Elongation Factor ELL (Eleven-Nineteen Lysine-rich Leukemia) Acts as a Transcription Factor for Direct Thrombospondin-1 Regulation

The eleven-nineteen lysine-rich leukemia (ELL) gene undergoes translocation and fuses in-frame to the multiple lineage leukemia gene in a substantial proportion of patients suffering from acute forms of leukemia. Studies show that ELL indirectly modulates transcription by serving as a regulator for transcriptional elongation as well as for p53, U19/Eaf2, and steroid receptor activities. Our in vitro and in vivo data demonstrate that ELL could also serve as a transcriptional factor to directly induce transcription of the thrombospondin-1 (TSP-1) gene. Experiments using ELL deletion mutants established that full-length ELL is required for the TSP-1 up-regulation and that the trans-activation domain likely resides in the carboxyl terminus. Moreover, the DNA binding domain may localize to the first 45 amino acids of ELL. Not surprisingly, multiple lineage leukemia-ELL, which lacks these amino acids, did not induce expression from the TSP-1 promoter. In addition, the ELL core-response element appears to localize in the -1426 to -1418 region of the TSP-1 promoter. Finally, studies using zebrafish confirmed that ELL regulates TSP-1 mRNA expression in vivo, and ELL could inhibit zebrafish vasculogenesis, at least in part, through up-regulating TSP-1. Given the importance of TSP-1 as an anti-angiogenic protein, our findings may have important ramifications for better understanding cancer.

A 16-term error model based on linear equations of voltage and current variables

Formulation of a 16-term error model, based on the four-port ABCD-matrix and voltage and current variables, is outlined. Matrices A, B, C, and D are each 2 x 2 submatrices of the complete 4 x 4 error matrix. The corresponding equations are linear in terms of the error parameters, which simplifies the calibration process. The parallelism with the network analyzer calibration procedures and the requirement of five two-port calibration measurements are stressed. Principles for robust choice of equations are presented. While the formulation is suitable for any network analyzer measurement, it is expected to be a useful alternative for the nonlinear y-parameter approach used in intrinsic semiconductor electrical and noise parameter measurements and parasitics' deembedding.

黄土丘陵区人工刺槐林土壤活性有机碳与碳库管理指数演变

土壤碳库管理指数是表征土壤碳变化的重要量化指标,研究黄土丘陵区人工刺槐林土壤活性有机碳与碳库管理指数的变化过程对认识该地区生态恢复过程中土壤质量的演变及其效果评价具有重要意义。【方法】采用时空互代法,以典型侵蚀环境纸坊沟流域生态恢复过程中不同年限的人工刺槐林为研究对象,选取坡耕地和天然侧柏林为参照,分析了植被恢复过程中土壤有机碳(TOC)、活性有机碳(LOC)、非活性有机碳(NLOC)及碳库管理指数(CPMI)的演变特征,并运用相关和回归分析方法对生态恢复过程中碳库各组分和恢复年限进行拟合。【结果】营造刺槐林可以显著增加土壤碳库各组分含量,并随恢复年限呈显著线性关系,50a时TOC、LOC、NLOC和碳库指数(CPI)分别较坡耕地增加271%、174%、467%和271%,其中NLOC增加速率略高于LOC,表明植被恢复增加的土壤碳素绝大多数以非活性形态贮存起来,而为了满足生物生长所必须的活性物质来源,土壤碳库必须维持一定的活度状态来满足碳素的动态转化平衡,碳库管理指数在营造刺槐林初期显著降低,随后先增加后降低,与刺槐林生长特性密切相关;但与天然林相比差距仍然较大,恢复50a时TOC、LOC和NLOC仅...

非局部理论新框架和基于新框架的塑性应变梯度理论

<正>纳米材料和器件的蓬勃发展,微机电系统和微电子元件微型化趋势,先进材料微结构设计以及精细薄膜涂层,促使材料科学家和力学家关注微米尺度和纳米尺度范围内材料的力学行为。大量实验表明,当非均匀塑性变形的特征长度在微米量级时,金属材料材料呈现很强的尺度效应。典型的实验包括:细铜丝扭转;纯镍薄膜弯曲;不同金属材料的微纳米压痕;炭化硅粒子增强的铝-镁基

窄通道内热厚材料表面火焰传播的实验研究

利用高度为14 mm的水平窄通道对微重力条件下聚甲基丙烯酸甲酯(PMMA)和聚乙烯(PE)塑料材料表面的火焰传播进行了地面实验模拟研究. 在环境气体氧气浓度为30％和50％、低速气流速度小于15 cm/s的实验条件下, 实验测量了窄通道内材料表面火焰传播速度随气流速度的变化, 它们与微重力下热厚材料火焰传播速度的理论预测结果符合得相当好. 分析认为, 窄通道能够有效地限制浮力对流, 提高燃料表面固相热辐射在火焰传播中的相对作用, 从而提供模拟微重力下热厚材料表面火焰传播特性的实验环境

黄土高原地区土壤干层综合研究

IEECAS SKLLQG

西安附近苹果林地的土壤干层

IEECAS SKLLQG

长期不同培肥黑土磷酸酶活性动态变化及其影响因素

<正> 由于自然环境恶化和不合理的农业经营方式,导致黑土质量下降。长期以来从土壤理化性质方面对黑土质量下降原因的研究较多,而从土壤生

城市森林发展战略与生态规划

<正>1城市森林的概念及研究内容 1.1城市森林的提出及概念 城市森林这一概念的提出已有 30余历史,1962年,美国肯尼迪政 府在户外娱乐资源调查报告中,首 次使用“城市森林”这一名词。自 1965年加拿大Erik Jorgensen教授提 出城市林业概念以来,城市林业与 城市森林先后在北美、欧洲乃至全 球掀起了研究热潮。