RESUMO
A novel Conus peptide, conorfamide-Sr1, has been characterized. The sequence of the natural peptide was determined using standard Edman sequencing methods and mass spectrometry, and confirmed by chemical synthesis. The peptide has 12 amino acids and no cysteine residues. The following sequence was obtained: GPMGWVPVFYRF-NH(2). No other peptide from a vermivorous Atlantic Conus species has previously been characterized. Conorfamide-Sr1 belongs to the RFamide neuropeptide family, and is the first RFamide peptide to be found in any venom. The presence of conorfamide-Sr1 as a major peptide in Conus spurius venom suggests that Conus lineages in the Atlantic may have evolved novel Conus venom peptide families.
Assuntos
Venenos de Moluscos/química , Peptídeos/química , Sequência de Aminoácidos , Animais , Evolução Biológica , Espectrometria de Massas , Dados de Sequência Molecular , Neuropeptídeos/químicaRESUMO
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.