Kashiwagi A, Kashiwagi K, Takase M, Hanada H, Nakamura M
Laboratory for Amphibian Biology, Faculty of Science, Hiroshima University, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 1997 Nov;118(3):499-503. doi: 10.1016/s0305-0491(97)00216-2.
The present study examines differences in the hydrogen peroxide (H2O2) detoxifying enzyme, catalase, found in the tails and livers of diploid and haploid Rana rugosa. Investigative techniques include measurement of catalase activity and tests for temperature stability and chemical inhibition. Catalase from the tails of pre-climactic (stage XXIII) haploids was found to be over three times as H2O2 destructive as catalase from similar tails of diploids. Catalase from the livers of newly metamorphosed (stage XXV) froglets, on the other hand, displayed only one third the activity seen in diploid livers. The catalase in haploid tail and liver proved to be more heat resistant, retaining 40-60% of its original activity after 5 min of treatment at 55 degrees C, whereas diploid catalase was totally inactivated under the same conditions. Haploid and diploid catalase also responded differently to inhibition using urea and aminotriazole. These differences suggest that haploid catalase has diverged from normal diploid catalase through molecular modification, resulting in abnormal systems for H2O2 metabolism, which in turn are thought to be responsible for organ dysfunction and early death seen in haploid individuals.
本研究检测了二倍体和单倍体虎纹蛙尾巴和肝脏中过氧化氢（H2O2）解毒酶——过氧化氢酶的差异。研究技术包括过氧化氢酶活性的测定以及温度稳定性和化学抑制测试。发现处于临高潮期（XXIII期）的单倍体尾巴中的过氧化氢酶对H2O2的破坏作用是类似二倍体尾巴中过氧化氢酶的三倍多。另一方面，新变态（XXV期）幼蛙肝脏中的过氧化氢酶活性仅为二倍体肝脏中所见活性的三分之一。单倍体尾巴和肝脏中的过氧化氢酶被证明更耐热，在55摄氏度处理5分钟后仍保留其原始活性的40-60%，而二倍体过氧化氢酶在相同条件下完全失活。单倍体和二倍体过氧化氢酶对尿素和氨基三唑抑制的反应也不同。这些差异表明，单倍体过氧化氢酶通过分子修饰与正常二倍体过氧化氢酶发生了分化，导致H2O2代谢系统异常，进而被认为是单倍体个体出现器官功能障碍和过早死亡的原因。
