Search

Two echinoderm species, the sea urchin Paracentrotus lividus and the feather star Antedon mediterranea, were exposed for 28 days to several EDCs: three putative androgenic compounds, triphenyltin (TPT), fenarimol (FEN), methyltestosterone (MET), and two putative antiandrogenic compounds, p,p′-DDE (DDE) and cyproterone acetate (CPA). The exposure nominal concentrations were from 10 to 3000 ng L-1, depending on the compound. This paper is an attempt to join three different aspects coming from our ecotoxicological tests: (1) the chemical behaviour inside the experimental system; (2) the measured toxicological endpoints; (3) the biochemical responses, to which the measured endpoints may depend. The chemical fate of the different compounds was enquired by a modelling approach throughout the application of the 'Aquarium model'. An estimation of the day-to-day concentration levels in water and biota were obtained together with the amount assumed each day by each animal (uptake in lg animal-1 d-1 or ng g-wet weight-1 d-1). The toxicological endpoints investigated deal with the reproductive potential (gonad maturation stage, gonad index and oocyte diameter) and with the regenerative potential (growth and histology). Almost all the compounds exerted some kind of effect at the tested concentrations, however TPT was the most effective in altering both reproductive and regenerative parameters (also at the concentration of few ng L-1). The biochemical analyses of testosterone (T) and 17β-estradiol (E2) also showed the ability of the selected compounds to significantly alter endogenous steroid concentrations. [ABSTRACT FROM AUTHOR]

A new simple model, based on the fugacity approach, has been developed to provide a predictive tool useful in the planning phase of aquatic ecotoxicological tests for assessing the actual daily concentrations in water. In our experiments, three nominal concentrations (100,  225, and 500  ng  L -1 ) of triphenyltin chloride (TPT-Cl) were employed for an exposure period of 28 days in 50  L aquaria with the echinoderm Antedon mediterranea as test species. Extracts from water and biota samples collected during the experiments were analysed by GC-MS/MS, after the extraction/derivatization step. An indicative mean BCF (V/V) on a fresh weight base of 3.5  ×  10 4   ±  0.8  ×  10 4 (standard deviation) could be calculated for A. mediterranea. Three different compartments (air, water and biota) and main advection/reaction processes are taken into account in the model design, and the comparison between predicted and measured concentrations in both water and biota for the three concentrations tested confirmed that the assumptions given in our model application were valid and useful for further applications. [ABSTRACT FROM AUTHOR]

Starfish can regenerate entire arms following their loss by both autotomic and traumatic amputation. Although the overall regenerative process has been studied several times in different asteroid species, there is still a considerable gap of knowledge as far as the detailed aspects of the repair phase at tissue and cellular level are concerned, particularly in post-traumatic regeneration. The present work is focused on the arm regeneration model in the Mediterranean red starfish Echinaster sepositus; to describe the early cellular mechanisms of arm regeneration following traumatic amputation, different microscopy techniques were employed. In E. sepositus, the repair phase was characterized by prompt wound healing by a syncytial network of phagocytes and re-epithelialisation followed by a localized subepidermal oedematous area formation. Scattered and apparently undifferentiated cells, intermixed with numerous phagocytes, were frequently found in the wound area during these first stages of regeneration and extensive dedifferentiation phenomena were seen at the level of the stump, particularly in the muscle bundles. A true localized blastema did not form. Our results confirm that regeneration in asteroids mainly relies on morphallactic processes, consisting in extensive rearrangement of the existing tissues which contribute to the new tissues through cell dedifferentiation, redifferentiation, and/or migration., (© 2015 by the Wound Healing Society.)

The red starfish Echinaster sepositus is an excellent model for studying arm regeneration processes following traumatic amputation. The initial repair phase was described in a previous paper in terms of the early cicatrisation phenomena, and tissue and cell involvement. In this work, we attempt to provide a further comprehensive description of the later regenerative stages in this species. Here, we present the results of a detailed microscopic and submicroscopic investigation of the long regenerative phase, which can be subdivided into two subphases: early and advanced regenerative phases. The early regenerative phase (1-6 weeks p.a.) is characterized by tissue rearrangement, morphogenetic processes and initial differentiation events (mainly neurogenesis and skeletogenesis). The advanced regenerative phase (after 6 weeks p.a.) is characterized by further differentiation processes (early myogenesis), and obvious morphogenesis and re-growth of the regenerate. As in other starfish, the regenerative process in E. sepositus is relatively slow in comparison with that of crinoids and many ophiuroids, which is usually interpreted as resulting mainly from size-related aspects and of the more conspicuous involvement of morphallactic processes. Light and electron microscopy analyses suggest that some of the amputated structures, such as muscles, are not able to replace their missing parts by directly re-growing them from the remaining tissues, whereas others tissues, such as the skeleton and the radial nerve cord, appear to undergo direct re-growth. The overall process is in agreement with the distalization-intercalation model proposed by Agata and co-workers. Further experiments are needed to confirm this hypothesis., (© 2015 by the Wound Healing Society.)