Microscopic overview of crinoid regeneration

Abstract

Crinoids are well known for their striking regenerative potential and can rapidly and completely regenerate arms lost following self-induced or traumatic amputation. Thus they provide a valuable experimental model for investigation of the regenerative process from the macroscopic to the molecular level. In these last years we have studied in detail the overall process of arm regeneration in the comatulid Antedon mediterranea. This phenomenon can be described on the whole as a typical blastemal regeneration in which new structures develop from migratory pluripotential, actively proliferating cells in the presence of presumptive regulatory factors. The overall process can be subdivided into three main phases: a repair phase, an early regenerative phase, and an advanced regenerative phase, whose crucial aspects are related to common fundamental mechanisms such as cell migration and proliferation, intervention of stem cells and/or dedifferentiated cells, contribution of putative growth factors, particularly in terms of specific neurally derived factors, and mechanisms of pattern formation. This article focuses on the main aspects of the phenomenon and gives a brief account of the most recent and relevant results. Our approach employs classical methods of light (LM) and electron (TEM and SEM) microscopy, immunocytochemistry, and histofluorescence on experimentally induced arm regenerations of standard or abnormal type obtained in significantly different experimental conditions, including extreme mutilations (explants) or exposure to pseudo-estrogenic environmental contamination.

Energy metabolism and regeneration impaired by seawater acidification in the infaunal brittlestar,Amphiura filiformis

“…Based on histological studies, Wood et al (Wood et al, 2008) suggested that unfed A. filiformis increases protein metabolism by the breakdown of muscle tissues to fuel increased energetic demands in response to seawater acidification. It is likely that enhanced catabolism and cell turnover/dedifferentiation of muscle tissues following traumatic amputation in brittlestars and crinoids is related to cell differentiation to produce stem cells to regenerate lost tissues rather that fueling calcification processes (Candia Carnevali and Bonasoro, 2001;Biressi et al, 2010). However, despite increased NH 4 + excretion rates, the present study could not demonstrate any changes in ratios between ADM and DM between pH treatments, which would have indicated an increased utilization of muscle tissue or other amino acid compounds as an energy source.…”

Ciona intestinalis and Oxycomanthus japonicus, Representatives of Marine Invertebrates

“…Crinoids are known to possess a strong capacity for regeneration, and have been studied using a variety of crinoids, such as the sea lily M. rotundus [1,26] and the comatulid Antedon mediterranea [5]. Comatulids regenerate most of their organs and many studies have focused on arm regeneration [5].…”

“…Comatulids regenerate most of their organs and many studies have focused on arm regeneration [5]. Regeneration is dependent on the nervous system and goes through three main phases: a repair phase, an early regenerative phase and an advanced regenerative phase [5].…”

Bridging the regeneration gap: insights from echinoderm models

“…First, a growing amount of molecular information about the regeneration process is available. Echinoderms show nerve-dependent regeneration [2][3][4][5][6][7] , and regeneration in these organisms has been shown to involve growth factors. For example, the bone morphogenetic protein/transforming growth factor-β (BMP/TGFB)-signalling pathway has been shown to function in regeneration in brittlestars and crinoids 5,9,10 , the HOX-signalling pathway in brittlestars and seastars 6 , and the Ependymin pathway in the sea cucumber 7 .…”

“…These molecular pathways are repeatedly encountered during regeneration throughout the animal kingdom 1 . Second, all of the classical cellular and molecular tools are available for these models: EST libraries, not to mention the complete genome of the sea urchin Strongylocentrotus purpuratus 8 , immunohistochemistry 4,6,9 , in situ hybridization 5,10 , real-time PCR 7,10 , microarrays 11 , proteomics and so on. Echinoderm models allow analysis both in vivo and in vitro (for example, cell and tissue explant cultures 12 ).…”