 Gene expression in prokaryotes is influenced by an RNA @-@ based system similar in some respects to RNAi . Here , RNA @-@ encoding genes control mRNA abundance or translation by producing a complementary RNA that anneals to an mRNA . However these regulatory RNAs are not generally considered to be analogous to miRNAs because the dicer enzyme is not involved . It has been suggested that CRISPR interference systems in prokaryotes are analogous to eukaryotic RNA interference systems , although none of the protein components are orthologous . 
