苯丙烯酸对黄瓜幼苗生理特性的影响

采用基质栽培模拟实验,研究了不同浓度苯丙烯酸对黄瓜幼苗生理特性的影响.结果表明,苯丙烯酸对黄瓜幼苗的光合色素、光合速率、蒸腾速率和根系活力产生了抑制作用.当处理浓度为25μmol·L^-1时,对类胡萝卜素产生抑制作用,对叶绿素a、叶绿素b为促进作用;当浓度为50μmol·L^-1时,对光合速率、蒸腾速率和根系活力均产生显著的抑制作用(P<0.05),并随着处理浓度的增加抑制作用增强;当浓度为150μmol·L^-1时,对叶绿素a、叶绿素b产生显著抑制作用(P<0.05);随着处理浓度的增加,对黄瓜上述生理特性的抑制作用增强.低浓度苯丙烯酸(25～50μmol·L^-1)对幼苗根系活力的抑制强度不大,可在处理后期得到恢复;高浓度(100～150μmol·L^-1)处理则表现出显著的抑制作用,随着处理时间延长,抑制作用增强(P<0.05).     

2,5-Hexanedione induced apoptosis in rat spinal cord neurons and VSC4.1 cells via the proNGF/p75NTR and JNK pathways

Increasing evidence suggests that n-hexane induces nerve injury via neuronal apoptosis induced by its active metabolite 2,5-hexanedione (HD). However, the underlying mechanism remains unknown. Studies have confirmed that pro-nerve growth factor (proNGF), a precursor of mature nerve growth factor (mNGF), might activate apoptotic signaling by binding to p75 neurotrophin receptor (p75NTR) in neurons. Therefore, we studied the mechanism of the proNGF/p75NTR pathway in HD-induced neuronal apoptosis. Sprague–Dawley (SD) rats were injected with 400 mg/kg HD once a day for 5 weeks, and VSC4.1 cells were treated with 10, 20, and 40 mM HD in vitro. Results showed that HD effectively induced neuronal apoptosis. Moreover, it up-regulated proNGF and p75NTR levels, activated c-Jun N-terminal kinase (JNK) and c-Jun, and disrupted the balance between B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax). Our findings revealed that the proNGF/p75NTR signaling pathway was involved in HD-induced neuronal apoptosis; it can serve as a theoretical basis for further exploration of the neurotoxic mechanisms of HD.     

微载体技术在软骨损伤修复中的应用与展望北大核心CSCD

软骨内部无血管结构、细胞外基质含量高的特点,使软骨组织的自我恢复能力很差。在临床治疗中,轻度的软骨缺损通常采用物理治疗或药物治疗方式,严重者需进行手术治疗。近年来,软骨组织工程技术为治疗软骨缺损提供了新的思路,与传统的手术治疗方式相比,结合软骨组织工程技术进行治疗具有创口小、恢复佳的优点。将微载体技术融入组织工程支架的设计中,可以利用微载体直径小、能够负载多种生长因子的特点,进一步扩展支架功能、促进软骨组织再生。文中首先对微载体技术进行介绍,对近年来微载体的主要制备方式和创新内容进行了概括总结,作为后续介绍的基础内容。然后对应用于软骨修复中的微载体进行了材料和功能上的划分,介绍了不同材料、不同功能微载体的属性特征和在软骨修复方面的具体应用,最后结合该领域发展历程对其今后发展趋势及方向进行展望,并基于笔者团队关于骨软骨一体化层状支架的研究,提出了通过微载体优化层状支架性能的思路,有望制备出更贴合天然软骨结构特征的仿生支架。     

温度和水分变化对冻土区泥炭地土壤氮循环功能基因丰度的影响

以大兴安岭多年冻土区泥炭地为研究对象,通过室内模拟增温实验,研究温度升高对不同深度（0-150 cm）土壤氮循环功能基因丰度的影响。同时针对0-20 cm和20-40 cm土壤设置两个水分处理,分别为土壤原始含水量和淹水状态,研究水分变化对表层土壤氮循环功能基因丰度的影响。结果表明温度升高显著提高了活动层（0-60 cm）、过渡层（60-80 cm）、永冻层（80-100 cm）中nifH、nirK基因丰度,温度升高显著提高了活动层（0-40 cm）和过渡层（60-80 cm）中nirS基因丰度。温度升高显著提高了过渡层（60-80 cm）NH₄⁺-N和较深永冻层（140-150 cm）NO₃^--N的含量,但降低了过渡层（60-80 cm）NO₃^--N和较深永冻层（120-150 cm）NH₄⁺-N的含量,相关性分析表明,NH₄⁺-N含量与nifH和nirS基因丰度呈显著正相关,NO₃^--N含量与nirK基因丰度呈显著正相关,说明温度升高能够通过改变微生物丰度促进过渡层固氮作用和反硝化作用。在增温条件下,淹水处理使表层土壤nirS和nirK基因丰度及NH₄⁺-N含量降低,但提高了NO₃^--N含量,说明淹水造成了过度还原的条件使反硝化底物浓度降低,降低反硝化微生物活性进而抑制了土壤反硝化作用。该结果对于明确未来气候变化影响下冻土区泥炭地土壤氮循环过程具有重要意义。     

Theoretical investigation on the heats of formation and detonation performance in polydinitroaminocubanes

A series of polydinitroaminocubanes have been designed computationally. We calculated the heats of formation, the detonation velocity (D) and detonation pressure (P) of the title compounds by density function theory (DFT) with 6-311?G** basis set. The relationship between the heats of formation and the molecular structures is discussed. The result shows that all cubane derivatives have high and positive heats of formation, which increase with increasing number of dinitroamino groups. The detonation performances of the title compound were estimated by Kamlet-Jacobs equation, and the result indicated that most cubane derivatives have good detonation performance over RDX (hexahydro-1,3,5-trinitro-1,3,5-trizine) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane). In addition, we also found that the heat of detonation (Q) is another very important impact in increasing detonation performance except density. The relative stabilities of the title compound are discussed in the terms of the calculated heats of formation, and the energy gaps between the frontier orbitals. The results have not only shown that these compounds may be used as high energy density compounds (HEDCs), but also provide some useful information for further investigation.     

农业生态系统养分循环再利用的作物产量增益

在辽西褐土上进行8年的田间试验结果表明,在不同化肥基础上,每年以60％的收获产品堆腐后循环回田,平均分别可获得29．6％（不施化肥）、15．2％（N肥）、11．1％（NP肥）和9．2％（NPK肥）的增产率,或分别每年增产粮食1.33、0．99、0．79、0．64t·hm－2．养分循环再利用的作物增产效益在试验的8年中有着逐年增长趋势,表明以堆肥形式循环回田养分对作物的增产作用存在着明显的残效叠加效应,因此,只有通过长期田间试验方能准确评估农业系统中养分循环再利用的作物产量增益．     

指导学生认识蘑菇的孢子印

蘑菇以其低脂肪高蛋白的品质成为人们日常食用的具有保健功能的上等菜肴,各地农贸市场以及超市均有出售,常见的蘑菇不下20多种,广大学生对此并不陌生。然而学生对蘑菇所产生的用于繁殖的孢子所知甚少,仅听说过孢子,但从未见过。为此,笔者在我系及附中进行生物学课外科技活动辅导时,开展了认识蘑菇孢子印的活动,效果很好。简介如下。     

Down‐regulated HDAC3 elevates microRNA‐495‐3p to restrain epithelial‐mesenchymal transition and oncogenicity of melanoma cells via reducing TRAF5

MicroRNAs (miRNAs) are emerging biomarkers in biological processes and the role of miR‐495‐3p has been identified in melanoma, while the detailed molecular mechanisms remain to be further explored. We aim to explore the effect of histone deacetylase 3 (HDAC3) and miR‐495‐3p on epithelial‐mesenchymal transition (EMT) and oncogenicity of melanoma cells by regulating tumour necrosis factor receptor‐associated factor 5 (TRAF5). Levels of HDAC3, miR‐495‐3p and TRAF5 in melanoma tissues and pigmented nevus tissues were determined, and the predictive roles of HDAC3 and miR‐495‐3p in prognosis of melanoma patients were measured. The melanoma cells were screened and transfected with relative oligonucleotides and plasmids, and the expression of HDAC3, miR‐495‐3p and TRAF5, and phenotypes of melanoma cells were gauged by a series of assays. The relations between HDAC3 and miR‐495‐3p, and between miR‐495‐3p and TRAF5 were confirmed. HDAC3 and TRAF5 were increased while miR‐495‐3p was decreased in melanoma cells and tissues, and the low expression of miR‐495‐3p as well as high expression of HDAC3 indicated a poor prognosis of melanoma patients. Inhibited HDAC3 elevated miR‐495‐3p to suppress EMT and oncogenicity of melanoma cells by reducing TRAF5. HDAC3 particularly bound to miR‐495‐3p and TRAF5 was the target gene of miR‐495‐3p. Our results revealed that down‐regulated HDAC3 elevates miR‐495‐3p to suppress malignant phenotypes of melanoma cells by inhibiting TRAF5, thereby repressing EMT progression of melanoma cells. This study may provide novel targets for melanoma treatment.     

Cancer targeting gene-viro-therapy for pancreatic cancer using oncolytic adenovirus ZD55-IL-24 in immune-competent mice

Cancer targeting gene-viro-therapy (CTGVT) may prove to be an effective treatment for pancreatic cancer (PC). This study was intended to explore the anti-tumor effect of ZD55-IL-24 (oncolytic adenovirus ZD55 harboring IL-24) on PC in immune-competent mice. The expression of gene harbored by oncolytic adenovirus ZD55 in PC cells was detected by reporter-gene assays. The in vitro anti PC ability of ZD55-IL-24 was tested by MTT, crystal violet staining and apoptosis assays. The in vivo anti PC effect of ZD55-IL-24 was further observed in an immune-competent mice model by detecting anti-tumor immunity and induction of apoptosis. The expression of gene harbored by ZD55 in PC cells was significantly higher than that harbored by the replicated-deficient adenovirus, and the amount of gene expression was time-dependent and dose-dependent. Both ZD55-IL-24 and ZD55 inhibited PC cells growth, but the anti-tumor effect of ZD55-IL-24 was significantly stronger than that of ZD55, and the ability of ZD55-IL-24 in inducing PC apoptosis was significantly stronger than that of ZD55. The tumor-forming rate of group ZD55-IL-24 was the lowest, and the tumor-growing rate was also significantly lower than that of group ZD55 in immune-competent PC models. Moreover, ZD55-IL-24 mediated more anti-cancer immunity effects by induction of stronger T-lymphocytes response to PC cells, higher levels of γ-IFN and IL-6 cytokines. ZD55-IL-24-mediated CTGVT could inhibit PC growth not only by inducing oncolysis and apoptosis but enhancing the anti-cancer immune effects by inducing T cell response to PC and up-regulating γ-IFN and IL-6 cytokine in immune-competent mice. This may serve as a candidate therapeutic approach for the treatment of PC.