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The puffer fish is poisonous, but not venomous, while a rattlesnake is venomous but not poisonous. Both can kill you with their toxins. Sound confusing? Let鈥檚 try to clear it up.
A poison is any substance that, when introduced into a living organism, kills or injures it in some way. If the poison is produced by a living organism, such as bacteria, plants, fungi or animals, then it is called a toxin. Both the puffer fish and the rattlesnake produce toxins, but they do not deliver them the same way.
If a toxin is delivered via a sting or bite, it is called a venom. All toxins are poisons, but not all poisons are toxins. Potassium cyanide is a poison, but it is not a toxin because it isn鈥檛 produced by a living organism.
To simplify things, if you bite it and you die, it鈥檚 poisonous. If it bites you and you die, it鈥檚 venomous. In both cases, the culprit is a toxin.
When a toxin is eaten or absorbed through the skin, it is usually referred to as a poison, so a rattlesnake would not be poisonous because it can be eaten. Its toxin is found only in its venom. The puffer fish, despite the protruding spikes on its skin, is not venomous because the spikes do not contain tetrodotoxin, the potentially lethal toxin found in some of the fish鈥檚 organs. In Japan, puffer fish is a delicacy and is featured in some restaurants, where it is prepared by chefs specifically trained to remove all parts of the fish that can harbour tetrodotoxin.
While the spikes on the puffer do not deliver tetrodotoxin, a 鈥渄agger shoe鈥� did exactly that in Ian Fleming鈥檚 1957 novel From Russia, With Love. James Bond collapses after being kicked by villain Rosa Klebb with a tetrodotoxin-coated blade that springs out from her shoe.
As explained in Dr. No, the next Bond novel, 007 survived because a doctor thought he had been poisoned with curare and treated him with the appropriate curare antidote 鈥� which happened to work for tetrodotoxin poisoning. Curare causes paralysis by blocking the action of the neurotransmitter acetylcholine and drugs that increase levels of acetylcholine, such as physostigmine, can serve as an antidote for curare poisoning. There is no antidote for tetrodotoxin, so we have to assume that it was Bond鈥檚 strong constitution that allowed him to live another day.
While there is no antidote for tetrodotoxin, there is for snake venom. That takes us back to the 1890s, when French physician Albert Calmette became intrigued with the lethal venom of the Indian cobra while working at the Pasteur Institute in Ho Chi Minh City (then Saigon). He knew about the work of Emil von Behring, who had inoculated horses with the bacteria that cause diphtheria and isolated an 鈥渁ntitoxin鈥� from the horse鈥檚 blood that could treat the disease. Calmette followed a similar procedure with cobra venom and isolated an antivenom in a similar fashion.
The same procedure is used today, but the problem is that snake venom has great variability in chemical composition and every type of snake requires a different antivenom. These are not always available and about 125,000 people die every year from snake bites.
While snake venom can kill, it can also cure. A number of medications have been developed based upon studying the chemistry of snake venom. Perhaps the best example is Captopril, a drug widely used to lower blood pressure.
In 1965, a peptide from the venom of the Brazilian pit viper was isolated and found to inhibit the action of angiotensin-converting enzyme (ACE) that is involved in raising blood pressure. While this peptide, a short chain of amino acids, inhibited ACE in lab studies, it could not be used as a medicine because it was quickly broken down during digestion. After studying the structure of the peptide, researchers came up with a molecule that was stable and mimicked its activity. This came to be known as Captopril, the first in a class of ACE-inhibitors that have become a mainstay in managing cardiovascular disease.
Other venomous creatures have also contributed to the advancement of pharmacology. Cone snails are beautifully coloured sea snails, but it is best to leave them alone. They are equipped with a little 鈥渉arpoon鈥� with which they can attack either prey or a predator and inject a potent venom.
A synthetic peptide modeled on one of the peptides in the snail鈥檚 venom is a more powerful pain killer than morphine but is not addictive. Being a peptide, it cannot be taken orally and has to be injected into the cerebrospinal fluid, so it has limited use, but can be very effective when all else fails.
The venom in the saliva of the Gila monster, a lizard native to the southern U.S., contains a peptide very similar to GLP-1, the natural hormone that regulates blood sugar and promotes a feeling of fullness. GLP-1 cannot be used as a drug because it has a very short lifetime when introduced into the bloodstream, but the Gila monster鈥檚 peptide is longer lasting and studying its amino acid sequence led to a synthetic peptide that is effective when injected. Exenatide (Byetta) became the first 鈥淕LP-1 agonist,鈥� a drug that mimics the action of GLP-1.聽.
While there are no venomous plants, there certainly are poisonous ones. You would do well to stay clear of any manchineel trees that you may encounter on a trip to Florida. The fruit of the tree was described by Columbus as 鈥渄eath apples,鈥� although one wonders about how he discovered this. That bit of information is conveyed on a sign posted on manchineel trees that also warns to avoid any contact with the tree and to forget about seeking shelter from the rain under the tree鈥檚 leaves because rain can dislodge sap that can cause terrible blisters.
Blisters are one thing, death quite another. An episode of the hit television series White Lotus features an attempted murder with the seeds of the 鈥減ong-pong tree鈥� native to Asia. The tree bears fruit with seeds that that contain cerberin, a 鈥渃ardiac glycoside鈥� that can stop the heart, justifying the term 鈥渟uicide tree.鈥�
In the show, the murderer changes his mind and knocks the toxic pina colada he had prepared with the seeds out of the intended victims鈥� hands. So there was no need to involve possible treatments for the poisoning in the plot. That would be atropine, a toxin found in the bella donna plant.
Toxins can kill or cure.
