The Eye- Sea Cucumbers Provide Insights Into Tissue Regeneration
This modest sea dwelling creature has now shed light on genes for tissue regeneration. Sea cucumbers aren’t exactly the most exciting aquatic species. Distantly related to starfish and sea urchins, the sea cucumber in appearance lacks the brio and allure of its cousins, and except for a few variations among subspecies, the general body plan of the cucumber basically resembles a large, leathery sausage crawling along the ocean floor.
But now, scientists have found in the humble sea cuke an unlikely muse for some exciting new medical technologies.
A new high-definition genome sequence of the sea cucumber provides molecular insights into its ability to regenerate, it also helps explain why the sea cucumber has such a radically different skeletal structure from other members of the echinoderm phylum, and may be useful for understanding evolution of the animal kingdom.
Apart from sharing common ancestry with chordates, sea cucumbers exhibit a unique morphology and exceptional regenerative capacity. Many of these regenerative mechanisms used by sea cucumbers are the same as those being used by other animals to heal and repair – this includes us humans.
To locate the source of the sea cucumber’s regenerative
powers, a team of Chinese scientists sequenced 92 percent of the genome of the Japanese sea cucumber, Apostichopus japonicus. The researchers surveyed more than 30,000 of the species’ genes.Their analysis suggests sea cucumbers diverged from a group of hemichordates, a small group of marine invertebrates including acorn worms, some 533 million years ago. Some 54 million years later, sea cucumbers split from the rest of the echinoderm classes. Over time, sea cucumbers minimized the expression of genes related to biomineralization, which explains the organism’s soft body.
The researcher further went on to reveal that these sea floor crawlers host a unique set of duplicated genes, called PSP94-like genes, which allow them to regenerate their internal organs. This evolved alongside the sea cucumber’s ability to eject its innards to ward off predators.
Scientists found the expression of another set of duplicated genes, fibrinogen-related proteins, were also linked with regeneration.
Additionally, they found that A. japonicus harbored orthologs of mammalian pluripotency factors like Sox2, c-Myc, Oct4, and Klf4, some of which were upregulated shortly after the sea cucumbers shed their viscera. This further hinted to the researchers that regenerative mechanisms in sea cucumbers have similarities to those of vertebrates.
“The sea cucumber is a particularly promising model animal for regenerative medicine,” said Jianhai Xiang, a researcher with the Institute of Oceanology at the Chinese Academy of Sciences, and the availability of its genome should aid efforts to study the biology of regeneration and determine if echinoderm regrowth can offer insights that can be applied to human medicine. “Our findings should also facilitate the understanding of the requirements for sustainable utilization and effective breeding of echinoderms, in support of the high-value sea cucumber industry,” which includes its use as a source of food and traditional Chinese medicine.
