Expression of lactose permease in contiguous fragments as a probe for membrane-spanning domains

The lactose permease of Escherichia coli is a membrane transport protein containing 12 transmembrane hydrophobic domains connected by hydrophilic loops. Coexpression of lacY gene fragments encoding contiguous polypeptides corresponding to the first and second halves of the permease [Bibi, E., & Kaback, H. R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 4325-4329] or the first two transmembrane domains and the remainder of the molecule [Wrubel, W., Stochaj, U., Sonnewald, U., Theres, C., & Ehring, R. (1990) J. Bacteriol. 172, 5374-5381] leads to active lactose transport. It is shown here that contiguous permease fragments with discontinuities in loop 1 (periplasmic), loop 6 (cytoplasmic), or loop 7 (periplasmic) exhibit transport activity; however, fragments with discontinuities in transmembrane domains III or VII fail to do so. The results are consistent with the interpretation that contiguous permease fragments with discontinuities in hydrophilic loops form functional duplexes, while fragments with discontinuities in transmembrane alpha-helical domains do not. On the basis of this notion, a series of contiguous, nonoverlapping permease fragments with discontinuities at various positions in loop 6, putative helix VII, and loop 7 were coexpressed to approximate the boundaries of putative transmembrane domain VII. Contiguous fragments with a discontinuity between Leu222 and Trp223 or between Gly254 and Glu255 are functional, but fragments with a discontinuity between Cys234 and Thr235, between Gln241 and Gln242, or between Phe247 and Thr248 are inactive. Therefore, it is likely that Leu222 and Gly254 are located in hydrophilic loops 6 and 7, respectively, while Cys234, Gln241, and Phe247 are probably located within transmembrane domain VII.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phasic firing time locked to cocaine self-infusion and locomotion: dissociable firing patterns of single nucleus accumbens neurons in the rat

The activity of single nucleus accumbens (NAcc) neurons of rats was extracellularly recorded during intravenous cocaine self-administration sessions (0.7 mg/kg per infusion, fixed ratio 1). We reported previously that NAcc neurons showed a change, usually a decrease, in firing rate during the first 1 min after the cocaine-reinforced lever press. This postpress change was followed by a progressive reversal of that change, which began within the first 2 min after the press and was not complete until the last 1 min before the next lever press (termed the change + progressive reversal firing pattern). In the present study we documented a regular pattern of locomotion that occurred in parallel with the change + progressive reversal firing pattern. This observation suggested that discharges time locked to locomotion may determine the change + progressive reversal firing pattern. However, 55% of the neurons failed to show firing time locked to locomotion that could have contributed to the change + progressive reversal firing pattern. Moreover, for all neurons, the change + progressive reversal firing pattern was apparent even if the calculation of firing rate excluded all periods of locomotion. The present data showed that the change + progressive reversal firing pattern is not solely attributable to phasic changes in firing time locked to the execution of locomotion. The change + progressive reversal firing pattern closely mirrors changes in drug level and dopamine overflow observed by previous researchers and may thus be a component of the neurophysiological mechanism by which drug level regulates drug-taking behavior during an ongoing self-administration session.     

采空区下近距离煤层巷道围岩稳定性分析及控制

针对近距离煤层工况条件下,下部特厚综放工作面开采时存在覆岩应力变化大、矿压显现明显、工作面支护难度加大,煤壁片帮、顶板漏冒事故多等问题,以王庄煤矿开采的2号和3-5号煤层工作面为工程背景,通过理论分析、采用UDEC离散元软件和FLAC 3D软件建模分析及现场应用实践等方法,对近距离特厚煤层开采条件下工作面采空区覆岩运动及顶板应力变化规律进行了研究分析。结果表明,上部2号已开采煤层覆岩关键层岩体发生断裂对下部3-5号煤层工作面来压强度影响巨大,容易引发工作面采空区顶板大面积来压。据此提出优化30501工作面巷道布置,将原回风巷向内侧偏移25.4 m,工作面倾斜长由原来的180 m缩短为154.6 m,从而减小上部煤层工作面留设的区段煤柱应力影响范围,同时通过优化工作面开采工艺、合理确定工作面三机设备选型和端头及超前支护方案。现场应用结果表明,工作面在掘进和回采过程中矿压显现程度及次数明显降低和减少,未发生过顶板、瓦斯等大型事故,实现了安全高效回采。     

Characterization of poly(vinyl alcohol)/gold nanocomposites obtained by in situ gamma-irradiation method

Gamma-irradiation induced reduction of gold (Au) ions was performed in aqueous poly(vinyl alcohol) (PVA) solution. PVA/Au nanocomposites with different contents of inorganic phase were prepared by solvent evaporation. The colloids and corresponding nanocomposites show visible light absorption with strong excitonic peak in the wavelength range from 520 to 550 nm. Morphological and structural characterizations of gold nanoparticles (Au NPs) and nanocomposites were performed by TEM, XRD, and FTIR measurements. Also, Mie and Maxwell-Garnett theories were applied to calculate optical properties of Au colloids and PVA/Au nanocomposites, respectively. The changes of heat resistance upon the increase of inorganic phase were correlated to the decrease in crystal perfection of polymer. Improvement of thermal stability of nanocomposites, compared with the neat PVA, was observed when the content of inorganic phase exceeds 1 wt %. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

海堤（塘）工程防浪墙的优化设计

文章通过对海堤（塘）工程设计中人们容易忽视的防浪墙净高度、位置及综合功能设计的全面深入研究,论述了防浪墙净高度、位置及综合功能设计对工程投资和综合开发建设的重要性。并分别提出了相应的结论性意见,可供广大滩涂治理工作者参考。     

Phenolics and physico‐chemical characteristics of persimmon during post‐harvest storage

Garden picked mature but unripe fresh persimmon fruits were unipackaged in different thicknesses of polyethylene (PE) and stored at room (18.5–30°C) and refrigerated temperature (6 ± 1°C). Maximum mean methanol extractable sinapine (0.168%( catechin (1.51%( and leucoanthocyanidine (10.94 ΔA550/g) were recorded in the unipackaged samples kept at room temperature during 6 weeks storage, whereas the minimum values for water extractable phenolics (sinapin, catechin and procyanidin) were recorded in unipackaged samples under refrigerated temperature. The mean maximum weight loss of 12.58 and 7.90% was recorded in control samples kept at room temperature and low temperature, respectively. The weight loss for unipackaged in different thicknesses of PE ranged between 0.93–0.96% and 0.43–0.45% for samples kept at room and low temperature, respectively. Changes in texture values were significantly faster in control than unipackaged samples (P < 0.05). Low temperature combined with unipackaging in PE film performed better for the maintenance of overall fruit quality during post‐harvest storage.     

Central nervous system abscesses due to Coccidioides species

The internalization of basic fibroblast growth factor (FGF-2) was studied in Chinese hamster lung fibroblasts (CCL39). Recombinant FGF-2 was derivatized with a photoactivable agent, N-hydroxysuccinimidyl-4-azidobenzoate (HSAB), iodinated, and used to visualize intracellular FGF-2-affinity-labeled molecules after internalization at 37 degrees C. Iodinated HSAB-FGF-2 maintained the properties of natural FGF-2 such as affinity for heparin, binding to Bek and Fig receptors, interaction with high- and low-affinity binding sites, and reinitiating of DNA synthesis in CCL39 cells. Affinity-labeling experiments at 4 degrees C with 125I-HSAB-FGF-2 led to the detection of several FGF-cell surface complexes with apparent molecular mass of 80, 100, 125, 150, 170-180, 220, 260, and about 320 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), whereas two specific bands at 80 and 130-160 kDa were obtained using the homobifunctional cross-linking reagent, disuccinimidyl suberate. When the cells, preincubated with 125I-HSAB-FGF-2 at 4 degrees C and then washed, were shifted to 37 degrees C, irradiation of the internalized labeled FGF-2 led to detection of a similar but fainted profile with one major specific band at 80 kDa. Heparitinase II treatment of the cells reduced binding of 125I-HSAB-FGF-2 to its cell surface sites by 80% and internalization by 55%, indicating the involvement of heparan sulfate proteoglycans in these processes. Among the heparitinase-sensitive bands was the 80-kDa complex.     

Digital watermarking using Hall property image decomposition method

Most of the existing singular value decomposition-based digital watermarking methods are not robust to geometric rotation, which change the pixels’ locations without maintaining the corresponding changes to the pixel’s intensity values of entire image and yield high computational cost. To answer this, we propose a digital image watermarking algorithm using the Hall property. In the proposed method, a digital watermark image is factorized into lower-triangular, upper-triangular, and permutation matrices. The permutation matrix is used as the valid key matrix for authentication of the rightful ownership of the watermark image. The product of the lower and upper triangular matrices is processed with a few iterations of the Arnold transformation to obtain the scrambled data. The scrambled data are embedded into particular sub-bands of a cover image using Wavelet transform. Our experiments show that the proposed algorithm is highly reliable and computationally efficient compared with state-of-the-art methods that are based on singular value decomposition.     

Image denoising with norm weighted fusion estimators

In recent era, the weighted matrix rank minimization is used to reduce image noise, promisingly. However, low-rank weighted conditions may cause oversmoothing or oversharpening of the denoised image. This demands a clever engineering algorithm. Particularly, to remove heavy noise in image is always a challenging task, specially, when there is need to preserve the fine edge structures. To attain a reliable estimate of heavy noise image, a norm weighted fusion estimators method is proposed in wavelet domain. This holds the significant geometric structure of the given noisy image during the denoising process. Proposed method is applied on standard benchmark images, and simulation results outperform the most popular rivals of noise reduction approaches, such as BM3D, EPLL, LSSC, NCSR, SAIST, and WNNM in terms of the quality measurement metric PSNR (dB) and structural analysis SSIM indices.