Pamela Lyon
Bioelectricity and the Evolution of Multicellular Individuality: Hints from the Microworld
The role of bioelectricity in tissue regeneration in multicellular organisms is now well established and its roles in embryonic development, cancer growth and wound healing are being actively investigated.1-5 Ion channels and bioelectricity mediated by ion channels are found in all known free-living cells, however.6 This is why bacteria and unicellular eukaryotes (e.g., yeast) are being studied as potential generators of usable bioelectricity.7-9 A bacterial ion channel provided the basis for the Nobel Prize-winning elucidation of how neuronal ion channels work.10 A bacterial ion channel— Gloeobacter Ligand-gated Ion Channel (GLIC)—is now the go-to model for investigating the mechanisms of anaesthesia,11-13 long a biomedical mystery and believed to throw light on another famous biological mystery: consciousness (of which we shall not speak). The paper will explore the ancient origins of ion channel-mediated bioelectricity and its possible role in the evolution of multicellular individuality using two principal examples. First is Bacillus subtilis biofilms, communities of thousands of bacterial cells that behave collectively, research into which pioneered the contemporary field of microbial bioelectricity. Next is the ‘slug’ stage of development in the eukaryotic social amoebae Dictyostelium discoideum, in which thousands of formerly free-living cells combine into an individual unit capable of motility. Polymathic developmental biologist Michael Levin has described bioelectricity as the ‘cognitive glue’ enabling cellular collectives to make developmental decisions and behave as a coherent unit at vastly differing scales, from cellular aggregates in prokaryotes and microbial eukaryotes to tissues in multicellular organisms to individual organisms.14 This is an argument in support of that proposition.
Keywords: bioelectricity, ion channels, evolution, Bacillus subtilis, Dictyostelium discoideum, anaesthesia
References
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