Oncogenic Ras induces cell-cycle arrest in mammalian cells and in fertilized Xenopus eggs. How oncogenic Ras induces cell-cycle arrest remains unclear. We previously showed that oncogenic Ras induces cell-cycle arrest in activated Xenopus egg extracts (cycling extracts) and that the induced cell-cycle arrest correlates with hyperphosphorylation of a 32 kDa protein. However, the identity of the 32 kDa protein was not known. By using a sucrose density-gradient centrifugation, Triton X-100-acetic acid-urea (TAU)-gel electrophoresis, composite agarose-polyacrylamide gel electrophoresis (CAPAGE), SDS-PAGE, and partial tryptic peptide sequence analysis, the 32 kDa protein has now been identified as S6, a 40S subunit ribosomal protein. Hence, our results indicate that the oncogenic Ras-induced cell-cycle arrest is correlated with hyperphosphorylation of S6, suggesting that phosphorylation of S6 plays an important role in the induced cell-cycle arrest. It has been shown that conditional deletion of gene encoding S6 in mammalian cells prevents proliferation, demonstrating the importance of S6 in cell proliferation. The exact role S6 plays in cell proliferation is unclear. However, phosphorylation of S6 has been implicated in the regulation of protein synthesis. Thus, our results are consistent with the concept that oncogenic Ras induces S6 phosphorylation to influence protein synthesis, thereby contributing to the cell-cycle arrest. In addition, our results also demonstrate that composite agarose-polyacrylamide gel electrophoresis is suitable for the separation of large molecular complexes.
<p>High-density development has reduced greenery and water coverage, thus reducing the environment's ability to regulate temperature. Temperatures in urban areas are significantly higher than in suburban areas, resulting in severe heat island effects. The urban heat island intensity in many cities in Taiwan is generally higher than 2.5&#176;C in summer. One of the causes is the poor ventilation of dense buildings. Therefore, the construction of wind corridor systems based on the current urban conditions is an excellent way to improve the quality of heat dissipation.</p><p>The paper first reviews the definition of a wind corridor system and introduces the existing urban cases. Afterwards, the long-term climate data provided by the National Science and Technology Center for Disaster Reduction and the Taiwan Climate Change Projection Information and Adaptation Knowledge Platform, the High-Density Street-Level Air Temperature Observation Network data from the Building and Climate Laboratory of National Cheng Kung University, and the overlay of Landsat satellite computer visual and cadastral map data are used. The data were combined to investigate the appropriate hierarchical structure of the wind corridor systems in Taichung City.</p><p>A Natural Wind Corridor is the long-term natural wind trend mapped from the data mentioned above. Then, based on the Natural Wind Corridor, the Urban Wind Corridor System at the height of 2 metres is constructed by the Least-Cost Path (LCP) analysis with roughness length grids. Implementing the Urban Wind Corridor at different scales, such as in urban and local areas, is discussed. We defined that wind passage is facilitated when the roughness length is less than 1 metre, and the path is allowed to deflect in advance when it encounters large areas of high roughness length (over 2 metres). The deflection angle should not exceed 30&#176;. To define the Primary and Secondary Wind Corridor, we calculate the number of high-roughness-length grids that each route passes through. Wind corridors are classified as Type II when the grid amount of the route passing through, which contains greater than 1 metre in roughness length, is between 35% and 50% of the study domain. If this value is less than 35%, the wind corridor is classified as Type I.</p><p>Besides, the Computational Fluid Dynamics (CFD) simulation was used to verify the effectiveness of the heat mitigation strategies and provide recommendations on implementation methods, such as limiting the minimum site ventilation ratio by area.</p><p>We found that the LCP analysis has the advantage of being fast and less costly, but it also limits the results, e.g., the exclusive starting wind direction limits the interpretation. We suggest that supplementary conditions can be set for the difference in the nature of upwind and downwind areas.</p>
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