The tie that binds: Eicosanoids in invertebrate biology

Eicosanoids are oxygenated compounds formed from C20 polyunsaturated fatty acids by reactions involving at least 1 step of mono- or dioxygenase-depend ent oxidation. These compounds have been detected in species representing a ll major animal taxa including numerous insect species. Although these comp ounds are best understood in human biology where they have immense clinical medicinal significance, they are now recognized as universally important t o all life forms. Indeed, these compounds appear to have been recruited int o roles as biological signaling moieties long before the origin of the Meta zoa During the ensuing evolutionary diversification of animals, eicosanoids have been commandeered into a plethora of biological roles, some of which are known only from invertebrates. In this review we provide a brief chemic al overview of the diversity of eicosanoids that have been discovered and d iscuss a number of physiological, behavioral and ecological systems where t hese compounds have been shown to be of major importance. Our discussions a re couched in terms of comparative biology, and where it is appropriate, in clude evolutionary speculations.