Selection Mechanisms for Mutants As Studied by the Medaka Specific-Locus Test System.

1.在该项目结束时，累计检查的青鳉胚胎总数达到488，890个。这个胚胎数相当于总共1，198，2-79个基因座。将野生型雄性青鳉暴露于γ射线、裂变中子或乙基亚硝基脲。这些处理的雄性被允许与未处理的雌性测试青鳉交配，其在3个基因座上是纯合隐性的，即。e. B/B ; gu/gu ; lf/lf。伽马辐照使用<137>位于东京大学核科学与工程研究中心的111-TBq ^ Cs伽马源进行。使用的剂量率为0.95戈伊/min。4.裂变中子辐照是在UTR-Kinki反应堆（近畿大学原子能研究所，与S。近藤和T.博士Ito）在以下条件下在1瓦下操作：dDn/dt=16.9 cGy/hr，dDg/dt=24.8 cGy/hr。用乙基亚硝基脲（ENU）对青鳉进行处理， ...更多信息 在27 ° C下在ImM ENU水溶液（pH=5.8）中温育2小时，随后用自来水充分冲洗。自发总突变率为4.2x10^<-5>/位点，而自发存活突变率为5.5x10^<-6>/位点，该值vdry接近小鼠的值（8.1x10^<-6>/位点，Ressell &amp; Kelly（1982））。发现每单位剂量（rad）的γ射线对青鳉精子、spegmatids和精原细胞的诱发活性突变率分别为176、51和7.5（x10^<-8>/位点）。基于上述获得的值，用于诱导精子、精子细胞和精原细胞的可行突变的加倍γ射线剂量估计分别为3.2、12和98拉德（cGy）。Wg已经建立了一种从具有各种严重程度的畸形的个体青鳉胚胎中获得细胞系的方法，这些畸形预期会导致显性致死突变。令人惊讶的是，来自濒死畸形胚胎的细胞系在一年内比来自正常对照组的没有畸形的胚胎更活跃地生长。我们还建立了一种检测雄性生殖细胞DNA损伤的AP-PCR方法，以期为研究发育过程中的胚胎选择机制提供更直接的线索。少

1. The total cumulative number of the Medaka embryos examined at the end of this project reached 488, 890. This number of embryos corresponds to a total of 1, 198, 2-79 loci.2. The wild type male Medaka were exposed to gamma-rays, fission neutron or ethylnitrosourea. These treated males were allowed to mate with non-treated female tester Medaka which are homozygous recessive at the 3 loci, i. e. b/b ; gu/gu ; lf/lf.3. The gamma-irradiations were done using a 111-TBq ^<137>Cs gamma source located in the Research Center for Nuclear Science and Engineering, The University of Tokyo. The dose-rate used was 0.95 Gy/min.4. The irradiations with fission neutron were performed in the UTR-Kinki reactor (Atomic Energy Research Institute, Kinki University, in collaboration with Prof. S. Kondo and Dr. T. Ito) operated at 1 Watt with the following conditions : dDn/dt=16.9 cGy/hr, dDg/dt=24.8 cGy/hr.5. The treatments of the Medaka with ethylnitrosourea (ENU) were done by allowing the male Medaka to s … More wim in 1 mM aqueous solution of ENU (pH=5.8) at 27ﾟC for 2 hours, following by extensive rinse with tap water.6. The spontaneous total mutation 5 rate was 4.2x10^<-5>/locus, while the spontaneous viable mutation rate was 5.5x10^<-6>/locus, a value vdry close to that of the mouse (8.1x10^<-6>/locus, Ressell & Kelly (1982)).7. The induced rates of viable mutation per unit dose (rad) of gamma-rays for the Medaka sperm, spegmatids and spermatogonia were found to be respectively 176, 51 and 7.5 (x10^<-8>/locus).8. Based on the above-obtained values, the doubling gamma-ray dose for the induction of viable mutation was estimated to be 3.2, 12 and 98 rad (cGy) for sperm, spermatids and spermatogonia, respectively.9. Wg have established a method to obtain cell lines from individual Medaka embryos with malformation of various severities which is expected to result in dominant lethal mutation. Surprisingly, cell lines from moribund malformed : embryos tended to grow over a year more actively than those from the normal' controls without malformation.10. We also established an AP-PCR method to examine induced DNA damages in male getm cells, which is expected to give more direct clue to study the mechanisms of embryonic selection during development. Less