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Cell-free synthesis systems can complete the transcription and translation process in vitro to produce complex proteins that are difficult to be expressed in traditional cell-based systems. Such systems also can be used for the assembly of efficient localized multienzyme cascades to synthesize products that are toxic to cells. Cell-free synthesis systems provide a simpler and faster engineering solution than living cells, allowing unprecedented design freedom. This paper reviews the latest progress on the application of cell-free synthesis systems in the field of enzymatic catalysis, including cell-free protein synthesis and cell-free metabolic engineering. In cell-free protein synthesis: complex proteins, toxic proteins, membrane proteins, and artificial proteins containing non-natural amino acids can be easily synthesized by directly controlling the reaction conditions in the cell-free system. In cell-free metabolic engineering, the synthesis of desired products can be made more specific and efficient by designing metabolic pathways and screening biocatalysts based on purified enzymes or crude extracts. Through the combination of cell-free synthesis systems and emerging technologies, such as: synthetic biology, microfluidic control, cofactor regeneration, and artificial scaffolds, we will be able to build increasingly complex biomolecule systems. In the next few years, these technologies are expected to mature and reach industrialization, providing innovative platforms for a wide range of biotechnological applications.
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Engenharia Metabólica , Redes e Vias Metabólicas , Sistema Livre de Células/metabolismo , Catálise , Proteínas de Membrana/metabolismoRESUMO
To investigate the properties of carotenoids from the extremophile Deinococcus xibeiensis R13, the factors affecting the stability of carotenoids extracted from D. xibeiensis R13, including temperature, illumination, pH, redox chemicals, metal ions, and food additives, were investigated. The results showed that low temperature, neutral pH, reducing agents, Mn2+ , and food additives (xylose and glucose) can effectively improve the stability of Deinococcus carotenoids. The carotenoids of D. xibeiensis R13 exhibited strong antioxidant activity, with the scavenging rate of hydroxyl radicals reaching 71.64%, which was higher than the scavenging efficiency for 1,1-diphenyl-2-picrylhydrazyl free radicals and 2,2'-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) free radicals (44.55 and 27.65%, respectively). In addition, the total antioxidant capacity reached 0.60 U/ml, which was 2.61-fold that of carotenoids from the model strain Deinococcus radiodurans R1. Finally, we predicted the gene clusters encoding carotenoid biosynthesis pathways in the genome of R13 and identified putative homologous genes. The key enzyme genes (crtE, crtB, crtI, crtLm, cruF, crtD, and crtO) in carotenoid synthesis of D. xibeiensis R13 were cloned to construct the multigene coexpression plasmids pET-EBI and pRSF-LmFDO. The carotenoid biosynthesis pathway was heterologously introduced into engineered Escherichia coli EBILmFDO, which exhibited a higher yield (7.14 mg/L) than the original strain. These analysis results can help us to better understand the metabolic synthesis of carotenoids in extremophiles.
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Carotenoides , Deinococcus , Antioxidantes/metabolismo , Carotenoides/química , Carotenoides/metabolismo , Deinococcus/genética , Deinococcus/metabolismo , Aditivos Alimentares , Radicais Livres/metabolismoRESUMO
Traditional microwave photonic systems cannot implement frequency up-conversion with phase tunable capability, which plays an important role for phase array beamforming. Here, a method that can implement both upconversion and downconversion with a broadband full-degree phase-shift capability by constructing an optical path with a Hilbert transform function is presented. Owing to the Hilbert transform path, the dual-drive Mach-Zehnder modulator (DMZM) bias information, which initially influences the amplitudes of the output signals, are transferred to their phases. As a result, the phase-shift capability of the output radio frequencies (RFs) and intermediate frequencies (IFs) can be achieved by simply adjusting the bias voltage of the DMZM without using an optical filter. Experimental results demonstrate that a 360° phase shift can be achieved when the IF signal below 4-GHz and the RF signal between 8 and 16-GHz are converted into each other.
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We propose and experimentally demonstrate a stable radio frequency (RF) phase dissemination scheme for a long-haul optical ï¬ber loop link based on frequency mixing. Using a single optical source in both directions of the loop link, additional timing jitter caused by group velocity dispersion (GVD) can be eliminated. Impressive scalability provided by the optical link ensures that arbitrary-access node can obtain an RF signal with a stabilized phase to meet the requirements of multiple users. In our experiment, a 2.4 GHz RF signal is distributed to arbitrary points along a 100 km ï¬ber-optic loop link steadily. Stabilities of the recovered signals from two accessing nodes are recorded. The root-mean-square (RMS) phase jitter of the received signal at either accessing node is reduced from 1.87 rad to no more than 0.027 rad during 1800-second measuring time.
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To quantitatively measure content connectivity and provide protection for different kinds of content, the concept of k-node (edge) content connectivity is proposed recently. Based on k-node (edge) content connectivity, k-node (edge) content connected elastic optical datacenter network (KC-EODN) is proposed to design disaster-resilient and spectrum-efficient optical datacenter networks. In KC-EODN, k independent end-to-content paths are established for each request. However, it will consume too much resource to assign dedicated spectrum for each end-to-content path. Spectrum sharing among multiple end-to-content paths of different requests can greatly improve resource efficiency. In this paper, a novel perfect matching based sharing principle among multiple end-to-content paths of different requests is proposed. Based on the new proposed sharing principle, we present the shared end-to-content backup path protection (SEBPP) scheme for KC-EODN. Integer linear program (ILP) model and heuristic algorithms are designed for SEBPP scheme with the objective of minimizing the total of working and backup spectrum resources. Numerical results show that the proposed SEBPP scheme can greatly reduce spectrum consumption while ensuring the survivability against natural disaster and multi-failures.
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A microwave photonic frequency downconversion system with wideband and continuous phase-shift function is proposed and experimentally demonstrated. In the proposed system, a radio frequency (RF) and a local oscillator (LO) signal drive two arms of a dual-drive Mach-Zehnder modulator (DMZM). A fiber Bragg grating (FBG) is used for reflecting the first-order sidebands of both RF and LO signals. Due to phase independence between RF and LO optical sidebands, the phase-shifting operation for an output intermediate frequency (IF) signal can be implemented either by adjusting the bias voltage of DMZM or by controlling the optical wavelength of laser. Experimental results demonstrate a full 0° to 360° phase shift, while an RF signal between 12 GHz to 20 GHz is downconverted to IFs below 4 GHz. The phase deviation is measured less than 2°, and the fluctuation of magnitude response is measured less than ±1 dB over a wideband frequency range.
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An indirect approach based on phase measurement is proposed to measure the rotational Doppler frequency shift, which takes full advantage of the phase structure of orbital angular momentum (OAM) beams in radio domain, using a vector network analyzer (VNA) as a phase discriminator. A proof-of-concept experiment is established by an optical-controlled system with the OAM state of 1. By analyzing the experiment's results, the rotational Doppler frequency shift is measured as 24.83 Hz (max error rate 0.67%) at 50π rad/s rotational velocity, deducing the rotational velocity as 50.18π (average error rate 0.36%).
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INTRODUCTION: Herbs are an important resource for new drug development. However, the conventional approach for the discovery of new compounds from herbs was time-consuming, tedious, and inefficient. OBJECTIVES: Establish a quick approach to identify new minor constituents in herbs. METHODS: The constituents in herbs were firstly analysed using ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). Based on the accurate masses, isotopic ions, and the characteristic fragmentation ions in the mass spectra, the molecular compositions and possible structures of compounds were first deduced. After being enriched by a preparative HPLC method, the potential new minor structures were definitely identified by an on-line UHPLC-solid phase extraction-nuclear magnetic resonance-mass spectrometry (UHPLC-SPE-NMR-MS) approach. RESULTS: By combined the use of UHPLC-Q-TOF-MS, preparative HPLC and UHPLC-SPE-NMR, three new minor compounds were definitely identified as bis-3,4-dihydroxyphenylpropanoid-substituted catechins (A2 and A3) and 4â³-formyl-astilbin (B5). In addition, five isomers of bis-dihydroxyphenylpropanoid-substituted catechin (A1, A4-A7), four isomers of 4â³-formyl-astilbin (B1-B4), engeletin formates and isomers (C1-C5), formyl-cinchonains (D1-D4), formyl-caffeoylshikimic acid (E1-E4) were also tentatively determined by MS and MS/MS characterisation. CONCLUSION: The combination of UHPLC-Q-TOF-MS, preparative HPLC and UHPLC-SPE-NMR-MS techniques is a quick and effective approach for finding new minor constitutes from herbs.
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Cromatografia Líquida de Alta Pressão/métodos , Descoberta de Drogas/métodos , Medicamentos de Ervas Chinesas/química , Espectroscopia de Ressonância Magnética/métodos , Espectrometria de Massas/métodos , Plantas Medicinais/químicaRESUMO
Plant secondary metabolism drives the generation of metabolites used for host plant resistance, as biopesticides and botanicals, even for the discovery of new therapeutics for human diseases. Flavonoids are one of the largest and most studied classes of specialized plant metabolites. To quickly identify the potential bioactive flavonoids in herbs, a metabolites software-assisted flavonoid hunting approach was developed, which mainly included three steps: firstly, utilizing commercial metabolite software, a flavonoids database was established based on the biosynthetic pathways; secondly, mass spectral data of components in herbs were acquired by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF-MS); and finally, the acquired LC-MS data were imported into the database and the compounds in the herbs were automatically identified by comparison of their mass spectra with the theoretical values. As a case study, the flavonoids in Smilax glabra were profiled using this approach. As a result, 104 flavonoids including 27 potential new compounds were identified. To our knowledge, this is the first report on profiling the components in the plants utilizing the plant metabolic principles with the assistance of metabolites software. This approach can be extended to the analysis of flavonoids in other plants.
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Flavonoides/química , Flavonoides/metabolismo , Extratos Vegetais/química , Plantas/química , Plantas/metabolismo , Metabolismo Secundário/fisiologia , Cromatografia Líquida de Alta Pressão/métodos , Software , Espectrometria de Massas em Tandem/métodosRESUMO
This paper focuses on random multi-link failures protection in optical mesh networks, instead of single, the dual or sequential failures of previous studies. Spare resource efficiency and failure robustness are major concerns in link protection strategy designing and a k-regular and k-edge connected structure is proved to be one of the optimal solutions for link protection network. Based on this, a novel pre-configured polyhedron based protection structure is proposed, and it could provide protection for both simultaneous and sequential random link failures with improved spare resource efficiency. Its performance is evaluated in terms of spare resource consumption, recovery rate and average recovery path length, as well as compared with ring based and subgraph protection under probabilistic link failure scenarios. Results show the proposed novel link protection approach has better performance than previous works.
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We propose a novel photonic downconversion method based on optical carrier reusing. In the proposed system, the phase modulator (PM) is placed between two narrowband fiber Bragg gratings (FBGs), which are designed to reflect the optical carrier and transmit the optical sidebands. The optical carrier is modulated in the PM in two directions and is not injected into the photodetector (PD). Thus, the utilization ratio of the optical carrier is enhanced and the power saturation in the PD is avoided. Consequently, the system gain can be improved. In addition, a 2×2 optical coupler is cooperated with a balanced PD behind these two FBGs. Resulting from the subtle design of the phase difference, gain is furthermore doubled and intensity noise can be reduced simultaneously. In the experiments, 29 dB gain improvement is measured compared with the traditional dual-series intensity modulators method. The noise floor is reduced by 12.1 dB.
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A system for generating radio frequency signals with orbital angular momentum (OAM) is proposed and certificated for the first time, which employs an array of multiple optical-true-time-delay elements and circular antennas array (CAAs). A constructive Fourier series theory about CAAs collectively forming an OAM radio beam is demonstrated. An optical spectrum processor offers the four lines high-resolution time delay by adding a series of linear optical phase shifts. The OAM radio beam with topological charge L=1 is produced and measured successfully.
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Optical networks with flexible bandwidth provisioning have become a very promising networking architecture. It enables efficient resource utilization and supports heterogeneous bandwidth demands. In this paper, two novel spectrum defragmentation approaches, i.e. Maximum Path Connectivity (MPC) algorithm and Path Connectivity Triggering (PCT) algorithm, are proposed based on the notion of Path Connectivity, which is defined to represent the maximum variation of node switching ability along the path in flexible bandwidth networks. A cost-performance-ratio based profitability model is given to denote the prons and cons of spectrum defragmentation. We compare these two proposed algorithms with non-defragmentation algorithm in terms of blocking probability. Then we analyze the differences of defragmentation profitability between MPC and PCT algorithms.
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Algoritmos , Redes de Comunicação de Computadores , Modelos Teóricos , Dispositivos Ópticos , Simulação por ComputadorRESUMO
A method to realize a highly linear microwave photonics link is proposed based on the dual-drive dual-parallel Mach-Zehnder modulator (MZM). The scheme theoretically eliminates third-order intermodulation distortion (IMD3) completely by taking all the sidebands in the optical spectrum that cause IMD3 into consideration. Without digital linearization and other optical processors, the method utilizes simple electrical signal phase control. Microwave signals are symmetrically single sideband modulated in the two MZMs. IMD3 suppression of approximately 30 dB is experimentally demonstrated, and the spurious-free dynamic range is improved by 12 dB·Hz2/3.
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The general model of beam wander for a coherent Gaussian beam propagating through atmospheric turbulence is extended to the case of a partially polarized electromagnetic Gaussian-Schell model (EGSM) beam. The expression of the beam wander is obtained by characterizing the EGSM beam with the effective beam parameters. The effects of initial spatially coherent lengths, degree of polarization, and phase curvature are examined in detail. A condition is derived under which beams with different spatial coherence and degrees of polarization will generate the same beam wander.
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Centrosomal protein 55 (CEP55) is a centrosome- and midbody-associated protein that is overexpressed in several cancers. However, the underlying molecular mechanism of CEP55-mediated progression and metastasis of esophageal squamous cell carcinoma (ESCC) is not clear. In the current study, we detected CEP55 mRNA by qRT-PCR while protein expression was detected by western blot analysis and immunohistochemistry (IHC). In addition, we knocked down CEP55 and investigated the ability of CEP55 to affect colony formation and migration. Here, we report that CEP55 mRNA and protein expression was significantly increased in ESCC. IHC staining showed that CEP55 expression correlated with TNM stage (p=0.046) and lymph node metastases (p=0.024). According to overall survival (OS) and disease-free survival (DFS), patients whose tumors expressed a higher level of CEP55 had a poorer prognosis than those with low expression level of CEP55. A multivariate analysis revealed that CEP55 expression was an independent prognostic indicator for patients with ESCC. Knockdown of CEP55 decreased the colony formation ability and migration of ESCC cells and also reduced the phosphorylation of Src, FAK, and ERK. Therefore, our study implied that CEP55 may be a valuable biomarker and a potential target in the treatment of patients with ESCC.
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The determination of low abundant endogenous components is a challenge for the clinical samples. Histamine, a crucial endogenous component, fulfils various regulatory and mediatory functions in human, and the change of content is a critical index for the diagnosis of some diseases, especially allergy, asthma, and anaphylactic shock. However, it is challenging to detect histamine because of the low stability and concentration in complex biological samples. Here we developed an ultra-sensitive and accurate LC-MS/MS quantification method based on derivatization, isotope dilution, and solid phase extraction. The derivatization of histamine with diisopropyl phosphite (DIPP) not only enhanced the retention on the LC column but also improved the ionization efficiency. Next, solid phase extraction was applied to remove the interference, which finally resulted in standing out of the trace histamine from the high contents of the matrix. The lowest limit of quantification (LLOQ) was 0.1 pg/mL that is enough low to determine the histamine in one cell and low nano-liter of serum. This approach was successfully applied for the quantification of histamine in clinical serum samples of asthma patients and mast cell treated with chemicals modulating histamine release.
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Histamina , Espectrometria de Massas em Tandem , Cromatografia Líquida , Histamina/análise , Humanos , Técnicas de Diluição do Indicador , Extração em Fase SólidaRESUMO
Polyunsaturated fatty acids (PUFAs) play a pivotal role in the biological effects, and are the potential biomarkers for some diseases. However, the structural diversity and similarity, the low concentration, and the interference of high abundant endogenous components challenge the PUFAs profiling. Herein, a novel analytical approach, off-line and on-line solid phase extraction-nano-liquid chromatography-quadrupole-time-of-flight mass spectrometry (off-line and on-line SPE-nano-LC-Q-TOF-MS), was established to monitor the PUFAs. The combination of off-line and on-line SPE removed most of impurities, and the recoveries ranged from 80.1% to 93.0% and the matrix effects were from 85.1% to 92.8%. Using this method, 51 PUFAs could be separated well and quantified with the limits of quantification between 0.006 and 2.2â¯pg. Finally, this developed method was applied successfully to simultaneously qualify and quantify the potential biomarkers in the allergic patients. 21 PUFAs including LTB4, 5S-, 11S-, 15S-HETE and 15S-HEPE showed significant differences. Our study indicated that the established method has the potential to sensitively and accurately determine the PUFAs in biological samples.
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Análise Química do Sangue/métodos , Cromatografia Líquida , Ácidos Graxos Insaturados/sangue , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Ácidos Graxos Insaturados/química , HumanosRESUMO
The effect of initial frequency chirp is investigated numerically to obtain efficient supercontinuum radiation in photonic crystal fibers (PCFs) with two closely spaced zero-dispersion wavelengths. The positive chirps, instead of zero or negative chirps, are recommended because self phase modulation and four-wave mixing can be facilitated by employing positive chirps. In contrast with the complicated and irregular spectrum generated by negative-chirped pulse, the spectrums generated by positive-chirped pulses are wider and much more regular. Moreover, the saturated length of the PCF, corresponding to the maximal spectrum width, can be shortened greatly and the efficiency of frequency conversion is also improved because of initial positive chirps. Nearly all the energy between the zero-dispersion wavelengths can be transferred to the normal dispersion region from the region within the two zero-dispersion wavelengths provided that the initial positive chirp is large enough.
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FADS1 (fatty acid desaturase 1) plays a crucial role in fatty acid metabolism, and it was recently reported to be involved in tumorigenesis. However, the role of FADS1 expression in esophageal squamous cell carcinoma (ESCC) remains unknown. In the current study, we investigated the expression and clinical pathologic and prognostic significance of FADS1 in ESCC. Immunohistochemical analyses revealed that 58.2% (146/251) of the ESCC tissues had low levels of FADS1 expression, whereas 41.8% (105/251) exhibited high levels of FADS1 expression. In positive cases, FADS1 expression was detected in the cytoplasm of cells. Correlation analyses demonstrated that FADS1 expression was significantly correlated with tumor location (p=0.025) but not with age, gender, histological grade, tumor status, nodal status or TNM staging. Furthermore, patients with tumors expressing high levels of FADS1had a longer disease-free survival time (p<0.001) and overall survival time (p<0.001). Univariate and multivariate analyses revealed that, along with nodal status, FADS1 expression was an independent and significant predictive factor (p<0.001). In conclusion, our study suggested that FADS1 might be a valuable biomarker and potential therapeutic target for ESCC.