The Bacterial Metabolite Indole Inhibits Regeneration of the Planarian Flatworm Dugesia japonica

Abstract

SummaryPlanarian flatworms have been used for over a century as models for regeneration. Planarians live in aquatic environments with constant exposure to microbes, but the mechanisms by which bacteria may mediate planarian regeneration are largely unknown. We characterized the microbiome of laboratory populations of the planarian Dugesia japonica and determined how individual bacteria impact D. japonica regeneration. Eight to ten taxa in the phyla Bacteroidetes and Proteobacteria consistently occur across planarian colonies housed in different research laboratories. Individual members of the D. japonica microbiome can delay regeneration including the development of eye spots and blastema formation. The microbial metabolite indole is produced in significant quantities by two bacteria that are consistently found in the D. japonica microbiome and contributes to delays in regeneration. Collectively, these results provide a baseline understanding of the bacteria associated with the planarian D. japonica and demonstrate how metabolite production by host-associated microbes can affect regeneration.

Kynurenine Metabolism in the Fat Body Non-autonomously Regulates Imaginal Disc Repair in Drosophila

“…Trp-derived metabolites function in diverse situations. As for tissue regeneration, a recent planarian study implied the involvement of indole, a Trp catabolite via the microbiome, impaired regeneration ( Lee et al., 2018 ). Ischemia by cardiac arrest is reported to change the plasma KynA level in rats, pigs, and humans ( Ristagno et al., 2013 ), and a study reported that KynA has a protective effect against ischemic tissue damage ( Olenchock et al., 2016 ), which supports our idea that KynA regulates tissue repair non-autonomously.…”

Molecular Dissection of Early Defense Signaling Underlying Volatile-Mediated Defense Regulation and Herbivore Resistance in Rice

“…In Arabidopsis, high doses of indole in the growth medium modulate root growth by interacting with the auxinsignaling machinery (Bailly et al, 2014). Indole can also act as an intracellular signaling molecule in bacteria (Kim and Park, 2015) and suppress regeneration of the planarian worm Dugesia japonica (Lee et al, 2018), suggesting that it is a modulator of a wide variety of physiological processes in different organisms.…”

Analysis of Polysaccharide Fraction from Yerba Mate (Ilex paraguariensisSt. Hil.) on Regeneration of Planarian (Girardia tigrina)

“…[31,32] The effect of structurally different compounds was assessed on planarian growth. Some studies reported a negative effect of indole on planarian regeneration, [33] as well as an improvement in growth produced by F neuropeptide. [28] Also, melatonin was found to selectively reduce the mitotic activity of cells in the anterior portion of the planarians, without effect on posterior end's regeneration.…”