrystalline molybdenum oxides allows the intergrowth of Mo2C and Mo2N into the 2D nonlayered heterostructure. X‐ray fine structure analysis coupled with high resolution X‐ray photoelectron spectroscopy demonstrate that Mo2C and Mo2N in the microdomains can chemically bond with each other, producing the abundant active N–Mo–C interfaces toward water splitting. Consequently, h‐TMCN affords low overpotentials, high turnover frequencies, rapid charge transfer, and superior long‐term stability toward electrocatalytic water oxidation. The present work demonstrates the feasibility of developing a broad range of 2D nonlayered heterostructures for high efficiency chemical energy conversion. 相似文献
32.
Jiabao Li Shichun Cai Yuanming Luo Xiuzhu Dong 《Applied and environmental microbiology》2011,77(17):6141-6147
Feruloyl esterases (Faes) constitute a subclass of carboxyl esterases that specifically hydrolyze the ester linkages between ferulate and polysaccharides in plant cell walls. Until now, the described microbial Faes were mainly from fungi. In this study, we report that Cellulosilyticum ruminicola H1, a previously described fibrolytic rumen bacterium, possesses three different active feruloyl esterases, FaeI, FaeII, and FaeIII. Phylogenetic analysis classified the described bacterial Faes into two types, FaeI and FaeII in type I and FaeIII in type II. Substrate specificity assays indicated that FaeI is more active against the ester bonds in natural hemicelluloses and FaeIII preferentially attacks the ferulate esters with a small moiety, such as methyl groups, while FaeII is active on both types of substrates. Among the three feruloyl esterase genes, faeI was the only one induced significantly by xylose and xylan, while pectin appeared to moderately induce the three genes during the late log phase to stationary phase. Western blot analysis determined that FaeI and FaeIII were secreted and cytoplasmic proteins, respectively, whereas FaeII seemed to be cell associated. The addition of FaeI and FaeII but not FaeIII enhanced the activity of a xylanase on maize cob, suggesting a synergy of the former two with xylanase. Hence, we propose that the three feruloyl esterases work in concert to hydrolyze ferulate esters in natural hemicelluloses. 相似文献
33.
34.
35.
A new genus and species of heteronemertean, Yinia pratensis gen. nov. and sp. nov., collected from low salinity waters (salinity
0.2–0.4 ‰) at Changjiang River Estuary, is described and illustrated. The species possesses a proboscis with an outer circular
and an inner longitudinal muscle layer, and is placed in family Lineidae sensu Gibson. The following combination of morphological
features distinguishes the new species from any other genera in this family: proboscis with two muscle crosses; dermis without
connective tissue layer between gland cells and body wall outer longitudinal muscle layer; rhynchocoel wall circular muscles
not interweaving with adjacent body wall longitudinal muscles; foregut with circular somatic muscles and subepithelial gland
cell layer; neurochord cells present in central nervous system; caudal cirrus missing; blood system developed into alimentary
plexus extending almost the full length of the body. Another significant character is that the lobular excretory cells are
extremely well developed which may represent adaptation to water of low salinity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
36.
Haixia Chen Malin Strand Jon L. Norenburg Shichun Sun Hiroshi Kajihara Alexey V. Chernyshev Svetlana A. Maslakova Per Sundberg 《PloS one》2010,5(9)
Background
It has been suggested that statistical parsimony network analysis could be used to get an indication of species represented in a set of nucleotide data, and the approach has been used to discuss species boundaries in some taxa.Methodology/Principal Findings
Based on 635 base pairs of the mitochondrial protein-coding gene cytochrome c oxidase I (COI), we analyzed 152 nemertean specimens using statistical parsimony network analysis with the connection probability set to 95%. The analysis revealed 15 distinct networks together with seven singletons. Statistical parsimony yielded three networks supporting the species status of Cephalothrix rufifrons, C. major and C. spiralis as they currently have been delineated by morphological characters and geographical location. Many other networks contained haplotypes from nearby geographical locations. Cladistic structure by maximum likelihood analysis overall supported the network analysis, but indicated a false positive result where subnetworks should have been connected into one network/species. This probably is caused by undersampling of the intraspecific haplotype diversity.Conclusions/Significance
Statistical parsimony network analysis provides a rapid and useful tool for detecting possible undescribed/cryptic species among cephalotrichid nemerteans based on COI gene. It should be combined with phylogenetic analysis to get indications of false positive results, i.e., subnetworks that would have been connected with more extensive haplotype sampling. 相似文献37.
The phenomenon of codon usage bias is known to exist in many genomes and it is mainly determined by mutation and selection. To understand the patterns of codon usage in nemertean mitochondrial genomes, we use bioinformatic approaches to analyze the protein-coding sequences of eight nemertean species. Neutrality analysis did not find a significant correlation between GC12 and GC3. ENc-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENc values are below it. ENc-plot suggested that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally and we propose that codons containing A or U at third position are used preferentially in nemertean species, regardless of whether corresponding tRNAs are encoded in the mitochondrial DNA. Context-dependent analysis indicated that the nucleotide at the second codon position slightly affects synonymous codon choices. These results suggested that mutational and selection forces are probably acting to codon usage bias in nemertean mitochondrial genomes. 相似文献
38.
Heather H. Nelson Carmen J. Marsit Brock C. Christensen E.A. Houseman Milica Kontic Joseph L. Wiemels Margaret R. Karagas Margaret R. Wrensch Shichun Zheng John K. Wiencke Karl T. Kelsey 《Epigenetics》2012,7(6):559-566
Epigenetic alterations are a common event in lung cancer and their identification can serve to inform on the carcinogenic process and provide clinically relevant biomarkers. Using paired tumor and non-tumor lung tissues from 146 individuals from three independent populations we sought to identify common changes in DNA methylation associated with the development of non-small cell lung cancer. Pathologically normal lung tissue taken at the time of cancer resection was matched to tumorous lung tissue and together were probed for methylation using Illumina GoldenGate arrays in the discovery set (n = 47 pairs) followed by bisulfite pyrosequencing for validation sets (n = 99 pairs). For each matched pair the change in methylation at each CpG was calculated (the odds ratio), and these ratios were averaged across individuals and ranked by magnitude to identify the CpGs with the greatest change in methylation associated with tumor development. We identified the top gene-loci representing an increase in methylation (HOXA9, 10.3-fold and SOX1, 5.9-fold) and decrease in methylation (DDR1, 8.1-fold). In replication testing sets, methylation was higher in tumors for HOXA9 (p < 2.2 × 10−16) and SOX1 (p < 2.2 × 10−16) and lower for DDR1 (p < 2.2 × 10−16). The magnitude and strength of these changes were consistent across squamous cell and adenocarcinoma tumors. Our data indicate that the identified genes consistently have altered methylation in lung tumors. Our identified genes should be included in translational studies that aim to develop screening for early disease detection. 相似文献
39.
Erin Maloney Dorota Stankowska Jian Zhang Marek Fol Qi-Jian Cheng Shichun Lun William R. Bishai Malini Rajagopalan Delphi Chatterjee Murty V. Madiraju 《PLoS pathogens》2009,5(7)
The well-recognized phospholipids (PLs) of Mycobacterium tuberculosis (Mtb) include several acidic species such as phosphatidylglycerol (PG), cardiolipin, phosphatidylinositol and its mannoside derivatives, in addition to a single basic species, phosphatidylethanolamine. Here we demonstrate that an additional basic PL, lysinylated PG (L-PG), is a component of the PLs of Mtb H37Rv and that the lysX gene encoding the two-domain lysyl-transferase (mprF)-lysyl-tRNA synthetase (lysU) protein is responsible for L-PG production. The Mtb lysX mutant is sensitive to cationic antibiotics and peptides, shows increased association with lysosome-associated membrane protein–positive vesicles, and it exhibits altered membrane potential compared to wild type. A lysX complementing strain expressing the intact lysX gene, but not one expressing mprF alone, restored the production of L-PG and rescued the lysX mutant phenotypes, indicating that the expression of both proteins is required for LysX function. The lysX mutant also showed defective growth in mouse and guinea pig lungs and showed reduced pathology relative to wild type, indicating that LysX activity is required for full virulence. Together, our results suggest that LysX-mediated production of L-PG is necessary for the maintenance of optimal membrane integrity and for survival of the pathogen upon infection. 相似文献
40.
Zhiwen Lian Guibao Ke Hong Zhang Caoshuai Dou Xueqin Chen Bohou Li Fengxia Zhang Shichun Wen Qiong Wu Yubin Xia Nan Jiang Zhuo Li Sijia Li Xingchen Zhao Jianchao Ma Ting Lin Feng Wen Lixia Xu Shuangxin Liu 《Biochemistry and Biophysics Reports》2021
Podocyte injury is sufficient to cause glomerulosclerosis and proteinuria, eventually leading to kidney failure. Previous studies found that podocytes and neurons had similar biological characteristics. Growth-associated protein-43 (GAP-43) is a growth cone protein in neurons, and a marker of axonal and synaptic growth. However, it is not known whether GAP-43 is expressed in podocytes. Compared with normal glomerular podocytes, GAP-43 was significantly reduced in patients with glomerular diseases. GAP-43 also significantly reduced in lipopolysaccharide (LPS)-treated podocytes. We found that the decreased expression of nephrin, the cell marker of the podocyte, was significantly recovered with GAP-43 overexpression. In contrast, the migration ability in LPS-treated podocyte was reduction after GAP-43 overexpressing. Moreover, overexpression of GAP-43 attenuated podocyte apoptosis by up-regulating the ratio of Bcl-2/Bax with LPS treatment. Finally, Plaue and Rcan1 which are downstream target gene of NFATc1 decreased with overexpression of GAP-43 podocytes. We concluded that GAP-43 attenuated podocyte injury by inhibiting calcineurin/NFATc1 signaling. The findings may provide a promising treatment for podocyte injury-related diseases. 相似文献