Nishimura Kazuhiko, Yanase Takako, Araki Noriko, Ohnishi Yoshihiro, Kozaki Shunji, Shima Kensuke, Asakura Masahiro, Samosomsuk Worada, Yamasaki Shinji
Course of Veterinary Science, Graduate School Life and Environmental Sciences, Osaka Prefecture University 1-1, Gakuencho, Sakai, Osaka 599-8531, Japan.
J Parasitol. 2006 Apr;92(2):211-7. doi: 10.1645/GE-633R.1.
We studied the effects of polyamines, which are necessary for proliferation and antioxidation in Trypanosoma brucei gambiense Wellcome strain (WS) and Trypanosoma brucei brucei ILtat 1.4 strain (IL). No difference was found in activity of ornithine decarboxylase (ODC), a key enzyme in polyamine synthesis in trypanosomes, in both strains maintained in vitro; higher (P < 0.05) ODC values were found in IL in vivo. However, WS in vivo exhibited higher proliferation rates with higher spermidine content and decreased host survival times than IL. The in vitro proliferation and polyamine contents of WS increased with the addition of polyamine to the 1-difluoromethylornithine culture medium, but not IL. These results suggested that WS uses extracellular polyamine for proliferation. In the in vitro culture, WS was less tolerant of hydrogen peroxide (oxidative stress) than IL, and malondialdehyde levels in WS were higher than in IL. The expression of trypanothione synthetase mRNA in WS in vitro was higher than in IL. These results suggest that IL is dependent on the synthesis of polyamines for proliferation and reduction of oxidative stress, whereas WS is dependent on the uptake of extracellular polyamines. A thorough understanding of the differences in the metabolic capabilities of various trypanosomes is important for the design of more effective medical treatments.
我们研究了多胺的作用，多胺对于布氏冈比亚锥虫威康株（WS）和布氏布氏锥虫ILtat 1.4株（IL）的增殖和抗氧化作用是必需的。在体外培养的两种菌株中，鸟氨酸脱羧酶（ODC）（锥虫多胺合成中的关键酶）的活性未发现差异；在体内，IL中的ODC值更高（P < 0.05）。然而，WS在体内表现出更高的增殖率，亚精胺含量更高，宿主存活时间比IL更短。向1-二氟甲基鸟氨酸培养基中添加多胺后，WS的体外增殖和多胺含量增加，但IL没有。这些结果表明，WS利用细胞外多胺进行增殖。在体外培养中，WS对过氧化氢（氧化应激）的耐受性低于IL，WS中的丙二醛水平高于IL。WS体外的锥虫硫醇合成酶mRNA表达高于IL。这些结果表明，IL依赖于多胺的合成来进行增殖和减轻氧化应激，而WS依赖于细胞外多胺的摄取。深入了解各种锥虫代谢能力的差异对于设计更有效的医学治疗方法很重要。
