Attachment and Short‐Term Maintenance of Motility and Viability of Entamoeba Histolytica In A Defined Medium*

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Abstract
Organic requirements for attachment to glass, elongation and motility of E. histolytica were determined. The trophozoite, which was grown axenically only in highly complex media with reduced O2 tensions, remains rounded and detached when placed in a Tris-HCl buffered solution containing NaCl, KCl, MgCl2 and CaCl2. A maintenance medium in which the amebae could attach to glass, elongate and remain motile and viable for 12-24 h was devised with the addition of cysteine, ascorbic acid, bovine serum albumin and the vitamin solution of medium NCTC # 107. Tris-HCl was the most effective buffer tested and the optimal pH was 6.9-7.0. Survival, but not attachment, of the amebae was decreased at osmolalities ranging between 110-180 mosmol/kg, whereas both functions were decreased above .apprx. 260 mosmol/kg. Bovine serum albumin, the most effective of the proteins tested and the vitamin solution helped maintain attachment of some ameba strains, but were not required by other strains. The requirements for cysteine and ascorbic acid were absolute and highly specific. During incubation in the maintenance medium, cell volumes decreased. Sensitivity of the organisms to agglutination by concanavalin A, wheat germ agglutinin, soybean agglutinin and fucose binding protein remained unchanged.