The Secret Of Sea Cucumber Regeneration

Scientists in China have peered into the sea cucumber’s genome to identify genes that might be responsible for its superior regenerative capabilities.

AsianScientist (Oct. 18, 2017) – In a study published in PLOS Biology, scientists in China have identified how the sea cucumber regenerates parts of its body.

Sea cucumbers are unique in their capacity to regenerate damaged or lost body parts and viscera to a much greater extent than other echinoderms like sea urchins or sea stars. In particular, sea cucumbers are known for their ability to expel their viscera as a strategy to scare off predators, regenerating their guts within several weeks.

To explore the genetic underpinnings of these features, scientists at the Chinese Academy of Sciences (CAS) in China performed high-definition genomic sequencing of the sea cucumber Apostichopus japonicus (also known as the Japanese sea cucumber), covering about 92 percent of its estimated 880 megabases of DNA, including more than 30,000 genes.

By comparing the genome of A. japonicus with that of other organisms, the authors found evidence that the echinoderms diverged from hemichordates (a small group of marine deuterostomes that includes the acorn worms) about 533 million years ago and the sea cucumbers split off from other the echinoderm classes about 479 million years ago.

They also showed that while the sea urchin genome includes 31 genes for biomineralization, critical for forming a calcified skeleton, the sea cucumber has only seven such genes. Moreover, they demonstrated that the sea cucumber expressed these biomineralization genes at much lower levels throughout development, likely accounting for their softer bodies compared to sea urchins.

The authors found a group of duplicated genes, called prostatic secretory protein of 94 amino acids (PSP94)-like genes, that were specifically expressed in the regenerating intestines of the sea cucumber, which had no corresponding genes in other echinoderms. This finding suggests that these genes may be crucial to the animals’ ability to quickly regrow their viscera.

A second group of genes, called fibrinogen-related proteins, were also duplicated and highly expressed during regeneration, indicating their contribution to the sea cucumber’s superior regenerative capability.

“The sea cucumber is a particularly promising model animal for regenerative medicine,” said Professor Xiang Jianhai of the CAS, adding that 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,” he explained.



The article can be found at: Zhang et al. (2017) The Sea Cucumber Genome Provides Insights into Morphological Evolution and Visceral Regeneration.

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Source: PLOS; Photo: Xu Quiang.
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