show Abstracthide AbstractAmoebaozas are in many aspects interesting research objects; they combine features of single-cell organisms with complex, comparable to multicellular organisms, signaling and protective systems. Acanthamoeba castellanii is a cosmopolitan species and developed diverged feeding abilities and strong anti-bacterial resistance; Entamoeba histolytica is a parasitic amoeba, who underwent massive gene lost and its genome is almost twice smaller than the genome of A. castellanii. Nevertheless, both species prosper, demonstrating fitness to their specific environments. Here we compared transcriptomes of A. castellanii and E. histolytica to learn how different environmental conditions influence genome evolution and physiology restructuring. A. castellannii showed great metabolic activity and plasticity, while E. histolytica revealed several interesting features in its translational machinery, cytoskeleton, antioxidant protection and nutritional behavior. Despite the fact that these two amoebas are popular study objects and cause human diseases, their genomes still luck complete annotation, which is clearly demonstrated in our study.