In the sea anemone Bartholomea annulata, four different types of cnidocysts, basitrichous isorhizas, microbasic p-mastigophores, microbasic amastigophores and spirocysts were identified. In relation to the efficacy of different substances to induce discharge of nematocysts we observe that distilled water induced more than 70% of microbasic pmastigophores to discharge, whereas spirocysts were discharged in a lesser extent (∑20%). The median lethal dose (LD 50 ) in mice was found after injection of 700.7 mg protein per kg of body weight from the crude extract. The protein with neurotoxic effect was isolated using low-pressure liquid chromatography. The neurotoxic activity was determined using sea crabs (Ocypode quadrata), injecting 15 mg of crude extract or isolated fraction into the third walking leg, and violent motor activity followed by progressive loss of sensibility to external stimuli, further leading to full paralysis were observed. The active fraction (called V) eluted at 43.9 min.Sea anemones as well as corals, hydrozoans, scyphozoans and cubozoans, are included in the Phylum Cnidaria, the only group in the animal kingdom with the ability to produce cnidocysts. Cnidocysts are among the largest and most complex intracellular secretion products known (Holstein & Tardent 1984). There are 28 types of morphologically distinct cnidocysts, which are divided into three subcategories: nematocysts (25 different types), spirocysts (2 types), and one type of ptychocysts (Mariscal 1974). From these three subcategories, only nematocysts inject toxins into prey, and thus they are considered as the most sophisticated lethal weapons in the animal kingdom (Tardent 1995).Nematocysts from sea anemones contain complex mixtures of biologically active compounds, mainly consisting of peptides and proteins (Béress 1982;Hessinger 1988;Kem 1988;Norton 1991). Although the first toxins isolated from these cnidarians were neurotoxins (Béress & Béress 1974), cardiotoxins (Simpson et al. 1990), and several cytolysins (Kem 1988), protease inhibitors have also been found (Delfín et al. 1996). Indeed, although some anemone toxins have been extensively investigated during recent years, information regarding the biological activity of many of them is scarce. In the particular case of Bartholomea annulata, the only report in the literature is the study by Santamaría et al. (2002). In this study, the authors evaluated the haemolytic and peroxidative responses by the crude extract in mice erythrocytes. In consideration of the information mentioned above, the aim of this work is to evaluate the biotoxic parameters of both the crude extract and the partially purified venom from B. annulata in different experimental models.
Materials and MethodsIn order to identify the different types of cnidocysts present in tentacles of B. annulata, preparations were preserved with 4% formaldehyde, glycerine and 96% ethyl alcohol, and analyzed by light microscopy (20¿, 40¿ and 100¿). Cnidocysts from both fresh and frozen specimens were also observed i...