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Background: Many diseases have been associated with intestinal microbial dysbiosis. Host-microbial interactions regulate immune function, which influences the development of gastric cancer.Aims: The aims were to investigate the characteristics of intestinal microbiota composition in gastric cancer patients and correlations between the intestinal microbiota and cellular immunity.Methods: Fecal samples were collected from 116 gastric cancer patients and 88 healthy controls from Shanxi Province, China. The intestinal microbiota was investigated by 16S rRNA gene sequencing. Peripheral blood samples were also collected from the 66 gastric cancer patients and 46 healthy controls. The populations of peripheral T lymphocyte subpopulations and NK cells were analyzed by flow cytometry.Results: The intestinal microbiota in gastric cancer patients was characterized by increased species richness, decreased butyrate-producing bacteria, and the enrichment of other symbiotic bacteria, especially Lactobacillus, Escherichia, and Klebsiella. Lactobacillus and Lachnospira were key species in the network of gastric cancer-associated bacterial genera. The combination of the genera Lachnospira, Lactobacillus, Streptococcus, Veillonella, and Tyzzerella_3 showed good performance in distinguishing gastric cancer patients from healthy controls. There was no significant difference in enterotype distribution between healthy controls and gastric cancer patients. The percentage of CD3+ T cells was positively correlated with the abundance of Lactobacillus and Streptococcus, and CD3+ T cells, CD4+ T cells, and NK cells were associated with Lachnospiraceae taxa.Conclusions: Our study revealed a dysbiotic intestinal microbiota in gastric cancer patients. The abundance of some intestinal bacterial genera was correlated with the population of peripheral immune cells. [ABSTRACT FROM AUTHOR]

During the Meso-Cenozoic, the eastern Ordos Basin (EOB) underwent a complex tectonothermal process influenced by the destruction of North China Craton, significantly affecting the thermal maturation of the Late Paleozoic source rocks. Tectonothermal modeling and maturation of coal-bearing shales were performed in the EOB to reveal the geological process of shale gas generation. Organic geochemical data for shales show that TOC values vary from 0.96 wt% to 21.36 wt% and R o values range from 1.56% to 2.47%, as well as that organic matter mainly consists of type III kerogen—indicating excellent potential, and sufficient maturity, for gas generation. Thermal modeling suggests that heat flow in the EOB significantly increased as a result of intense magmatic activities during the Yanshanian orogeny, with peak values of 108 and 128 mW/m2 in the northern and southern regions, respectively. Consequently, great variations in maturation history are seen in different regions of the EOB, with the Taiyuan and Shanxi shales reaching the wet gas and dry gas stages, respectively, in the northern region and all shales reaching the dry gas stage in the southern region. Hydrocarbons were generated at 237 Ma and peaked around 162 Ma, whereas hydrocarbon expulsion began at 230 Ma and peaked at 131 Ma. Rapid subsidence in the Triassic brought the shales to the oil generation window and Early Cretaceous magmatic activities led to rapid maturation of shales, again reaching the gas generation stage. Accordingly, extremely high levels of thermal maturity are well documented in hydrocarbons' alkane composition and stable carbon isotope ratio. Gas geochemical data (δ13C 1 vs. C 1 /C 2+3 , δ13C 1 vs. C 2+) imply that that hydrocarbons are from highly mature thermogenic gas generated mainly from humus, and this offers great support for thermal maturation modeling. Regionally, coal-bearing shales have been steadily uplifted and eroded since the Late Cretaceous, causing partial destruction of gas reservoirs. The tectonothermal evolution and hydrocarbon generation of EOB were controlled primarily by magmatic thermal effects resulting from the westward subduction of the Pacific plate. • Tectonothermal modeling and maturation of coal-bearing shales were studied in the EOB to reveal the geological process of shale gas generation. • Hydrocarbons were generated at 237 Ma and peaked around 162 Ma, whereas hydrocarbon expulsion began at 230 Ma and peaked at 131 Ma. • Extremely high levels of thermal maturity are well documented in hydrocarbons' alkane composition and stable carbon isotope ratio. • The tectonothermal evolution and hydrocarbon generation of EOB were controlled primarily by magmatic thermal effects resulting from the westward subduction of the Pacific plate. [ABSTRACT FROM AUTHOR]