蛔虫
The first SmY RNA was discovered in 1996 in purified "Ascaris lumbricoides" spliceosome preparations, as was another called SmX RNA that is not detectably homologous to SmY. Twelve SmY homologs were identified computationally in "Caenorhabditis elegans", and ten in "Caenorhabditis briggsae". Several transcripts from these SmY genes were cloned and sequenced in a systematic survey of small non-coding RNA transcripts in "C. elegans".