Monitoring the activation of neuronal nitric oxide synthase in brain tissue and cells with a potentiometric immunosensor

An all solid state potentiometric immunosensor (ASPI) has been developed to study the activation process of neuronal nitric oxide synthase (nNOS), the enzyme involved in the synthesis of nitric oxide generated under physiological conditions. At first, an all solid state H⁺-selective ISE was fabricated with the carboxylated poly(vinyl chloride) (PVC-COOH) film containing H⁺ ionophore, antibody was then immobilized on the polymer layer. The immunocomplex formation was detected by monitoring pH change due to interaction between urease labeled secondary antibody and antigen. Experimental parameters such as the amount of phosphorylated nNOS immobilized on the electrode surface and pH responses due to the antibody–antigen reaction were studied in detail. The calibration plot of the potentiometric potential vs. phosphorylated nNOS concentration exhibited a linear relationship in the range of 3.4–340.0 μg/ml. The calibration sensitivity of the phosphorylated nNOS immunosensor was −0.073 ± 0.002 mV/μg ml⁻¹. The detection limit of nNOS was determined to be 0.2 μg/ml based on five-time measurements (95% confidence level, k = 3, n = 5). The reliability of the immunosensor was examined with rat brain tissues as well as neuronal cells, and the results shown were good, implying a promising approach for a novel electrochemical immunosensor platform with potential applications to clinical diagnosis.     

中度嗜盐菌Martelella sp. AD-3 降解菲过程中水杨酸-5-羟化酶的酶学性质

[目的]研究中度嗜盐菌Martelella sp.AD-3在降解菲过程中水杨酸-5-羟化酶的活性与菲降解效率的关系及其酶学性质.[方法]通过HPLC分析菲的降解效率和AD-3菌粗酶液催化水杨酸的产物,根据NADH在340 nm处的吸光度变化计算水杨酸-5-羟化酶的活性.[结果]水杨酸-5-羟化酶是一种诱导酶,在AD-3菌的对数生长期和稳定初期时活性较高,酶活力大小与该菌对菲的降解速率基本一致.在菲浓度为200 mg/L、生长盐度为3％、pH为9.0的培养条件下,AD-3菌株表达的水杨酸-5-羟化酶的活力最高,为132.8 nmol/(min·mg).水杨酸-5-羟化酶催化水杨酸降解时的最适温度、pH和盐度分别为30℃、7.5和3％,酶的最大反应速率为200 nmol/(min· mg)、米氏常数Km为8.7μmol/L.[结论]AD-3菌在降解菲的过程中表达水杨酸-5-羟化酶,该酶的活性与菲降解速率具有相关性.     

Drosophila katanin-60 depolymerizes and severs at microtubule defects

Microtubule (MT) length and location is tightly controlled in cells. One novel family of MT-associated proteins that regulates MT dynamics is the MT-severing enzymes. In this work, we investigate how katanin (p60), believed to be the first discovered severing enzyme, binds and severs MTs via single molecule total internal reflection fluorescence microscopy. We find that severing activity depends on katanin concentration. We also find that katanin can remove tubulin dimers from the ends of MTs, appearing to depolymerize MTs. Strikingly, katanin localizes and severs at the interface of GMPCPP-tubulin and GDP-tubulin suggesting that it targets to protofilament-shift defects. Finally, we observe that binding duration, mobility, and oligomerization are ATP dependent.     

哈密天山北路墓地出土颅骨的测量性状

本文是对出土于新疆哈密地区天山北路青铜时代墓地颅骨测量性状的研究。文中公布了24例天山北路墓地古代人群77项颅骨测量性状基本数据, 在此基础上, 对男、女两性的测量性状特点进行了统计分析, 并结合考古学文化研究和分子生物学研究的相关结论对实验结果进行了讨论和推论。主要研究结论如下: 一是该人群虽已经形成了具有自身特点的、共性的体质特征, 但人群内部也存在些许差异, 尤其是在男性个体数据之中。二是该人群是由分别具有东、西方体质特征的祖先人群混杂融合而成, 是处于当时大人种分布过渡地带的过渡人群。