The vast majority of human DNA lies outside of the genes within the cells. Of this, recent work has discovered that 85% of these stretches of DNA appear to make RNA - which, for the most part, has yet-to-be-determined functions.
Today, scientists estimate that only 1.5 percent of the genome consists of genes.â€ś
The lab investigates the remaining 98.5% - which (referencing similarly-scaled problems in) they call the 'Dark Matter' of the human genome.
Much of the human genome is composed of intergenic sequence, the regions between genes. Intergenic sequence was once thought to be transcriptionally silent 'junk DNA', but it has recently become apparent that intergenic regions can be transcribed. However, the scope, nature, and identity of this intergenic transcription remain unknown. Here, by analyzing a large set of RNA-seq data, we found that >85% of the genome is transcribed, allowing us to generate a comprehensive catalog of an important class of intergenic transcripts: long intergenic noncoding RNAs (lincRNAs). We found that the genome encodes far more lincRNAs than previously known.â€ť
We believe that the regulatory noncoding RNAs that have been discovered are just the 'tip of the iceberg' in a set of important biology that we are far from understanding.â€ś
Further reading : Junk DNA: A Journey through the Dark Matter of the Genome by Professor Nessa Carey, Columbia University Press, 2015.
Junk DNA can play vital and unanticipated roles in the control of gene expression, from fine-tuning individual genes to switching off entire chromosomes. These functions have forced scientists to revisit the very meaning of the word â€śgeneâ€ť and have engendered a spirited scientific battle over whether or not this genomic â€śnonsenseâ€ť is the source of human biological complexity.â€ť
A 2023 study, which examined the DNA of the mammal group, identified nearly half a million 'regulatory elements' (outside the genes) which they call UNannotated Intergenic COnstrained RegioNs (UNICORNs)
The research team suggest that the UNICORN regions very probably have functions in demarcating genetic elements that are important in tissue types, or at development time points.
â€ś[they] almost certainly affect gene regulation in ways that are not yet understood.â€ť Ref. Scientific American, Apr. 2023.
Ideas for new topics, and suggested additions / corrections for older ones, are always welcome.
If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !
Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.
( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)
You are currently viewing an auto-translated version of Wikenigma
Please be aware that no automatic translation engines are 100% accurate, and so the auto-translated content will very probably feature errors and omissions.
Nevertheless, Wikenigma hopes that the translated content will help to attract a wider global audience.