Cellular and molecular profiles of anterior nervous system regeneration in Diopatra claparedii Grube, 1878 (Annelida, Polychaeta)

Mohd Ulul Ilmie Ahmad Nazri,Mohd Hafizi Mahmud,Basri Saidi,Mohd Noor Mat Isa,Zolkapli Ehsak,Othman Ross,Izwandy Idris,Wan Iryani Wan Ismail

doi:10.1016/j.heliyon.2021.e06307

Mohd Ulul Ilmie Ahmad Nazri, Mohd Hafizi Mahmud + Show 6 more

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https://doi.org/10.1016/j.heliyon.2021.e06307

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Abstract

The polychaete Diopatra claparedii Grube, 1878 is among those organisms successfully carrying out full body regeneration, including the whole nervous system. Thus, D. claparedii potentially can be regarded for the nervous system regeneration (NSR) study. However, data on the property of its nervous system and the NSR profile are still lacking. In this study, we investigated the morphology of D. claparedii anterior nervous system (ANS) and examined the cellular and molecular profiles on its early anterior NSR. The nervous system of D. claparedii consists of a symmetry brain with nerves branching off, circumpharyngeal connectives that connect the brain and nerve cord as well as obvious segmental ganglia. Moreover, we identified changes in the cellular condition of the ganglionic cells in the regenerating tissue, such as the accumulation of lysosomes and lipofuscins, elongated mitochondria and multiple nucleoli. Furthermore, mRNA of tissues at two regenerating stages, as well as intact tissue (non-regenerating), were sequenced with Illumina sequencer. We identified from these tissues 37,248 sequences, 18 differential expressed proteins of which upregulated were involved in NSR with noelin-like isoform X2 turned up to be the highest being expressed. Our results highlight the cellular and molecular changes during early phase of NSR, thus providing essential insights on regeneration within Annelida and understanding the neurodegenerative diseases.

Highlights

Nervous system regeneration (NSR), or known as neuroregeneration, is defined as restoration and regrowth of the lost neuron or nerve tissue to regain normal function
We investigated the morphology of D. claparedii anterior nervous system (ANS) and examined the cellular and molecular profiles on its early anterior nervous system regeneration (NSR)
A study conducted on an adult serpulid polychaete has demonstrated the outgrowth of a cerebral ganglion as the first feature established during neurogenesis (Brinkmann and Wanninger, 2009)

Summary

Introduction

Nervous system regeneration (NSR), or known as neuroregeneration, is defined as restoration and regrowth of the lost neuron or nerve tissue to regain normal function. In invertebrates, such as echinoderms, the regeneration capacity is remarkable as they can regenerate both internal and external parts, including the nervous system (Ortega and Olivares-Ban~uelos, 2020). In some adult insects, it was found that persistent neurogenesis occurs in the mushroom bodies which are known to function in learning and memory (Cayre et al, 2002). Especially mollusks, and insects, neuroplasticity has been reported to occur for axon sprouting and synapse formation (Pyza, 2013). The cause of neurodegeneration, on the contrary, might be due to the absence of the neuroplasticity process

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