基于生命周期理论的道路客运发展

将生命周期理论应用到道路客运中,提出了道路客运生命周期理论。该理论将客运发展分为进入期、成长期、成熟期和衰退期4个阶段,并建立Gompertz模型来定量分析道路客运的发展规律,分析了道路客运在各个阶段的表现形式和相应阶段应采取的发展策略。最后以某省为例,将该理论运用到实际案例中,拟合出符合实际的Gompertz曲线,验证了该理论在道路客运发展研究中的有效性。     

Cell cycle regulation of central spindle assembly

The bipolar mitotic spindle is responsible for segregating sister chromatids at anaphase. Microtubule motor proteins generate spindle bipolarity and enable the spindle to perform mechanical work. A major change in spindle architecture occurs at anaphase onset when central spindle assembly begins. This structure regulates the initiation of cytokinesis and is essential for its completion. Central spindle assembly requires the centralspindlin complex composed of the Caenorhabditis elegans ZEN-4 (mammalian orthologue MKLP1) kinesin-like protein and the Rho family GAP CYK-4 (MgcRacGAP). Here we describe a regulatory mechanism that controls the timing of central spindle assembly. The mitotic kinase Cdk1/cyclin B phosphorylates the motor domain of ZEN-4 on a conserved site within a basic amino-terminal extension characteristic of the MKLP1 subfamily. Phosphorylation by Cdk1 diminishes the motor activity of ZEN-4 by reducing its affinity for microtubules. Preventing Cdk1 phosphorylation of ZEN-4/MKLP1 causes enhanced metaphase spindle localization and defects in chromosome segregation. Thus, phosphoregulation of the motor domain of MKLP1 kinesin ensures that central spindle assembly occurs at the appropriate time in the cell cycle and maintains genomic stability.     

升阳十一味丸对胃癌细胞凋亡及细胞周期的影响

研究复方蒙药升阳十一味丸对体外培养的人胃癌MGC—803细胞凋亡及细胞周期的影响。以不同浓度的蒙药处理MGC—803细胞,通过MTT法检测药物作用后细胞的增殖情况,并计算生长抑制率。利用倒置光学显微镜、Hochest33342/PI荧光染色、流式细胞术,研究蒙药诱导细胞凋亡的作用及对细胞周期的影响。结果蒙药能抑制MGC—803细胞的增殖,并具有良好的量效关系。2.5 mg/mL药物作用MGC—803细胞48 h后,光镜下可见核固缩、核碎裂等凋亡细胞形态学变化。流式细胞仪检测到"亚G1峰",细胞周期分析表明S期细胞较对照组增多,G2/M期细胞下降,阻滞于S期。说明蒙药升阳可明显抑制胃癌MGC—803细胞的增殖,并在一定浓度范围内诱导细胞凋亡,这可能是其发挥抗肿瘤的作用主要途径之一。     

Cell cycle and cell signal transduction in marine phytoplankton

tAs unicellular phytoplankton, the growth of a marine phytoplankton population results directly from the completion of a cell cycle, therefore, cell-environment communication is an important way which involves signal transduction pathways to regulate cell cycle progression and contribute to growth, metabolism and primary production and respond to their surrounding environment in marine phytoplankton. Cyclin-CDK and CaM/Ca²⁺ are essentially key regulators in control of cell cycle and signal transduction pathway, which has important values on both basic research and applied biotechnology. This paper reviews progress made in this research field, which involves the identification and characterization of cyclins and cell signal transduction system, cell cycle-control mechanisms in marine phytoplankton cells, cell cycle proteins as a marker of a terminal event to estimate the growth rate of phytoplankton at the species level, cell cycle-dependent toxin production of toxic algae and cell cycle progression regulated by environmental factors.