Abstract
The neurotoxic effects produced by a tentacle venom extract and a fraction were analyzed and correlated by in vivo and in vitro approaches. The tentacle venom extract exhibited a wide range of protein components (from 24 to >225 kDa) and produced tetanic reactions, flaccid paralysis, and death when injected into crabs. Two chromatography fractions also produced uncontrolled appendix movements and leg stretching. Further electrophysiological characterization demonstrated that one of these fractions potently inhibited ACh-elicited currents mediated by both vertebrate fetal and adult muscle nicotinic acetylcholine receptors (nAChR) subtypes. Receptor inhibition was concentration-dependent and completely reversible. The calculated IC50 values were 1.77 μg/μL for fetal and 2.28 μg/μL for adult muscle nAChRs. The bioactive fraction was composed of a major protein component at ~90 kDa and lacked phospholipase A activity. This work represents the first insight into the interaction of jellyfish venom components and muscle nicotinic receptors.
Highlights
Scyphozoan jellyfish produce venoms that possess potent biological activities [1]
A. aurita specimens were originally collected as polyps from coastal waters of the Gulf of Mexico (Veracruz, México) and subsequently raised to ephyras and adult jellyfish in the facilities of the marine park “Xcaret” (Quintana Roo, México)
Since it has been demonstrated that the venom of Aurelia aurita jellyfish contains phospholipase A2 activity [12], we investigated the presence of this activity in the neurotoxic fractions identified in this study (TVE and fractions 4 and 5)
Summary
Scyphozoan jellyfish produce venoms that possess potent biological activities [1]. A similar feature has been suggested for other scyphozoan jellyfish venoms that appear to induce the opening or activation of non-selective cationic channels and a subsequent increase of inward sodium-elicited currents [13,14,15,16]. The vertebrate muscle nAChRs are divided into fetal (α1β1γδ) and adult (α1β1εδ) subtypes depending on the subunit stoichiometry and the developmental stage of muscle [18] Both subtypes are found at the postsynaptic membrane of the neuromuscular junction and their inhibition has been demonstrated to lead to skeletal muscle paralysis [19]. We assessed some A. aurita neurotoxic compounds on fetal and adult muscle nAChRs using the voltage clamp technique. The neurotoxic compounds were tested in a qualitative enzymatic assay used as a preliminary indicator of phospholipase activity
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