[Identification of Entamoeba histolytica chromosomes by pulsed field gradient electrophoresis].

The use of pulsed field gradient electrophoresis (PFG) has simplified the study of chromosomic organization in protozoan parasites whose chromosomes do not condense during division. In this paper we used PCG to analyzed chromosome organization Entamoeba histolytica's. In the conditions which we used (200 volts, 24 hours, 3 minute pulses and the anode at 7.5 cm. from the end of the cathode) 6 and 9 band of amebic DNA were resolved. By means of a ribosomal DNA probe from Trypanosoma brucei amebic DNA was detected in the gels representing chromosomal sizes, in accord with the reproducibility of our results and the hybridization pattern we obtained. The numbers of 6 to 9 obtained for PFG is in accord with the results which we have previously reported. The suggest that Entamoeba histolytica has between 12 and 16 structures similar to chromosomes, if Entamoeba histolytica were diploid, and therefore each band would consist of two chromosomes. Nevertheless small condensations of DNA similar to minichromosomes of kinetoplasas cannot be ruled out, and this would considerably increase the number of chromosomes estimated in this paper.