PCR-based approaches for identification of multi-copy transgene integration sites in mouse genome

Transgenic mice have become one of the most im- portant resources in studying gene functions in vivo since the technology was established in the 1980s[1―3]. So far, most of the transgenic mice were generated by DNA microinjection into fertilized eggs, in…     

Duplication-degeneration as a mechanism of gene fission and the origin of new genes in Drosophila species

Gene fission and fusion, the processes by which a single gene is split into two separate genes and two adjacent genes are fused into a single gene, respectively, are among the primary processes that generate new genes. Despite their seeming reversibility, nothing is known about the mechanism of gene fission. Because the nucleotide sequences of fission genes record little about their origination process, conventional analysis of duplicate genes may not be powerful enough to unravel the underlying mechanism. In a survey for young genes in species of the Drosophila melanogaster subgroup using fluorescence in situ hybridization, we identified a young gene family, monkey king, whose genesis sheds light on the evolutionary process of gene fission. Its members originated 1-2 million years ago as retroposed duplicates and evolved into fission genes that separately encode protein domains from a multidomain ancestor. The mechanism underlying this process is gene duplication with subsequent partial degeneration.     

A novel data channel fault detection mechanism in optical burst switching networks

Fault detection in optical burst switching （OBS） networks will be a challenging task in the future. A novel mechanism based on probe burst （PB） and a new key concept is proposed to detect faults of OBS networks by sampling the health of data channels, which solve the difficulty of optical monitoring schemes while keeps the transparency of data network to Internet protocol （IP） packets. It takes full advantage of the characteristics of OBS, including architecture and signalling scheme, and introduces the excellent performances of single-hop-test used in electrical communication networks into OBS environment while avoids the shortcoming that any optical burst must undergo an optical-electric-optical （OEO） conversion. Well designed PB can provide exact criterion for judging whether protection/restoration should be excuted according to hard or soft fault identification.     

The first record of Helicoprion Karpinsky （Helicoprionidae） from China

A new species,Helicoprion jingmenense sp. nov.,from the Lower Permian Qixia Formation of Hubei Province,China,is described based on a nearly complete symphyseal tooth spiral preserved as part and counterpart. The specimen is a large elliptical symphyseal tooth spiral with 41/3 volutions,with cutting blade being relatively wide,and its width being greater than the height after 31/2 volution,middle portion being higher than the cutting blade,narrowed base being short. There is a distinct space not covered by enameloid in two adjacent tooth crowns in the outermost two volutions; the height of the compound root is moderate,and the ventral groove is about 1/10 of the same tooth crown. In com-parison with other known Helicoprion species of the world,the new species resembles H. ferrieri and H. bessonowi. However,it can be easily distinguished from H. ferrieri by the wider cutting blade,the shorter narrowed base and lower compound root,and also from H. bessonowi by its more narrowed compound root and less than 39 tooth crowns per volution. Helicoprion jingmenense sp. nov. is obvi-ously different from helicoprionid species previously found in China in general shape,size and his-tology. However,it is very difficult to identify their relationships because of the fragmentary nature of holotypes of the latter. Because the new specimen is the first record of Helicoprion and the most com-plete fossil dentition of helicoprionids from China,the new species is of significance for biostratigra-phy and paleobiogeography.     

Prestin is the motor protein of cochlear outer hair cells

The outer and inner hair cells of the mammalian cochlea perform different functions. In response to changes in membrane potential, the cylindrical outer hair cell rapidly alters its length and stiffness. These mechanical changes, driven by putative molecular motors, are assumed to produce amplification of vibrations in the cochlea that are transduced by inner hair cells. Here we have identified an abundant complementary DNA from a gene, designated Prestin, which is specifically expressed in outer hair cells. Regions of the encoded protein show moderate sequence similarity to pendrin and related sulphate/anion transport proteins. Voltage-induced shape changes can be elicited in cultured human kidney cells that express prestin. The mechanical response of outer hair cells to voltage change is accompanied by a 'gating current', which is manifested as nonlinear capacitance. We also demonstrate this nonlinear capacitance in transfected kidney cells. We conclude that prestin is the motor protein of the cochlear outer hair cell.     

Synthesis of urchin-like Sn–ZnO–C composite and its enhanced electrochemical performance for lithium-ion batteries

Urchin-like Sn–ZnO–C composite have been successfully prepared by thermal annealing of ZnSn(OH)6precursor in acetylene/argon gas(1/9;v/v).The phase of the urchin-like Sn–ZnO–C has been characterized by X-ray diffraction(XRD)and Raman spectrum.The images of scanning electron microscopy(SEM)and transmission electron microscope(TEM)demonstrate that the Sn–ZnO–C composite with an average of 3 lm in diameter is composed of many core–shell nanowires and carbon nanotubes emanated from the center.The thermal annealing temperature and time have crucial effects on the formation of urchin-like structure and carbon content of the Sn–ZnO–C composites.As an anode for lithium-ion batteries,the urchin-like Sn–ZnO–C composite delivers a discharge capacity of 1,034.5 mAh/g in initial cycle and 571.9 mAh/g reversible discharge capacity after 25 cycles at a current density of 50 mA/g.The superior energy storage properties highlight the urchin-like Sn–ZnO–C composite as a potential alternative anode material in lithium-ion batteries.     

A new adaptive fast motion estimation algorithm based on local motion similarity degree (LMSD)

In the motion vector field adaptive search technique (MVFAST) and the predictive motion vector field adaptive search technique (PMVFAST), the size of the largest motion vector from the three adjacent blocks (left, top, top-right) is compared with the threshold to select different search scheme. But a suitable search center and search pattern will not be selected in the adaptive search technique when the adjacent motion vectors are not coherent in local region. This paper presents an efficient adaptive search algorithm. The motion vector variation degree (MVVD) is considered a reasonable factor for adaptive search selection. By the relationship between local motion similarity degree (LMSD) and the variation degree of motion vector (MVVD), the motion vectors are classified as three categories according to corresponding LMSD; then different proposed search schemes are adopted for motion estimation. The experimental results show that the proposed algorithm has a significant computational speedup compared with MVFAST and PMVFAST algorithms, and offers a similar, even better performance.     

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

This work constructed a machine learning (ML) model to predict the atmospheric corrosion rate of low-alloy steels (LAS). The material properties of LAS, environmental factors, and exposure time were used as the input, while the corrosion rate as the output. 6 different ML algorithms were used to construct the proposed model. Through optimization and filtering, the eXtreme gradient boosting (XGBoost) model exhibited good corrosion rate prediction accuracy. The features of material properties were...     

基础矩阵估计综合算法的几何意义及分析

研究了基础矩阵参数的几何意义,提出了新的估计基础矩阵的约束条件,首无用给的约束求出Ｆ阵的４个参数,而这２个参数正好是２个对极点的仿射坐标,然后通过解线方程组获得其余４个参数,而这４个参数表示了对极线束间的对应关系,最后,经过对真实图像和合成数据的测试表明本方法有明显的几何意义,可获得几何特性稳定的Ｆ阵。