猫扣带回前部内脏伤害感受神经元的膜电学特性

目的：研究猫扣带回前部内脏大神经刺激相关神经元的膜电生理特性,以便从神经元水平进一步了解大脑皮质内脏伤害感受的特性及机制,为痛觉理论“特异性学说”提供新的实验依据。方法：应用在体玻璃微电极细胞内电位记录技术及细胞内注入极化电流的方法,测量和计算神经元的膜电学参数。结果：将20只猫扣带回前部176个内脏大神经刺激相关神经元,分为内脏伤害(148个)和非伤害(28个)感受神经元。发现它们在膜电阻、时间常数、膜电容及I—V曲线等方面存在差异。注入去极化电流引发的放电幅值及频率也存在差异。结论：扣带回前部内脏伤害与非伤害感受神经元可能在细胞膜结构、细胞大小等形态学方面存有差别。     

Disruption of YPS1 and PEP4 genes reduces proteolytic degradation of secreted HSA/PTH in Pichia pastoris GS115

Human serum albumin (HSA) and human parathyroid hormone (1-34) [PTH (1-34)] fusion protein [HSA/PTH (1-34)] is a promising long-acting form of PTH (1-34) for osteoporosis treatment. Secretory expression of intact HSA/PTH (1-34) in Pichia pastoris GS115 was accompanied by two degradation fragments, with molecular weights around 66 kDa, in addition to the well-known ~45 kDa HSA-truncated fragment, resulting in a low yield of intact protein. In this study, two internal cleavage sites were identified in the PTH (1-34) portion of the fusion protein by Western Blot analysis. To minimize proteolytic cleavages, several protease genes including PEP4 (encoding proteinase A), PRB1 (proteinase B) and seven YPSs genes (yapsin family members) were knocked out respectively by disruption of the individual genes and the selective combinations. Reduced degradation was observed by single disruption of either PEP4 gene or YPS1 gene, and the lowest level of degradation was observed in a pep4△yps1△ double disruptant. After 72 h of induction, more than 80 % of the HSA/PTH (1-34) secreted by the pep4△yps1△ double disruptant remained intact, in comparison to only 30 % with the wild-type strain.     

Suppression of tomato bacterial wilt by anaerobic soil disinfestation and associations with production of antagonistic compounds

Plant and Soil - Anaerobic soil disinfestation (ASD) has been proven to be an effective and environmentally friendly method for controlling soil-borne plant diseases. Mechanisms of ASD-mediated...     

Transcriptome Profile of a Long-Juvenile Soybean Genotype Huaxia-3 Under Short and Long Photoperiod

Plant Molecular Biology Reporter - The j allele delays flowering and enhances yield of long juvenile (LJ) soybean under short day (SD) condition. However, the underlying mechanism of j in flowering...     

长期不同施氮水平对草原植物群落结构的影响

为探讨施氮对贝加尔针茅草原植物群落结构的影响,该研究于内蒙古贝加尔针茅草原设置不同施氮水平0(N0)、15(N15)、30(N30)、50(N50)、100(N100)、150(N150)、200(N200)和300(N300)kg·hm-2·a-1,研究连续施氮9年后贝加尔针茅草原群落物种组成、重要值、多样性及生物量等指标对不同施氮水平的响应。结果表明:(1)长期施氮导致植物群落物种组成发生了明显的变化,在高浓度氮素添加量下群落物种数最低,但可显著提高优势种在群落中的重要值(P<0.05)。(2)长期施氮使贝加尔针茅草原植物多样性指数不同程度地降低,使优势度指数增加,其中N300添加水平效果最为明显(P<0.05)。(3)长期施氮使草原植被生产力(地上、地下生物量)整体呈先上升后下降的趋势,地上生物量在N100水平时出现峰值,地下生物量在N50水平时出现最大值(P<0.05),且根系分布具有明显的表聚特征(0~10 cm)。(4)RDA分析表明,寸草苔和狭叶柴胡地上生物量与土壤pH呈显著正相关关系(P<0.05);展枝唐松草和二裂委陵菜地上生物量与土壤有机质含量呈显著正相关关系(P<0.05)。研究认为,长期不同施氮水平均可改变贝加尔针茅草原群落物种组成,降低物种多样性,对植物群落结构有着明显的影响。     

土壤水分时间稳定性研究进展

土壤水分是陆地生态系统中不可或缺的组成部分,在地表水文过程中起着关键作用,连接着一系列的水文、生态、气候和地质学过程,是陆地生态系统健康运行的关键。以土壤水分时间稳定性概念为主线,从时间稳定性概念、研究方法、应用和影响因素等方面,系统阐述了土壤水分时间稳定性近年来的研究进展,探讨了代表性测点的选取标准以及土壤水分时间稳定性的影响因素。结合目前的研究进展,提出了未来的研究重点:加强多因素综合作用对土壤水分时间稳定性的研究;结合"3S"技术、计算机模拟和野外实测来研究时间稳定性的尺度问题;如何高效选择代表性测点;探讨时间稳定性概念在植被恢复区和气候敏感区的研究与应用。     

高糖通过诱导自噬障碍促进心肌细胞H9c2凋亡

目的探讨自噬对高糖（HG）诱导的心肌细胞H9c2凋亡的影响。 方法MTT法检测H9c2细胞活力;hoechst33258染色法检测凋亡细胞;Western Blot检测H9c2细胞促凋亡蛋白Bax和自噬相关蛋白（Beclin-1和P62）的表达。各组的OD值和蛋白条带灰度值均采用析因设计的方差分析,各组间差异用单因素ANOVA分析。 结果HG能诱导H9c2细胞活力降低：12、24、48 mmol/L的HG细胞活力分别为Control组（100%）的[（79.5±2.23）%]（t = 3.143,P = 0.043）、[（54.6±3.08）%]（t = 12.425,P = 0.000）和[（37.2±2.59）%]（t = 13.761,P = 0.000）;与Control组（100%）比较,甘露醇等渗对照组的细胞活力值为[（101.0±1.27）%]（t = 0.012,P = 0.094）。HG诱导H9c2细胞hoechst33258阳性细胞增加,且能诱导促凋亡蛋白Bax表达增加：与Control组比较,12、24、48 mmol/L的HG处理组凋亡蛋白Bax/β-actin灰度值分别为（1.29±0.25,t = 2.32,P = 0.045）、（1.42±0.23,t = 10.247,P = 0.000）和（1.81±0.29,t = 16.324,P = 0.000）。HG诱导自噬障碍：与Control组比较,自噬相关蛋白Beclin-1/β-actin灰度值分别为（0.82±0.16,t = 4.243,P = 0.032）、（0.78±0.19,t = 11.341,P = 0.000）和（0.62±0.11,t = 13.455,P = 0.000）,P62蛋白/β-actin蛋白灰度值分别为（1.29±0.25,t = 4.442,P = 0.014）、（1.42±0.23,t = 13.341,P = 0.000）和（1.81±0.29,t = 15.851,P = 0.000）。自噬诱导剂雷帕霉素可逆转HG诱导的hoechst33258阳性细胞增加,且逆转HG诱导的Bax表达升高：与control组比较,HG组、HG和雷帕霉素共处理组、雷帕霉素组的Bax/β-actin灰度值分别为（1.51±0.31,t = 14.342,P = 0.000）、（1.42±0.23,t = 9.621,P = 0.004）和（1.81±0.12,t = 0.172,P = 0.124）。 结论HG可促进心肌细胞H9c2凋亡,且能诱导自噬障碍,自噬诱导剂的运用逆转了HG对H9c2细胞的凋亡作用,表明自噬障碍是HG诱导H9c2细胞凋亡的重要机制。     

Looking for high energy density compounds among polynitraminepurines

A series of purine derivatives with nitramine groups are calculated by using density functional theory (DFT). The molecular theory density, heats of formation, bond dissociation energies and detonation performance are investigated at DFT-B3LYP/6-311G** level. The isodesmic reaction method is employed to calculate the HOFs of the energies obtained from electronic structure calculations. Results show that the position of nitramine groups can influence the values of HOFs. The bond dissociation energies and the impact sensitivity are analyzed to investigate the thermal stability of the purine derivatives. The calculated bond dissociation energies of ring-NHNO₂ and NH-NO₂ bond show that the NH-NO₂ bond should be the trigger bond in pyrolysis processes. The H₅₀ of most compounds are larger than that of CL-20 and RDX.     

Structural divergence is more extensive than sequence divergence for a family of intrinsically disordered proteins

The p53 transactivation domain (p53TAD) is an intrinsically disordered protein (IDP) domain that undergoes coupled folding and binding when interacting with partner proteins like the E3 ligase, MDM2, and the 70 kDa subunit of replication protein A, RPA70. The secondary structure and dynamics of six closely related mammalian homologues of p53TAD were investigated using nuclear magnetic resonance (NMR) spectroscopy. Differences in both transient secondary structure and backbone dynamics were observed for the homologues. Many of these differences were localized to the binding sites for MDM2 and RPA70. The amount of transient helical secondary structure observed for the MDM2 binding site was lower for the dog and mouse homologues, compared with human, and the amount of transient helical secondary structure observed for the RPA70 binding site was higher for guinea pig and rabbit, compared with human. Differences in the amount of transient helical secondary structure observed for the MDM2 binding site were directly related to amino acid substitutions occurring on the solvent exposed side of the amphipathic helix that forms during the p53TAD/MDM2 interaction. Differences in the amount of transient helical secondary structure were not as easily explained for the RPA70 binding site because of its extensive sequence divergence. Clustering analysis shows that the divergence in the transient secondary structure of the p53TAD homologues exceeds the amino acid sequence divergence. In contrast, strong correlations were observed between the backbone dynamics of the homologues and the sequence identity matrix, suggesting that the dynamic behavior of IDPs is a conserved evolutionary feature. Proteins 2013; 81:1686–1698. © 2013 Wiley Periodicals, Inc.