Search Results (4)

The barrel jellyfish (Rhizostoma pulmo), like other cnidarians, shows cnidocytes containing cnidae, responsible for the jellyfish’s stinging properties. The sting of R. pulmo can cause contact dermatitis or urticaria and even systemic symptoms. Recent studies have identified stinging-cell structures in the mucous secretion released in the water column by Cassiopea xamachana, belonging to the same order as R. pulmo. The present paper verifies the release of stinging-cell structures in the water by R. pulmo and reports the case of two 17-year-old adolescents (one male and one female) who were affected by epidermal rashes consistent with the irritating sensations of stinging water. The reaction happened twice in the Ionian Sea; the patients were in proximity to R. pulmo but, on both occasions, there had been absolutely no direct contact with the jellyfish’s tentacles. To test the hypothesis of stinging water caused by R. pulmo, samples of sea water and mucous harvested in close proximity to a living jellyfish were taken and analyzed under a microscope at different magnifications. The microscopic analysis showed the presence of free and aggregated nematocysts in both the samples of water and mucous. It is likely that the free and aggregated nematocysts observed were discharged in the water by the jellyfish and were dispersed by water currents that led them to come into contact with the patients’ skin. At present, it is not known what predisposes humans to the perception of stinging water, and it is reasonable to affirm that caution should be advised for people with an allergic history when entering the water in the presence of jellyfish. Further investigations are required to better understand both the pathophysiological pathways underlying the stinging water phenomenon and the minimum concentration of urticating elements that is able to trigger the onset of stinging water. Full article

The jellyfish Rhizostoma pulmo, Macrì 1778 (Cnidaria, Rhizostomae) undergoes recurrent outbreaks in the Mediterranean coastal waters, with large biomass populations representing a nuisance or damage for marine and maritime activities. A preliminary overview of the antioxidant activity (AA) of R. pulmo proteinaceous compounds is provided here based on the extraction and characterization of both soluble and insoluble membrane-fractioned proteins, the latter digested by sequential enzymatic hydrolyses with pepsin and collagenases. All jellyfish proteins showed significant AA, with low molecular weight (MW) proteins correlated with greater antioxidant activity. In particular, collagenase-hydrolysed collagen resulted in peptides with MW lower than 3 kDa, ranging 3–10 kDa or 10–30 kDa, with AA inversely proportional to MW. No cytotoxic effect was detected on cultured human keratinocytes (HEKa) in a range of protein concentration 0.05–20 μg/mL for all tested protein fractions except for soluble proteins higher than 30 kDa, likely containing the jellyfish venom compounds. Furthermore, hydrolyzed jellyfish collagen peptides showed a significantly higher AA and provided a greater protective effect against oxidative stress in HEKa than the hydrolyzed collagen peptides from vertebrates. Due to a high reproductive potential, jellyfish may represent a potential socioeconomic opportunity as a source of natural bioactive compounds, with far-reaching beneficial implications. Eventually, improvements in processing technology will promote the use of untapped marine biomasses in nutraceutical, cosmeceutical, and pharmaceutical fields, turning marine management problems into a more positive perspective. Full article

Jellyfish outbreaks in marine coastal areas represent an emergent problem worldwide, with negative consequences on human activities and ecosystem functioning. However, potential positive effects of jellyfish biomass proliferation may be envisaged as a natural source of bioactive compounds of pharmaceutical interest. We investigated the biochemical composition of mature female gonads and lysozyme antibacterial activity of oocytes in the Mediterranean barrel jellyfish Rhizostoma pulmo. Chemical characterization was performed by means of multinuclear and multidimensional NMR spectroscopy. The ovaries of R. pulmo were mainly composed of water (93.7 ± 1.9% of wet weight), with organic matter (OM) and dry weight made respectively of proteins (761.76 ± 25.11 µg mg⁻¹ and 45.7 ± 1.5%), lipids (192.17 ± 10.56 µg mg⁻¹ and 9.6 ± 0.6%), and carbohydrates (59.66 ± 2.72 µg mg⁻¹ and 3.7 ± 0.3%). The aqueous extract of R. pulmo gonads contained free amino acids, organic acids, and derivatives; the lipid extract was composed of triglycerides (TG), polyunsaturated fatty acids (PUFAs), diunsaturated fatty acids (DUFAs), monounsaturated fatty acids (MUFAs), saturated fatty acids (SFAs), and minor components such as sterols and phospholipids. The R. pulmo oocyte lysate exhibited an antibacterial lysozyme-like activity (mean diameter of lysis of 9.33 ± 0.32 mm corresponding to 1.21 mg/mL of hen egg-white lysozyme). The occurrence of defense molecules is a crucial mechanism to grant healthy development of mature eggs and fertilized embryos (and the reproductive success of the species) by preventing marine bacterial overgrowth. As a corollary, these results call for future investigations for an exploitation of R. pulmo biomasses as a resource of bioactive metabolites of biotechnological importance including pharmaceuticals and nutrition. Full article

Prefoldin is a hexameric molecular chaperone found in the cytosol of archaea and eukaryotes. Its hexameric complex is built from two related classes of subunits, and has the appearance of a jellyfish: Its body consists of a double β-barrel assembly with six long tentacle-like coiled coils protruding from it. Using the tentacles, prefoldin captures an unfolded protein substrate and transfers it to a group II chaperonin. Based on structural information from archaeal prefoldins, mechanisms of substrate recognition and prefoldin-chaperonin cooperation have been investigated. In contrast, the structure and mechanisms of eukaryotic prefoldins remain unknown. In this study, we succeeded in obtaining recombinant prefoldin from a thermophilic fungus, Chaetomium thermophilum (CtPFD). The recombinant CtPFD could not protect citrate synthase from thermal aggregation. However, CtPFD formed a complex with actin from chicken muscle and tubulin from porcine brain, suggesting substrate specificity. We succeeded in observing the complex formation of CtPFD and the group II chaperonin of C. thermophilum (CtCCT) by atomic force microscopy and electron microscopy. These interaction kinetics were analyzed by surface plasmon resonance using Biacore. Finally, we have shown the transfer of actin from CtPFD to CtCCT. The study of the folding pathway formed by CtPFD and CtCCT should provide important information on mechanisms of the eukaryotic prefoldin–chaperonin system. Full article