RESUMO
Aurelia aurita is scyphozoan, abundant in the Mexican Caribbean during summer. Although usually innocuous, there is evidence of it causing harm to humans. This work investigates the biological activities of crude and fractionated extracts of A. aurita. Live specimens were collected between July and September 1999 from the Mexican Caribbean. The tentacular margin was dissected immediately and frozen at -50ºC. A nematocyst suspension was prepared, discharged, and the supernatants lyophilized. Hemolytic assay was performed with lyophilized crude extract on bovine, sheep, and human red blood cells. Erythrocyte sensitivity to the toxin was ranked in descending order: human, sheep, and bovine. Toxic activity on Artemia nauplii was evaluated using the same crude extract for different exposure periods (3, 5, and 10 hours); only 48 and 72 hour old Artemia nauplii showed 50 per cent mortality. Partial toxin purification was completed by sequential liquid chromatography using three gels (Sephadex G-200, DEAE Sephadex A-50, and Sephadex G-100). Intramuscular neuroactivity was detected in the crab Ocypode quadrata for two partially purified fractions. These fractions were found to have molecular weight components of 66 and 45 kDa, respectively.
Assuntos
Animais , Artemia , México , Venenos , CifozoáriosRESUMO
In this study, we determined hemolysis activity in human and sheep erythrocytes, and characterized the electrical responses in Xenopus oocyte membrane elicited by the venom of the jellyfish Cassiopea xamachana (Cx). The Cx venom produced hemolysis in both species, being more potent on human red cells. The electrophysiological study showed that the Cx venom elicited three different responses in the oocytes. One current was generated in all the oocytes tested and corresponded with a slow inward current (I(Cx)) associated with an increase in membrane conductance. I(Cx) was concentration-dependent and had a reversal potential of -10.3+/-0.4 mV. Ionic substitution studies indicated that the conductive pathway was mainly permeable to cations and non-selective. The oocyte membrane resistance was completely recovered after washout of the venom, this suggested that the effect was due to generation of a specific membrane conductance as opposed to a possible non-specific membrane breakdown. A comparative study with three distinct native cationic channels present in the oocyte membrane [i.e. (1) hemi-gap-junction channels, (2) mechanosensitive channels, and (3) the ouabain-sensitive channel activated by palytoxin], showed that I(Cx) might correspond to opening of mechanosensitive channels or to activation of an unknown cationic channel located in the oocyte membrane. The bioactive fraction eliciting I(Cx) were peptides and was separated from two other peptidic hemolytic fractions by chromatography.
Assuntos
Venenos de Cnidários/farmacologia , Hemólise/efeitos dos fármacos , Animais , Sobrevivência Celular/efeitos dos fármacos , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Venenos de Cnidários/antagonistas & inibidores , Venenos de Cnidários/química , Estimulação Elétrica , Eletrofisiologia , Eritrócitos/efeitos dos fármacos , Gadolínio/farmacologia , Junções Comunicantes/efeitos dos fármacos , Humanos , Potenciais da Membrana/efeitos dos fármacos , Óvulo/efeitos dos fármacos , Técnicas de Patch-Clamp , Ovinos , XenopusRESUMO
BACKGROUND: Seabather's eruption (SBE) is a highly pruritic dermatosis affecting swimmers and divers in marine waters off Florida, in the Gulf of Mexico, and the Caribbean Sea. Its cause has been attributed to various organisms but recently to the larvae of the schyphomedusa, Linuche unguiculata. OBJECTIVE: We attempted to determine whether immature and adult Linuche cause SBE. METHODS: Episodes of SBE in the Cancun and Cozumel area of the Mexican Caribbean were evaluated during the season of high tourism (January-June). This time corresponds to the moments in the life cycle when the three swimming stages of L unguiculata-ephyrae, medusae, and larvae-can be sequentially observed. Our methods include (1) observations by divers, biologists, and students coinciding with stinging outbreaks and the onset of SBE; (2) serologic evaluation of individuals stung by L unguiculata; and (3) the demonstration of Linuche nematocysts on the affected skin. RESULTS: All 3 swimming Linuche stages can cause SBE. CONCLUSION: The offending stages of Linuche can be identified by the cutaneous lesion's morphology and the time of year.
Assuntos
Venenos de Cnidários/intoxicação , Prurido/etiologia , Dermatopatias Vesiculobolhosas/etiologia , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Feminino , Humanos , Estágios do Ciclo de Vida , Masculino , Pessoa de Meia-Idade , Cifozoários/crescimento & desenvolvimento , NataçãoRESUMO
Multiple stages of Liriope tetraphylla caused paresthesias leading to chafing and excoriations in swimmers along the Southern Uruguayan and Northern Argentinean Atlantic coasts. These episodes appear seasonally in the summer and affect groups of bathers in shallow water (1-3 m).
Assuntos
Mordeduras e Picadas/complicações , Parestesia/etiologia , Dermatopatias/etiologia , Zooplâncton , Adulto , Animais , Humanos , Masculino , Parestesia/patologia , Prurido/etiologia , Prurido/patologia , Cifozoários , Dermatopatias/patologiaRESUMO
Adult Linuche unguiculata medusae cause seabather's eruption just like that animal's larval form. This observation explains the wide seasonal incidence and the fact that lesions can appear on exposed skin.