Structure of the human CLC-7/Ostm1 complex reveals a novel state

CLC-7 functions as a Cl?/H+ exchanger in lysosomes. Defects in CLC-7 and its β-subunit, Ostm1, result in osteopetrosis and neurodegeneration. Here, we present the cryogenic electron microscopy (cryo-EM) structure of the human CLC-7/Ostm1 complex (HsCLC-7/Ostm1) at a resolution of 3.6 ?. Our structure reveals a new state of the CLC-7/Ostm1 heterotetramer, in which the cytoplasmic domain of CLC-7 is absent, likely due to high flexibility. The disordered cytoplasmic domain is probably not able to restrain CLC-7 subunits and thus allow their relative movements. The movements result in an approximately half smaller interface between the CLC-7 transmembrane domains than that in a previously reported CLC-7/Ostm1 structure with a well-folded cytoplasmic domain. Key interactions involving multiple osteopetrosis-related residues are affected by the interface change.     

基于遗传算法的船舶分段运输调度方法

为解决船厂平板运输车搬运船舶分段的日程计划问题,建立了利用最少数量的平板运输车完成分段搬运作业,以及所有分段搬运作业完成时间最小化的两阶段优化模型,提出了基于遗传算法的2种启发式方法以实现模型求解,并用数值实验的方法进行验证.结果表明,所提出的2种方法都能够较好地完成船舶分段运输调度计划,并实现平板运输车的高效利用.     

高效液相色谱法同时测定树鼩脑组织中的去甲肾上腺素,多巴胺,5-羟色胺及色氨酸

应用高效液相色谱(HPLC)--荧光检测,在一根带有预柱的LKB Superpac ODSC_(18)钢柱上,使用离子对系统做为洗脱液,对一组正常活动规律的树鼩脑组织液中的去甲肾上腺素(NE)、多巴胺(DA)、5-羟色胺(5-HT)及色氨酸(TRP)进行测定。荧光检测的波长为激发波长280nm,发射波长360nm得到各物质最小检测限量为:40ng NE和80ngDA(信噪比3:1)以及10ng5-HT和15ng TRP(信噪比4:1)。此方法具有实验操作简单、方便、快速、灵敏度较高、样品易于处理等特点。     

pHi regulatory ion transporters: an update on structure, regulation and cell function

Intracellular pH (pH_i) is a major regulator of various and critical cellular functions. A close regulation of pH_i is thus mandatory to maintain normal cellular activity. To this end, all cells express ion transporters that carry across their plasma membrane H⁺ or equivalent H⁺ into and out of the cell. Besides pH_i, these ion transporters are under the regulation of neurohormonal stimuli. This review summarises the molecular identity, regulation and function of the main membrane pH-regulatory ion transporters. Received 30 December 1998; received after revision 4 February 1999; accepted 9 February 1999     

组织胺在兔十二指肠纵肌收缩中的作用及递质间的相互关系

以家兔离体十二指肠纵肌方向的张力为指标，观察了乙酰胆碱（Ａｃｈ）、去甲肾上腺素（ＮＥ）、组织胺（Ｈｉｓｔａｍｉｎｅ）对十二指肠的作用，探讨了组织胺对Ａｃｈ，ＮＥ的调制作用．实验表明，在正常情况下兔离体十二指肠收缩活动比较规律，并出现梭形波，纵肌的张力变化呈现周期性．Ａｃｈ对十二指肠的作用依其剂量的不同而不同．ＮＥ通过β抑制性受体对十二指肠产生抑制作用，而β兴奋性受体和α兴奋性受体介导兴奋．组织胺对十二指肠的作用与肠的机能状态有关，Ｈ１型受体介导兴奋．阈下剂量的组织胺可激活ＮＥ的α受体使ＮＥ表现为兴奋作用，对Ａｃｈ具有调制作用     

用可编程控制器实现的重型平台运输车转向控制系统

根据 1 30t升降平台运输车对转向系统的特殊要求 ,通过分析转向驱动机构的传动特性 ,采用C2 0 0HG可编程控制器为核心设计了该车的转向控制系统 ,编制了控制软件 在以PID为基础的控制算法中结合车轮的不同位置和偏转方向进行计算修正 ,达到了车轮在所处的任意位置向左或向右偏转时 ,转向系统的工作速度特性都基本保持一致 从而使转向过程中各车轮组之间的偏转关系始终满足车辆转向特性要求 ,实现转向控制系统的准确、稳定和快速灵敏     

Effect on membrane transport in the erythrocytes by band 3 cross-linking

Band 3 and glucose transport protein (GluT1) are two kinds of important proteins in the human erythrocyte membranes. Bis(sulfosuccinimidyl)suberate (BS³), an impermeable cross-linker of band 3, inhibited NO₂ ⁻ transport, showing that anion exchange is affected by the association state of band 3 in the intact erythrocyte membranes. At the same time, the rates of glucose transport of both exit and entry declined. The amount of monomers of band 3 was decreased after treatment of the erythrocytes with BS³, but there was no change in GluT1 according to the SDS-PAGE patterns. This demonstrates that band 3 and GluT1 would be linkaged together in the erythrocyte membranes for the requirement of rapid and cooperative performance of physiological functions of the membrane proteins.     

Iron metabolism in the mononuclear phagocyte system

The maintenance of body iron homeostasis requires the coordination of multiple regulatory mechanisms of iron metabolism. The mononuclear phagocyte system （MPS, composed of monocytes, macrophages, and their precursor cells） is crucial in the maintenance of iron homeostasis. Recycling of iron is carried out by specialized macrophages via engulfment of aged erythrocytes. The iron stores of macrophages depend on the levels of recovered and exported iron. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. Recent studies characterizing the function and regulation of natural resistance-associated mac- rophage protein 1 （Nrampl）, divalent metal transporter 1 （DMT1）, HLA-linked hemechromatosis gene （HFE）, ferroportin 1 （FPN1）, and hepcidin are rapidly expanding our knowledge on the molecular level of MPS iron handling. These studies are deepening our under- standing about the molecular mechanism of iron homeostasis and iron-related diseases.