DNA sequences corresponding to the ariel gene family of Entamoeba histolytica are not present in E-dispar

For the identification of quantitative genetic differences between pathogen ic Entamoeba histolytica and the closely related but nonpathogenic species E. dispar, a set of 68 independent probes that had previously been isolated from an E. histolytica cDNA library were hybridized to total genomic DNA o f both amoeba species. Besides ehcp5, the sequence that codes for cysteine proteinase 5 and has recently been shown to be missing in E. dispar, only o ne of the probes exclusively reacted with E. histolytica DNA, whereas the r emainder hybridized to DNA of both species. Sequence analysis revealed that the specific probe represents a copy of the multicopy ariel gene family, w hich has 80% sequence identity to srehp, the gene encoding a serine-rich E. histolytica membrane protein. In contrast to ariel, srehp is present in bo th amoeba species, suggesting that the ariel gene product might have a part icular function in E. histolytica.