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

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.

Characterisation and Regeneration of Diopatra claparedii Nervous System

“…Our investigation supports that polychaetes from the genus Diopatra have a complete and advanced nervous system that leads to their special ability to regenerate the nervous system (Pires et al, 2012;Pires et al, 2016;Nazri et al, 2021). This understanding might be beneficial to be applied in medicine as an animal model.…”

“…Beckers et al (2019) reported that the anterior CNS consists of a dorsal prostomial brain with several commissures and connectives connecting to the ventral nerve cord. Other than that, D. claparedii has also been reported to possess those characteristics based on the study conducted by Nazri et al (2021).…”

“…The sampling was done on 22 nd July 2017, from 9 am to 2 pm during the low tide. Parameter readings such as temperature, pH and salinity were obtained in the sampling area to mimic their habitat in laboratory conditions (Nazri et al, 2021).…”

“…The samples were removed from their tubes and rinsed with artificial seawater to remove the debris and other living organisms attached to the tubes. Correspondingly, tanks were prepared with sediment from Pantai Morib and artificial seawater with a ratio of 1:3 (Pires et al, 2012;Hussain et al, 2018;Che Soh et al, 2020;Nazri et al, 2021) with water conditioner (Tensiongon, Mydilab). Then, the tubes were placed into tanks filled with 6 kg of sediment and 18 L of artificial seawater with a salinity of 28±1.…”

“…The nervous system of class Polychaeta has a lot more to discover. In polychaetes, a ground nervous system pattern is suggested and described based on developmental and regeneration studies (Orrhage & Mu, 2005;Nazri et al, 2021;Helm et al, 2022). Diopatra claparedii, which can be discovered from Malaysia shores, has the ability to perform both anterior and posterior regeneration (Nazri et al, 2021).…”