The IMES-1 RNA motif is a conserved RNA structure that was identified in marine environmental sequences by two studies based on metagenomics and bioinformatics, the first analyzing metatranscriptome (RNA) data[2] and the second using metagenome (DNA) data.
However, the species that use these RNAs are most closely related to known alphaproteobacteria and gammaproteobacteria.
[2] IMES-1 RNAs make up a significant portion of marine RNA transcripts[2] and are exceptionally abundant in that over five times as many IMES-1 RNAs were found as ribosomes[1] in RNAs sampled from the Pacific Ocean.
[2][3] Only two bacterial RNAs are known (6S RNA and transfer RNA) to be more highly transcribed than ribosomes.
IMES-1 RNAs were also detected in abundance in Block Island Sound in the Atlantic Ocean.