Self-Assembly of DNA–Peptide Supermolecules: Coiled-Coil Peptide Structures Templated by d-DNA and l-DNA Triplexes Exhibit Chirality-Independent but Orientation-Dependent Stabilizing Cooperativity

DNA nanostructures have been designed and used in many different applications. However, the use of nucleic acid scaffolds to promote the self-assembly of artificial protein mimics is only starting to emerge. Herein five coiled-coil peptide structures were templated by the hybridization of a d -DNA triplex or its mirror-image counterpart, an l -DNA triplex. The self-assembly of the desired trimeric structures in solution was confirmed by gel electrophoresis and small-angle X-ray scattering, and the stabilizing synergy between the two domains was found to be chirality-independent but orientation-dependent. This is the first example of using a nucleic acid scaffold of l -DNA to template the formation of artificial protein mimics. The results may advance the emerging POC-based nanotechnology field by adding two extra dimensions, that is, chirality and polarity, to provide innovative molecular tools for rational design and bottom-up construction of artificial protein mimics, programmable materials and responsive nanodevices.     

Saturable Absorption and Bistable Switching of Single Mode Fiber Core-Guided Light by a 6 nm-thick,Few Layers Graphene Coating on the Cladding Surface

The coupling of less than 80 µW of in-plane polarized near-infrared light in a 6 nm-thick graphene layer deposited on an optical fiber produces important permittivity changes leading to bistability and self-starting 50% modulation of over 1 W of continuous wave light in the core. These features arise from resonant coupling of core-guided light into the cladding by a 12-degree tilted, 1 cm long fiber Bragg grating via narrowband, polarization-dependent resonances that allow the selection of cladding modes with electric fields polarized in the plane of the graphene. The pulse repetition rate of the modulation increases from 10 to 269 Hz for input powers ranging from 0.3 to 1.33 W in the core, with no evidence of saturation. Investigations into the origin of these effects through physical modelling and different experimental conditions point to photo-induced Joule heating in the graphene layer giving rise to temperature increases of the order of 60 °C and corresponding permittivity changes in the graphene and underlying silica fiber. Those changes lead to shifts in the resonance positions which result in the equivalent of saturable absorption for light guided in the core without direct contact with the absorbing graphene layer.     

Continuous g-frame and g-Riesz sequences in Hilbert spaces

A continuous g-frame is a generalization of g-frames and continuous frames, but they behave much differently from g-frames due to the underlying characteristic of measure spaces. Now, continuous g-frames have been extensively studied, while continuous g-sequences such as continuous g-frame sequence, g-Riesz sequences, and continuous g-orthonormal systems have not. This paper addresses continuous g-sequences. It is a continuation of Zhang and Li, in Numer. Func. Anal. Opt., 40 (2019), 1268-1290, where they dealt with g-sequences. In terms of synthesis and Gram operator methods, we in this paper characterize continuous g-Bessel, g-frame, and g-Riesz sequences, respectively, and obtain the Pythagorean theorem for continuous g-orthonormal systems. It is worth that our results are similar to the case of g-ones, but their proofs are nontrivial. It is because the definition of continuous g-sequences is different from that of g-sequences due to it involving general measure space.     

DNA detection by dye labeled oligonucleotides using surface enhanced Raman spectroscopy

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象山港黄墩支港菲律宾蛤仔种群COI和ITS1基因序列特征及遗传多样性分析

为了解象山港黄墩支港菲律宾蛤仔种质资源的遗传多样性现状, 采用COI和ITS1分子标记对该种群进行了基因序列特征和遗传多样性分析. 结果表明 在该种群30个个体中扩增得到的COI基因序列长度均为709bp, ITS1序列长度范围在693~729bp(共有746个位点). COI基因序列的位点中有670个保守位点(占94.50%)、39个变异位点(占5.50%); ITS1序列的位点中有保守位点671个(占89.95%)、变异位点62个(占8.31%)和缺失/插入位点13个(占1.74%). COI基因序列的保守性高于ITS1序列. 在COI基因序列中碱基(A+T)的占比(65.84%)高于(C+G), 而ITS1序列中则是碱基(A+T)占比(37.59%)低于(C+G). COI和ITS1序列的遗传距离分析均显示群体内遗传分化不明显. 基于COI基因序列和ITS1序列构建的遗传进化树显示 各科贝类分别相聚, 象山港菲律宾蛤仔位于帘蛤科的分支中, 其COI序列与杂色蛤进化关系最近. 遗传进化树中各种贝类的聚类关系与传统分类学结果相一致, 可作为分类的参考. COI和ITS1序列的平均核苷酸差异数分别为5.497和6.549, 核苷酸多样性指数分别为0.00775和0.00973, 单倍型数目分别为21和28, 单倍型多样性分别为0.963和0.993, 根据COI和ITS1两个序列计算得到的菲律宾蛤仔象山港群体单倍型多样性均大于0.5, 核苷酸多样性指数均大于0.005, 表明该种群遗传多样性丰富, 并处于稳定状态. 本研究结果补充了菲律宾蛤仔遗传多样性方面的研究资料, 并可为象山港菲律宾蛤仔种质资源保护和遗传育种提供理论基础.     

Convergence of Picard’s iteration using projection algorithm for noncyclic contractions

Given $A$ and$B$ two nonempty subsets of a metric space, a mapping $T:A\cup B\to A\cup B$ is noncyclic provided that $T\left(A\right)?A$ and $T\left(B\right)?B$. A point $(p,q)\in A\times B$ is called a best proximity pair for the noncyclic mapping $T$ if $p=Tp,q=Tq$ and $d(p,q)=\mathrm{dist}(A,B)$. In this article, we survey the convergence of Picard’s iteration to a best proximity pair for noncyclic contractions using a projection algorithm in uniformly convex Banach spaces, where the initial point is in the proximal set of $A$. We also provide some sufficient conditions to ensure the existence of a common best proximity pairs for a pair of noncyclic mappings.     

Optimal harvesting policy of an inland fishery resource under incomplete information

A new mathematical model for finding the optimal harvesting policy of an inland fishery resource under incomplete information is proposed in this paper. The model is based on a stochastic control formalism in a regime‐switching environment. The incompleteness of information is due to uncertainties involved in the body growth rate of the fishery resource: a key biological parameter. Finding the most cost‐effective harvesting policy of the fishery resource ultimately reduces to solving a terminal and boundary value problem of a Hamilton‐Jacobi‐Bellman equation: a nonlinear and degenerate parabolic partial differential equation. A simple finite difference scheme for solving the equation is then presented, which turns out to be convergent and generates numerical solutions that comply with certain theoretical upper and lower bounds. The model is finally applied to the management of Plecoglossus altivelis, a major inland fishery resource in Japan. The regime switching in this case is due to the temporal dynamics of benthic algae, the main food of the fish. Model parameter values are identified from field measurement results in 2017. Our computational results clearly show the dependence of the optimal harvesting policy on the river environmental and biological conditions. The proposed model would serve as a mathematical tool for fishery resource management under uncertainties.     

Complete genome sequence of Bacillus megaterium JX285 isolated from Camellia oleifera rhizosphere

Bacillus megaterium strain JX285, isolated from rhizosphere red soil sample, can solubilize inorganic phosphorus, which increases the amount of available phosphorus and promotes plant growth. To investigate the mechanisms underlying phosphate solubilization, we sequenced the entire genome of B. megaterium strain JX285 (CGMCC 1.1621), which comprises a circular chromosome of 5,066,463 bp and seven plasmids of 167,030, 128,297, 60,905, 134,795, 9,598, 37,455, and 6332 bp, respectively. The whole genome sequence includes 5948 protein-coding genes, 124 tRNAs, and 29 rRNAs, and has been deposited at Genbank/EMBL/DDBJ with accession numbers CP018874–CP018881. We detected genes associated with organic acid production, which may be vital for phosphate conversion. Furthermore, phosphatase-encoding genes were also detected. The information embedded in the genome will assist in studying the mechanisms of phosphate solubilization. In conclusion, analysis of the JX285 genome will further our knowledge regarding this strain and may contribute to its biotechnological application.