Potential for host-symbiont communication via neurotransmitters and neuromodulators in an aneural animal, the marine sponge .

Interkingdom signalling within a holobiont allows host and symbionts to communicate and to regulate each other's physiological and developmental states. Here we show that a suite of signalling molecules that function as neurotransmitters and neuromodulators in most animals with nervous systems, specifically dopamine and trace amines, are produced exclusively by the bacterial symbionts of the demosponge . Although sponges do not possess a nervous system, expresses rhodopsin class G-protein-coupled receptors that are structurally similar to dopamine and trace amine receptors.