Exploitation of shape memory alloy actuator using resistance feedback control and its development

The relationship between phase transformation and electric re sistivity of Ti-42.6Ni-7Cu SMA was investigated. In the isothermal tensile tests, stress—strain curve shows large hysteresis and nonlinearity, whereas the resistivity—strain curve can be fitted by linearity. The resistivity of SMAs can be determined from the volume fractions of the martensitic and austenitic phas es. This characteristics leads to that the resistance of the SMAs is used as a parameter of strain of SMAs. A SMA actuator using resistance feedback control system was proposed, which can control and retain positioning at any positions without using sensor devices, and the deviation of position of this system was less than 3 μm.     

Fabrication, nanostructures and electronic properties of nanodiamond-based solar cells

Nanodiamond-based solar cells were fa bricated and the photovoltaic properties were investigated. Fullerene (C60) and fullerenol (C60(OH)10-12) were used as n-type semiconductors, and diamond nan oparticles and metal phthalocyanine derivative were used as p-type semiconductors. The nanostructures of the solar cel ls were investigated by transmission electron microscopy and X-ray diffracometry, and the electronic property was discussed.     

Common variation in GPC5 is associated with acquired nephrotic syndrome

Severe proteinuria is a defining factor of nephrotic syndrome irrespective of the etiology. Investigation of congenital nephrotic syndrome has shown that dysfunction of glomerular epithelial cells (podocytes) plays a crucial role in this disease. Acquired nephrotic syndrome is also assumed to be associated with podocyte injury. Here we identify an association between variants in GPC5, encoding glypican-5, and acquired nephrotic syndrome through a genome-wide association study and replication analysis (P value under a recessive model (P(rec)) = 6.0 × 10(-11), odds ratio = 2.54). We show that GPC5 is expressed in podocytes and that the risk genotype is associated with higher expression. We further show that podocyte-specific knockdown and systemic short interfering RNA injection confers resistance to podocyte injury in mouse models of nephrosis. This study identifies GPC5 as a new susceptibility gene for nephrotic syndrome and implicates GPC5 as a promising therapeutic target for reducing podocyte vulnerability in glomerular disease.     

Live imaging of yeast Golgi cisternal maturation

There is a debate over how protein trafficking is performed through the Golgi apparatus. In the secretory pathway, secretory proteins that are synthesized in the endoplasmic reticulum enter the early compartment of the Golgi apparatus called cis cisternae, undergo various modifications and processing, and then leave for the plasma membrane from the late (trans) cisternae. The cargo proteins must traverse the Golgi apparatus in the cis-to-trans direction. Two typical models propose either vesicular transport or cisternal progression and maturation for this process. The vesicular transport model predicts that Golgi cisternae are distinct stable compartments connected by vesicular traffic, whereas the cisternal maturation model predicts that cisternae are transient structures that form de novo, mature from cis to trans, and then dissipate. Technical progress in live-cell imaging has long been awaited to address this problem. Here we show, by the use of high-speed three-dimensional confocal microscopy, that yeast Golgi cisternae do change the distribution of resident membrane proteins from the cis nature to the trans over time, as proposed by the maturation model, in a very dynamic way.     

Direct observation of steps in rotation of the bacterial flagellar motor

The bacterial flagellar motor is a rotary molecular machine that rotates the helical filaments that propel many species of swimming bacteria. The rotor is a set of rings up to 45 nm in diameter in the cytoplasmic membrane; the stator contains about ten torque-generating units anchored to the cell wall at the perimeter of the rotor. The free-energy source for the motor is an inward-directed electrochemical gradient of ions across the cytoplasmic membrane, the protonmotive force or sodium-motive force for H+-driven and Na+-driven motors, respectively. Here we demonstrate a stepping motion of a Na+-driven chimaeric flagellar motor in Escherichia coli at low sodium-motive force and with controlled expression of a small number of torque-generating units. We observe 26 steps per revolution, which is consistent with the periodicity of the ring of FliG protein, the proposed site of torque generation on the rotor. Backwards steps despite the absence of the flagellar switching protein CheY indicate a small change in free energy per step, similar to that of a single ion transit.     

Generation of cell polarity in plants links endocytosis, auxin distribution and cell fate decisions

Dynamically polarized membrane proteins define different cell boundaries and have an important role in intercellular communication-a vital feature of multicellular development. Efflux carriers for the signalling molecule auxin from the PIN family are landmarks of cell polarity in plants and have a crucial involvement in auxin distribution-dependent development including embryo patterning, organogenesis and tropisms. Polar PIN localization determines the direction of intercellular auxin flow, yet the mechanisms generating PIN polarity remain unclear. Here we identify an endocytosis-dependent mechanism of PIN polarity generation and analyse its developmental implications. Real-time PIN tracking showed that after synthesis, PINs are initially delivered to the plasma membrane in a non-polar manner and their polarity is established by subsequent endocytic recycling. Interference with PIN endocytosis either by auxin or by manipulation of the Arabidopsis Rab5 GTPase pathway prevents PIN polarization. Failure of PIN polarization transiently alters asymmetric auxin distribution during embryogenesis and increases the local auxin response in apical embryo regions. This results in ectopic expression of auxin pathway-associated root-forming master regulators in embryonic leaves and promotes homeotic transformation of leaves to roots. Our results indicate a two-step mechanism for the generation of PIN polar localization and the essential role of endocytosis in this process. It also highlights the link between endocytosis-dependent polarity of individual cells and auxin distribution-dependent cell fate establishment for multicellular patterning.     

Germline loss-of-function mutations in SPRED1 cause a neurofibromatosis 1-like phenotype

We report germline loss-of-function mutations in SPRED1 in a newly identified autosomal dominant human disorder. SPRED1 is a member of the SPROUTY/SPRED family of proteins that act as negative regulators of RAS->RAF interaction and mitogen-activated protein kinase (MAPK) signaling. The clinical features of the reported disorder resemble those of neurofibromatosis type 1 and consist of multiple café-au-lait spots, axillary freckling and macrocephaly. Melanocytes from a café-au-lait spot showed, in addition to the germline SPRED1 mutation, an acquired somatic mutation in the wild-type SPRED1 allele, indicating that complete SPRED1 inactivation is needed to generate a café-au-lait spot in this syndrome. This disorder is yet another member of the recently characterized group of phenotypically overlapping syndromes caused by mutations in the genes encoding key components of the RAS-MAPK pathway. To our knowledge, this is the first report of mutations in the SPRY (SPROUTY)/SPRED family of genes in human disease.