Study finds Vitamin E is the key to saving sea cucumbers from extinction

They clean the ocean floor, support biodiversity, and are disappearing fast. Sea cucumbers are slow and sedate, but crucial to ocean health. They are also in demand as a food source in various countries.

A recent study on captive farmed sea cucumbers has revealed that feeding them the right nutrients, like Vitamin E, might protect their health and promote immunity. 

Vitamin E boosts collagen production and strengthens the body’s antioxidant defenses. This helps maintain a healthy gut and supports safer, more sustainable cultivation of juveniles, called seedlings.

Why sea cucumbers need care

The Japanese spiky sea cucumber, scientifically named Apostichopus japonicus, is an important marine resource that has seen rising demand. However, overfishing has reduced their natural populations, upsetting the balance of the marine ecosystem. 

Farming sea cucumbers can help reduce strain on wild populations. The cultivation of juveniles is known as “seedling” cultivation because the planktonic larvae resemble small seedlings.

Growing seedlings in captivity ensures a stable supply of young sea cucumbers and reduces the need to harvest them from the wild.

Sea cucumbers lack an advanced immune system and rely on their innate or built-in immune defenses. Farmers often use antibiotics to treat infections during cultivation. However, frequent antibiotic use can lead to resistance.

The residual antibiotics may also pollute the environment and pose serious risks to food safety. This has led scientists to search for safer and smarter strategies.

Researchers now focus on improving immunity by feeding them proper nutrients, instead of depending on antibiotics. One key player in this scenario is Vitamin E (VE), which is a fat-soluble vitamin.

Nodal gene links immunity and repair

For the study, researchers turned their attention to collagen, since it is needed for a healthy gut wall. It provides physical support to the epithelial cells and helps in adhesion and alignment.

Collagen establishes a stable environment around the cell, called the extracellular matrix, that facilitates epithelial cell adhesion, migration, and renewal. All of these are key to tissue regeneration. 

One major pathway for collagen synthesis is the transforming growth factor-β (TGF-β) pathway. TGF-β is a family of signaling proteins that includes the key gene Nodal. 

Nodal stands out due to its ability to regulate inflammation and immune function. Not just that, it helps in the proliferation of fibroblasts, the cells responsible for forming collagen. This suggests that Nodal may play a vital role in tissue repair by kick-starting collagen production. 

Vitamin E benefits hinge on Nodal

The researchers analyzed the role of Vitamin E and the Nodal gene in enhancing the health of sea cucumbers.

Researchers used RNA interference (RNAi), which switches off specific genes, to silence the Nodal gene in experimental animals.

They fed juvenile sea cucumbers with 200 mg/kg of Vitamin E and observed significant improvement in growth, gut structure, and immunity. But when researchers silenced the Nodal gene, these benefits declined sharply. 

The drop was particularly pronounced in sea cucumbers that did not receive Vitamin E in their diet. Interestingly, in those that received the vitamin, these negative effects were partially buffered, even with the gene silenced. 

This suggested that Vitamin E enhanced the antioxidant defense mechanism and collagen synthesis through a Nodal-dependent pathway.

How Vitamin E builds gut defenses

In recent years, scientists have recognized the intestine as a front-line player in immune regulation. A healthy gut is the body’s first line of defense against pathogens. 

Researchers often look at the height and width of villi – the finger-like projections in the gut – and the thickness of the mucosal layer to assess the health of the gut. An intact gut lining and well-developed villi form a strong shield against infection.

Studies have shown that VE supplementation improved gut structure in various aquatic animals. For instance, it increased the villus height and mucosal thickness in channel catfish. Similarly, in Pompano, it boosted the height, width, and surface area of the villi. 

For a stable gut lining, the epithelial cells should be tightly packed and arranged in an orderly way, with strong intercellular tight junctions (TJs).

These junctions rely on strong support from the villi. TJs are mainly composed of collagen-rich connective tissue. 

To understand how this collagen framework holds together, researchers examined the role of the Nodal gene.

Vitamin E as an antibiotic alternative

This study highlighted the importance of targeted nutrition in improving the gut health of sea cucumbers.

Vitamin E offers a safer alternative to the use of antibiotics in the cultivation of healthy sea cucumbers, and possibly other forms of aquaculture.

It opens up new possibilities for supporting tissue regeneration and overall resilience in farmed sea cucumbers.

Future research should explore how other dietary immune boosters might interact and contribute to gut function in this species. 

The full study was published in the journal Biology.

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