分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Wang, Xu-Ying
Wang, Dian-Bing
Bi, Li-Jun
Zhang, Xian-En
Wang, Xu-Ying
Zhang, Ji-Bin
Zhang, Zhi-Ping
Ding, Wei
摘要： S-layer proteins create a cell-surface layer architecture in both bacteria and archaea. Because S-layer proteins self-assemble into a native-like S-layer crystalline structure in vitro, they are attractive building blocks in nanotechnology. Here, the potential use of the S-layer protein EA1 from Bacillus anthracis in constructing a functional nanostructure is investigated, and apply this nanostructure in a proof-of-principle study for serological diagnosis of anthrax. EA1 is genetically fused with methyl parathion hydrolase (MPH), to degrade methyl parathion and provide a label for signal amplifi cation. EA1 not only serves as a nanocarrier, but also as a specific antigen to capture anthrax-specific antibodies. As results, purified EA1-MPH forms a single layer of crystalline nanostructure through self-assembly. Our chimeric nanocatalyst greatly improves enzymatic stability of MPH. When applied to the detection of anthrax-specific antibodies in serum samples, the detection of our EA1-MPH nanostructure is nearly 300 times more sensitive than that of the unassembled complex. Together, it is shown that it is possible to build a functional and highly sensitive nanosensor based on S-layer protein. In conclusion, our present study should serve as a model for the development of other multifunctional nanomaterials using S-layer proteins.
分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2024-02-01 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： The radio telescope possesses high sensitivity and strong signal collection capabilities. While receiving celestial radiation signals, it also captures Radio Frequency Interferences (RFIs) introduced by human activities. RFI, as signals originating from sources other than the astronomical targets, significantly impacts the quality of astronomical data. This paper presents an RFI fast mitigation algorithm based on block Least Mean Square (LMS) algorithm. It enhances the traditional adaptive LMS filter by grouping L adjacent time-sampled points into one block and applying the same filter coefficients for filtering within each block. This transformation reduces multiplication calculations and enhances algorithm efficiency by leveraging the time-domain convolution theorem. The algorithm is tested using baseband data from the Parkes 64 m radio telescope's pulsar observations and simulated data. The results confirm the algorithm's effectiveness, as the pulsar profile after RFI mitigation closely matches the original pulsar profile.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-05
Guo, Yu
Ma, Chao
Wang, Xu
Wang, Xin
Liu, Pi
Lin, Jianping
Guo, Yu
Ma, Chao
Wang, Xu
Wang, Xin
Liu, Pi
Lin, Jianping
Lou, Zhiyong
Lou, Zhiyong
Sun, Yuna
Lou, Zhiyong
Shen, Shu
Deng, Fei
Wang, Hualin
Wang, Wenming
摘要： Hantaviruses, which belong to the genus Hantavirus in the family Bunyaviridae, infect mammals, including humans, causing either hemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS) in humans with high mortality. Hantavirus encodes a nucleocapsid protein (NP) to encapsidate the genome and form a ribonucleoprotein complex (RNP) together with viral polymerase. Here, we report the crystal structure of the core domains of NP (NPcore) encoded by Sin Nombre virus (SNV) and Andes virus (ANDV), which are two representative members that cause HCPS in the New World. The constructs of SNV and ANDV NPcore exclude the N- and C-terminal portions of full polypeptide to obtain stable proteins for crystallographic study. The structure features an N lobe and a C lobe to clamp RNA-binding crevice and exhibits two protruding extensions in both lobes. The positively charged residues located in the RNA-binding crevice play a key role in RNA binding and virus replication. We further demonstrated that the C-terminal helix and the linker region connecting the N-terminal coiled-coil domain and NPcore are essential for hantavirus NP oligomerization through contacts made with two adjacent protomers. Moreover, electron microscopy (EM) visualization of native RNPs extracted from the virions revealed that a monomer-sized NP-RNA complex is the building block of viral RNP. This work provides insight into the formation of hantavirus RNP and provides an understanding of the evolutionary connections that exist among bunyaviruses. IMPORTANCE Hantaviruses are distributed across a wide and increasing range of host reservoirs throughout the world. In particular, hantaviruses can be transmitted via aerosols of rodent excreta to humans or from human to human and cause HFRS and HCPS, with mortalities of 15% and 50%, respectively. Hantavirus is therefore listed as a category C pathogen. Hantavirus encodes an NP that plays essential roles both in RNP formation and in multiple biological functions. NP is also the exclusiv
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Wang, Dian-Bing
Fleming, Joy
Bi, Li-Jun
Zhang, Xian-En
Tian, Bo
Zhang, Zhi-Ping
Wang, Xu-Ying
Tian, Bo
Yang, Rui-Fu
摘要： Detection of Bacillus anthracis in the field, whether as a natural infection or as a biothreat remains challenging. Here we have developed a new lateral-flow immunochromatographic assay (LFIA) for B. anthracis spore detection based on the fact that conjugates of B. anthracis spores and super-paramagnetic particles labeled with antibodies will block the pores of chromatographic strips and form retention lines on the strips, instead of the conventionally reported test lines and control lines in classic LFIA. As a result, this new LFIA can simultaneously realize optical, magnetic and naked-eye detection by analyzing signals from the retention lines. As few as 500-700 pure B. anthracis spores can be recognized with CV values less than 8.31% within 5 min of chromatography and a total time of 20 min. For powdery sample tests, this LFIA can endure interference from 25% (w/v) milk, 10% (w/v) baking soda and 10% (w/v) starch without any sample pre-treatment, and has a corresponding detection limit of 6 x 10(4) spores/g milk powder, 2 x 10(5) spores/g starch and 5 x 10(5) spores/g baking soda. Compared with existing methods, this new approach is very competitive in terms of sensitivity, specificity, cost and ease of operation. This proof-of-concept study can also be extended for detection of many other large-sized analytes. (C) 2014 The Authors. Published by Elsevier B.V.
分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2024-02-01 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： To address the problem of real-time processing of ultra-wide bandwidth pulsar baseband data, we designed and implemented a pulsar baseband data processing algorithm (PSRDP) based on GPU parallel computing technology. PSRDP can perform operations such as baseband data unpacking, channel separation, coherent dedispersion, Stokes detection, phase and folding period prediction, and folding integration in GPU clusters. We tested the algorithm using the J0437-4715 pulsar baseband data generated by the CASPSR and Medusa backends of the Parkes, and the J0332+5434 pulsar baseband data generated by the self-developed backend of the NanShan Radio Telescope. We obtained the pulse profiles of each baseband data. Through experimental analysis, we have found that the pulse profiles generated by the PSRDP algorithm in this paper are essentially consistent with the processing results of Digital Signal Processing Software for Pulsar Astronomy (DSPSR), which verified the effectiveness of the PSRDP algorithm. Furthermore, using the same baseband data, we compared the processing speed of PSRDP with DSPSR, and the results showed that PSRDP was not slower than DSPSR in terms of speed. The theoretical and technical experience gained from the PSRDP algorithm research in this article lays a technical foundation for the real-time processing of QTT (Qi Tai radio Telescope) ultra-wide bandwidth pulsar baseband data.
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