Effect of crude venom from nematocysts of Pelagia noctiluca (Scyphozoa) on spread discharge of acontia of Calliactis parasitica (Anthozoa).

The present investigation was aimed at assessing the toxic power of crude venom from Pelagia noctiluca nematocysts on spread discharge of in situ acontial nematocytes. Spread discharge, under 553mMNaSCN plus 10 mM Ca2+, consists of the protrusion and firing of the nematocytes all along the acontial filament. Acontia from Calliactis parasitica were treated with the discharging solution under a constant flow as a control condition. In a separate experiment acontia were firstly treated with Pelagia noctiluca crude venom aliquots and then with the discharging solution to prove spread discharge. Crude venom blocked the discharge with a dose-dependent irreversible effect. From these results arises that crude venom of Pelagia noctiluca nematocysts can affect the spread discharge with a mechanism that is still unknown. It could be hypothesized that crude venom can block gap junctions probably involved in this cellular communication. Nevertheless either a damage of cells involved in nematocyte activation or even the inhibition of Ca2+ influx, needed for discharge triggering, could be even suggested. Other studies will verify crude venom action mechanisms and may confirm the spread discharge as an interesting biological assay aimed at toxicological investigations.