Esophageal squamous cell carcinoma (ESCC) is the major type of esophageal carcinoma, one of the main reasons of cancer-caused death. While the therapeutic effect on ESCC patents is still unsatisfactory as a result of tumor aggression, recurrence and metastasis. RNA-binding proteins, microRNAs and specific genes get involved in tumorigenesis and development of tumors in a large proportion. In several reports, SEMA4D is an oncogene and miR-4319 is a tumor suppressor. We discovered the interaction of SEMA4D with HuR and miR-4319, whereas the detailed mechanism in ESCC was yet to be researched. At first, SEMA4D was significantly overexpressed in ESCC cells, and its knockdown repressed cell proliferation and migration as well as accelerated cell apoptosis. And then HuR was proved to stabilize SEMA4D mRNA by binding to its 3'UTR. In addition, miR-4319 targeted and degraded SEMA4D. Taken together, SEMA4D was regulated competitively by HuR and miR-4319. Collectively, HuR and miR-4319 co-regulating SEMA4D affected cell proliferation, apoptosis and migration in ESCC. This research explored the regulatory mechanism on SEMA4D in ESCC and provided optional therapeutic targets for ESCC patients.
MicroRNAs (miRNAs) play an essential role in cancer diagnosis and prognosis. Developing a new method for sensitive detection of miRNAs is constantly in demand. The CRISPR/Cas12a system is a recently discovered CRISPR-RNA (crRNA) guided DNA manipulation tool. Cas12a can nonspecifically cleave single-stranded DNA after specific recognition of target DNA. This intrinsic feature gives Cas12a tremendous potential in molecular diagnostics. Herein, we design a sensitive and versatile miRNA detection platform based on CRISPR/Cas12a system combined with a hybridization chain reaction (HCR) circuit. In this design, the HCR circuit acts as a signal transducer to convert miRNA into DNA duplexes that can activate the trans -cleavage activity of Cas12a, realizing amplification of target miRNA specific signal rather than target miRNA itself. The proposed detection platform enables sensitive detection of model target miR-21 with a low detection limit of 0.29 fM. In addition, this platform can sensitively detect different miRNAs (miR-17 and miR-155) by simply adjusting the first hairpin without changing the crRNA. The consistency between the proposed platform and RT-qPCR in miRNA detection from different cell lines validated its practicability, demonstrating its potential in clinical diagnosis of cancers and monitoring therapy.
The satellite imaging traffic modeling and simulation is mainly discussed in this thesis. Firstly, there are two kinds of satellite reconnaissance imaging traffic models are built. They are focus and bar scan. And some calculation examples of them are given according to the parameters of Starlite reconnaissance satellite constellation of U.S. Secondly, the information storage capacity of the reconnaissance satellite without satellite transmission network is simulated and calculated which illustrates satellite transmission network is necessary. Lastly, the transmission of satellite recon imaging information through a satellite transmission network is simulated and some primary simulation conclusions are given.
Talents are the prerequisite for the prosperity and development of an industry. The training of advanced higher tourism talents is essential to tourism development. However, the training models of advanced tourism talents in China are highly homogenous. The competitiveness of the talents thus cultivated cannot satisfy the demand of tourism development. Therefore, it is imperative to diversify the education of advanced tourism talents. Targeting at the graduates and students from the tourism major of colleges, this paper evaluated the training status of advanced tourism talents through questionnaire survey and interview, and pointed out various problems with the current training models: the training objectives are homogenous; the curriculum is too extensive; the faculty resources are insufficient; the teaching methods are backward and too theoretical; the students lack correct positioning, hard-working spirit, professionalism, and work abilities. Based on the survey results, diversified education strategies were proposed for advanced tourism talents from three dimensions: training objectives, training process, and training outputs. Then, a talent training model that integrates industry and teaching was created, highlighting the importance of work abilities. Besides, the authors presented the design concept of diversified curriculum, and provided a diversified practice teaching system. Taking the Thai language international tour guide major of a school for example, the diversification of training objectives, process, and outputs was discussed in detail. The research results provide a good reference for improving the training effect and teaching reform of advanced tourism talents.
A disposable electrochemical biosensor for detection of DNA sequence related to Microcystis was described. After depositing gold nanoparticles (AuNPs) onto a screen-printed carbon electrode (SPCE) surface by electrodeposition, the DNA probe which is complementary to a specific gene sequence related to Microcystis was immobilized onto the AuNPs modified SPCE via a thiol linker at the 5' end. On the electrode surface the immobilized single-stranded DNA could undergo hybridization in the solution containing DNA specific-sequence of Microcystis. Using methylene blue as the indicator, DNA immobilization and hybridization were characterized by cyclic voltammetry and differential pulse voltammetry. Parameters, such as the deposition conditions of gold nanopariticle and the preconcentration time of MB, were optimized. In addition, the control experiments with non-complementary and single base mismatch sequences were investigated and results demonstrated the high selectivity of the biosensor.
To study whether apoptin gene induces apoptosis in human melanoma cells A375 via the activation of caspase-3.The human melanoma cells A375 were transiently transfected with recombinant pcDNAA3 plasmid, which contained apoptin gene, and the apoptosis was measured by DNA agarose electrophoresis, RT-PCR and flow cytometry. Caspase-3 relative activity was analyzed by colorimetric assay at various time.At 48 h after transfection, the apoptin gene could induce apoptosis of human melanoma cells A375 in vitro and the mRNA of apoptin gene could be detected by RT-PCR. Caspase-3 activity began to rise at 24 h after transfection and reached the peak at 72 h.Apoptin gene can induce apoptosis in human melanoma cells A375 via active caspase-3 and the activity of caspase-3 is time-dependent.
The hot deformation behaviors and microstructural evolution of an equiatomic NbZrTiTa refractory high entropy alloy (RHEA) were studied by using isothermal compression tests in a range of temperatures (900 °C~1200 °C) and strain rates (10 - 3 s -1 ~1 s -1 ). A category of Arrhenius power law relationship was constructed and the activation energy was calculated to be 336~403 kJ mol -1 throughout the strain. The dislocation piling-up and kink bands found in local microstructural areas at low temperatures and high strain rates contributed to intense strain hardening and subsequent strain softening. As the temperature increased and the strain rate decreased, a sharp drop in flow stress was observed after the peak stress. This may be explained by dislocations pinned by short-range ordering (SRO) structures being unlocked. The higher dislocation density and newly emerging fine grains near deformed grain boundaries suggested that the dynamic recrystallization (DRX) was responsible for the continuous flow softening. Discontinuous DRX (DDRX) was the main DRX mechanism in this work, however, the isolated equiaxed grains in initial grains and large cumulative misorientation along the interior of the deformed grains were also found at the high temperatures and low strain rates, which demonstrated that the continuous DRX (CDRX) occurred.
The 21st century is the era of ecological civilization.Contradictions between man and nature are bound to lead to the intensification of education for sustainable development,to find a new mode of education.Strengthening bio-culture education is an effective way of building the conservation-oriented society,ridding human of the ecological crisis.Seeking the path of strengthening bio-culture education will benefit to the effectiveness of ecological education.
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