Temperature-induced in vitro transformation of Leishmania mexicana. I. Ultrastructural comparison of culture-transformed and intracellular amastigotes.
Temperature-induced in vitro transformation of Leishmania mexicana. I. Ultrastructural comparison of culture-transformed and intracellular amastigotes.
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温度诱导的墨西哥利什曼原虫体外转化。
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
Hensen Sa
中科院分区：
文献类型：
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作者：
Hunter Kw;Cook Cl;Hensen Sa
通过将孵育温度升高至34 ℃，将在26 ℃下在含有10%血清的哺乳动物细胞培养基中体外指数生长的墨西哥利什曼原虫前鞭毛体转化为无鞭毛体样形式。在第一个24-48小时的转化过程中，细长的鞭毛前鞭毛体失去了鞭毛，变得更小，更卵形。到72小时，转化完成，通过活体染料排除判断，大于95%的寄生虫存活。此外，这些新转化的寄生虫能够感染巨噬细胞样肿瘤细胞系P388 D1，并且在回到26 ℃的孵育温度时可以重新转化为前鞭毛体阶段。转化的无鞭毛体样寄生虫在培养中仅存活3天，即使每天更新培养基，可能表明需要通常存在于细胞内环境中的一些因子或因子。超微结构的研究显示，在光学显微镜下观察到相同的总体变化，也表现出在细胞器和膜结构之间的无鞭毛体吞噬溶酶体的P388 D1和培养衍生的无鞭毛体形式的密切相似性。根据这些生物学和形态学标准，转化的寄生虫似乎是无鞭毛体，尽管需要进一步的生物化学研究来证实它们与细胞内形式的严格相似性。然而，温度诱导的转化过程本身应该为研究环境对真核基因表达的影响提供一个很好的模型系统。
: Promastigotes of Leishmania mexicana growing exponentially in vitro at 26 degrees C in mammalian cell culture medium with 10% serum were transformed to amastigote-like forms by elevating the incubation temperature to 34 degrees C. During the first 24-48 h of the transformation process the slender flagellated promastigotes lost their flagella and became smaller and more ovoid. By 72 h, transformation was complete with greater than 95% of the parasites viable as judged by vital dye exclusion. Moreover, these newly transformed parasites were capable of infecting the macrophage-like tumor cell line P388D1, and could reconvert to the promastigote stage upon return to an incubation temperature of 26 degrees C. The transformed amastigote-like parasites survived only 3 days in culture even with daily renewal of the culture medium, possibly indicating the requirement for some factor or factors normally present in the intracellular milieu. Ultrastructural studies revealed the same gross changes observed under light microscopy, and also demonstrated a close similarity in cellular organelles and membrane structure between amastigotes within phagolysosomes of P388D1 and the culture-derived amastigote forms. By these biologic and morphologic criteria the transformed parasites appear to be amastigotes, though further biochemical studies are needed to confirm their strict analogy to intracellular forms. However, the temperature-induced transformation process itself should provide an excellent model system for studying the effects of environment on eukaryotic gene expression.