淮河流域蒸散发时空变化与归因分析

蒸散发（Evapotranspiration,ET）是联结土壤-植被-大气过程的纽带,对理解地表水热平衡至关重要。因此,量化分析ET时空变化特征、揭示其主要控制因子对区域用水管理和农业生产十分重要。利用遥感数据和气象数据,基于BEPS模型估算了1981-2019年的淮河流域ET,分析了该区域ET时空分布特征,并通过敏感度系数和贡献率方法对该区域的ET多年变化特征进行了归因分析,最后借助数值实验方法深入探究影响特湿润年（2003年）ET较低的主要原因。结果表明：（1）1981-2019年淮河流域多年平均ET为549.83 mm,其中夏季ET占全年ET的比值达到47.63%;1981年以来区域ET整体呈极显著上升趋势（4.41 mm/a,P<0.01）;季节上,除冬季外,其他三个季节的ET增幅均呈显著性增加（P<0.05）,四季增幅速率大小依次为：夏季>春季>秋季>冬季;空间上,中东部和南部ET较高,重心模型显示ET高值区域呈显著的由北向南的移动趋势;（2）归因分析结果表明,淮河流域ET对气温变化最敏感,其次为相对湿度、太阳总辐射、叶面积指数（LAI）和降水,但ET对LAI的正敏感性逐渐增强导致LAI的显著升高对流域ET年际变化贡献最大（44.5%）,其次是气温的升高（25.93%）;同时,LAI是春、夏、秋三季ET变化的主导因素,气温是冬季ET变化的主导因素;（3）数值实验显示高相对湿度是引起特湿润年（2003年）ET明显偏低的最主要因素,这与导致长时间序列ET变化的原因不同。因此,建议今后加强极端气候条件下ET变化的归因分析,为更有效地应对全球气候变化提供决策服务。研究结果能够为认识淮河流域环境变化对水循环影响及合理分配区域水资源提供科学参考。     

探索以“霍乱弧菌检测虚拟仿真实验”为载体的混合式实验教学模式

虚拟仿真实验是一种现代信息化和智慧教学的重要方法,对高等医学院校教学质量的发展起到重要的推进作用。我们自主开发建设的“霍乱弧菌检测与防控虚拟仿真实验”,既弥补了因生物安全问题不能开展的实验教学,也解决了微生物学检验实验教学中存在的操作标准化问题。采用“三步进阶”混合教学模式,实现以“学生为中心”的师生互动模式,创建“设计性实验报告”,与育人元素有机结合,培育医学生的职业使命感。细化考核标准,实现过程性评价。探索课前启发铺垫、课中内化升华、课后巩固拓展混合式实验教学模式,有效提高学生的实验技能,实现知行合一、素能共育的教学目标。     

黄帚橐吾不同密度斑块植物、土壤和微生物碳氮磷生态化学计量特征

植物-土壤作为构成生态系统养分循环的连续体,在某种程度上决定了草地生态系统的养分平衡和系统稳定性。碳(C)、氮(N)和磷(P)是生态系统中三种主要的营养元素,它们参与了生态系统的养分循环,在生态系统结构功能维持中起着基础性作用,且生态系统内部的C、N、P循环在植物、土壤和微生物之间相互转换。为了探究黄帚橐吾(Ligularia virgaurea)在扩散过程中对草地生态系统养分循环的影响,以黄帚橐吾微斑块为研究对象,根据斑块密度界定6个密度梯度,分别为D0(0 株/m²)、D1(43 株/m²)、D2(99 株/m²)、D3(163 株/m²)、D4(332 株/m²)和D5(621 株/m²),分析了不同密度斑块的草地植物、土壤和土壤微生物生物量C、N、P含量及其生态化学计量的变化情况。结果表明,随着黄帚橐吾密度的增大,草地植物群落的C含量呈增加趋势,植物N含量略微上升后显著下降,且当黄帚橐吾密度 ≥ 160株/m²时,植物N含量显著降低,植物P含量呈先降低后升高的趋势,C∶N比呈逐渐上升趋势,C∶P比呈先上升后降低趋势,N∶P比呈先上升后降低趋势;土壤C、N、P含量均呈先增加后降低趋势,其中C含量在D2达到最大值,N含量为D1-D4高于D0和D5,但各斑块差异不显著,P含量为D3显著高于其余斑块,C∶N在D5达到最大值,C∶P在D2达到最大值,土壤N∶P呈略微降低后又有所增加,土壤养分主要受N限制;MBC随着黄帚橐吾密度的增加有降低趋势,而MBN和MBP变化均表现为”N”字型,MBN∶MBP呈先增加后降低趋势。通过相关性分析和RDA分析得到,黄帚橐吾密度与植物C、N、MBN以及MBP显著相关,植物C含量和土壤C含量与MBN呈显著正相关,土壤养分与微生物量的关系更为密切。     

生物胺降解酶研究进展及其应用

生物胺是存在于发酵食品和酒精饮料中的潜在胺类危害物。如果人体摄入过量的生物胺,则会引起呼吸困难、呕吐和发烧等过敏反应。生物胺降解酶是通过将生物胺氧化成醛类物质来实现降解生物胺的一类酶。目前发现的具有降解生物胺能力的酶主要包括胺氧化酶、胺脱氢酶和多铜氧化酶。本文详细阐述了这3类主要生物胺降解酶的催化机理、底物特异性、酶学性质、应用特性和它们对生物胺的降解效果,归纳和总结了生物胺降解酶的异源表达和分子改造的研究进展,并对生物胺降解酶在基因挖掘、分子改造和表达等方面的研究趋势进行了展望,以期为研究和开发食品中生物胺的酶法降解策略提供参考。     

DNASE1L3 inhibits proliferation,invasion and metastasis of hepatocellular carcinoma by interacting with β‐catenin to promote its ubiquitin degradation pathway

As a member of the deoxyribonuclease 1 family, DNASE1L3 plays a significant role both inside and outside the cell. However, the role of DNASE1L3 in hepatocellular carcinoma (HCC) and its molecular basis remains to be further investigated. In this study, we report that DNASE1L3 is downregulated in clinical HCC samples and evaluate the relationship between its expression and HCC clinical features. In vivo and in vitro experiments showed that DNASE1L3 negatively regulates the proliferation, invasion and metastasis of HCC cells. Mechanistic studies showed that DNASE1L3 recruits components of the cytoplasmic β‐catenin destruction complex (GSK‐3β and Axin), promotes the ubiquitination degradation of β‐catenin, and inhibits its nuclear transfer, thus, decreasing c‐Myc, P21 and P27 level. Ultimately, cell cycle and EMT signals are restrained. In general, this study provides new insight into the mechanism for HCC and suggests that DNASE1L3 can become a considerable target for HCC.

Decreased expression of DNASE1L3 is associated with poor prognosis in patients with HCC DNASE1L3 inhibits the proliferation and cell cycle of HCC cells in vitro and promotes the invasion and metastasis of HCC cells DNASE1L3 inhibits the tumorigenicity and metastasis of HCC cells in vivo DNASE1L3 interacts with β‐catenin and promotes its binding to the β‐catenin destroying complex DNASE1L3 interacts with P21 and stabilizes P21 by mediating the deubiquitin activity     

Endocytosis of Peptidase Inhibitor SerpinE2 promotes Myocardial Fibrosis through activating ERK1/2 and β-catenin Signaling Pathways

Cardiac fibrosis is one of the common pathological processes in many cardiovascular diseases characterized by excessive extracellular matrix deposition. SerpinE2 is a kind of protein that inhibits peptidase in extracellular matrix and up-regulated tremendously in mouse model of cardiac fibrosis induced by pressure-overloaded via transverse aortic constriction (TAC) surgery. However, its effect on cardiac fibroblasts (CFs), collagen secretion and the underlying mechanism remains unclear. In this study, DyLight® 488 green fluorescent dye or His-tagged proteins were used to label the exogenous serpinE2 protein. It was showed that extracellular serpinE2 translocated into CFs by low-density lipoprotein receptor-related protein 1 (LRP1) and urokinase plasminogen activator receptor (uPAR) of cell membrane through endocytosis. Knockdown of LRP1 or uPAR reduced the level of serpinE2 in CFs and down-regulated the collagen expression. Inhibition of the endocytosis of serpinE2 could inhibit ERK1/2 and β-catenin signaling pathways and subsequently attenuated collagen secretion. Knockdown of serpinE2 attenuates cardiac fibrosis in TAC mouse. We conclude that serpinE2 could be translocated into cardiac fibroblasts due to endocytosis through directly interact with the membrane protein LRP1 and uPAR, and this process activated the ERK1/2, β-catenin signaling pathways, consequently promoting collagen production.     

基于中国生态系统研究网络的典型森林生态系统土壤保持功能分析

森林生态系统土壤保持功能在控制土壤侵蚀以及维持生态安全方面具有不可替代的作用。根据不同气候带降雨特征进行降雨侵蚀力参数校正,基于中国生态系统研究网络(CERN)的森林生态系统长期定位观测样地2005—2015年监测数据利用修正的通用土壤流失方程(RUSLE)定量分析了典型森林生态系统土壤保持功能的时空变化特征,并探讨了土壤保持功能的影响因素。研究结果表明:①日雨量侵蚀力模型在降雨丰富的热带模拟效果优于降雨相对较少的亚热带和温带,参数校正后模拟效果明显提升;②研究期内10个典型森林生态系统土壤保持量变化范围为4.44—891.67 t hm^-2 a^-1,呈现北低南高的空间格局(R²=0.65^***);土壤保持率均达到97%以上;③降雨、归一化植被指数、土壤质地和植被林龄是影响森林生态系统土壤保持功能的主要影响因素;降雨量与土壤保持量显著相关(R²=0.52^*),NDVI和土壤质地与实际土壤侵蚀量显著相关(R²=0.64^**