To regrow lost body parts, hydra change how their genes are expressed, Inside Science reports.
It adds that hydra can famously regrow body parts from the smallest sliver of tissue, including new heads, and that a new paper appearing in Genome Biology & Evolution explores how hydra regenerate. In it, researchers led by the University of California, Irvine's Ali Mortazavi conducted a time-series analysis in which they compared gene expression among hydra during head regeneration and asexual budding. They uncovered nearly 300 genes that are differentially expressed during the two processes, suggesting that they are not regulated in the same way.
"If you're making a new finger, you would expect it to be done in the same way, even if it's during regeneration. But actually, it turns out it's done differently — different genes are turned on, and at different times," co-author Aide Macias-Muñoz, now at UC-Santa Barbara tells Inside Science. "But somehow it still ends up with the same result."
The researchers additionally profiled open chromatin within the hydra genome during those times and used ATAC-seq and ChIP-seq data to find nearly 10,000 candidate promoters and more than 3,000 candidate enhancer-like elements. They write in their paper that this finding suggests complex developmental enhancers evolved prior to the cnidarian-bilaterian evolutionary spilt.