Bursts in microRNA (miRNA) diversity often line up with sudden increases in morphological complexity, especially in the context of the nervous system. In a 2022 bioRxiv preprint, researchers uncovered an miRNA repertoire expansion (orange) in the ancestor of coleoid cephalopods—the group that includes squids and octopuses, generally thought to be more intelligent than any other invertebrates—on par with ones seen in the ancestors of vertebrates (blue) and placental mammals (green).
The term “noncoding RNA” is a catch-all for sequences in the genome that are transcribed but typically not translated. These molecules, which account for the majority of the transcribed sequences in the genome, are now thought to play key roles in brain evolution and function. Noncoding RNAs can be classified based on their size, structure, location, or function, with dozens of different kinds described to date. Here are four types of noncoding RNA frequently studied in brain tissues.
Long noncoding ...
