Extracellular DNA traps in a ctenophore demonstrate immune cell behaviors in a non-bilaterian

Abstract

The formation of extracellular DNA traps (ETosis) is a first response mechanism by specific immune cells following exposure to microbes. Initially characterized in vertebrate neutrophils, cells capable of ETosis have been discovered recently in diverse non-vertebrate taxa. To assess the conservation of ETosis between evolutionarily distant non-vertebrate phyla, we observed and quantified ETosis using the model ctenophore Mnemiopsis leidyi and the oyster Crassostrea gigas. Here we report that ctenophores – thought to have diverged very early from the metazoan stem lineage – possess immune-like cells capable of phagocytosis and ETosis. We demonstrate that both Mnemiopsis and Crassostrea immune cells undergo ETosis after exposure to diverse microbes and chemical agents that stimulate ion flux. We thus propose that ETosis is an evolutionarily conserved metazoan defense against pathogens.

Reproductive success of inbred strain MV31 of the ctenophoreMnemiopsis leidyiin a self-sustaining inland laboratory culture system

“…Ctenophores exhibit a number of interesting biological features, including regeneration [12][13][14][15], bi-oluminescence [16][17][18], rows of giant cilia used for locomotion [19][20][21], proprioceptive organs [22][23][24], immune cells [25][26][27], functional through-gut [28], prototypical nerve nets [29][30][31], and adaptations to extreme environments [32]. The genomes of several ctenophore species have now been sequenced and annotated [11,29,[33][34][35].…”