Extracellular cultivation and morphological characterization of amastigote-like forms of Leishmania panamensis and L. braziliensis.
Two strains of the Leishmania braziliensis complex have been adapted to grow extracellularly at elevated temperature as amastigote-like forms in a cell-free medium. These parasites can be serially cultivated and maintained at 32 degrees C for L. panamensis (WR442; L. braziliensis panamensis) and at 28 degrees C for L. braziliensis (M5052; L. braziliensis braziliensis). Several observations are presented that the forms adapted at elevated temperature are amastigote-like. Morphologically, the amastigote-like organisms appear rounded to ovoid and are immotile and smaller than promastigotes; the flagellum of the amastigote-like forms does not extend beyond the flagellar pocket. In comparison, the promastigotes are very elongated, with a nucleus at mid-cell length and a very long flagellum. By electron microscopy, the short flagellum of the amastigote-like form is within a distended flagellar pocket; the 9 + 2 axonemal configuration is present but the paraxial rod is not observed. By contrast, the flagellum of the promastigote has a paraxial rod which extends from the axosome level. In addition, these amastigote-like forms of Leishmania are able to infect, to survive and to divide within the macrophage cell line J774.
Eperon
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Yale University School of Medicine, Department of Epidemiology and Public Health, New Haven, Connecticut 06510.
McMahon-Pratt
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D000818:Animals; D002460:Cell Line; D003470:Culture Media; D007891:Leishmania / Q000254:growth & development*; D007892:Leishmania braziliensis / Q000254:growth & development* / Q000648:ultrastructure; D008264:Macrophages / Q000469:parasitology*; D008854:Microscopy, Electron; D013696:Temperature
D003470:Culture Media