An unexpected discovery has overturned people's long-term beliefs in biological science. This study suggests that chitin, a molecule previously thought not to exist in vertebrates, has been shown to trigger allergic/immune responses in mammals and is endogenous in fish and amphibians.
Scientists at the Benaroa Institute (BRI) at Virginia Mason University have made an unexpected discovery that has overturned people's long-standing beliefs in biological science. This study was led by Dr. Chris Amemiya, a member of BRI, and mainly conducted by Joyce Tang. It is published on the website of Contemporary Biology. This study suggests that chitin, a molecule previously thought not to exist in vertebrates, has been shown to trigger allergic/immune responses in mammals and is endogenous in fish and amphibians.
Based on our observations, it is evident that the way vertebrates use chitin may be very different from invertebrates or fungi, "Dr. Amemiya pointed out. We hope that by studying the biological effects of chitin in vertebrates, we will discover a wide range of generalizable principles, allowing us to expand its use in biomedical and practical applications
Chitin is mainly considered a molecule that forms hard structures, such as fungal cell walls and the exoskeleton of invertebrates such as insects and crustaceans. It is a polymer composed of many repeating units of a sugar called n-acetylglucosamine, which naturally occurs in many organisms and forms a strong and flexible material. When combined with other materials such as proteins and minerals, this material becomes stronger, forming a protective shell for insects and crustaceans.
People generally believe that vertebrates lack chitin, which is largely based on the assumption that a gene called chitin synthase is lacking in the vertebrate genome, and the activity of this gene is necessary for the production of chitin. However, after careful examination of the genomes of many vertebrates, Amemiya's laboratory found that the genes of fish and amphibians are very similar to those of chitin synthase genes found in insects. Through a variety of experimental methods, including genomics, developmental biology and chemical purification and analysis, the author has proved that chitin synthase genes are active in fish and amphibians, and they produce chitin internally.
Dr. Steven Ziegler, Director of the BRI Immunology Research Program, pointed out that "these findings seem to overturn previous assumptions about vertebrates and chitin." Previous studies by Dr. Ziegler and Dr. Richard Locksley (UCSF) have shown that chitin can cause allergic reactions in mice. Combining Dr. Amemiya's discovery of identifying chitin in fish and amphibians, this reveals a paradox about the role of chitin in vertebrates and the evolution of chitin synthase genes. Chitin is expressed in fish and amphibians, however, the chitin synthase gene is no longer maintained in the mammalian genome, and exposure to chitin triggers an immune response.
Chitin has a wide range of current and potential applications in agriculture, industry, and medicine. Chitin is a natural plant antifungal defense reaction used in agriculture to prevent fungal infections and as fertilizer. In addition, due to the extensibility of chitin polymers, they are also used in biomedical applications, including surgical sutures, wound healing methods, drug delivery vessels, and tissue engineering scaffolds. Chitin has recently been proven to be a good biodegradable plastic material.
