12:04 GMT15 August 2020
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    The study shows that mammalian immune cells display a lower activation rate when exposed to peptides containing amino acids that are rare on our planet but are “commonly found on meteorites”.

    The immune systems of terrestrial mammals may be hard-pressed to detect and combat germs from beyond our planet, which could be based on amino acids different from those of lifeforms on Earth, phys.org reports citing a new study conducted by scientists from the universities of Aberdeen and Exeter.

    According to the media outlet, the researchers conducted their study on mice, testing mammal immune cells' response to peptides containing two amino acids “that are rare on Earth but are commonly found on meteorites” - isovaline and α-aminoisobutyric acid.

    "The world is now only too aware of the immune challenge posed by the emergence of brand new pathogens," said Professor Neil Gow, Deputy Vice-Chancellor (Research and Impact) at the University of Exeter.

    The study's results show that the immune cells display lower activation levels, as compared to exposure to peptides comprised entirely of amino acids common on Earth.

    "Life on Earth relies on essential 22 amino acids. We hypothesised that lifeforms that evolved in an environment of different amino acids might contain them in their structure", said lead author Dr. Katja Schaefer, of the University of Exeter. "We chemically synthetised 'exo-peptides' containing amino acids that are rare on Earth, and tested whether a mammal immune system could detect them. Our investigation showed that these exo-peptides were still processed, and T cells were still activated, but these responses were less efficient than for 'ordinary' Earth peptides".

    As Shaefer surmised, the researchers “therefore speculate that contact with extra-terrestrial microorganisms might pose an immunological risk for space missions aiming to retrieve organisms from exoplanets and moons."

    Tags:
    study, immune system, microbes, planets, space
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