Reptile venom is complex mixtures of biological compounds secreted in venom glands and delivered through spurs, stingers or fangs. It contains enzymes, proteins, peptides, lipids, nucleosides and carbohydrates. It also contains metal ions.게코도마뱀
Snakes use venom for hunting and self-defense, as well as for digesting prey. This natural weapon drains the energy of a snake, so they only use it when threatened or to kill their prey.
Venom from some snakes, particularly elapids and viperids, attacks the nervous system directly. These toxins block nerve signals, paralyzing the muscles, including those used for breathing, and often killing victims who do not receive prompt medical treatment.
Snake venom researchers have found many toxins that affect diverse functions in the nervous system 게코도마뱀 . These include neurotoxins, which attack postsynaptic targets such as voltage-dependent ion channels, and cytotoxins, which attack cells that are vital for the functioning of nerves. For example, a neurotoxin isolated from the venom of a black-necked cobra (Naja and other genera) can directly disrupt the electrical impulses that nerves and muscles use to communicate. This venom can kill reptiles within minutes by stopping the muscles that help them breathe, and the dead muscle cells clog the kidneys as they try to filter out the proteins.
Another type of toxin is a presynaptic neurotoxin, such as those in the venoms of viperids. These toxins, such as crotoxin from the pit viper C. durissus terrificus and a-agkistrodotoxin from the Agkistrodon halys pallas, act on presynaptic neuromuscular junctions to prevent the release of the neurotransmitter acetylcholine. They can also reduce the influx of calcium ions into nAChR by inhibiting adenosine triphosphate hydrolysis, causing depolarization and blocking aChR-induced inhibition of twitch responses in cultured neurons.
Hemotoxic and neurotoxic venoms are two ends of a continuum, as most venomous snake species contain a mixture of the two types of proteins in their venom. But th 게코도마뱀 e relative lethality of venoms may differ between species. It may also vary with the age of a given snake.
The hemotoxic venom in snakes kills its prey and can also cause deadly internal bleeding (hemorrhagic) in humans. This venom is found in boomslangs (Dispholidus typus) and twig snakes (Thelotornis spp). These toxins break down blood cells, thin the blood, and cause clotting problems. Hemotoxic venom can trigger multiple types of bleeding in humans, including bleeding at the bite site, and in the gastro-intestinal tract and genito-urinary tract. This can be augmented by toxin-induced vasodilation and vascular damage, such as the destruction of capillary basement membranes.
Hemotoxic venom may also cause hypotension and shock. It can induce systemic blood loss by degrading the plasmin protein that helps clot the blood and by causing the vWF factor to decrease. In addition, some venom proteins can inhibit platelet function and cause a “true” anticoagulant effect.
Hemotoxic venom from sea snakes (Daboia russelii), cobras (Naja spp) and mambas (Dendroaspis spp) can directly damage nerves in the body. This can cause breathing problems, muscle death and vision problems. These venoms can also cause kidney failure from the buildup of dead muscle cells that clogs the kidneys. The venoms of most snake species are mixtures of hemotoxic and neurotoxic proteins. This is why it’s important to understand the type of snake that bit you and use the right antivenom when necessary. Different venom types are designed to serve different roles, from subduing ectotherms, to killing larger endotherms for food, or to cause pain and paralysis in predators and antagonists.
Virtually all snake venoms contain cytotoxic proteins that disrupt cellular structures, causing local cell death or necrosis. Cytotoxic proteins are found in all venom families but are particularly abundant in king cobra (Ophiophagus) and viper (Viperidae) venoms. These proteins typically act by interacting with anionic phospholipid membranes, disrupting their structure and forming pores which lead to cell lysis, inactivation or depolarization of the cell. These events trigger a series of deleterious cellular cascades which result in the death of the cell and consequent tissue necrosis and oedema.
The cytotoxic proteins in snake venoms can be divided into myotoxins that target skeletal muscle fibres and cardiotoxins which target heart muscles. Some cytotoxic proteins attack multiple target groups at the same time, resulting in indiscriminate tissue death referred to as cytotoxicity.
Ecologically, the neurotoxic proteins in viper and rattlesnake venoms tend to focus on endothermic prey (like mammals, birds and other vertebrates) while hemotoxins dominate in ectothermic snake venoms like those of spitting cobras and adder family members.
These complex venoms are delivered by snakes through hollow, movable fangs that inject venom into prey via a modified salivary gland located in the front of the mouth. Despite its lethal capabilities, the majority of snake bites lead to only mild and occasionally serious complications, such as pain, swelling and bleeding from the mouth, nose or throat.
For decades, scientists have believed that animal venom is sterile, thanks to the presence of antimicrobial chemicals. But a new study, led by Sterghios Moschos, an associate professor in the cellular and molecular sciences department at Northumbria University, has found that snake and spider venoms are surprisingly populated with microorganisms, including bacteria that can cause infection in humans who suffer a bite.
The researchers looked for bacterial 16S sequences in the venom of five snake and two spider species and compared them with a sample of the animals’ oral flora. They then used culture and culture-free methods to search for bacteria in the venom samples and identified them by DNA analysis. They found culturable microorganisms in all but one sample of the venom of black-necked spitting cobras (Naja nigricollis), and that strain had remarkably resilient genes, suggesting that it evolved to survive extreme conditions.
The researchers also showed that the venom possessed significant antimicrobial properties, which could be useful for treating bacterial infections caused by snake bites. But they point out that the venom must first survive the process of lyophilization, which is basically freeze-drying, in order to be useful for antibiotic treatment. That’s why it’s important to seek emergency medical care immediately after a possible snake bite. Keep in mind, too, that a venomous bite can be fatal even for a healthy individual who gets prompt emergency care and antivenom.