Genetic effects of combined gamma-rays-ENU treatments as revealed by the Medaka specific-locus test system

根据近10年来对90多万个胚胎进行了240万个基因座的检测，我们认为青鳉特异基因座检测系统的基础已经建立。因为我们的研究迄今为止采用的治疗方法是暴露在单一的药剂中，包括伽马射线、ENU或反应堆辐射，我们决定先用青鳉特异性基因座测试系统检测γ-射线- ENU联合处理的遗传效应。将50只樱花品系的野生型成年雄性在室温下暴露于4.75戈伊的γ-射线-ENU，射线照射20 - 30分钟后，在27 ℃下暴露于0.5mM ENU 2小时。每个处理的雄性与我们的试验菌株AA 2的雌性交配。在联合处理后的第一天至30天进行了胚胎的广泛连续收集。检查的遗传终点是显性致死、总突变和可行突变。观察结果与 关于我们 根据自发率的倍数增加[90%置信上限/下限]初步计算了加和或协同作用，显性致死率分别为0.0557 [0.0566/0.0550]/配子、3.79 [5.51/2.61]x10^<-5>/位点和4.17 [12.6/1.38] x10 ^<-6>/位点，精子、精细胞、精母细胞、分化期精原细胞和干精原细胞的显性致死率分别为0.584 [0.605/0.565]、0.550 [0.563/0.537]、0.394 [0.413/0.375]、0.394 [0.413/0.375]，0.123 [0.134/0.114]和0.0493 [0.0525/0.464]。减数分裂后的精子、精子细胞和精母细胞的观察值高于基于简单相加作用的预期值，但低于基于协同作用的预期值。然而，对于包括分化精原细胞和茎精原细胞在内的减数分裂前期细胞，观察到的显性致死率低于两种预期的致死率。观察到的总突变率与预期的总突变率之间的情况几乎与显性致死率相同。观察到的可行的减数分裂后以及减数分裂前的突变频率没有显着不同的基础上，预期的简单相加，协同作用的基础上预期的速率几乎10倍高于前两组的速率。总突变率与活突变率的比值随减数分裂后暴露到减数分裂前暴露的变化而由辐射型变为ENU型。少

On the basis of the data accumulated during the last ten years by examining more than 900,000 embryos corresponding to approx.2,400,000 loci, we consider that the basis of the Medaka specific-locus test system has been well setablished. Because the treatment so far adopted in our study was exposure to a single agent including gamma-rays, ENU or reactor radiation, we decided to precede to examine the genetic effects of combined gamma-rays-- ENU treatments by using the Medaka specific-locus test system.Fifty wild type adult males of the Sakura strain were exposed at room temperature to 4.75 Gy of gamma-rays followed 20 to 30 min.later by an exposure to 0.5mM ENU for 2 hours at 27ﾟC.Each treated male was mated to a female of our tester strain AA2. Extensive sequential collection of embryos was done from the first day through 30 days after the combined treatments. The genetic endpoints examined were dominant lethals, total mutations and viable mutations. Observed results were compared with … More those already obtained for separate treatments with gamma-rays or ENU.The additivity or synergism was tentatively calculated on the basis of fold-increase over spontaneous rates [90% upper confidence limit/lower limit], which were 0.0557 [0.0566/0.0550]/gamete, 3.79 [5.51/2.61]x10^<-5>/locus, and 4.17 [12.6/1.38]x 10^<-6>/locus, respectively, for dominant lethals, total mutation and viable mutation.The observed dominant lethal rates for sperm, spermatids, spermatocytes, differentiating spermatogonia and stem spermatogonia were, respectively, 0.584 [0.605/0.565], 0.550 [0.563/0.537], 0.394 [0.413/0.375], 0.123 [0.134/0.114], and 0.0493 [0.0525/0.464]. The observed values for the postmeiotics including sperm, spermatids and spermatocytes were higher than the value expected on the basis of simple additivity, but lower than that expected on the basis of synergism. With regard to the premeiotics including differentiating and stem spermatogonia, however, the observed dominant lethal rates were lower than both the two expected rates. The situation between the observed and expected rates of total mutations was almost the same as that for dominant lethals. The observed viable mutation frequencies for the postmeiotics as well as the premeiotics were not significantly different from that expected on the basis of simple additivity, the rates expected on the basis of synergism being almost 10-fold higher than the previous two sets of rates. The ratio of total mutation rate to viable one changed from radiation-type to ENU-type with changes from postmeitic exposure to premeiotic exposure. Less