Glittering Worms Can Reveal the Secrets of Change

In 1961, Osamu Shimomura and Frank Johnson separated a protein from jellyfish bright green under UV light. Corals, too, can fluoresce in many colors, thanks to the same proteins. Now Harvard University scientists are genetically modifying the three banded panther worms so that the creature can emit a similar green glow, according to a new role published in the journal Progressive Cell. Their hope is to reveal the secrets of change.

Most animals show some kind of change: changing the hair, for example, or knitting the broken bone back. But some creatures are capable of even more amazing transformation abilities, and the study of the mechanisms by which they can do so could have important implications for human aging. If a salamander loses a leg, the branch grows back, for example, while other lizards can remove their tails as a distraction to avoid predators and then grow again later. Zebra fish can regenerate lost or damaged fins, as well as repair damaged heart, retina, pancreas, brain, or spinal cord. Cut a planarian flatworm, a jellyfish, or a sea anemone in half, and it will change its entire body.

And then there’s the three-banded panther worm (Hofstenia miamia), a small creature that looks like a heavy grain of rice, named for the mark of this trio of cream-colored stripes all over its body. If the panther worm is cut into three parts, each part can be a fully formed worm in eight weeks or more. These larvae are commonly found in the Caribbean, Bahamas, and Bermuda, as well as Japan, and they are hardy predators, no more than taking a few bites from their fellow panther worms when they are hungry and not. find another prey. . They also offer a good new model for the study of transformation mechanics.

Coauthor Mansi Srivastava, an evolutionary biologist at Harvard University, has been studying the three-banded panther worm since 2010, when she was a postdoc scholar in Peter Reddien’s lab at MIT’s Whitehead Institute. They collected 120 or more of the Bermuda larvae and brought them back to Cambridge. The larvae do not immediately adapt to laboratory life: Srivastava and Reddien need to know the right level of salinity for their water and find an acceptable food source. The larvae ignored the liver that Reddien fed his planarian flatworms, and some resorted to cannibalism to survive. Eventually, researchers learned that panther worms were loved brine shrimp (aka sea ​​monkeys), and the creatures finally began to develop and reproduce.

A report in 1960 said the larvae could regrow their severed heads, but there was little scientific follow-up. Reddien and Srivastava’s early experiments proved that panther worms can not only grow on their heads, they can reproduce almost any part of the body, such as planarian flatworms — even if the two are far rag relationship. Srivastava now runs his own laboratory at Harvard that studies the evolution of panther worms.

In 2019, Srivastava and his lab released the full sequence of the panther worm’s genome, as well as their identification of several “DNA switches” that appear to control genes for mutation throughout the body. . In particular, they targeted a section of noncoding DNA that controls whether a type of “master control gene” for mutation, known as early growth response (EGR), is activated. EGR can, in turn, transfer other genes involved in various on or off processes. If EGR is not activated, transformation of larvae will not occur.

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