† These authors contribute equally to this work.Exosomes play important roles in many physiological and pathological processes. However, the exosome-cell interaction mode and the intracellular trafficking pathway of exosomes in their recipient cells remain unclear. Here, we report that exosomes derived from K562 or MT4 cells are internalized more efficiently by phagocytes than by non-phagocytic cells. Most exosomes were observed attached to the plasma membrane of non-phagocytic cells, while in phagocytic cells these exosomes were found to enter via phagocytosis. Specifically, they moved to phagosomes together with phagocytic polystyrene carboxylate-modified latex beads (biospheres) and were further sorted into phagolysosomes. Moreover, exosome internalization was dependent on the actin cytoskeleton and phosphatidylinositol 3-kinase, and could be inhibited by the knockdown of dynamin2 or overexpression of a dominant-negative form of dynamin2. Further, antibody pretreatment assays demonstrated that tim4 but not tim1 was involved in exosomes uptake. We also found that exosomes did not enter the internalization pathway involving caveolae, macropinocytosis and clathrin-coated vesicles. Our observation that the cellular uptake of exosomes occurs through phagocytosis has important implications for exosome-cell interactions and the exosome intracellular trafficking pathway.

This study delved into the pore-throat heterogeneity of the tight sandstone in the Ordos basin for NMR and Rate-Controlled Mercury Intrusion tests (RCMI). The aim of the present study was to qualitatively and quantitatively characterize microscopic heterogeneity of a pore throat based on the merits of NMR and RCMI. On this basis, the effect of pore-throat heterogeneity on gas-phase percolation capacity was studied by a gas-water relative permeability test. As revealed from the results, ① the difference in fractal characteristics of the same sample is caused by the different principles and range in measuring pore throats of two experiments. The pore heterogeneity was characterized by the NMR test, while the throat heterogeneity was characterized by the RCMI test. ② D t1 ranges from 2.51 to 2.92, and D t2 ranges from 2.93 to 2.99, whereas D max ranges from 2.66 to 2.95 based on RCMI tests, revealing that the Shihezi sandstones exhibited moderate to high complexity and heterogeneity of the pore structure. ③ With the increase of D t2 and D max , the effective seepage space is narrowed for the gas phase, and the interference in gas-water two phases tends to increase. As a result, low gas-phase permeability, high bound water saturation, and a small common infiltration area are achieved. ④ The more robust the pore-throat heterogeneity, the slower the gas-phase permeability curve will rise with the increase in gas saturation, which reflect the higher producing water ratio of the reservoir, suggesting that microscopic heterogeneity of the pore throat restrains the migration of the two-phase fluid and sweep area of single-phase fluid. The stronger the pore-throat heterogeneity, the worse the exchange of gas and liquid will be. The research results have important guiding significance for tight gas development of the Shihezi reservoir.

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The architecture analysis of the different orders sedimentary bodies is of great significance to the efficient development of oil and gas fields. In order to investigate the effects of the architectural interfaces on reservoir quality and heterogeneity, this study takes the Gudong oil field as a case to investigate the architectural characteristics of hierarchical bounding surfaces using detailed descriptions of core and wireline logs. Architectural models from the 7th-order to the 3rd-order are analyzed, and the developmental characteristics of the 5th-order braided river, 4th-order single sandstone, and 3rd-order accretion are summarized. The interlayer between two braided rivers is floodplain mud deposition, with poor physical properties, stable thickness, and strong blocking capacity. Two models of interlayers are found in the 4th-order deposition. The first interlayer is between the braided filling channel and midchannel bar, which is composed of generally fine-grained sediments with calcium cementation and poor physical properties. The second interlayer is a transformation belt between two midchannel bars and is generally composed of gravel-scoured deposition with penetration capability. The 3rd-order surfaces are defined as the surfaces of accretions within midchannel bars. Two models of interlayers are also found in the 3rd-order surfaces of accretions. The paleocurrent of the sandy braided river is reconstructed by synthesizing the core data, well logging data, and production performance data. A total of 1 fluvial system (7th-order), 2 compound braided rivers (6th-order), 11 braided rivers (5th-order), 41 midchannel bars (4th-order), and 96 accretions (3rd-order) are developed in the study area.