Institute of Tropical Medicine, Nagasaki University
Abstract
Examinations were done of the cooling method, the effect of the cryo-protective substance such as glycerol (GLY) and dimethyl sulfoxide (DMSO), and of salt concentration on the low temperature preservation of Trichomonas vaginalis and Tritrichomonas foetus in a -25C or a -75C freezer. The following results were obtained: 1. In the -25C freezer trichomonad survived for several days in the presence of GLY or DMSO. The longest survival record was two weeks in T. vaginalis and one week in T. foetus, whereas the survival rate in either species was quite low. 2. Both the trichomonad species in a sample with GLY or DMSO placed directly into the -75C freezer could survive for a month or longer, but the survival rate was low. 3. The pre-cooling method in which a sample was pre-cooled in the-25C freezer then transfered into the -75C freezer was found to give a good effect to a rise in the survival rate of trichomonads. 4. In a 5-day storage in the -75C freezer by the pre-cooling method, the survival rate became higher than 70% in T. vaginalis and nearly 10% in T. foetus in the presence of 2.5～7.5% DMSO, while it remained lower than 20% in T. vaginals and only several percents in T. foetus in the presence of 10% GLY. 5. In a one-day storage in the presence of 5.0% DMSO by the pre-cooling method, the survival rate of T. vaginalis was higher in 0.9～1.5% NaCl than in the lower salt concentration. As the highest survival rate of T. foetus was 30.4% in 0.3% NaCl, the optimum salt concentration for T. foetus was thought to be lower than that for T. vaginalis. 6. As a conclusion it could be said that the pre-cooling method might be useful for the low temperature preservation of trichomonad and would be applicable to the cases of other parasitic protozoa.この実験は,トリコモナス類を-25度および-75度フリーザー中で,低温保存するための冷却方法,凍害保護剤(ジメチル・スルホキサイド(DMSO),およびグリセリン(GLY))の影響,および至適塩濃度について検討したものである.得られた成績は,以下の通りである.1.-25度のフリーザー中では,トリコモナスは,DMSOやGLYを添加しても,数日間しか生存できなかった.このフリーザー中での最長生存期間はT. vaginalisでは2週間,T. foetusでは1週間であった.しかし生存率は,どちらもきわめて低かった.2.GLYやDMSOの存在下で,-75変のフリーザーにトリコモナスを直接冷却し保存した場合は,両方の種とも1ケ月あるいは,それ以上生存した.しかし生存率は低率であった.5.あらかじめ材料を-25度のフリーザーで予備凍結し,-75度のフリーザーに移して保存する場合には,トリコモナスの生存率は高くなった.4.予備凍結法を用い,-75度フリーザー中で5日間保存後しらべると,2.5～7.5%DMSOを加えた材料では,T. vaginalisは,生存率70%以上,T. foetusは10%前後であった.一方GLYを加えた材料ではT. vaginalisは,生存率20%,T. foetusは,わずかに数パーセントであった.5. 5%DMSOを加えた材料を予備凍結し,1日間,-75度フリーザー中に保存後の各塩濃度におけるトリコモナスの生存率は,T. vaginalisでは塩濃度0.9～1.5%の場合が,それよりも低い塩濃度よりも高い生存率をしめした.一方T. foeiusの場合,最も生存率が高かったのは,塩濃度0.3%の場合で,30.4%であった.6.結論として,予備凍結法は,トリコモナス類の低温保存に有用で,その他の寄生性原虫類の場合にも応用できるものと考えられる
