Active transport of Ca2+ by an artificial photosynthetic membrane

Transport of calcium ions across membranes and against a thermodynamic gradient is essential to many biological processes, including muscle contraction, the citric acid cycle, glycogen metabolism, release of neurotransmitters, vision, biological signal transduction and immune response. Synthetic systems that transport metal ions across lipid or liquid membranes are well known, and in some cases light has been used to facilitate transport. Typically, a carrier molecule located in a symmetric membrane binds the ion from aqueous solution on one side and releases it on the other. The thermodynamic driving force is provided by an ion concentration difference between the two aqueous solutions, coupling to such a gradient in an auxiliary species, or photomodulation of the carrier by an asymmetric photon flux. Here we report a different approach, in which active transport is driven not by concentration gradients, but by light-induced electron transfer in a photoactive molecule that is asymmetrically disposed across a lipid bilayer. The system comprises a synthetic, light-driven transmembrane Ca2+ pump based on a redox-sensitive, lipophilic Ca2+-binding shuttle molecule whose function is powered by an intramembrane artificial photosynthetic reaction centre. The resulting structure transports calcium ions across the bilayer of a liposome to develop both a calcium ion concentration gradient and a membrane potential, expanding Mitchell's concept of a redox loop mechanism for protons to include divalent cations. Although the quantum yield is relatively low (approximately 1 per cent), the Ca2+ electrochemical potential developed is significant.     

Systemic Research Practices Towards the Development of an Eco-Community in Vietnam: some Joint Post-Facto Reflections

In this article we discuss how an interdisciplinary research team partnered with a variety of stakeholders concerned with and/or affected by the impacts of climate change in the Red River Delta of Vietnam. The research, undertaken from 2016 to 2018, drew upon a wide range of methods to investigate systemically these impacts – with a view to the research inputting into the development of (more) sustainable ways of living. The research solicited various accounts of the experience of climate change in the community, set up learning processes in community meetings, and created an interface with government officials positioned at commune, district, provincial, and national levels. The intention was to offer support towards developing a learning process (broadly defined as including learnings/systemic inquiry across organizational levels of the society) to pursue options for sustainable living. The article offers our post-facto reflections which render more explicit (to ourselves and for the benefit of audiences) how the research team, with Hoang as lead researcher, facilitated the inquiry process towards developing a synthesis which underscored the assets for resilience to climate change and supported interventions to strengthen such (defined) assets.

     

Chemical compass model of avian magnetoreception

Approximately 50 species, including birds, mammals, reptiles, amphibians, fish, crustaceans and insects, are known to use the Earth's magnetic field for orientation and navigation. Birds in particular have been intensively studied, but the biophysical mechanisms that underlie the avian magnetic compass are still poorly understood. One proposal, based on magnetically sensitive free radical reactions, is gaining support despite the fact that no chemical reaction in vitro has been shown to respond to magnetic fields as weak as the Earth's ( approximately 50 muT) or to be sensitive to the direction of such a field. Here we use spectroscopic observation of a carotenoid-porphyrin-fullerene model system to demonstrate that the lifetime of a photochemically formed radical pair is changed by application of < or =50 microT magnetic fields, and to measure the anisotropic chemical response that is essential for its operation as a chemical compass sensor. These experiments establish the feasibility of chemical magnetoreception and give insight into the structural and dynamic design features required for optimal detection of the direction of the Earth's magnetic field.     

本溪地区BIF中玄武质围岩的高场强元素特征

辽宁本溪地区条带状铁矿(BIF)与其玄武质火山围岩之间的时空关联非常密切.对于玄武质火山围岩高场强元素(HFSE)的研究表明:wNb/wTa比值(7.00~19.93)表现出明显的分异,而wZr/wHf比值(33.46~38.28)则变化不大;从弓长岭到南芬、歪头山样品的wNb/wTa比值变化具有明显的循序性.这种高场强元素的迁移和分异特征反映出俯冲作用与盆地演化之间的关联.研究区玄武质火山围岩(wNb/wYb)N比值大于1(1.21~18.45,平均2.72),这进一步表明,其形成的构造背景为陆内弧后盆地提供了有利于BIF形成的条件.     

基于热压块的不锈钢粉尘还原实验

为了从不锈钢粉尘中回收利用Fe,Cr和Ni等,对不锈钢粉尘热压块制备及其自还原过程进行了研究.在热压温度为200℃,热压压力为35 MPa条件下,抗压强度达到900 N/个以上.高温条件下,煤热解产生的挥发分可参与不锈钢粉尘还原反应,当还原温度为1 400,1 450℃时,挥发分还原作用率达到0.4.据XRD分析和热力学计算,自还原过程中含铬物质的物相转变顺序为Fe Cr2O4,Cr2O3,Cr7C3,[Cr]Fe-Cr-Ni-C.当还原温度为1 450℃,烟煤中固定碳与粉尘中可去除氧的物质量的比(xc/xo)为0.72时,不锈钢粉尘热压块不能完全还原;当xc/xo大于0.8,还原20 min时,不锈钢粉尘热压块能完全还原.     

A mutation in stratifin is responsible for the repeated epilation (Er) phenotype in mice

Stratifin (Sfn, also called 14-3-3sigma) is highly expressed in differentiating epidermis and mediates cell cycle arrest. Sfn is repressed in cancer, but its function during development is uncharacterized. We identified an insertion mutation in the gene Sfn in repeated epilation (Er) mutant mice by positional cloning. Er/+ mice expressed a truncated Sfn protein, which probably contributes to the defects in Er/Er and Er/+ epidermis and to cancer development in Er/+ mice.