Acetylcholinesterase activity in the developing and regenerating nervous system of the acoel Symsagittifera roscoffensis

Abstract

Bery, A. and Martínez, P. 2011. Acetylcholinesterase activity in the developing and regenerating nervous system of the acoel Symsagittifera roscoffensis. -Acta Zoologica (Stockholm) 92: 383-392.The use of the cholinergic system is widespread in the animal kingdom. It controls different processes, including reproduction and neural transmission. However, its evolutionary history is not yet well understood. For instance, the role played by the cholinergic system in the nervous system of basal bilaterian taxa, where the first signs of architectural complexity appear, is still unknown. Here, we describe the structure of the cholinergic system during the development and regeneration of the acoel flatworm Symsagittifera roscoffensis, using acetylcholinesterase (AchE) activity as a marker. In this species, AchE activity is observed at all developmental stages, including in the early embryos. The juvenile and adult patterns reveal the presence of a complex nervous system that includes three pairs of longitudinal neurite bundles, which are connected to an anterior centralized mass of neurons and neural processes formed by two pairs of connectives and four commissures. The power of the technique also allows the detection of newly born neurons as they are incorporated into the growing nervous system (during regeneration).

An Emerging System to Study Photosymbiosis, Brain Regeneration, Chronobiology, and Behavior: The Marine Acoel Symsagittifera roscoffensis

“…Of note, and highly relevant as an experimental system, is their ability to regenerate a full brain from scratch. This is a rather unique feature and allows researchers to follow the regeneration process of a brain with remarkable detail . Planarians and acoelomorphs have distinctive totipotent stem cells (neoblasts) responsible for the renewal of all cell types during development, growth, and regeneration .…”

“…This is a rather unique feature and allows researchers to follow the regeneration process of a brain with remarkable detail. [2,[41][42][43][44][45][46] Planarians [47,48] and acoelomorphs [49][50][51] have distinctive totipotent stem cells (neoblasts) responsible for the renewal of all cell types during development, growth, and regeneration. [47,52] For the first time, using EdU staining (i.e., marking DNA of dividing cells to follow cell proliferation), neoblasts on S. roscoffensis juveniles is presented ( Figure 2b).…”

The nervous system of Isodiametra pulchra (Acoela) with a discussion on the neuroanatomy of the Xenacoelomorpha and its evolutionary implications

“…Species on which the most work has been conducted are the convolutids Convolutriloba longifissura [8,18-22] and Symsagittifera roscoffensis [10,12,23-25] and the isodiametrid Isodiametra pulchra [26,27]. The latter lives in marine mud flats in Maine (USA) and measures about 1 mm in length.…”

Characterization of the bHLH Family of Transcriptional Regulators in the ACOELS. roscoffensisand their Putative Role in Neurogenesis

“…Juveniles of S. roscoffensis are about 220 μm after hatching and the brain occupies more than a third of their body length, a striking difference when compared to the adult specimens, where the brain occupies only a small anterior region (approximately an eighth of the animal's length) [12,16,[20][21][22].…”