Junk DNA: goodbye!: finding DNA enhancer regions (Introduction)

by David Turell , Monday, November 16, 2020, 23:27 (1468 days ago) @ David Turell

Human regions are hard to find without comparisons to other species:

https://cosmosmagazine.com/nature/marine-life/sea-sponge-with-quite-a-story-to-tell/?ut...

"Many human traits, such as height and disease susceptibility, depend on genes that are encoded in our DNA. These genes are switched on and off and further fine-tuned by important but hard-to-find regions in the genome.

"A particularly important class of these regions are known as enhancers, which boost the likelihood that a particular gene will be activated. Trying to find enhancers based on the genome sequence alone is incredibly difficult, like finding a light switch in a dark room.

***

"In a new study published in Science, we found that humans, mice, zebrafish — and most likely the entire animal kingdom — share enhancer regions with a sea sponge that comes from the Great Barrier Reef. Because sea sponges and humans last shared a common ancestor more than 700 million years ago, this means the functional mechanism has been preserved across all this time.

***

"...we extracted enhancer DNA from the sea sponge and injected it into a single cell from a zebrafish embryo. We found that while the sea sponge enhancer sequences were very different from zebrafish enhancer sequences, they still worked: they successfully and consistently drove the expression of a fluorescent protein in certain types of zebrafish cells.

"Based on computational predictions, we also identified and tested similar enhancers from humans and mice, to show that these sequences drive the expression of a fluorescent protein in similar zebrafish cell types during development.

"We discovered that despite differences between the genetic sequences of sponges and humans due to millions of years of evolution, we could identify a similar set of genomic instructions that controls gene expression in both organisms.

"Our findings represent a fundamental discovery in understanding the connection between our genomes and our physical traits.

"The sections of DNA that are responsible for controlling gene expression are notoriously difficult to find, study and understand. Even though they make up a significant part of the human genome, researchers are only beginning to understand this genetic “dark matter”."

Comment: Complete proof of common descent, if we ever needed it. More junk DNA gone, and more complexity understood. Genes primarily code for protein but networks of other DNA regions perform lots of the organizational work making phenotypes and physiological systems..