植物果胶的生物合成与功能

果胶作为植物细胞壁多糖之一,其结构和功能非常复杂。果胶主要由同型半乳糖醛酸聚糖(HG)、鼠李半乳糖醛酸聚糖I (RGI)和鼠李半乳糖醛酸聚糖II (RGII)组成。果胶类成分在维持细胞壁结构的完整性以及细胞间黏附和信号转导等方面发挥重要作用。研究果胶类成分的结构、分布和功能,对理解细胞壁高级结构的构建和功能具有重要意义...     

Functional proteomic analysis of a three-tier PKCepsilon-Akt-eNOS signaling module in cardiac protection

Cardiac protective signaling networks have been shown to involve PKCepsilon. However, the molecular mechanisms by which PKCepsilon interacts with other members of these networks to form task-specific modules remain unknown. Among 93 different PKCepsilon-associated proteins that have been identified, Akt and endothelial nitric oxide (NO) synthase (eNOS) are of importance because of their independent abilities to promote cell survival and prevent cell death. The simultaneous association of PKCepsilon, Akt, and eNOS has not been examined, and, in particular, the formation of a module containing these three proteins and the role of such a module in the regulation of NO production and cardiac protection are unknown. The present study was undertaken to determine whether these molecules form a signaling module and, thereby, play a collective role in cardiac signaling. Using recombinant proteins in vitro and PKCepsilon transgenic mouse hearts, we demonstrate the following: 1) PKCepsilon, Akt, and eNOS interact and form signaling modules in vitro and in the mouse heart. Activation of either PKCepsilon or Akt enhances the formation of PKCepsilon-Akt-eNOS signaling modules. 2) PKCepsilon directly phosphorylates and enhances activation of Akt in vitro, and PKCepsilon activation increases phosphorylation and activation of Akt in PKCepsilon transgenic mouse hearts. 3) PKCepsilon directly phosphorylates eNOS in vitro, and this phosphorylation enhances eNOS activity. Activation of PKCepsilon in vivo increased phosphorylation of eNOS at Ser(1177), indicating eNOS activation. This study characterizes, for the first time, the physical, as well as functional, coupling of PKCepsilon, Akt, and eNOS in the heart and implicates these PKCepsilon-Akt-eNOS signaling modules as critical signaling elements during PKCepsilon-induced cardiac protection.     

Impact of altered substrate utilization on cardiac function in isolated hearts from Zucker diabetic fatty rats

The goal of this study was to determine whether changes in cardiac metabolism in Type 2 diabetes are associated with contractile dysfunction or impaired response to ischemia. Hearts from Zucker diabetic fatty (ZDF) and lean control rats were isolated and perfused with glucose, lactate, pyruvate, and palmitate. The rates of glucose, lactate, pyruvate, and palmitate oxidation rates and glycolysis were determined during baseline perfusion and low-flow ischemia (LFI; 0.3 ml/min for 30 min) and after LFI and reperfusion. Under all conditions, ATP synthesis from palmitate was increased and synthesis from lactate was decreased in the ZDF group, whereas the contribution from glucose was unchanged. During baseline perfusion, the rate of glycolysis was lower in the ZDF group; however, during LFI and reperfusion, there were no differences between groups. Despite these metabolic shifts, there were no differences in oxygen consumption or ATP production rates between the groups under any perfusion conditions. Cardiac function was slightly depressed before LFI in the ZDF group, but during reperfusion, function was improved relative to the control group despite the increased dependence on fatty acids for energy production. These data suggest that in this model of diabetes, the shift from carbohydrates to fatty acids for oxidative energy production did not increase myocardial oxygen consumption and was not associated with impaired response to ischemia and reperfusion.     

Effects of Nerve Growth Factor and Basic Fibroblast Growth Factor Promote Human Dental Pulp Stem Cells to Neural Differentiation

Dental pulp stem cells (DPSCs) were the most widely used seed cells in the field of neural regeneration and bone tissue engineering, due to their easily isolation, lack of ethical controversy, low immunogenicity and low rates of transplantation rejection. The purpose of this study was to investigate the role of basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) on neural differentiation of DPSCs in vitro. DPSCs were cultured in neural differentiation medium containing NGF and bFGF alone or combination for 7 days. Then neural genes and protein markers were analyzed using western blot and RT-PCR. Our study revealed that bFGF and NGF increased neural differentiation of DPSCs synergistically, compared with bFGF and NGF alone. The levels of Nestin, MAP-2, βIII-tubulin and GFAP were the most highest in the DPSCs?+?bFGF?+?NGF group. Our results suggested that bFGF and NGF signifiantly up-regulated the levels of Sirt1. After treatment with Sirt1 inhibitor, western blot, RT-PCR and immunofluorescence staining showed that neural genes and protein markers had markedly decreased. Additionally, the ERK and AKT signaling pathway played a key role in the neural differentiation of DPSCs stimulated with bFGF?+?NGF. These results suggested that manipulation of the ERK and AKT signaling pathway may be associated with the differentiation of bFGF and NGF treated DPSCs. Our date provided theoretical basis for DPSCs to treat neurological diseases and repair neuronal damage.     

Colorimetric recognition of aromatic amino acid enantiomers by gluconic acid-capped gold nanoparticles

In this work, we prepared gold nanoparticles (AuNPs) by employing gluconic acid (GlcA) as reducing-cum-stabilizing agent. The proposed GlcA-AuNPs successfully worked as a colorimetric sensor for visual chiral recognition of aromatic amino acid enantiomers, namely tyrosine (d/l-Tyr), phenylalanine (d/l-Phe), and tryptophan (d/l-Trp). After adding L-types to GlcA-AuNPs solution, the color of the mixture changed from red to purple (or gray), while no obvious color change occurred on the addition of D-types. The effect can be detected by naked eyes. The particles have been characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, zeta potential, the dynamic light scattering analysis as well as UV–Vis spectroscopy. This assay can be used to determine the enantiomeric excess of l-Trp in the range from 0 to + 100%. The method has advantages in simplicity, sensitivity, fast response, and low cost.

     

基于三维生态足迹模型的长江中游城市群平衡性分析与生态补偿研究

长江中游城市群是长江经济带的重要组成部分，明晰生态足迹平衡性对城市群区域间生态补偿以及长江中游城市群生态可持续发展具有重要意义。研究采用三维生态足迹模型和基尼系数，核算长江中游城市群各市生态足迹及生态承载力，并对其生态足迹空间平衡性进行分析；同时依据三维生态足迹相关理论，计算各市生态补偿金额。结果表明：①2000-2015年长江中游城市群整体生态足迹持续上升，由65.52 hm²/人增加至139.38 hm²/人，年增长率为7.52%，武汉城市圈和襄荆宜城市群对生态足迹增长的贡献最大；②生态承载力呈下降趋势，由11.25 hm²/人减小至10.73 hm²/人，从土地利用类型来看，耕地和林地是提供生态承载能力的最主要因素；③生态足迹的综合基尼系数处于0.425-0.488之间，整体上处于"集聚程度较大"的区间范围，空间分布显示出不平衡性；④2000-2015年长江中游城市群生态补偿支付区和补偿金额持续增加，各子城市群生态补偿差异大小关系为：环鄱阳湖城市群 > 环长株潭城市群 > 武汉城市圈和襄荆宜城市群。通过分析区域生态足迹、生态承载力的时空变化特征并提出对应补偿方案，以期为长江中游城市群生态建设和管理提供决策依据。