Elisabetta Giacco

The mauve stinger Pelagia noctiluca (Forsskal, 1775). Distribution, ecology, toxicity and epidemiology of stings. A review.

The toxicity of Cnidaria is a subject of concern due to its influence on humans. In particular, jellyfish blooms can highly affect human economical activities, such as bathing, fishery, tourism, etc., as well as the public health. Stinging structures of Cnidaria (nematocysts) produce remarkable effects on human skin, such as erythema, swelling, burning and vesicles, and at times further severe dermonecrotic, cardio- and neurotoxic effects, which are particularly dangerous in sensitive subjects. In several zones the toxicity of jellyfish is a very important health problem, thus it has stimulated the research on these organisms; to date toxicological research on Cnidarian venoms in the Mediterranean region is not well developed due to the weak poisonousness of venoms of jellyfish and anemones living in this area. In spite of this, during last decades several problems were also caused in the Mediterranean by stinging consequent to Cnidarian blooms mainly caused by Pelagia noctiluca (Forsskål, 1775) which is known to be the most venomous Mediterranean jellyfish. This paper reviews the knowledge on this jellyfish species, particularly considering its occurrence and toxicity.

Standardized methods for acute and semichronic toxicity tests with the copepod Acartia tonsa

The availability of standardized protocols for both organism culture and bioassay with ecologically relevant species is of great concern in ecotoxicology. Acartia tonsa represents an important, often dominant, member of zooplankton communities and meets all the practical criteria suggested for model species. New standardized procedures for laboratory culturing of the copepod A. tonsa and standardized methods for acute (24- and 48-h) and semichronic (7-d, static-renewal) toxicity tests with the nauplius stage are described. In both cases, eggs are the starting stage, and nauplius immobilization is the endpoint. The methods were the object of an intercomparison test involving nine laboratories, and nickel was the reference toxicant. Relative reproducibility was 24, 25, and 34% for 24-h, 48-h, and 7-d tests, respectively.

A standardization of Amphibalanus (Balanus) amphitrite (Crustacea, Cirripedia) larval bioassay for ecotoxicological studies.

A series of 10 intra-laboratory bioassays and an inter-laboratory assay involving nine laboratories, were performed to validate the use of Amphibalanus amphitrite larvae as test organisms for ecotoxicological studies. The standardization protocol utilized Cadmium Nitrate as a reference toxicant and larval immobilization (after 24 and 48 h) as the end-point. The statistical data analysis showed high homogeneity in intra-laboratory EC(50) values among bioassay repetitions (coefficient of variation (CV)=15.8% after 24 h and 16.9% after 48 h); also CV values obtained in inter laboratory comparison exercise were not higher than the 50%, variation coefficient mentioned in the ISO standards for the precision of inter-laboratory assays. The results demonstrated that the protocol implemented for the balanus larval bioassay comply with the international standards both for intra- and inter-laboratory precision.

Assessment of the Antimicrobial Activity of Algae Extracts on Bacteria Responsible of External Otitis.

External otitis is a diffuse inflammation around the external auditory canal and auricle, which is often occurred by microbial infection. This disease is generally treated using antibiotics, but the frequent occurrence of antibiotic resistance requires the development of new antibiotic agents. In this context, unexplored bioactive natural candidates could be a chance for the production of targeted drugs provided with antimicrobial activity. In this paper, microbial pathogens were isolated from patients with external otitis using ear swabs for over one year, and the antimicrobial activity of the two methanol extracts from selected marine (Dunaliella salina) and freshwater (Pseudokirchneriella subcapitata) microalgae was tested on the isolated pathogens. Totally, 114 bacterial and 11 fungal strains were isolated, of which Staphylococcus spp. (28.8%) and Pseudomonas aeruginosa (P. aeruginosa) (24.8%) were the major pathogens. Only three Staphylococcus aureus (S. aureus) strains and 11 coagulase-negative Staphylococci showed resistance to methicillin. The two algal extracts showed interesting antimicrobial properties, which mostly inhibited the growth of isolated S. aureus, P. aeruginosa, Escherichia coli, and Klebsiella spp. with MICs range of 1.4 × 109 to 2.2 × 1010 cells/mL. These results suggest that the two algae have potential as resources for the development of antimicrobial agents.

Neurotoxic and Neuroactive Compounds from Cnidaria: Five Decades of Research….and More

Cnidarians are numbered among the most venomous organisms. Their venoms are contained in intracellular capsules, nematocysts, which inject the content into preys/attackers through an eversion system resembling a syringe needle. Several cnidarian venoms have activity against the nervous system, being neurotoxic, or affect other systems whose functioning is under nerve control. Besides direct damage to nerve cells, the activity on ionic conductance, blockade of neuromuscular junctions, and influence on action potentials and on voltage-gated channels have been described. Therefore, cnidarians can be a useful source of nervous system-targeted compounds which could have, in perspective, a role in the therapy of some nervous system diseases. Following this idea, this article aims to review the existing data about the neuroactive properties of cnidarian venoms and their possible usefulness in tackling some neurological diseases as well as neurodegenerative age-related diseases whose incidence is expected to raise in the next decades owing to the increase of life expectancy.

Tigriopus fulvus: The interlaboratory comparison of the acute toxicity test.

The paper reports the results of an interlaboratory comparison involving 11 laboratories, with the objectives of apply and validate a new standardized ecotoxicological method on marine crustacean Tigriopus fulvus. Copper was chosen as reference toxicant as indicated in the official method. The results of two independent tests performed by all the participants, demonstrated that the new method is simple, fast and easy to learn. This is confirmed even by the values of z-score index calculated for each laboratory and the relative coefficient of variation (CV) which are 6.32% after 24h, 6.56 after 48h and 35.3% after 96h, mentioned in the ISO standards for the precision of interlaboratory assays. Therefore its use could be recommended in environmental studies and monitoring.

Settlement of the alien mollusc Brachidontes pharaonis in a Mediterranean industrial plant: Bioassays for antifouling treatment optimization and management

In this work, we investigated the efficacy of three new biocides (77351, 73532, 73503--NALCO®) as specific antifouling products against adult organisms of the bivalve Brachidontes pharaonis (Fischer P., 1870), a Lessepsian species introduced in the Mediterranean Sea by sea transport (ballast water), and which has recently shown invasive behaviour in an industrial plant in Southern Italy (Sicily). These biocides were tested to verify their efficacy, as well as their environmental compatibility at discharge point, using the crustacean belonging to the genus Artemia (Leach, 1819) as model organism, according to Government Decree (D. Lgs) No. 152/06. Biocides were also tested using alternative crustaceans, Amphibalanus amphitrite (Darwin, 1854), and Tigriopus fulvus (Fischer, 1860), in order to check whether their introduction as model species in the national regulation could affect discharge limit concentrations (DLC) due to their different sensitivity, with likely economic and technical repercussions in the industrial water treatment sector.

Ecotoxicological assessment of the micelle encapsulator F-500.

Surfactants are synthetic chemicals utilized as detergents and cleaning products or as dispersants and emulsifiers to face water pollution. In spite of this, due to their wide diffusion, surfactants can induce water and soil pollution, notably in developed countries, and can be toxic to organisms. Taking into account that the assessment of new compounds is mandatory in the European Union, in this research the ecotoxicity of fire-fighting micelle encapsulator F-500, newly utilized as dispersant in seawaters polluted with oil dumping, was evaluated. The assessment was carried out on a battery of test-organisms (freshwater algae, crustaceans, and larval fish; seawater algae, crustaceans, and bivalves; soil earthworms, and seeds) as well as on cultured cells (L-929 mouse fibroblasts), which were exposed to F-500 concentrations. According to the toxicity thresholds provided by GESAMP, F-500 resulted to be slightly or moderately toxic to all test-organisms, excluding the freshwater alga Pseudokirchneriella subcapitata that suffered highly toxic effects with IC50 values ranging from 0.21 to 0.49mg/L. The IC50 for mouse fibroblasts was 5.41µg/L after 24h treatment.