[Cellular behavior of axenic amebas cultured in the presence of different carbohydrates]. / Comportamiento celular de amibas axénicas cultivadas en presencia de diferentes carbohidratos.

Carbohydrates are an essential requirement of the culture medium in many cells. Axenic cultures of amebas require a concentration of 0.5 to 1.0 per cent glucose. The purpose of this work is to demonstrate possible differences on the carbohydrates requirements between pathogenic and nonpathogenic amebas strains. The experimental work was done in two phases: a) observation of the cultures growing at different concentrations of glucose in TP-S-1 medium (0, 0.25, 0.50, 1.0 and 2.0 g/100 ml), and b) the substitution of glucose by other carbohydrates: D-fructose; D-galactose; D-manitol, maltose, lactose, sucrose and soluble starch. Four axenic strains were used: Entamoeba histolytica HM-2:IMSS and HK-9:NIH; E. invadens PZ and E. moshkovskii FIC. Enumeration of cultured protozoa was determinated with the aid of an hemacytometer. The results obtained indicate no difference between pathogenic strains (HM-2, HK-9 and PZ), at the concentrations of glucose in the medium (0.5 g/100 ml), however FIC strain (unique non-pathogenic strain tested), had the highest growth when 0.25 per cent glucose was used. All strains supported without any significant difference in growth, the substitution of glucose by maltose and starch.

Division nuclear y presencia de microtubulos en la diferenciacion de Entamoeba invadens. / Nuclear division and presence of microtubules in the differentiation invadens

El curso de la division nuclear, asi como el tiempo en el que ocurren las divisiones nucleares durante la diferenciacion de Entamoeba invadens IP-1 fueron estudiados a traves de microscopia optica y microscopia electronica. Las divisiones nucleares ocurrieron entre las 28 y 32 h de iniciado el enquistamiento, alcanzando una maxima proporcion de aproximadamente 50 por ciento a las 30 horas.Durante la division nuclear es carecteristica la presencia de una estructura central densa que desaparecee antes de la metafase y alrededor de la cual se inicia la condensacion de cromatina. Los cromosomas, atipicos en relacion a los de eucariotes superiores, son evidentes particularmente durante la anafase. Condensaciones de cromatina asociadas a la membrana nuclear no participan en la formacion de cromosomas y la membrana nuclear permanece intacta durante todo el proceso de division nuclear. Existe la formacion de un huso intranuclear formado por microtubulos de aproximadamente 240 A de diametro. No fueron detectados centriolos