Mg, Mn, and Co Ions Enhance the Formation of Entamoeba histolytica Cyst-Like Structures Resistant to Sodium Dodecyl Sulfate

Background eba histolytica forms cyst-like structures (CLS) in PEHPS but not in TYS-33 medium. Sodium dodecyl sulfate [(SDS (0.1%)] dissolves most of them in 10 min, but not natural cysts. Chitin is responsible mainly for cyst wall resistance. Its synthesis depends on Mg2+, Mn2+, or Co2+, whose action is interactive. With the aid of the Simplex method, we analyzed the effect of 20 blends of these cations to find the one that, when added to PEHPS, produced the highest proportion of CLS resistant to 1% SDS (RCLS). s ncentration of Mg2+, Mn2+, and Co2+ was determined in PEHPS and TYI-S-33 with a flame atomic absorption spectrometer. The proportion of RCLS produced in PEHPS with each ion blend was tested. The CLS and RCLS affinity to fluorescein wheat germ agglutinin (WGA/FITC), which binds chitin, was determined. s contained a similar concentration of Co2+ (0.52 μM) and 3.4 and 1.6 times more Mg2+ (798 μM) and Mn2+ (3.15 μM) than TYI-S-33, respectively. The proportion of RCLS increased gradually in PEHPS until reaching 3.6 ± 1.43% with MgCl2 1.22 mM, MnCl2 14.44 mM, and CoCl2 19.44 mM (ion blend No. 20). Both CLS and RCLS bound WGA/FITC. The RCLS formed in the presence of ion blend No. 20 appeared wrinkled. sions Mn2+, and Co2+ enhanced the ability of PEHPS to form RCLS, possibly because these ions stimulated their chitin synthesis. Although ion blend No. 20 produced the highest proportion of RCLS, this high ion concentration may be toxic for encysting amebas.