TECHNOLOGY

Glowing worms can shed light on the secrets of regeneration


In 1961, Osamu Shimomura and Frank Johnson isolated a protein from jellyfish green glow under ultraviolet light. Corals can also shine in a wide variety of shapes, thanks to similar proteins. Now scientists at Harvard University have genetically modified the three-banded tiger worm to enable the creature to emit a similar green glow, according to new paper Published in the magazine developmental cell. Their hope is to reveal the secrets of renewal.

Most animals show some form of regeneration: regrowth of hair, for example, or weaving broken bones back together. But some creatures are especially capable of amazing regenerative feats, and studying the mechanisms by which they achieve these feats could have important implications for human aging. If the salamander loses a leg, The party will grow again, for example, while some geckos can separate their tails as a distraction to avoid predators and later regrow. Zebra fish can regrow a lost or damaged fin, as well as repair a damaged heart, retina, pancreas, brain or spinal cord. Cut the flatworm, jellyfish, or sea anemone in half and you’ll regenerate their entire body.

Then there is the three-banded tiger worm (Hofsteinia Miami), a small creature that looks a bit like a full grain of rice, and was so named because of its distinctive triangular mark of cream-colored stripes on its body. If the tiger worm is cut into three parts, each part will turn into a fully formed worm within eight weeks or so. These worms are found primarily in the Caribbean, the Bahamas, and Bermuda, as well as Japan, and are voracious predators, no higher than taking a few bites from their fellow tiger worms if they are hungry enough and cannot find other prey. It also presents a promising new paradigm for studying regeneration mechanisms.

Co-author Mansi Srivastava, a Harvard evolutionary biologist, has been studying the three-banded tiger worm since 2010, when she was a postdoc in Peter Redin’s lab at MIT’s Whitehead Institute. They collected 120 or so worms in Bermuda and brought them back to Cambridge. The worms did not immediately adapt to laboratory life: Srivastava and Ridian had to figure out the correct salinity levels for their water and find an acceptable food source. The worms didn’t care for the liver. Redin was feeding planarian flatworms, and some resorted to cannibalism to stay alive. In the end, researchers discovered that tiger worms liked it brine shrimp (Also known as sea ​​monkeys), and the creatures finally began to thrive and reproduce.

A report in 1960 claimed that worms can regrow severed heads, but there has been little scientific follow-up. Reddien and Srivastava’s early experiments demonstrated that tiger worms can not only regrow their heads but can also regenerate almost any part of the body, just like flatworms – although the two are only distantly related. Srivastava now runs her own laboratory at Harvard University to study regeneration in tiger worms.

In 2019, Srivastava and her lab released the complete genetic sequence of the tiger worm, as well as their identification of a number of “DNA switches” that appear to control genes for whole-body regeneration. Specifically, they identified a segment of non-coding DNA that controls the activation of a type of “master control gene” for regeneration, known as early growth response (EGR). EGR, in turn, can turn on or off other genes involved in various processes. If the EGR is not activated, regeneration will not occur in the worms.



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