Microgravity experiments of two-phase flow patterns aboard Mir Space Station

A first experimental study on two-phase how patterns at a long-term, steady microgravity condition was conducted on board the Russian Space Station "MIR" in August 1999. Carbogal and air are used as the liquid and the gas phase, respectively. Bubble, slug, slug-annular transitional, and annular hows are observed. A new region of annular how with lower liquid superficial velocity is discovered, and the region of the slug-annular transitional flow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug-annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase how patterns in the present experiments are discussed.

PLOD3基因3'调控区的人类特异突变改变miR-124a对PLOD3的调控

microRNAs(miRNAs)是一类在转录后水平调控基因表达的不编码蛋白质的小RNA(长度20-24个碱基).其中,miR-124a是一个在哺乳动物中枢神经系统高度表达的miRNA,在神经前体细胞向神经元分化的过程中起着举足轻重的作用.由于miRNAs特异性地识别靶基因的3'端调控区(3'UTR)的靶序列,因此,在人类起源过程中基因3'UTR的单核苷酸序列变异有可能导致miRNA调控的改变.通过靶基因预测和3'UTR区在哺乳动物代表物种间的同源序列比较,我们发现miR-124a的靶基冈中有一个基因(PLOD3)3UTR的靶位点中存在人类特异突变位点.利用体外报告基因系统,发现PLOD3基因3'UTR靶位点中所含的一个人类特异的突变导致miR-124a对PLOD3的调控效率降低.研究表明,miRNAs靶基因3'UTR的序列变异具有功能效应,它有可能足人类中枢神经系统在起源和演化中发挥关键作用的重要遗传机制之一.