長崎市郊外で発見された無尾類の住血原虫-1-Trypanosoma rotatorium(Mayer,1843)〔英文〕
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無尾類の住血原虫額は,多くの点で原始的特徴を備えており,広く寄生原虫類の進化を理解する上で大変重要である.また医動物学の手近な実験材料としても注目されている.筆者は,1974年7～8月,たまたま長崎市郊外茂木で無尾類を入手し,その住血原虫を調べることができたので,その成績を報告しておく.1) Trypanosoma rotatorium (Mayer 1843)が,ツチガエル(Rana rugosa)の成体の50%から,またオタマジャクシの67%から検出された.トノサマガエル(Rana nigromaculata)は5匹検査しただけであるが,そのうち2匹からT. rotatoriumがみつかった.2)検出されたトリパノゾーマは,次の3型にわけることができる.第1型はもっとも小さく,虫体体長は38～49.5ミクロン,体幅は1.5～2ミクロンである.この型はオタマジャクシの血液中にみられ,1例のみ非常に若いツチガエルの成体から検出された.第II型は,体長60～80ミクロン,体幅3～8ミクロンのトリパノゾーマで,体後端がとがっている.この型はオタマジャクシにのみみられた.第III型は,さまざまの形態のトリパノゾーマを含み,さらにいくつかの亜型にわけることができる.概して虫体は大きくまるく,特に虫体後端もまるい.この型は成体からのみ検出され,オタマジャタシからは発見されなかった.3)チスイビル(Hirudo nipponia)が,オタマジャクシとともに発見され,盛んにオタマジャタシを吸血するのが観察された.このヒルの消化管内にもトリパノゾーマが発見された.このヒルが,T. rotatoriumの媒介者ではないかと考えられる.4) Dactylosoma ranarum (Kruse, 1890)も,ツチガエル成体の赤血球内に寄生しているのが観察された.この原虫については,続報で詳しく報告する.During a period of July to August, 1974, blood examinations of frogs and tadpoles were carried out to find out any haemoparasite in Mogi, near Nagasaki City. The following results were obtained. 1) Trypanosoma rotatorium (Mayer, 1843) is detected from 50% of adults and 67% of tadpoles in Rana rugosa, and in the case of Rana nigromaculata, although only 5 adults could be collected, 2 of them had T. rotatorium, 2) Three morphological types were distiguished as follows; Type I: This is the smallest among them, and the total length including free flagellum is 38～49.5μ and the width at the widest point is 1.5～2μ. Trypanosomes belonging to this type are usually observed in the blood of tadpoles, except only one case of this type was obtained from an apparently very young frog. Type II: This type is a large form with the pointed posterior end and the narrow undulating membrane, measuring 60～80μ in the total length including a short free flagellum and 3～8μ in the width at the widest part. This type was found only from the tadpole. Type III: This type includes various shapes of trypanosome detected from the adults, and most of the parasite have a very large round body and the round posterior end. Short free flagellum and narrow undulating membrane with many waves are usually observed, but absence of undulating membrane and free flagellum was observed in some individuals. This type is never found from the blood of tadpole. 3) The leeches, Hirudo nipponia were observed in the same place where the tadpoles were captured. Then the intestinal contents of the leeches were examined, in which few trypomastigotes and epimastigotes were detected. These forms might belong to T. rotatorium. 4) Dactylosoma ranarum (Kruse, 1890) were also detected from blood smears of some adult frogs of R. rugosa, as reported in the second paper of this series.