Tiny, transient loops of genetic material, detected and studied by the hundreds for the first time at Brown University, are providing new insights into how the body transcribes DNA and splices (or missplices) those transcripts into the instructions needed for making proteins.

The lasso-shaped genetic snippets — they are called lariats — that the Brown team reports studying in the June 17 edition of Nature Structural & Molecular Biology are byproducts of gene transcription. Until now scientists had found fewer than 100 lariats, mostly by poring over very small selections of introns, which are sections of genetic code that do not directly code for proteins, but contain important signals that direct the way protein-coding regions are assembled. In the new study, Brown biologists report that they found more than 800 lariats in a publicly available set of billions of RNA reads derived from human tissues.

"We used modern genomic methods, deep sequencers, to detect these rare intermediates of splicing," said William Fairbrother, associate professor of biology and senior author of the study. "It's the first ever report of these things being discovered at a genome scale in living cells, and it tells us a lot about this step of gene processing."