典型森林和草地生态系统呼吸各组分间的相互关系

生态系统呼吸是陆地生态系统碳收支的重要组成部分,分析其组分间的相互关系对理解生态系统呼吸过程和精确评价生态系统碳收支具有重要意义,也是当前碳循环研究工作的一大难点。本研究利用ChinaFLUX的长白山温带针阔混交林（CBS）,鼎湖山亚热带常绿阔叶林（DHS）和海北灌丛草甸（HBGC）三个典型生态系统的通量观测数据,采用经验统计方法,分析了其在中国典型生态系统中的适用性及敏感性,揭示了生态系统呼吸各组分的动态变化特征及相互关系。结果表明：采用本研究中的呼吸组分拆分方法所获结果与理论推测及实测数据大致相同,拆分结果对净初级生产力与总初级生产力的比值（NPP/GPP）较为敏感,NPP/GPP变化0.1时,自养呼吸在生态系统呼吸中的比例（Ra/RE）改变0.05。各生态系统中,生态系统呼吸及其组分在年内均表现出明显的单峰型变化特征,在夏季生长旺盛的时节达到最大值。异养呼吸与生态系统呼吸的比值（Rh/RE）也具有明显的季节变化,但在生态系统间表现出明显差异,CBS和HBGC分别表现出先增大后减小和先减小后增大的变化趋势,DHS则相对稳定,在0.5附近波动, Ra/RE的季节动态与Rh/RE相反。在年总量上,HBGC主要通过异养呼吸向大气排放CO2,异养呼吸占生态系统呼吸的60%,而CBS和DHS的自养呼吸和异养呼吸所占比重大致相似,异养呼吸占生态系统呼吸的49%。这说明,该统计学模型可以用来进行生态系统呼吸组分的拆分,进而可以为生态系统碳循环过程的精细研究提供参考数据,但今后应加强NPP/GPP的测定,以提高生态系统呼吸拆分的精度。     

基于能值的陆域受威胁和濒危物种价值估算——以福建省厦门市为例

开展受威胁和濒危物种价值评估是生物多样性研究的关键问题之一。当前受威胁和濒危物种研究正处于濒危等级界定和保护优先性确定阶段,存在不同保护等级交叉管理、价值评估方法欠缺及重复性计算等多方面问题。利用IUCN濒危等级和中国特有种等级名录确定厦门市不同濒危等级物种数,在此基础上利用能值转换率和修正的中国能值/货币比率对厦门市陆域受威胁和濒危物种价值进行估算。结果显示,通过多途径整理纳入估算的厦门市陆域野生动植物物种数为1444种,其中受威胁和濒危物种数为318种;2015年厦门市物种能值价值约为3.53×10~(11)元,2010年约为3.08×10~(11)元,其中两期受威胁和濒危物种能值价值均占物种总价值的88.31%;中国特有种等级对价值贡献最大达73.25%,其次是IUCN濒危等级达23.24%。研究表明,能值评估法能够客观凸显受威胁和濒危物种价值,研究结果可为生物多样性及物种保育的管理决策提供技术支撑。     

抗副溶血弧菌海洋真菌HL-3菌株的鉴定及其活性物质的分离

【背景】目前水产养殖中副溶血弧菌等水产致病菌的预防和治疗主要使用的是抗生素,短期内能够起到较好的效果,但是长期使用抗生素不仅使得病原菌的耐药性增加,而且会产生一系列问题。因此,寻找安全有效的抗生素替代品迫在眉睫。【目的】筛选具有抗副溶血弧菌活性的海洋微生物,鉴定其种类并优化其培养条件,并对其活性物质进行初步分离。【方法】利用稀释涂布平板法和平板划线法分离纯化海洋微生物,通过牛津杯法筛选具有抗副溶血弧菌活性的菌株。根据菌株的形态特征和ITS序列分析对活性菌株进行鉴定。通过筛选培养基种类和盐度确定其培养条件。通过半制备高效液相色谱制备化合物,并利用核磁共振波谱数据鉴定化合物的结构。【结果】从海螺、小黄鱼、对虾等11种样品中分离出海洋微生物菌株76株,其中真菌26株。筛选得到一株具有抗副溶血弧菌活性的真菌菌株HL-3,鉴定为黄曲霉。黄曲霉HL-3菌株在改良沙氏培养基条件下,产物化学多样性和抗菌活性较好。黄曲霉HL-3菌株在真菌5号培养基中产物单一且抗菌活性较好,纯化出来的化合物结构被鉴定为曲酸。曲酸对副溶血弧菌的最小抑菌浓度为4.0mg/mL。【结论】实验结果为进一步利用各种色谱手段分离纯化...     

Expression of CD45 lacking the catalytic protein tyrosine phosphatase domain modulates Lck phosphorylation and T cell activation

The function of the second protein tyrosine phosphatase domain (D2) in two-domain protein tyrosine phosphatases (PTP) is not well understood. In CD45, D2 can interact with the catalytic domain (D1) and stabilize its activity. Although D2 itself has no detectable catalytic activity, it can bind substrate and may influence the substrate specificity of CD45. To further explore the function of D2 in T cells, a full-length construct of CD45 lacking the D1 catalytic domain (CD45RABC-D2) was expressed in CD45+ and CD45- Jurkat T cells. In CD45- Jurkat T cells, CD45RABC-D2 associated with Lck but, unlike its active counterpart CD45RABC, did not restore the induction of tyrosine phosphorylation or CD69 expression upon T cell receptor (TCR) stimulation. Expression of CD45RABC-D2 in CD45+ Jurkat T cells resulted in its association with Lck, increased the phosphorylation state of Lck, and reduced T cell activation. TCR-induced tyrosine phosphorylation was delayed, and although MAPK phosphorylation and CD69 expression were not significantly affected, the calcium signal and IL2 production were severely reduced. This indicates that the non-catalytic domains of CD45 can interact with Lck in T cells. CD45RABC-D2 acts as a dominant negative resulting in an increase in Lck phosphorylation and a preferential loss of the calcium signaling pathway, but not the MAPK pathway, upon TCR signaling. This finding suggests that, in addition to their established roles in the initiation of TCR signaling, CD45 and Lck may also influence the type of TCR signal generated.     

CRISPR/Cas9-edited Pax6-GFP reporter system facilitates the generation of mouse neural progenitor cells during differentiation

正Embryonic stem cells(ESCs)obtained from blastocysts can self-renew and potentially differentiate into three germ layers,thus acting as a promising platform in cell-replacement therapies and developmental research(Evans and Kaufman,1981;Thomson et al.,1998).Neural specification of ESCs has been extensively studied due to their superior value as a cellular resource in studying neurodegenerative diseases(Tao and     

大枣中氨基酸类成分的薄层色谱分析

中药大枣中含有多种氨基酸类成分,建立大枣中主要氨基酸类成分的薄层色谱鉴定方法,为大枣的相关研究提供依据。采用薄层色谱法对大枣中氨基酸类成分进行定性鉴别,本法操作简单,重复性好,特征明显,可以作为大枣中四种氨基酸的薄层色谱鉴别依据。