Figure A: microRNAs (IMAGE) Arizona State University Caption microRNAs (miRNA) are recently discovered, short segments of RNA, which play vital roles in health and disease. microRNA over- or under-abundance can switch critical disease genes on or off, particularly in the case of certain cancers. The graphic shows highly conserved miRNA across species ranging from the nematode worm C. elegans to primates, including humans. Of note is the fact that while the number of protein-coding genes remains fairly constant throughout evolutionary time and across species (21K for free-living worms, 17K for drosopholid flies, 23K for echinoderms and 22K for primates), the number of conserved miRNA undergoes pronounced expansion in vertebrates, which also see a fourfold increase in miRNAs occurring in multi-copy families. The increased number and diversity of miRNAs in higher organisms are believed to play a critical role in sophisticated networks of gene regulation and may be eventual targets for life-saving therapies. Credit The Biodesign Institute at Arizona State University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.