Onfelt A, Magnusson J, Wikén M
Wallenberg Laboratory, Stockholm University, Sweden.
Hereditas. 1993;118(1):21-33. doi: 10.1111/j.1601-5223.1993.t01-3-00021.x.
Several studies have shown that the characteristically skewed sex ratio among the progeny of abo homozygous females, derived from heterozygous stocks and mated to attached XY males, can be modified during homozygous stock-keeping. This amelioration seems to have a complex mechanistic background, and both loss of the blood transposon from chromosome 2, where abo is located, and amplification of a specific heterochromatic element (ABO) have been suggested to work in this direction. There is also an increased frequency of non-disjunction associated with abo, beside the poor recovery of X0 males. Experiments were performed to see if there was a coordinated loss of both phenotypic expressions during homozygous stock-keeping and if non-disjunction was amenable to modification by quinacrine. We found an unexpected spontaneous amelioration of the phenotypic expressions of abo despite heterozygous stock-keeping. The spontaneous amelioration of non-disjunction and male lethality under heterozygous condition was coordinated while the process initiated by homozygosity slowly decreased non-disjunction and rapidly increased male recovery over generations, which may point to a mechanistic difference between the amelioration processes. Quinacrine was found to ameliorate the skewed sex ratio but did not affect non-disjunction. In these experiments larval and adult treatment, respectively, were employed and the respective controls revealed that also ageing before mating significantly increased male recovery and reduced non-disjunction. Ageing before mating and quinacrine seemed to act additively on male recovery, suggesting independent action, while interaction could be suspected between quinacrine and some ameliorating factor associated with brood. Some of the results also suggest that quinacrine acts indirectly and does not substitute for the abo gene product. Due to the action of quinacrine in other biological systems it is speculated that the compound compensates for a biochemical aberration in abo/abo females or their progeny, showing some relation to phospholipase activity and/or actin polymerisation state.
多项研究表明，从杂合品系获得并与附着型XY雄性交配的abo纯合雌性后代中典型的性别比例偏斜，在纯合品系饲养过程中可以得到改善。这种改善似乎有复杂的机制背景，有人提出位于2号染色体（abo所在位置）上的血液转座子缺失以及特定异染色质元件（ABO）的扩增都朝着这个方向起作用。除了X0雄性的回收率低之外，还存在与abo相关的不分离频率增加的情况。进行了实验以观察在纯合品系饲养过程中两种表型表达是否存在协同缺失，以及不分离是否可被喹吖因修饰。我们发现，尽管是杂合品系饲养，但abo的表型表达出现了意外的自发改善。杂合条件下不分离和雄性致死率的自发改善是协同的，而纯合引发的过程在几代中缓慢降低不分离率并迅速提高雄性回收率，这可能表明改善过程之间存在机制差异。发现喹吖因可改善偏斜的性别比例，但不影响不分离。在这些实验中分别采用了幼虫期和成虫期处理，各自的对照显示，交配前的老化也显著提高了雄性回收率并降低了不分离率。交配前的老化和喹吖因似乎对雄性回收率有累加作用，表明是独立作用，而喹吖因与某些与育雏相关的改善因子之间可能存在相互作用。一些结果还表明，喹吖因起间接作用，不能替代abo基因产物。由于喹吖因在其他生物系统中的作用，推测该化合物补偿了abo/abo雌性或其后代中的生化异常，这与磷脂酶活性和/或肌动蛋白聚合状态有一定关系。
