Tracking the dynamics of individual gut microbiome of sea cucumber Apostichopus japonicus during gut regeneration.

Yohei Yamazaki,Sayaka Mino,Tomoo Sawabe,Yuichi Sakai,Juanwen Yu

doi:10.7717/peerj.10260

Abstract

Sea cucumbers possess the remarkable capacity to regenerate their body parts or organs. Regeneration of host organs and/or body parts involves reconstruction of the host associated microbiota, however, the dynamics and contribution of microbiota to the regeneration process are largely unknown due to a lack of experimental models. To track the dynamics of individual gut microbiomes during gut regeneration, both caged mariculture and laboratory isolator systems of sea cucumbers (Apostichopus japonicus) were developed and longitudinal meta16S analyses were performed. Under natural environmental conditions in the caged mariculture system, both bacterial and eukaryotic communities in sea cucumbers’ guts appeared to be reconstructed within 4 months after evisceration. Using the laboratory isolator, which can trace daily dynamics, we found that fecal microbiota collected before evisceration were clearly different from those collected after evisceration. We also identified eight key bacteria, belonging to Alteromonadaceae, Rhodobacteraceae, Oceanospirillaceae and family-unassigned Gammaproteobacteria, suggesting that these bacteria might interact with the host during the gut regeneration process. Six of the eight key bacteria were isolated for further bioassay using the isolator developed in this study to test whether these isolates affect gut regeneration.

Highlights

Regeneration biology is one of the fundamental fields in biology (Nachtrab & Poss, 2012)
Early-stage dynamics of gut microbiome using the laboratory isolator To fill gaps in the understanding of early-stage dynamics of gut microbiome along with gut regeneration, we set up a laboratory isolator to monitor the dynamics of the fecal microbiota derived from identical specimens for 1 month and compared the regeneration group and the control group (Fig. S2)
PERMANOVA based on unweighted UniFrac disitances indicated that bacterial communities were significantly different between specimens (p < 0.01), and fecal microbiota collected before evisceration appeared to be different from those collected after evisceration (p < 0.01) (Fig. 2)

Summary

Introduction

Regeneration biology is one of the fundamental fields in biology (Nachtrab & Poss, 2012). Remarkable regenerative capacities have been observed in a wide range of animals species including mammals (e.g., African spiny mouse), amphibians (e.g., newts), urochordates (e.g., sea squirt), echinoderms (e.g., sea stars, sea cucumbers) and platyhelminthes (e.g., planaria) (Mashanov & García-Arrarás, 2011; Seifert et al, 2012; Umesono et al, 2013; Jeffery, 2015; Tanaka et al, 2016). As regeneration biology in the above animals has undergone research, a view has emerged splitting the continuum into three groups: wound healing, tissue repair, and regeneration (Galliot et al, 2017). Wound healing is often replaced by fibrotic scarring in mammals, and tissue repair involves functional restoration of the injured organs with no patterned 3D reconstruction. Tracking the dynamics of individual gut microbiome of sea cucumber Apostichopus japonicus during gut regeneration.

Methods

Results

Discussion

Conclusion