Functional genomics, synthetic biology and metabolic engineering require efficient tools to deliver long DNA fragments or multiple gene constructs. Although numerous DNA assembly methods exist, most are complicated, time-consuming and expensive. Here, we developed a simple and flexible strategy, unique nucleotide sequence-guided nicking endonuclease (UNiE)mediated DNA assembly (UNiEDA), for efficient cloning of long DNAs and multigene stacking. In this system, a set of unique 15-nt 3 0 single-strand overhangs were designed and produced by nicking endonucleases (nickases) in vectors and insert sequences. We introduced UNiEDA into our modified Cre/loxP recombination-mediated TransGene Stacking II (TGSII) system to generate an improved multigene stacking system we call TGSII-UNiE. Using TGSII-UNiE, we achieved efficient cloning of long DNA fragments of different sizes and assembly of multiple gene cassettes. Finally, we engineered and validated the biosynthesis of betanin in wild tobacco (Nicotiana benthamiana) leaves and transgenic rice (Oryza sativa) using multigene stacking constructs based on TGSII-UNiE. In conclusion, UNiEDA is an efficient, convenient and low-cost method for DNA cloning and multigene stacking, and the TGSII-UNiE system has important application prospects for plant functional genomics, genetic engineering and synthetic biology research.
Osteosarcoma is a common primary bone cancer that there are currently no effective treatment strategies for. Forkhead box M1 (FoxM1) is key in the development of osteosarcoma, and microRNA (miR)-216b serves an antitumor role by targeting FoxM1. Moreover, thiostrepton (TST), a natural thiazole antibiotic, induces antitumor effects and specifically targets FoxM1. Therefore, the present study investigated whether thiostrepton and miR-216b synergistically inhibited osteosarcoma cells by targeting FoxM1. The MTT assay, reverse transcription-quantitative PCR, a dual-luciferase reporter assay and flow cytometry were performed. Compared with the human osteoblast cell line hFOB1.19, miR-216b expression was significantly downregulated in the osteosarcoma cell lines U2OS, MG63 and Saos-2. By contrast, FoxM1 expression was significantly upregulated in osteosarcoma cell lines compared with the hFOB1.19 cell line. The results indicated that miR-216b targeted the 3'-untranslated region of FoxM1. Moreover, the results suggested that miR-216b cooperated with TST to decrease cell cytotoxicity and increase cell apoptosis. In addition, miR-216b cooperated with TST to increase Bax expression and decrease Bcl-2 expression. In conclusion, the combination of TST and miR-216b synergistically promoted osteosarcoma cell cytotoxicity and apoptosis by targeting FoxM1. Therefore, the present study suggested that the combination of TST and miR-216b may serve as a promising therapeutic strategy for osteosarcoma.
In order to solve the problem that the image information is difficult to handle due to the swing of the snake robot’s head during its serpentine locomotion, this paper improves the control function of the general winding gait for the orthogonal joint-connected snake-like robot, and the useful image information is obtained by reducing the swing of the camera-mounted snake’s head based on the improved function. Combining the Sigmoid function with the general function to control the rotation of the yaw joints and applying the Gaussian function to the pitch joints to lift the snake head off the ground, this new control function presented in this paper not only enables the joints to rotate smoothly, but also decreases the swing range of the snake head. Additionally, it can also fasten the robot’s movement. Experiments based on MATLAB and GAZEBO platform demonstrate the superiority and effectiveness of the improved winding gait.
The problem of antibiotic contamination in the environment has attracted much attention in recent years. However, studies on antibiotic contamination in groundwater have only emerged in the last 15 years. In this study, we systematically reviewed the detection methods, distribution characteristics, risk, fate, and sources of antibiotics in groundwater in China, listed the concentrations of the main antibiotic types, and obtained the maximum concentrations by comparing the literature published in the last 10 years. The results show that 65 antibiotics were detected in groundwater in China, with sulfonamides and quinolones receiving the most attention. Antibiotic concentrations are influenced by hydrogeological conditions and seasonal variations, and the ecological risk in most areas is low to medium risk, which is relatively manageable. The highest concentrations found in most of the literatures were in the range of 10–1000 ng/L, but the maximum concentration can reach 47,444.5 ng/L, which requires extra attention. In addition, this study makes recommendations for improving groundwater monitoring surveys and protection measures to prevent the antibiotic contamination of groundwater more effectively.
We propose a method of climbing pipe with different diameter, which enables snake robot to divide itself into 3 parts to complete transition on the pipe according to the joints’ state for now. To avoid controlling the robot from building dynamic model, a gait-based open-loop control framework is adopted. An extended kalman filter (EKF) is applied here to estimate the adaptive parameter of gait-based function for different 3 parts and corresponding joints. The adaptive parameter will help snake robot perceive the environment better and climb the pipe more steadily.
In the analysis of structure steel beam member of mechanical module and piping support in nuclear power plant, beam web shall be analyzed complying with the ASME III NF requirements against web local failure including web local yielding, web local crippling, web sideway buckling and web compression buckling when the beam is subjected to concentrated loads. Referring to the H Type steel structure beam of China GB code; this paper researches the tests of carrying capacity related to the above mentioned local failure mechanism. The results could show that the evaluation method of web local failure mechanism in ASME III NF cover the China GB code steel structure member on one hand; And on the other hand, the results could show the rationalities of the sectional dimension design of the member and the rationality of the beam span. And based on the analysis of the test results, reasonable suggestions could made for the above mentioned member dimension design and beam span design.
Organic light emitting display (OLED) is a new type of flat-panel display (FPD). And the research on the mix-signal driver chip for OLED is still going on. A single-chip passive-matrix OLED driver for 96 (RGB) X 64-pixel panel is presented in this paper. This driver chip has a 256-step contrast control and a 65k-color control. It consists of a digital controller, a SRAM as display data memory, a built-in DC-DC boost converter, an oscillator, 3 (RGB) reference current generators, 64 common drivers, and 96 X 3 segment drivers. The segment drivers use the pulse amplitude modulation (PAM) method to modulate grayscales and the voltage pre-charge technology to pre-charge the OLED pixels. This chip is a typical current-drive circuit. Simulation and analysis of its power consumption indicate that it is necessary for us to research the circuit design of the drivers and display mechanism (including pre-charge and discharge) further.
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