Structure prediction for the down state of a potassium channel voltage sensor

Voltage-gated potassium (Kv) channels, essential for regulating potassium uptake and cell volume in plants and electrical excitability in animals, switch between conducting and non-conducting states as a result of conformational changes in the four voltage-sensing domains (VSDs) that surround the channel pore. This process, known as gating, is initiated by a cluster of positively charged residues on the fourth transmembrane segment (S4) of each VSD, which drives the VSD into a 'down state' at negative voltages and an 'up state' at more positive voltages. The crystal structure of Kv1.2 probably corresponds to the up state, but the local environment of S4 in the down state and its motion in voltage gating remains unresolved. Here we employed several conditional lethal/second-site suppressor yeast screens to determine the transmembrane packing of the VSD in the down state. This screen relies on the ability of KAT1, a eukaryotic Kv channel, to conduct potassium when its VSDs are in the down state, thereby rescuing potassium-transport-deficient yeast. Starting with KAT1 channels bearing conditional lethal mutations, we identified second-site suppressor mutations throughout the VSD that recover yeast growth. We then constructed a down state model of the channel using six pairs of interacting residues as structural constraints and verified this model by engineering suppressor mutations on the basis of spatial considerations. A comparison of this down state model with the up state Kv1.2 structure suggests that the VSDs undergo large rearrangements during gating, whereas the S4 segment remains positioned between the central pore and the remainder of the VSD in both states.     

Non-Photorealistic Rendering in Chinese Painting of Animals

1 Introduction1 Non-photorealistic rendering (NPR) is a newly developed rendering technique in recent years. The goal of NPR is not rendering objects realistically but more creatively such as in simulating various painting styles. Curtis, et al. [1] simulates the physical property of media and substrate in watercolor. But his work only focused on 2D image processing and does not use the information of 3D model in 3D scene rendering. There is another important artistic style in NPR call…     

Variable selection and oversampling in the use of smooth support vector machines for predicting the default risk of companies

In the era of Basel II a powerful tool for bankruptcy prognosis is vital for banks. The tool must be precise but also easily adaptable to the bank's objectives regarding the relation of false acceptances (Type I error) and false rejections (Type II error). We explore the suitability of smooth support vector machines (SSVM), and investigate how important factors such as the selection of appropriate accounting ratios (predictors), length of training period and structure of the training sample influence the precision of prediction. Moreover, we show that oversampling can be employed to control the trade‐off between error types, and we compare SSVM with both logistic and discriminant analysis. Finally, we illustrate graphically how different models can be used jointly to support the decision‐making process of loan officers. Copyright © 2008 John Wiley & Sons, Ltd.     

Amphiphilic spectroscopic probes utilizing metal chelates

Summary The synthesis and initial applications are reported for 1-[p-(pamitamido)-phenyl]ethylenedinitrilotetraacetic acid. The results demonstrate the versatility of this spectroscopic probe molecule, which allows achoice of a particular technique for a particular system as well as use of multiple spectroscopic techniques for complementary information about hydrophobic region in biological systems.This work was supported in part by grant No. CA-16861 from the National Cancer Institute, DHEW.     

Susceptibility to strychnine convulsions in maturing rats

Résumé Chez le rat ce n'est pas la perméabilité du système nerveux central, mais le métabolisme du foie qui joue le rÔle principal dans la susceptibilité á la strychnine inoculée par voie intrapéritonéale.     

Characterization and relative abundance of maxi-chloride channels in Epstein-Barr virus (EBV) producer: B95-8 cells

Several Epstein-Barr virus (EBV)-transformed cell lines were used to investigate the pathogenesis of lymphoproliferative diseases and nasopharyngeal carcinoma. The studies focus on the events occurring inside the membrane. On only one occasion, the cell membrane of EBV-transformed B lymphocytes from a cystic fibrosis patient was found to express defective Cl channels (CFTR; Cystic Fibrosis Transmembrane conductance Regulator), as in the airway epithelial cell. No other type of channel in EBV-transformed cells has so far been investigated. In this study, the cell membrane of the B95-8 cell was examined by the patch-clamp technique and compared to the non-EBV-infected BJAB cell. The high conductance (300 pS) maxi-chloride (Cl) channel activity was the most frequently observed event in inside-out configurations. Under similar experimental conditions, we have found a significantly higher probability of detecting maxi-Cl channel activity on the cell membrane of B95-8 cells (69%) than on BJAB cells (27%), or as previously reported on resting murine B lymphocytes (38%) or intact human T lymphocytes (37%). The relative abundance of the maxi-Cl channel on B95-8 cells may be linked to EBV infection and/or secretory ability.     

退化系统的对数正态δ冲击维修模型(英文)

研究了一类退化系统的δ冲击模型.假定冲击来自于一个具有对数正态分布更新间距的更新过程,当冲击之间的间距小于一个阈值时,系统就会失效.作者采用更换策略N,即当且仅当系统已经失效N次时用一个全新的系统更换,然后得到了系统长期运行下的平均费用的表达式,并且找到了最优更换策略N*的解析表达式,最后给出了一个数值实例.     

Simultaneous range and radial velocity estimation with a single narrowband LFM pulse

The mismatch effect induced by the radial motion of a target is analyzed for linear frequency modulated(LFM) signals.Then,a novel integrated processing scheme is proposed to resolve the delay-Doppler coupling effect in LFM pulse compression.Therefore the range and radial velocity of the target can be simultaneously estimated with a narrowband LFM pulse.Finally,numerical simulation results demonstrate the effectiveness and good performance of the proposed method.     

Nonverbal deficit to understand others’minds in high function autism spectrum disorders

Deficits in understanding others’minds,evident in most individuals with autism spectrum disorders,have been suggested as a core deficit of autism.However,nonverbal ability has gone untested because most theory of mind measurement has involved verbal materials such as reading tasks.This raises the possibility that children with high function autism spectrum disorder would distinguish verbal and nonverbal component deficits.Thirty-two participants diagnosed with autism spectrum disorder by a trained psychiatr...