Protozoosin

Protozoosin is a fictional class of bioactive metabolites attributed to protozoa in speculative biology and science fiction. In this context, protozoosin refers to small amphipathic molecules produced by certain protozoan species that mediate intercellular communication and interactions with hosts. The term is used as a thought experiment to explore how protozoa might coordinate behavior, respond to stress, or manipulate host defenses.

Chemical characteristics are described variably in different works, but protozoosins are generally depicted as lipophilic molecules with a polar head group, allowing membrane association and diffusion through biofilms. Reported molecular weights range from a few hundred to around six hundred daltons. Stability is depicted as moderate in aqueous environments, with enzymatic modification possible by protozoan enzymes.

Biosynthesis is imagined to involve hybrid pathways combining fatty acid elongation, polyketide-like assembly, and peptide tailoring, occasionally within specialized organelles called protozoosomes. Proposed producers include both free-living ciliates and parasitic amoebae in the fictional biosphere.

Ecological and biological roles described in fiction include regulation of encystment, aggregation, and timing of developmental transitions; modulation of host cytokine responses; and serving as signals for inter-species cooperation or competition among protozoan communities. In some narratives, protozoosin-like molecules influence the composition of microbial communities in the host environment.

Protozoosin has no basis in verifiable experimental science and should be considered a speculative construct used in worldbuilding and fictional biology.