The lungfish cocoon is a living tissue with antimicrobial functions

Area of Science:

• Immunology
• Comparative Physiology
• Evolutionary Biology

Background:

• Terrestrialization is a survival strategy for African lungfish during dry seasons.
• Lungfish create a mucus cocoon for protection against desiccation for extended periods.
• The cocoon environment and its interaction with the host immune system are not fully understood.

Purpose of the Study:

• To investigate the immunological adaptations of African lungfish during terrestrialization.
• To understand the role of the lungfish cocoon in bacterial interaction and host defense.
• To elucidate the mechanisms by which lungfish prevent infection while surviving on land.

Main Methods:

• Light and electron microscopy to analyze cocoon structure.
• Transcriptomic analysis to identify immune responses in skin.
• In vivo experiments involving DNase I treatment to assess immune function.

Main Results:

• The lungfish cocoon is a living tissue that actively traps bacteria.
• Terrestrialized lungfish skin exhibits a state of inflammation with granulocyte recruitment.
• Granulocytes migrate into the cocoon and release extracellular traps, indicating an immune defense mechanism.
• DNase I treatment disrupts this defense, leading to dysbiosis and severe health issues.

Conclusions:

• African lungfish possess unique immunological adaptations for prolonged terrestrial survival.
• The cocoon and immune system work together to manage bacterial load and prevent infection.
• These findings offer insights into vertebrate adaptations to extreme environmental conditions and potential strategies for managing infections.