Trachynilysin, a neurosecretory protein isolated from stonefish (Synanceia trachynis) venom, forms nonselective pores in the membrane of NG108-15 cells.

Trachynilysin, a protein toxin isolated from the venom of the stonefish Synanceia trachynis, has been reported to elicit massive acetylcholine release from motor nerve endings of isolated neuromuscular preparations and to increase both cytosolic Ca2+ and catecholamine release from chromaffin cells. In the present study, we used the patch clamp technique to investigate the effect of trachynilysin on the cytoplasmic membrane of differentiated NG108-15 cells in culture. Trachynilysin increased membrane conductance the most when the negativity of the cell holding membrane potential was reduced. The trachynilysin-induced current was carried by cations and reversed at about -3 mV in standard physiological solutions, which led to strong membrane depolarization and Ca2+ influx. La3+ blocked the trachynilysin current in a dose-, voltage-, and time-dependent manner, and antibodies raised against the toxin antagonized its effect on the cell membrane. The inside-out configuration of the patch clamp technique allowed the recording of single channel activity from which various multiples of 22 pS elementary conductance were resolved. These results indicate that trachynilysin forms pores in the NG108-15 cell membrane, and they advance our understanding of the toxin's mode of action on motor nerve endings and neurosecretory cells

Secretagogue activity of trachylysin, a neurotoxic protein isolated from stonefish (Synanceia trachynis) venom

Approximately 400 to 500 species of marine fish may be poisonous to humans after ingestion. Most poisonous fish are nonmigratory reef fish and can be either herbivores or carnivores. Some of them have tissues that are toxic at all times, others are poisonous during certain periods of the year or in certain geographical areas, and still others have only specific organs that are toxic, and their toxicity may vary with time, location, and habitat. More than 200 species of marine fish, including stingrays, scorpionfish, weevers, and stargazers, possess some form of venom apparatus capable of inflicting serious and occasionally fatal wounds to humans. Most venomous fish are nonmigratory, shallowwater reef or inshore fish, and they use their venom apparatus as a defensive weapon. The Indian and Pacific Oceans and the Red Sea contain numerous genera and species of venomous fish belonging to the family Scorpaenidae. Members of this family are commonly called scorpionfish, and they include three stonefish (Synanceia) species, which possess numerous pairs of well-developed venom glands and cause severe disease in humans. The results of clinical and pharmacological studies indicate that stonefish venoms cause: intense pain in humans; extensive local tissue edema and necrosis of skin tissue; a marked increase in the spontaneous release of neurotransmitters; irreversible damage to and depolarization of muscle cells; muscle twitches, incoordination, and paralysis (neuromuscular blockade); hypotension; and respiratory and cardiac failure

Secretagogue activity of trachylysin, a neurotoxic protein isolated from stonefish (Synanceia trachynis) venom

Approximately 400 to 500 species of marine fish may be poisonous to humans after ingestion. Most poisonous fish are nonmigratory reef fish and can be either herbivores or carnivores. Some of them have tissues that are toxic at all times, others are poisonous during certain periods of the year or in certain geographical areas, and still others have only specific organs that are toxic, and their toxicity may vary with time, location, and habitat. More than 200 species of marine fish, including stingrays, scorpionfish, weevers, and stargazers, possess some form of venom apparatus capable of inflicting serious and occasionally fatal wounds to humans. Most venomous fish are nonmigratory, shallowwater reef or inshore fish, and they use their venom apparatus as a defensive weapon. The Indian and Pacific Oceans and the Red Sea contain numerous genera and species of venomous fish belonging to the family Scorpaenidae. Members of this family are commonly called scorpionfish, and they include three stonefish (Synanceia) species, which possess numerous pairs of well-developed venom glands and cause severe disease in humans. The results of clinical and pharmacological studies indicate that stonefish venoms cause: intense pain in humans; extensive local tissue edema and necrosis of skin tissue; a marked increase in the spontaneous release of neurotransmitters; irreversible damage to and depolarization of muscle cells; muscle twitches, incoordination, and paralysis (neuromuscular blockade); hypotension; and respiratory and cardiac failure

The contribution of intracellular calcium stores to mEPSCs recorded in layer II neurones of rat barrel cortex

Loading slices of rat barrel cortex with 50 μm BAPTA-AM while recording from pyramidal cells in layer II induces a marked reduction in both the frequency and amplitudes of mEPSCs. These changes are due to a presynaptic action. Blocking the refilling of Ca2+ stores with 20 μm cyclopiazonic acid (CPA), a SERCA pump inhibitor, in conjunction with neuronal depolarisation to activate Ca2+ stores, results in a similar reduction of mEPSCs to that observed with BAPTA-AM, indicating that the source for intracellular Ca2+ is the endoplasmic reticulum. Block or activation of ryanodine receptors by 20 μm ryanodine or 10 mm caffeine, respectively, shows that a significant proportion of mEPSCs are caused by Ca2+ release from ryanodine stores. Blocking IP3 receptors with 14 μm 2-aminoethoxydiphenylborane (2APB) also reduces the frequency and amplitude of mEPSCs, indicating the involvement of IP3 stores in the generation of mEPSCs. Activation of group I metabotropic receptors with 20 μm (RS)-3,5-dihydroxyphenylglycine (DHPG) results in a significant increase in the frequency of mEPSCs, further supporting the role of IP3 receptors and indicating a role of group I metabotropic receptors in causing transmitter release. Statistical evidence is presented for Ca2+-induced Ca2+ release (CICR) from ryanodine stores after the spontaneous opening of IP3 stores