Effects of Panmede and various horse serum concentrations on the axenic cultivation of Entamoeba histolytica strains in TPS-1 medium.

We analyzed the influence of Panmede and horse serum concentrations on the growth of five Entamoeba histolytica strains (HK9, HM1, HM2, HM3, and HM38) axenically cultivated in TPS-1 medium. Panmede was evaluated by comparing the growth of strain HM1 in medium prepared with each of 15 Panmede lots; the yields of E. histolytica trophozoites depended on the lot quality of Panmede, and their maximal values ranged from 8 x 10(3) to 8.9 x 10(4) amoebae/ml. The growth-promoting effect of eight lots of horse serum on strains HK9 and HM1 were studied using a single Panmede lot of good quality. Yields obtained with strain HK9 ranged from 8 x 10(4) to 1.8 x 10(5) amoebae/ml, whereas yields obtained with HM1 ranged from 3 x 10(4) to 1.2 x 10(5) amoebae/ml. Thus, the optimal serum concentration in TPS-1 medium that caused maximal growth of E. histolytica cultures depended on the quality of the serum lot and proved to be specific for each of the five E. histolytica strains investigated. It ranged from 18% (v/v) for strain HM2 to 28% (v/v) for strain HM1. Our results reveal that the growth of E. histolytica trophozoites in TPS-1 medium can be distinctly improved by selecting appropriate lots of Panmede and horse serum and using optimal serum concentrations.

Trophozoite and nuclear size, DNA base composition, and nucleotide sequence homology of several Entamoeba strains in axenic culture.

We carried out a comparative study of nuclear and trophozoite diameters and of DNA thermal denaturation in eight Entamoeba strains cultured axenically (four of them E. histolytica, two initially designated as E. invadens, one E. moshkovskii, and one E. histolytica-like), as well as an analysis of the overall DNA sequence homology of the non-E. histolytica strains. The average nuclear (N) and trophozoite (T) diameters (in micron) were, respectively: global averages +/- SD for E. histolytica strains, 6.5 +/- 2.5 and 28.8 +/- 3.7; E. invadens IP101, 5.8 and 27.5, and PZ, 7.8 and 33.6; E. moshkovskii FIC, 4.1 and 12.9; E. histolytica-like Laredo strain, 5.0 and 20.6. The GC content of DNA, estimated by thermal elution in hydroxyapatite, was around 23% in HK9 and its clone HK9-1 and around 27% in the HM2 and HM3 E. histolytica strains; it was 37% in the Laredo strain, 26% in IP101, 35% in PZ, and 33% in FIC. The reassociation kinetics of PZ strain DNA showed that it consists of 40% repeated sequences and 60% unique sequences. By means of DNA association experiments in which one of each pair of DNAs tested had been labeled in vitro with 125I, we found the following overall sequence homology among the strains tested: PZ-FIC, 38%; IP101-Laredo, 38%; IP101-FIC, 47%; PZ-Laredo, 49%; Laredo-FIC, 69%; and IP101-PZ, 83%. We conclude that trophozoites of different E. histolytica strains have similar nuclear size and GC content, whereas these parameters and the nucleotide sequences are clearly different in every other Entamoeba species.(ABSTRACT TRUNCATED AT 250 WORDS)

Incorporation and toxicity of 32P-orthophosphate and occurrence of polyphosphate in Entamoeba trophozoites.

We explored the requirements of inorganic phosphate (Pi), the incorporation of 32P-orthophosphate (32Pi), and the occurrence of inorganic polyphosphate (polyP) in axenic Entamoeba cultures. Maximal population densities and growth rates of Entamoeba histolytica trophozoites were attained in complete TP-S-1 medium. As 32Pi concentration was increased in the medium, its own incorporation and the culture growth rate were progressively inhibited, especially in Pi-deficient medium. PolyP grains were found in the cytoplasm and occasionally in the nuclear membrane of E. histolytica-like, E. invadens, and E. moshkovskii trophozoites.