Objective: The aim of our study was to investigate the impact of abdominal hypo-fraction irradiation on liver damage in rats so as to provide a reference for its clinical application. Methods: A total of 100 Wistar ra...Objective: The aim of our study was to investigate the impact of abdominal hypo-fraction irradiation on liver damage in rats so as to provide a reference for its clinical application. Methods: A total of 100 Wistar rats were equally randomized to five groups as control, 4 Gy, 6 Gy, 8 Gy and 12 Gy group, and the corresponding fractionated doses were offered. Liver functions were examined at the 2nd, 4th, 6th, 8th and 10th week after irradiation. Morphological changes were observed by HE staining. Expressions of Bcl-2 and Bax were examined by immunohistochemical technique. Results: In all irradiation groups, hepatocellular swell, degeneration, necrosis and even hepatic fibrosis could be seen. The differences of the liver coefficient, Glutamyl pyruvic transaminase (GPT), Glutamyl oxaloacetic transaminase (GOT) were significant among the groups and different time points (F = 11.833-781.972, F = 20.857-264.692, P < 0.001). Expressions of Bcl-2 and Bax were significantly different between each group (F = 211.607, 116.577; P < 0. 001), and between each time point (F = 54.083, 68.749; P < 0. 001). Conclusion: Compare with conventional fraction, abdominal hypo-fraction irradiation may cause radiation damage to rat liver, being dose-and-time dependent. Up-regulation of activating apoptosis protein Bax and down-regulation of inhibiting apoptosis protein Bcl-2 may involve in the process.展开更多
Soil is an essential part of the critical zone,and soil-microbe-plant system serves as a key link among lithosphere,biosphere,atmosphere and hydrosphere.As one of the habitats with the richest biodiversity,soil plays ...Soil is an essential part of the critical zone,and soil-microbe-plant system serves as a key link among lithosphere,biosphere,atmosphere and hydrosphere.As one of the habitats with the richest biodiversity,soil plays a critical role in element biogeochemistry on the earth surface(weathered crust).Here we review the soil biological processes that are relevant to mineral weathering,element cycling,and transformation,with an emphasis on rock weathering mediated by soil microbes,plant root and the rhizosphere.展开更多
Despite extensive studies on the mechanics of DNA under external constrains, such as tension, torsion, and bending, several important aspects have remained poorly understood. One biologically important example is the ...Despite extensive studies on the mechanics of DNA under external constrains, such as tension, torsion, and bending, several important aspects have remained poorly understood. One biologically important example is the mechanics of DNA under sharp bending conditions, which has been debated for a decade without thorough comprehension. The debate is about the interesting phenomenon raised from a series of different experiments: sharply bent DNA has a surprisingly high apparent bending flexibility that deviates from the canonical bending elasticity of DNA. This finding has motivated various theoretical models, which mainly incorporate the excitation of mechanical defects inside severely bent DNA molecules. Here, we review the recent progress on the understanding of the mechanics of sharply bent DNA and provide our view on this important question by interrogating the theoretical foundation of these experimental measurements.展开更多
Concentrations of suspended particle material(SPM), dissolved silicate(DSi), biogenic silica(BSi), phytoliths(plant produced siliceous microscopic structures), and other parameters were analyzed to examine the influen...Concentrations of suspended particle material(SPM), dissolved silicate(DSi), biogenic silica(BSi), phytoliths(plant produced siliceous microscopic structures), and other parameters were analyzed to examine the influence of both natural processes and human activities on silica delivery to the estuary of the Huanghe River(Yellow River). Our results indicate that the concentrations of DSi in the river decreased significantly since 1986. Approximately 34% of dissolved silica was trapped in the basin between 1986 and 2010 due to a reduction of soil erosion. Phytoliths comprised 67.2%–96.3% of BSi, with the smoothing bar type being the dominant form. Concentrations of BSi are significantly higher in the Huanghe River compared to other major rivers throughout the world due to its high sediment yield. We also found that the ratios of BSi/(BSi+DSi) and BSi/SPM were approximately 0.5 and 0.003 at Lijin near the river mouth, indicating that BSi carried in suspension by the Huanghe River was an important component of the rivers silica load. Significant amounts of BSi were also composed of phytoliths in Bohai Sea sediments near the Huanghe River estuary with the smoothing bar form again being the most abundant. The relatively high specific fluxes of BSi in the Huanghe River reflect its high turbidity and high erosion rates in the basin. The high sediment load originating on the Loess Plateau is likely responsible for the higher BSi flux, in agreement with a general trend of increasing BSi flux with increasing sediment flux in global river systems. This study demonstrates that BSi transported by rivers can be composed largely of phytoliths originating from the erosion of topsoils. The flux of phytoliths in river's suspended sediment load may therefore represent a significant contribution to the biogeochemical cycle of silica in coastal waters.展开更多
文摘Objective: The aim of our study was to investigate the impact of abdominal hypo-fraction irradiation on liver damage in rats so as to provide a reference for its clinical application. Methods: A total of 100 Wistar rats were equally randomized to five groups as control, 4 Gy, 6 Gy, 8 Gy and 12 Gy group, and the corresponding fractionated doses were offered. Liver functions were examined at the 2nd, 4th, 6th, 8th and 10th week after irradiation. Morphological changes were observed by HE staining. Expressions of Bcl-2 and Bax were examined by immunohistochemical technique. Results: In all irradiation groups, hepatocellular swell, degeneration, necrosis and even hepatic fibrosis could be seen. The differences of the liver coefficient, Glutamyl pyruvic transaminase (GPT), Glutamyl oxaloacetic transaminase (GOT) were significant among the groups and different time points (F = 11.833-781.972, F = 20.857-264.692, P < 0.001). Expressions of Bcl-2 and Bax were significantly different between each group (F = 211.607, 116.577; P < 0. 001), and between each time point (F = 54.083, 68.749; P < 0. 001). Conclusion: Compare with conventional fraction, abdominal hypo-fraction irradiation may cause radiation damage to rat liver, being dose-and-time dependent. Up-regulation of activating apoptosis protein Bax and down-regulation of inhibiting apoptosis protein Bcl-2 may involve in the process.
基金supported by Major Program of National Natural Science Foundation of China(Grant No.41090282)
文摘Soil is an essential part of the critical zone,and soil-microbe-plant system serves as a key link among lithosphere,biosphere,atmosphere and hydrosphere.As one of the habitats with the richest biodiversity,soil plays a critical role in element biogeochemistry on the earth surface(weathered crust).Here we review the soil biological processes that are relevant to mineral weathering,element cycling,and transformation,with an emphasis on rock weathering mediated by soil microbes,plant root and the rhizosphere.
基金supported by the Mechanobiology Institute at National University of Singapore and Singapore Ministry of Education Academic Research Fund Tier 2 (Grant No. MOE2013-T2-1-154)
文摘Despite extensive studies on the mechanics of DNA under external constrains, such as tension, torsion, and bending, several important aspects have remained poorly understood. One biologically important example is the mechanics of DNA under sharp bending conditions, which has been debated for a decade without thorough comprehension. The debate is about the interesting phenomenon raised from a series of different experiments: sharply bent DNA has a surprisingly high apparent bending flexibility that deviates from the canonical bending elasticity of DNA. This finding has motivated various theoretical models, which mainly incorporate the excitation of mechanical defects inside severely bent DNA molecules. Here, we review the recent progress on the understanding of the mechanics of sharply bent DNA and provide our view on this important question by interrogating the theoretical foundation of these experimental measurements.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41106072,41376093,41206064)Natural Science Foundation of Shandong(Grant No.ZR2010DM006)
文摘Concentrations of suspended particle material(SPM), dissolved silicate(DSi), biogenic silica(BSi), phytoliths(plant produced siliceous microscopic structures), and other parameters were analyzed to examine the influence of both natural processes and human activities on silica delivery to the estuary of the Huanghe River(Yellow River). Our results indicate that the concentrations of DSi in the river decreased significantly since 1986. Approximately 34% of dissolved silica was trapped in the basin between 1986 and 2010 due to a reduction of soil erosion. Phytoliths comprised 67.2%–96.3% of BSi, with the smoothing bar type being the dominant form. Concentrations of BSi are significantly higher in the Huanghe River compared to other major rivers throughout the world due to its high sediment yield. We also found that the ratios of BSi/(BSi+DSi) and BSi/SPM were approximately 0.5 and 0.003 at Lijin near the river mouth, indicating that BSi carried in suspension by the Huanghe River was an important component of the rivers silica load. Significant amounts of BSi were also composed of phytoliths in Bohai Sea sediments near the Huanghe River estuary with the smoothing bar form again being the most abundant. The relatively high specific fluxes of BSi in the Huanghe River reflect its high turbidity and high erosion rates in the basin. The high sediment load originating on the Loess Plateau is likely responsible for the higher BSi flux, in agreement with a general trend of increasing BSi flux with increasing sediment flux in global river systems. This study demonstrates that BSi transported by rivers can be composed largely of phytoliths originating from the erosion of topsoils. The flux of phytoliths in river's suspended sediment load may therefore represent a significant contribution to the biogeochemical cycle of silica in coastal waters.
