RESUMO
The enrichment of organic matter is the foundation for a high-quality shale deposition. It is generally believed that high productivity and persistent anoxic conditions facilitate the preservation and enrichment of organic matter. However, there is a lack of investigation into how the dynamic combination of productivity and anoxia affects organic matter enrichment. Here, the black shales of the Wufeng Formation and Longmaxi Formation in the western Chongqing area were selected, where oceanic anoxia and high productivity evolved as a function of the water depth. The main findings were as follows: (1) the distribution of high-quality shales in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation is closely related to the oxygen minimum zone (OMZ), indicating that the physicochemical conditions within the OMZ zone facilitated the development of high-quality shale; (2) in the late period of the Wufeng Formation, intense ocean upwelling in the middle shelf and outer shelf regions caused high productivity where thick-bedded high-quality shales were deposited; and (3) in the early period of the Longmaxi Formation, ocean upwelling weakened, accompanied by the expansion of the OMZ to shallow water regions, and high-quality shales were widely distributed. Based on the above findings, two depositional models were proposed to account for the formation of high-quality shales, and it is suggested that intense ocean upwelling during the late period of the Wufeng Formation and OMZ expansion during the early period of the Longmaxi Formation played crucial roles in facilitating the formation of high-quality shales. These two models present the spatial and temporal variability of high-quality shale development for the first time and can guide shale gas exploration and development strategies.
RESUMO
OBJECTIVE: In this study, we investigated the impact of perioperative administration of Bifidobacterium triplex viable capsules on the serum levels of circulating miR-21-5p, miR-135-5p, and miR-155-5p in patients with colorectal cancer (CRC). The purpose of this study is to provide a foundation for future research on the use of Bifidobacterium triplex viable capsules to enhance postoperative recovery in patients with CRC. METHODS: A total of 60 patients with primary CRC admitted to the Department of General Surgery at Shanxi Bethune Hospital between June 2020 and December 2020 were selected and randomly divided into two groups: 20 cases in the control group and 40 cases in the experimental group. The experimental group was administered oral Bifidobacterium triplex viable capsules during the perioperative period, while the control group was administered oral placebo. Before and after the perioperative period, the expression levels of miR-21-5p, miR-135-5p, and miR-155-5p were compared in the serum of both groups of patients. Furthermore, we established the prognostic value of these three miRNAs in CRC patients. RESULTS: After surgery, the expression levels of miR-21-5p, miR-135-5p, and miR-155-5p decreased in both groups of patients (P < 0.05). Significantly greater differences were observed between miR-21-5p and miR-135-5p (P < 0.001). Expression levels of serum miR-21-5p (P = 0.020) and miR-135-5p (P = 0.023) decreased significantly more in the experimental group than in the control group. The levels of the above three miRNAs after surgery did not correlate with 3-year OS (HR = 4.21; 95% CI 0.37-47.48; log-rank P = 0.20) or 3-year DFS (HR = 1.57; 95% CI 0.32-7.66; log-rank P = 0.55) in two groups. CONCLUSION: Radical surgery reduces the levels of serum miR-21-5p, miR-135-5p, and miR-155-5p expression in patients with CRC. The use of Bifidobacterium triplex viable capsules assists in achieving quicker perioperative recovery from radical surgery in CRC patients, and this underlying mechanism may be associated with the regulation of serum miR-21-5p, miR-135-5p, and miR-155-5p expression levels.