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Volume 11 No. 4
20 April 2006
Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803

Xingguo Liu, Wei Huang, Qingyu Wu

2006, 11(4): 379-390.   doi:10.1016/S1007-0214(06)70205-X
Abstract ( 223 )  ( 112 )   Save
Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. The unicellular Synechocystis sp. PCC 6803 has become a model organism for a range of biochemical and molecular biology studies aiming at investigating environmental stress response. The publication of the complete genome sequence of the cyanobacterium Synechocystis sp. PCC 6803 provided a tremendous stimulus for research in this field, and ...
Inhibitory Effect of Furosemide on Carbonic Anhydrase

Jianli Cui, Tongjin Zhao, Yan Jiang, Haimeng Zhou

2006, 11(4): 391-394.   doi:10.1016/S1007-0214(06)70206-1
Abstract ( 287 )  ( 107 )   Save
This study investigated the inhibitory effect of a high efficiency diuretic, furosemide, on carbonic anhydrase (CA). First, comparing the inhibitory effect of acetazolamide, a low efficiency diuretic, on CA, shows that furosemide or acetazolamide can quickly make CA inactive when its concentration is close to the enzyme concentration, different from the usual inhibitory kinetics in which the concentration of the inhibitor is far higher than the enzyme concentration. Secondly, the reaction of the...
Contributions of a Position Amino Acid Residues to the Conformational Stability of GCN4 Leucine Zipper

Xiang Wei, Xian'gang Zeng, Haimeng Zhou

2006, 11(4): 395-399.   doi:10.1016/S1007-0214(06)70207-3
Abstract ( 182 )  ( 107 )   Save
The stability of GCN4 leucine zipper and its four mutants in guanidine hydrochloride was detected to verify the contributions of different a position amino acid residues in polypeptide sequences to the forming and stability of parallel coiled coils. The changes of the circular dichroism spectra show that the displacement of the a position polar asparagine and the increase of asparagine in the GCN4 leucine zipper can reduce the α-helix content of the coiled coil structure. The mutants are less st...
Effect of Urea on Activity and Conformation of a Glycoprotein

Xiang Wei, Xiaoyun Wang, Bo Zhou, Haimeng Zhou

2006, 11(4): 400-407.   doi:10.1016/S1007-0214(06)70208-5
Abstract ( 190 )  ( 131 )   Save
The changes of the activity and conformation of Aspergillus niger phytase in urea were detected by far-ultraviolet circular dichroism (CD) spectra, fluorescence spectra, and enzyme activity assays. The results show that no enzyme activity can be detected after phytase is incubated for 10 h in 3.0 mol/L urea, even though at this urea concentration, less than 20% of the tertiary and secondary structures in the native enzyme changed. The inactivation reaction kinetics is found to be a monophasic fi...
Nicotinamide-Induced Apoptosis Can Be Enhanced by Melatonin in Mouse Myeloma Cells

Guiyou Zhang, Hongzhi Sheng, Jia Liu

2006, 11(4): 408-414.   doi:10.1016/S1007-0214(06)70209-7
Abstract ( 158 )  ( 131 )   Save
The mechanism of apoptosis induced by nicotinamide was investigated by treating mouse myeloma cells (Sp2/0) with various concentrations of nicotinamide. The typical hallmarks of apoptosis, including chromatin condensation and DNA fragmentation, were detected when cells were treated with nicotinamide at concentrations of 30, 40, 50, and 60 mmol/L. The apoptosis percentage increased with increasing nicotinamide concentration. Interestingly, the strong antioxidant melatonin did not restrain the apo...
Neural Stem Cell Affinity of Chitosan and Feasibility of Chitosan-Based Porous Conduits as Scaffolds for Nerve Tissue Engineering

Aijun Wang, Qiang Ao, Qing He, Xiaoming Gong, Kai Gong, Yandao Gong, Nanming Zhao, Xiufang Zhang

2006, 11(4): 415-420.   doi:10.1016/S1007-0214(06)70210-3
Abstract ( 138 )  ( 106 )   Save
Neural stem cells (NSCs) are currently considered as powerful candidate seeding cells for regeneration of both spinal cords and peripheral nerves. In this study, NSCs derived from fetal rat cortices were co-cultured with chitosan to evaluate the cell affinity of this material. The results showed that NSCs grew and proliferated well on chitosan films and most of them differentiated into neuron-like cells after 4 days of culture. Then, molded and braided chitosan conduits were fabricated and chara...
Compatibility of Chitosan-Gelatin Films with Adipose Tissue Derived Stromal Cells

Ling Zhang, Yuan Gao, Lijun Kong, Yandao Gong, Nanming Zhao, Xiufang Zhang

2006, 11(4): 421-426.   doi:10.1016/S1007-0214(06)70211-5
Abstract ( 144 )  ( 117 )   Save
Chitosan has been shown to be a promising material for various applications in tissue engineering. Recently, adipose tissue derived stromal cells (ADSCs) have been investigated as an alternative source of seed cells for tissue engineering. The compatibility of chitosan and chitosan-gelatin complexes with ADSCs is not known. In the present study, ADSCs were isolated and characterized by phenotype using fluorescence-activated cell sorting (FACS). The morphology, viability, and the ability of the A...
Porous Chitosan Microcarriers for Large Scale Cultivation of Cells for Tissue Engineering: Fabrication and Evaluation

Guangyuan Lu, Lin Zhu, Lijun Kong, Ling Zhang, Yandao Gong, Nanming Zhao, Xiufang Zhang

2006, 11(4): 427-432.   doi:10.1016/S1007-0214(06)70212-7
Abstract ( 216 )  ( 170 )   Save
Porous chitosan microspheres with diameters ranging from 180 μm to 280 μm were successfully prepared, using an anti-phase suspension method combined with temperature controlled freeze-extraction. The mean pore diameter could be regulated from 5 μm to 60 μm by varying the freezing temperature through the cooling rate. Results with in vitro chondrocyte cultures showed that cells could attach, proliferate, and spread on these porous microspheres as well as inside the microcarriers. The materials an...
Effect of Calcium on Spontaneous Quantal Transmitter Secretion from ACh-Loaded Myocytes

Lei Qi, Ruxin Li, Xiangping He, Zuoping Xie

2006, 11(4): 433-439.   doi:10.1016/S1007-0214(06)70213-9
Abstract ( 191 )  ( 119 )   Save
Spontaneous secretions occur in both neurons and non-neuronal cells, and calcium is important for these secretion processes. However, the detailed roles of calcium on the secretions have not yet been identified. In the present study, cultured Xenopus myocytes loaded with exogenous acetylcholine (ACh) into the cytoplasm in the absence of extracellular Ca2+ undergo spontaneous quantal ACh secretion as detected by the appearance of pulsatile miniature endplate currents. Analysis of the frequencies,...
Spontaneous Neurotransmitter Release Depends on Intracellular Rather than ER Calcium Stores in Cultured Xenopus NMJ

Song Ge, Ruxin Li, Lei Qi, Xiangping He, Zuoping Xie

2006, 11(4): 440-446.   doi:10.1016/S1007-0214(06)70214-0
Abstract ( 179 )  ( 99 )   Save
Calcium ions are important in many vital neuron processes, including spontaneous neurotransmitter release. Extracellular calcium has long been known to be related to spontaneous neurotransmitter release, but the detailed mechanism for the effect of intracellular Ca2+ on synaptic release has not yet been understood. In this research, 1,2-bis-(o-aminophenoxy)-ethane-N, N, N’, N’-tetraacetic acid tetraacetoxy-methyl ester (BAPTA-AM) was used to combine with cytosolic free Ca2+ in a calcium free med...
Cholesterol Depletion Reduces the Internalization of β-Amyloid Peptide in SH-SY5Y Cells

Qinghua Zhou, Li He, Senfang Sui

2006, 11(4): 447-451.   doi:10.1016/S1007-0214(06)70215-2
Abstract ( 188 )  ( 118 )   Save
Deposition of amyloid in the brain is a critical step in the pathogenesis of Alzheimer's disease. The endocytosis of β-amyloid peptide (Aβ) is an important factor among the many factors that contribute to the genesis of amyloid deposits. Since cholesterol participates in many important physiological processes, the present work investigated the relationship between the cellular cholesterol content and the endocytosis of the exogenic Aβ, and found that reduction of the cholesterol content by methy...
Lipid Rafts Identified on Synaptic Vesicles from Rat Brain

Li He, Jihua L� Qinghua Zhou, Senfang Sui

2006, 11(4): 452-458.   doi:10.1016/S1007-0214(06)70216-4
Abstract ( 289 )  ( 135 )   Save
For a long time, lipid rafts have been thought to participate in regulating neurotransmitter release. However, the existence of lipid rafts on synaptic vesicles (SVs) and the mechanism by which exocytosis-relative proteins distribute on this structure have not been fully investigated. There is also much controversial data concerning rafts on SVs and synaptic vesicle proteins which makes the results difficult to interpret. This study systematically analyzed the existence and properties of lipid r...
Characteristics of Baicalin Synergy with Penicillin or Notopterygium Ethanol Extracts Against Staphylococcus aureus

Zhen Meng, Sop Chongjin, Xuefu You, Dongming Xing, Wei Wang, Lijun Du

2006, 11(4): 459-461.   doi:10.1016/S1007-0214(06)70217-6
Abstract ( 988 )  ( 131 )   Save
Baicalin facilitates the effectiveness of both penicillin and Notopterygium ethanol extracts (NEE) on Staphylococcus aureus. Two Staphylococcus aureus strains, ATCC29213 and 03-21 (a clinical isolate), were tested. When combined with 128 μg ? mL?1 of baicalin, the minimum inhibitory concentration (MIC) of penicillin was reduced from 0.25 μg ? mL?1 to 0.06 μg ? mL?1, while that of NEE was reduced from 32 μg ? mL?1 to 8 μg ? mL?1 against ATCC29213. Against the 03-21 strain, the MIC of penicillin w...
Fractals in Spatial Patterns of Vegetation Formations

Zhiyuan Song, Daming Huang, Shiyomi Masae, Yusheng Wang, Takahashi Shigeo, Yoshimichi Hori, Yamamuru Yasuo, Jun Chen

2006, 11(4): 462-469.   doi:10.1016/S1007-0214(06)70218-8
Abstract ( 233 )  ( 109 )   Save
The spatial distribution patterns of species are always scale-dependent and spatially self-similar in ecological systems. In this work, vegetation distribution data collected from the vegetation map of the Xigaz?region was analyzed using a box-counting method. The power law of the box-counting dimension (DB) across a range of scales (5-160 km) confirms the fractal patterns for most vegetation formations, while the fluctuations of the scale-specific DB among the different abundance groups indicat...
Ionizing Groups at the Active Site of the Alkaline Phosphatase from Ostrea cucullate

Qiao Chen, Qin Wang, Jinhua Liao, Qingxi Chen

2006, 11(4): 470-474.   doi:10.1016/S1007-0214(06)70219-X
Abstract ( 210 )  ( 141 )   Save
The ionizing groups at the active site of alkaline phosphatase (ALP, EC 3.1.3.1) from Ostrea cucullate were studied using kinetic methods. The ionization constant, pKe, of the ionizing groups at the active site of the enzyme was found to be 10.11 at 37.0°C and the organic solvent, dioxin, had no effect on the pKe. The standard dissociation enthalpy (ΔHo) was determined to be 10.57 kcal/mol (1 cal=4.18 J). The results show that the dissociation group of the enzyme active center is the ?-NH3+ of l...
Real-Time Implementation of an Efficient Speech Enhancement Algorithm for Digital Hearing Aids

Jie Gao, Hui Zhang, Guangshu Hu

2006, 11(4): 475-480.   doi:10.1016/S1007-0214(06)70220-6
Abstract ( 212 )  ( 148 )   Save
In order to remove background noise and improve the quality of speech for digital hearing aids, a single-channel speech enhancement algorithm is proposed. The algorithm is implemented and assessed on a digital hearing aid platform based on the TI DSP TMS320VC5502 chip. Assuming that background noise is stationary or varies slowly, an energy-based voice activity detection algorithm is adopted by adaptively tracking the minima and maxima of the power envelope in noisy speech. The target speech is ...
Photoautotrophic Growth and Net Photosynthetic Rate of Sweet Potato Plantlets In Vitro as Affected by the Number of Air Exchanges of the Vessel and Type of Supporting Material

Yulan Xiao, Toyoki Kozai

2006, 11(4): 481-489.   doi:10.1016/S1007-0214(06)70221-8
Abstract ( 172 )  ( 123 )   Save
To produce high-quality sweet potato plantlets rapidly at low production costs, single nodal leafy cuttings of sweet potato (Ipomoea batatas (L.) Lam.) plantlets were cultured in vitro for 14 days on sugar- and phytohormone-free Murashige and Skoog (MS) liquid medium, at a photosynthetic photon flux (PPF) of 200 μmol ? m?2 ? s?1 and a CO2 concentration (v/v) of 1.8×10?3. A factorial experiment was conducted with two levels of the number of air exchanges of the vessel (NAE), 8.7-12.2 h?1 and ≥12....
Dissection of SARS Coronavirus Spike Protein into Discrete Folded Fragments

Shuang Li, Zhen Cai, Yong Chen, Zhanglin Lin

2006, 11(4): 490-494.   doi:10.1016/S1007-0214(06)70222-X
Abstract ( 220 )  ( 108 )   Save
The spike protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) mediates cell fusion by binding to target cell surface receptors. This paper reports a simple method for dissecting the viral protein and for searching for foldable fragments in a random but systematic manner. The method involves digestion by DNase I to generate a pool of short DNA segments, followed by an additional step of reassembly of these segments to produce a library of DNA fragments with random ends but con...
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