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.     

THE EFFECT OF MANURES ON THE BOLTING OF THE BEET PLANT

In sugar beet, the effect on bolting of additions of potash manures, of superphosphate, and of the mixture of these was not significant, whether applied at the time of sowing or previously. Dung applied in the previous autumn slightly increased the number of plants which went to seed, and when applied just before sowing it had a more marked effect. An amount of sulphate of ammonia which would have approximately the same stimulating effect as the dung gave a slightly larger amount of bolting.
On red beetroot, it was possible to compare larger and smaller dressings of various coarse organic manures, and of each of these with and without dressings of sulphate of ammonia. In all cases the sulphate of ammonia and each of the organic manures largely increased the amount of bolting, and a doubling of the organic manure dressing or the addition of sulphate of ammonia to it caused a further increase. Sewage sludge gave an abnormally large amount of bolting, but it is doubtful whether this was due to the larger amount of organic matter and nitrogen applied in this manure. In general, any manurial addition causing more vigorous growth leads to an increase in bolting. There is a very large variation in the amount of running to seed in the crop of red beetroot from different parts of the same field, but the effect of the manures on the proportion which bolted was not widely different.
The general question as to the reason why beet plants should bolt more in one season than in another is discussed, and it is suggested that a check to the plants in an early stage, whether caused by dryness or waterlogging, or by low temperature, followed by a vigorous growing period may have something to do with the matter. This would agree with the experiences recorded in the present paper.     

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