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Objective To explore the regulative effect of miR-214 on oxidative stress injury induced by hypoxia reoxygenation (H/R) in H9c2 myocardial cells though targeted inhibition of CaMKⅡ. Methods Rat myocardial H9c2 cells were randomly divided into 4 groups, ①control group: H9c2 cells without any treatment; ② H/R group: the myocardial cells were cultured in hypoxia for 24 h and then reoxygenation for 6 h; ③ mimics+H/R group: the myocardial cells were transfected with miR-214 and then cultured with H/R as above; ④ mimics negative control (MNC)+H/R group: the myocardial cells were transfected with miR-214's mimics negative control and then cultured with H/R as above. CCK-8 assay was used to detect the viability of cells. qPCR was adopted to detect the expression of miR-214. Flow cytometry, TUNEL assay, and SOD or MDA detect kits were used to determine the reactive oxygen species (ROS) levels and cell apoptosis. The association of miR-214 with CaMKⅡ was examined by double-luciferase reporter assay, and their changes at mRNA and protein levels were detected by qPCR and Western blotting. After H9c2 cells were transfected with recombinant adenovirus carrying CaMKⅡ gene or the control adenovirus, the regulative effect of miR-214 on oxidative stress of cells was examined by the above methods. Results CCK-8 assay showed that compared with normal group, the cell viability of H/R group was significantly decreased (P < 0.05), while miR-214 overexpression could obviously increase the cell viability (P < 0.05). qPCR results showed that the expression level of miR-214 was markedly downregulated in the H/R group than the control group, while notable increase of miR-214 was observed in the miR-214 mimics group (P < 0.05). Compared with the normal group, the ROS production, MDA level and TUNEL positive cells were obviously increased, while the SOD level was significantly decreased in H/R group (P < 0.05), but opposite trends were observed when the HR group compared to and the miR-214 mimics group (P < 0.05). TargetScan server indicated that there was binding site of miR-214 and CaMKⅡ. The dual luciferase reporter assay also confirmed that miR-214 could bind to CaMKⅡ in H9c2 cells. In addition, qPCR and Western blot results showed that H/R treatment increased the expression of CaMKⅡ at mRNA and protein levels, but miR-214 significantly inhibited the enhanced expression induced by H/R. Overexpression of CaMKⅡ in H9c2 cells resulted in partially blocked effects of miR-214 on oxidative stress and apoptosis induced by H/R treatment. Conclusion Overexpression of miR-214 can regulate oxidative stress and apoptosis of H9c2 cells by inhibiting CaMKⅡ at the transcription level.

It is a common method to use sequence stratigraphic theory to identify favourable intervals in hydrocarbon exploration. The Lower Cambrian shale of Well Jiangye-1 in Yangtze Region in Xiuwu Basin was chosen as the research object. The content of excess silicon of siliceous minerals in shale was calculated quantitatively, and the concentration distribution of Al, Fe, Mn showed that the excess silicon is of hydrothermally origin and the shale deposited in an environment with hydrothermal activity. Using U/Th values in the study, combined with lithology and logging data, in order to divide sequences of the Lower Cambrian shale in Yangtze Region in Xiuwu Basin. The result shows that the shale of the Lower Cambrian shale is recognized as 1 2nd sequence (TST-RST, TST = Transgressive systems tract; RST = Regressive systems tract) and then further subdivided into 5 3rd sequences (SQ1-SQ5). During the deposition of SQ2 and SQ3, hydrothermal activity was active, and their excess silicon content was generally above 20%-30%. Rising sea level and active hydrothermal activity were beneficial for the enrichment of siliceous minerals and organic matter. Based on the comparison of the reservoir parameters, it tells that SQ2 and SQ3 have relatively higher content of TOC, higher content of brittle minerals (such as siliceous minerals, carbonate minerals and so on), larger effective porosity and higher content of gas, which make it as the most favourable intervals of the Lower Cambrian in Xiuwu Basin.

Uranium deposits are crucial resources for the development of the nuclear energy. Among known sources of uranium, the uranium-rich shales have recently obtained significance. In this paper, the Lower Cambrian Wangyinpu Formation shale in the Xiuwu Basin, southern China, has been studied using a combination of techniques including element analysis (Al, Fe, and Mn), δ30Si silicon isotopic analysis, δ18O oxygen isotopic analysis, study of core samples. It has been observed that significant hydrothermal activity occurred in the Xiuwu Basin during the Early Cambrian period. The results show that 20%–40% of the silicon in most of the sections of the Lower Cambrian Wangyinpu Formation were inherited from the hydrothermal fluids, with temperatures ranging between 75∘C and 102∘C. It is concluded that more than 90% of the uranium in most of the sections of the Lower Cambrian Wangyinpu shale was derived from submarine hydrothermal fluids, while less than 10% from the terrigenous detritus. The enrichment of uranium in the basin was observed in the Middle-Upper part of the Wangyinpu Formation and the geological resources estimated to a tune of ~4.9×103 t. In this paper, we proposed a model for silicon and uranium enrichment in the Lower Cambrian shale controlled by hydrothermal activity in the Xiuwu Basin. This model also provides a scientific rationale for uranium further exploration and exploitation of the uranium resource.