血管活性肠多肽结合核苷酸性质的研究

采用光亲和技术检测了血管活性肠多肽(VIP)与核苷酸之间的相互作用,发现VIP可以特异性结合同位素标记的GTP,还发现未标记的GTP以及其它三磷酸核苷抑制这种结合,这意味着VIP与上述三磷酸核苷之间的结合是一种典型的可逆性的结合反应.发现低浓度的GDP,GMP不但不抑制VIP与同位素标记GTP的结合反应,反而增强这种结合.联系到其它研究者关于GTP影响VIP与其受体结合反应的结果,可认为VIP能可逆性地连接一种三磷酸核苷,这种连接受反应系统中不同核苷酸比例影响,通过这种连接来调节VIP与其受体之间的反应.     

Symmetry and Cell Division in Raphid Diatoms

The development and final morphology of the valve in raphe-bearingdiatoms exhibit a cryptic lateral polarity, and hence two typesof frustule can be distinguished. In the cis type both valveshave the same orientation; in the trans type they have oppositeorientations. Examination of a variety of taxa suggests thatin all dividing raphid diatoms, both new valves have the sameorientation and so only three types of division are possible:cis; cis + cis, cis trans + trans, trans; cis+trans. The possessionof different combinations of these explains the observed ratiosof cis: trans in different taxa, viz all cis; 1: 2 cis: trans;and roughly 1: 1 cis: trans. The implications of the resultsfor diatom systematics are examined, with special referenceto Navicula Bory. Diatom systematic, diatom valve morphogenesis, cell symmetry, raphe structure