Sequence of Plasmodium falciparum chromosomes 2, 10, 11 and 14

The mosquito-borne malaria parasite Plasmodium falciparum kills an estimated 0.7-2.7 million people every year, primarily children in sub-Saharan Africa. Without effective interventions, a variety of factors-including the spread of parasites resistant to antimalarial drugs and the increasing insecticide resistance of mosquitoes-may cause the number of malaria cases to double over the next two decades. To stimulate basic research and facilitate the development of new drugs and vaccines, the genome of Plasmodium falciparum clone 3D7 has been sequenced using a chromosome-by-chromosome shotgun strategy. We report here the nucleotide sequences of chromosomes 10, 11 and 14, and a re-analysis of the chromosome 2 sequence. These chromosomes represent about 35% of the 23-megabase P. falciparum genome.     

Phase-locking in double-point-contact spin-transfer devices

Spin-transfer in nanometre-scale magnetic devices results from the torque on a ferromagnet owing to its interaction with a spin-polarized current and the electrons' spin angular momentum. Experiments have detected either a reversal or high-frequency (GHz) steady-state precession of the magnetization in giant magnetoresistance spin valves and magnetic tunnel junctions with current densities of more than 10(7) A cm(-2). Spin-transfer devices may enable high-density, low-power magnetic random access memory or direct-current-driven nanometre-sized microwave oscillators. Here we show that the magnetization oscillations induced by spin-transfer in two 80-nm-diameter giant-magnetoresistance point contacts in close proximity to each other can phase-lock into a single resonance over a frequency range from approximately <10 to >24 GHz for contact spacings of less than about approximately 200 nm. The output power from these contact pairs with small spacing is approximately twice the total power from more widely spaced (approximately 400 nm and greater) contact pairs that undergo separate resonances, indicating that the closely spaced pairs are phase-locked with zero phase shift. Phase-locking may enable control of large arrays of coupled spin-transfer devices with increased power output for microwave oscillator applications.     

The suppression of star formation by powerful active galactic nuclei

The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.     

模糊滑动控制的一般方法(英文)

陈述了一种新的模糊逻辑控制方法,它可消除滑动控制所固有的抖动问题。方法的推导是将多开关滑动控制问题简化成等效的单开关问题。控制规律显示它是一种模糊滑动控制的一般方法。文献中的其他方法可由此法导出。模糊推理规则由两个输入变量组成。第一个输入变量是系统状态到所预定的状态空间中的超平面之间的方向距离;第二个输入变量的选择可根据应用而定,例如方向距离的导数、控制设计者所感兴趣的特定变量,或者某些状态变量的加权之和。这个新方法易于在高阶系统中实现,并且可以直接而明确地控制系统的动态过程。它消除了滑动控制和经典模糊滑动控制中的抖动问题。此外。新方法比其他类似方法的控制要简单。稳定性和性能分析显示了此法的有效性。此法已用于一带有典型驱动和反馈传感器的工业直流电机的位置控制之中。     

Research advances in gene therapy approaches for the treatment of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease of motor neurons that causes progressive muscle weakness, paralysis, and premature death. No effective therapy is available. Research in the motor neuron field continues to grow, and recent breakthroughs have demonstrated the possibility of completely achieving rescue in animal models of spinal muscular atrophy, a genetic motor neuron disease. With adeno-associated virus (AAV) vectors, gene transfer can be achieved with systemic non-invasive injection and minimal toxicity. In the context of this success, we review gene therapy approaches for ALS, considering what has been done and the possible future directions for effective application of the latest generation of vectors for clinical translation. We focus on recent developments in the areas of RNA/antisense-mediated silencing of specific ALS causative genes like superoxide dismutase-1 and other molecular pathogenetic targets, as well as the administration of neuroprotective factors with viral vectors. We argue that gene therapy offers new opportunities to open the path for clinical progress in treating ALS.     

Cellular therapy to target neuroinflammation in amyotrophic lateral sclerosis

Neurodegenerative disorders are characterized by the selective vulnerability and progressive loss of discrete neuronal populations. Non-neuronal cells appear to significantly contribute to neuronal loss in diseases such as amyotrophic lateral sclerosis (ALS), Parkinson, and Alzheimer’s disease. In ALS, there is deterioration of motor neurons in the cortex, brainstem, and spinal cord, which control voluntary muscle groups. This results in muscle wasting, paralysis, and death. Neuroinflammation, characterized by the appearance of reactive astrocytes and microglia as well as macrophage and T-lymphocyte infiltration, appears to be highly involved in the disease pathogenesis, highlighting the involvement of non-neuronal cells in neurodegeneration. There appears to be cross-talk between motor neurons, astrocytes, and immune cells, including microglia and T-lymphocytes, which are subsequently activated. Currently, effective therapies for ALS are lacking; however, the non-cell autonomous nature of ALS may indicate potential therapeutic targets. Here, we review the mechanisms of action of astrocytes, microglia, and T-lymphocytes in the nervous system in health and during the pathogenesis of ALS. We also evaluate the therapeutic potential of these cellular populations, after transplantation into ALS patients and animal models of the disease, in modulating the environment surrounding motor neurons from pro-inflammatory to neuroprotective. We also thoroughly discuss the recent advances made in the field and caveats that need to be overcome for clinical translation of cell therapies aimed at modulating non-cell autonomous events to preserve remaining motor neurons in patients.     

The importance of HLA-G expression in embryos,trophoblast cells,and embryonic stem cells

The nonclassical HLA-G molecule is a trophoblast-specific molecule present in almost every pregnancy. It differs from classical HLA class I molecules by the low degree of allelic variants and the high diversity of protein structures. HLA-G is reported to be a tolerogenic molecule that acts on cells of both innate and adaptive immunity. At the maternal–fetal interface HLA-G seems to be responsible largely for the reprogramming of local maternal immune response. This review will focus on the HLA-G gene expression profile in pregnancy, in preimplantation embryos, and in human embryonic stem cells with emphasis on the structural diversity of the HLA-G protein and its potential functional and diagnostic implications.