Toxin II isolated from the sea anemone Anemonia sulcata enhances activation of the action potential sodium ionophore of electrically excitable neuroblastoma cells by veratridine and batrachotoxin. This heterotropic cooperative effect is identical to that observed previously with scorpion toxin but occurs at a 110-fold higher concentration. Depolarization of the neuroblastoma cells inhibits the ...

Iodination of toxin II from the sea anemone Anemonia sulcata gives a labeled monoiododerivative that retains 80% of the original neurotoxicity. This derivative binds specifically to rat brain synaptosomes at 20 degrees C and pH 7.4 with a second-order rate constant of association ka = 4.6 x 10(4) M-1 sec-1 and a first-order rate constant of dissociation kd = 1.1 x 10(-2) sec-1. The binding occu...

Many stony coral-dwelling fishes exhibit adaptations to deal with hypoxia among the branches of their hosts; however, no information exists on the respiratory ecophysiology of obligate fish associates of non-coral organisms such as sea anemones and sponges. This study investigated metabolic and behavioral interactions between two-band anemonefish (Amphiprion bicinctus) and bulb-tentacle sea ane...

The effects of polypeptide neurotoxin from Anemonia sulcata on nerve conduction in crayfish giant axons and on frog myelinated fibers have been analyzed. The main features of toxin action are the following: (i) the toxin acts at very low doses and its action is apparently irreversible. (ii) The toxin selectively affects the closing (inactivation) of the Na+ channel by slowing it down considerab...

Jellyfish, hydras, corals and sea anemones (phylum Cnidaria) are known for their venomous stinging cells, nematocytes, used for prey and defence. Here we show, however, that the potent Type I neurotoxin of the sea anemone Nematostella vectensis, Nv1, is confined to ectodermal gland cells rather than nematocytes. We demonstrate massive Nv1 secretion upon encounter with a crustacean prey. Concomi...

Crabs of the genus Lybia have the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses on Lybia leptochelis from the Red Sea holding anemones of the genus Alicia (family Aliciidae). These anemones have not been found free living, only in association with L. leptochelis. In an attemp...

We investigated the effects of prolonged repolarization induced by slowed inactivation of Na+ channel on adrenaline-induced arrhythmias in halothane anesthetized, closed-chest dogs. We used sea anemone toxins (ATX-II and Anthopleurin-A) to prolong ventricular repolarization and examined their effects on adrenaline arrhythmias. Sea anemone toxins prolonged the QTc- and JTc-intervals (P<0.01), bu...

A new peptide, APETx1, which specifically inhibits human ether-a-go-go-related gene (HERG) channels, was purified from venom of the sea anemone Anthopleura elegantissima. APETx1 is a 42-amino acid peptide cross-linked by three disulfide bridges and shares 54% homology with BDS-I, another sea anemone K+ channel inhibitor. Although they differ in their specific targets, circular dichroism spectra...

Animals often retreat to refugia when alarmed and the time they spend hiding reflects an economic decision that trades off reducing predation risk with other beneficial activities. Typically, refugia such as burrows are static, but some refugia are dynamic. For species with defensive mutualisms, hiding might be contingent on their mutualist's behaviour. We disturbed and quantified hiding time i...