 A broad general distinction between plants and animals lies in the targeting of endogenously produced miRNAs; in plants, miRNAs are usually perfectly or nearly perfectly complementary to their target genes and induce direct mRNA cleavage by RISC, while animals' miRNAs tend to be more divergent in sequence and induce translational repression.This translational effect may be produced by inhibiting the interactions of translation initiation factors with the messenger RNA's polyadenine tail.Some eukaryotic protozoa such as "Leishmania major" and "Trypanosoma cruzi" lack the RNAi pathway entirely.