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981.
J. Y. Zhu Steve P. Verrill Hao Liu Victoria L. Herian Xuejun Pan Donald L. Rockwood 《Bioenergy Research》2011,4(3):201-210
This paper discusses a property associated with plant biomass recalcitrance to enzyme and microbial deconstructions in sugar production from cellulose and hemicelluloses. The hemicelluloses are more readily hydrolyzed to sugars than is cellulose. As a result, optimization to maximize individual glucose and hemicellulose sugar recovery is not possible. This property is an inherent feature of plant biomass and is named polydispersity of plant biomass recalcitrance (PPBR) in this study. A set of pretreatment experiments using eucalyptus and sulfite pretreatment to overcome recalcitrance of lignocelluloses was conducted. The results were used to predict the conditions for individually maximizing enzymatic glucose and xylose yields. The predicted maximal yields were used to quantitatively illustrate the PPBR concept. The effect of PPBR on pretreatment optimization and strategies for maximal sugar recovery using two-stage pretreatment are discussed. 相似文献
982.
Jiu-ru Zhao Yong-dong Li Li-min Pan Na Zhu Hong-xia Ni Guo-zhang Xu Yong-zhong Jiang Xi-xiang Huo Jun-qiang Xu Han Xia Na Han Shuang Tang Zhong Zhang Zheng Kou Simon Rayner Tian-xian Li 《中国病毒学》2011,26(6):418-427
A total of 100 HIN1 flu real-time-PCR positive throat swabs collected from fever patients in Zhejiang,Hubei and Guangdong between June and November 2009,were provided by local CDC laboratories.After MDCK cell culture,57 Influenza A Pandemic (H1N1) viruses were isolated and submitted for whole genome sequencing.A total of 39 HA sequences,52 NA sequences,36 PB2 sequences,31 PB1 sequences,40 PA sequences,48 NP sequences,51 MP sequences and 36 NS sequences were obtained,including 20 whole genome sequences.Sequence comparison revealed they shared a high degree of homology (96%~99%) with known epidemic strains (A/Califomia/04/2009(H1N1).Phylogenetic analysis showed that although the sequences were highly conserved,they clustered into a small number of groups with only a few distinct strains.Site analysis revealed three substitutions at loop 220 (221-228) of the HA receptor binding site in the 39 HA sequences:A/Hubei/86/2009 PKVRDQEG→PKVRDQEA,A/Zhejiang/08/2009 PKVRDQEG→PKVRDQER,A/Hubei/75/2009PKVRDQEG→PKVRDQGG,the A/Hubei/75/2009 was isolated from an acute case,while the other two were from patients with mild symptoms.Other key sites such as 119,274,292 and 294 amino acids of NA protein,627 of PB2 protein were conserved.Meanwhile,all the M2 protein sequences possessed the Ser32Asn mutation,suggesting that these viruses were resistant to adamantanes.Comparison of these sequences with other H1N1 viruses collected from the NCBI database provides insight into H1N1 transmission and circulation patterns. 相似文献
983.
The effects of melittin on growth and bacteriostasis of four pathogens were extensively investigated using scanning electron
microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that the melittin had a marked bacteriostatic
effect on the four pathogenic bacteria. Among these, E. cacotowora was influenced most powerfully and quickly, the yeast and F. fulva were the second, and the S. aureus was inhibited by a low concentration but was killed by a high concentration. It was observed in the experiments that melittin
killed pathogenic bacteria in three ways. One was by pore formation. After integrating melittin into the plasma membrane,
a vacuole was formed then penetrated, resulting in bacterial content leakage. The vacuole also experienced plasmolysis and
the growing cavity destroyed the membrane. A third effect was the formation of vacuoles in the cells which induced the pycnosis
of the cytoplasm resulting in a cell death. The mechanism of melittin bacteriostasis was the result of integrating melittin
with phospholipod double layers of the plasmalemma and the endomembranes. 相似文献
984.
Intracellular Ca2+ is vital for cell physiology. Disruption of Ca2+ homeostasis contributes to human diseases such as heart failure, neuron-degeneration, and diabetes. To ensure an effective
intracellular Ca2+ dynamics, various Ca2+ transport proteins localized in different cellular regions have to work in coordination. The central role of mitochondrial
Ca2+ transport mechanisms in responding to physiological Ca2+ pulses in cytosol is to take up Ca2+ for regulating energy production and shaping the amplitude and duration of Ca2+ transients in various micro-domains. Since the discovery that isolated mitochondria can take up large quantities of Ca2+ approximately 5 decades ago, extensive studies have been focused on the functional characterization and implication of ion
channels that dictate Ca2+ transport across the inner mitochondrial membrane. The mitochondrial Ca2+ uptake sensitive to non-specific inhibitors ruthenium red and Ru360 has long been considered as the activity of mitochondrial
Ca2+ uniporter (MCU). The general consensus is that MCU is dominantly or exclusively responsible for the mitochondrial Ca2+ influx. Since multiple Ca2+ influx mechanisms (e.g. L-, T-, and N-type Ca2+ channel) have their unique functions in the plasma membrane, it is plausible that mitochondrial inner membrane has more than
just MCU to decode complex intracellular Ca2+ signaling in various cell types. During the last decade, four molecular identities related to mitochondrial Ca2+ influx mechanisms have been identified. These are mitochondrial ryanodine receptor, mitochondrial uncoupling proteins, LETM1
(Ca2+/H+ exchanger), and MCU and its Ca2+ sensing regulatory subunit MICU1. Here, we briefly review recent progress in these and other reported mitochondrial Ca2+ influx pathways and their differences in kinetics, Ca2+ dependence, and pharmacological characteristics. Their potential physiological and pathological implications are also discussed. 相似文献
985.
986.
Human embryonic stem cells (hESCs) have great potential for use in developmental biology studies, functional genomics applications, drug screening, and regenerative medicine. A detailed understanding of the molecular mechanisms that are responsible for maintaining the undifferentiated and pluripotent nature of hESCs is essential for their effective therapeutic application. It has become evident that many complex cellular processes are carried out by assemblies of protein molecules (protein complexes). Blue native polyacrylamide gel electrophoresis (BN-PAGE) has been used to separate protein complexes from whole cell lysates. Using BN-PAGE, we resolved cytoplasmic and membrane-associated complexes from hESCs and characterised their composition, stoichiometry, and dynamics by denaturing SDS-PAGE. The reliability of the fractionation was examined by western blot analysis of membrane and cytosolic markers. MALDI TOF/TOF mass spectrometry identified 119 cytosolic and 69 membrane proteins from the BN-PAGE proteome maps. Potential protein complexes were validated by computational prediction of possible protein-protein interactions using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. Based on BN-PAGE gels and validation by databases, 82 heteromultimeric and 47 homomultimeric protein complexes have been found in hESCs. Resolving some of the protein complexes provided insight into the function of previously uncharacterised complexes in hESCs. 相似文献
987.
Li Y Zhao X Pan Z Xie Z Liu H Xu Y Li Q 《Animal : an international journal of animal bioscience》2011,5(12):1868-1873
DNA barcoding is an effective technique to identify species and analyze phylogenesis and evolution. However, research on and application of DNA barcoding in Canis have not been carried out. In this study, we analyzed two species of Canis, Canis lupus (n = 115) and Canis latrans (n = 4), using the cytochrome c oxidase subunit I (COI) gene (1545 bp) and COI barcoding (648 bp DNA sequence of the COI gene). The results showed that the COI gene, as the moderate variant sequence, applied to the analysis of the phylogenesis of Canis members, and COI barcoding applied to species identification of Canis members. Phylogenetic trees and networks showed that domestic dogs had four maternal origins (A to D) and that the Tibetan Mastiff originated from Clade A; this result supports the theory of an East Asian origin of domestic dogs. Clustering analysis and networking revealed the presence of a closer relative between the Tibetan Mastiff and the Old English sheepdog, Newfoundland, Rottweiler and Saint Bernard, which confirms that many well-known large breed dogs in the world, such as the Old English sheepdog, may have the same blood lineage as that of the Tibetan Mastiff. 相似文献
988.
Micro- and nanoparticulate drug-delivery systems (DDSs) play a significant role in formulation sciences. Most particulate DDSs are scaffold-free, although some particles are encapsulated inside other biomaterials for controlled release. Despite rapid progress in recent years, challenges still remain in controlling the homogenicity of micro-/nanoparticles, especially for two crucial factors in particulate DDSs: the size and shape of the particles. Recent approaches make use of microfabrication techniques to generate micro-/nanoparticles with highly controllable architectures free of scaffolds. This review presents an overview of a burgeoning field of DDSs, which can potentially overcome some drawbacks of conventional techniques for particle fabrication and offer better control of particulate DDSs. 相似文献
989.
Speech perception often benefits from vision of the speaker's lip movements when they are available. One potential mechanism underlying this reported gain in perception arising from audio-visual integration is on-line prediction. In this study we address whether the preceding speech context in a single modality can improve audiovisual processing and whether this improvement is based on on-line information-transfer across sensory modalities. In the experiments presented here, during each trial, a speech fragment (context) presented in a single sensory modality (voice or lips) was immediately continued by an audiovisual target fragment. Participants made speeded judgments about whether voice and lips were in agreement in the target fragment. The leading single sensory context and the subsequent audiovisual target fragment could be continuous in either one modality only, both (context in one modality continues into both modalities in the target fragment) or neither modalities (i.e., discontinuous). The results showed quicker audiovisual matching responses when context was continuous with the target within either the visual or auditory channel (Experiment 1). Critically, prior visual context also provided an advantage when it was cross-modally continuous (with the auditory channel in the target), but auditory to visual cross-modal continuity resulted in no advantage (Experiment 2). This suggests that visual speech information can provide an on-line benefit for processing the upcoming auditory input through the use of predictive mechanisms. We hypothesize that this benefit is expressed at an early level of speech analysis. 相似文献
990.