IMES-1 RNA motif
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{{cite journal |vauthors=Shi Y, Tyson GW, DeLong EF |title=Metatranscriptomics reveals unique microbial small RNAs in the ocean's water column |journal=Nature |volume=459 |issue=7244 |pages=266–269 |date=May 2009 |pmid=19444216 |doi=10.1038/nature08055 |bibcode=2009Natur.459..266S |s2cid=4340144 }} and the second using metagenome (DNA) data.{{cite journal |vauthors=Weinberg Z, Perreault J, Meyer MM, Breaker RR |title=Exceptional structured noncoding RNAs revealed by bacterial metagenome analysis |journal=Nature |volume=462 |issue=7273 |pages=656–659 |date=December 2009 |pmid=19956260 |doi=10.1038/nature08586 |pmc=4140389|bibcode=2009Natur.462..656W }} These RNAs are present in environmental sequences, and as of 2009 are not known to be present in any cultivated species. However, the species that use these RNAs are most closely related to known alphaproteobacteria and gammaproteobacteria. IMES-1 RNAs make up a significant portion of marine RNA transcripts and are exceptionally abundant in that over five times as many IMES-1 RNAs were found as ribosomes in RNAs sampled from the Pacific Ocean.{{cite journal |vauthors=Frias-Lopez J, Shi Y, Tyson GW, etal |title=Microbial community gene expression in ocean surface waters |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=105 |issue=10 |pages=3805–3810 |date=March 2008 |pmid=18316740 |pmc=2268829 |doi=10.1073/pnas.0708897105 |doi-access=free }} 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.