Zur Sauerstoffabhängigkeit der Rate strahleninduzierter Chromosomenaberrationen in Oozyten vonDrosophila melanogaster
SummaryAbrahamson's (1959) results concerning the influence of oxygen on the frequency of X-ray induced structural changes (half-translocations) inDrosophila oocytes were generally reproduced, especially the demonstration of a “reverse” oxygen effect (under special experimental conditions protecting action of oxygen, sensitization by nitrogen). In the course of our investigations the following new findings were obtained: 1. The added aberration frequencies of the 3rd and 4th day after the various treatments generally tend to decrease as compared with those of the first two days (dependence on state of maturity of the treated oocytes). 2.Preirradiation treatment by nitrogen increases the aberration frequency significantly. Possible explanations of this effect are discussed.
Modification of Chromosomal Aberration Yield by Postirradiation Treatment.
In Tradescantia microspores, postirradiation treatments can modify the numbers of chromosome exchanges induced by x rays. The postirradiation inibition of respiration by anoxia or carbon monoxide in the xam dark prevents the rejoining of breaks and consequently allows breaks to remain open and capable of forming exchanges with breaks induced later. The results with Tradescantia are qualitatively similar to the results ob tained with Vicia in that irradiation in the presence of oxygen produces inore breaks than does anoxic irradiation and that for rejoining cellular respiration (the production of ATP) is required. (auth)
Clozapine derived 2,3-dihydro-1H-1,4- and 1,5-benzodiazepines with D4 receptor selectivity: synthesis and biological testing.
Novel 4-arylpiperazin-1-yl-substituted 2,3-dihydro-1H-1,4- and 1H-1,5-benzodiazepines and their aza-analogues were synthesized as debenzoclozapine derivatives for evaluation as potential D4-ligands. While Ki values of some of the title compounds came within the range of clozapine, they showed an impressively greater selectivity over other dopamine receptor subtypes, especially D2. For the most promising compounds, intrinsic activity and binding properties to serotonin 5-HT1A and 5-HT2 were also determined.