Lethal Cocktail – The Venom

By | 2017-09-27T19:33:57+00:00 September 27th, 2017|Scientific|

Don’t ask how life is treating you; ask how you are treating life!

Once this is focused on, you will soon see you are not the victim of an unloved destiny, but rather the creator just as equal.

-Daniel Chidiac

 

Throughout the process of evolution, organisms were constantly subjected to harsh environmental conditions, competition, and predation from other dominating organisms. So to survive in such situations, organisms had to constantly adapt themselves to the changing environmental & social conditions and qualify nature’s survival tests. Only then did they stand a chance of reproducing and increasing their numbers as a specie – thus explained the “Survival of the Fittest” theory. In this context, organisms have evolved various mechanisms that can help them defend themselves from being attacked or consumed, and to ensure their survival. Plants have figured a way to produce toxins and save themselves from being eaten, similarly have few of the primitive organisms – this being referred to as “venom”. A toxin can be generalised as “a product derived from the metabolic activities of an individual/animal that on introduction into tissue or body of other living body produces adverse pathological effects which may result in death”. Venom is proteinaceous (made out of proteins) in character and antigenic (antigen-immune system related) in nature. Toxins can range from a number of complex, still incompletely characterised enzymes, to proteins or simple biological molecules such as formic acid produced by insects like ants etc.,.

Amongst the lizards, two species of HelodermaHeloderma suspectum, generally called ‘Gila monster,’ and Heloderma horridum, generally called ‘Mexican beaded lizard’ are known to be toxic. In these lizards, the upper teeth are grooved and there are four venom glands on each side that bath the teeth from the top. When they bite, the follow a ‘hold on and chew pattern’ in order to deliver the venom more efficiently. A bite from these lizards produces unbearable pain and swelling at the site of envenomation, which progresses upwards in the body. Though fatalities are rare, cardiovascular shock and central nervous system depression may occur.

In the case of amphibians, a few types of salamanders, toads, and frogs have potent toxins which are secreted from their skin. Toads generally secrete a repulsive substance from their skin that makes them highly undesirable to touch. Certain species like the Incilius alvarius (Colordo river toad) and Rhinella marina (Cane toad) are venomous, while the frogs from Dendrobates species like the poison dart frog and other dart frogs are poisonous, there even being records of the latter’s poison being used  in warfare by the local tribes. The event of pet animals like dogs accidently mouthing such toads, has resulted in some very serious poisoning. The symptoms of intoxication appear within a few minutes, and these may include profuse salivation, prostration, cardiac arrhythmia, pulmonary edema, hypertension, and even convulsions. It may take an approximate fifteen minutes for death to ensue, once the symptoms appear.

The unavailability of an effective antidote is a serious concern in such cases. However, symptomatic therapies can be lifesaving, if administered at the right time. Salamanders like Taricha torosa (California newt) pose a potent toxin called tetradotoxin which is similar to that found in the Puffer fish. Tetradotoxin is a neurotoxin that acts by blocking the sodium ion channels. The tetradotoxin molecules bind with the voltage gated sodium ion channels and inhibit the firing of action potential in the neuronal cell membrane. Even a recently discovered newt from India called the Himalayan newt or crocodile newt is deemed to be toxic by scientists.

Most of the animal toxins are proteinaceous colloidal substances, and snake venoms are a typical example of this. Much of these venom proteins have enzymatic properties and cause denaturisation of body proteins or membrane proteins and other biological molecules. Venom is a cocktail of a large number of potent and toxic compounds. The overall hazard from a snake bite is a combination of relative potency of snake venom and the amount of venom the snake can release during the bite. Some species of serpents can yield as much as 720mg of venom!

Apart from the toxicity of the venom, the size of the snake also plays a crucial role as larger snakes are likely to have a larger venom gland. When a snake strikes at its prey, most often the venom glands are emptied. If the supply of venom is not fully replenished in the venom gland, then the period lapsed between the last prey and the bite may be considered. Juveniles and yearlings can be more toxic then adults at times. For example, in the Rattle snakes and Copper heads, the venom potency can reach to maximum at an age of 6 – 9 months, and then a slight decrease may be noticed as they age, although there hasn’t been any marked difference recorded, based on the gender of the snake. While toxicity is largely dependent on the snake specie, body weight of the victim, dose of venom that entered into the victim are some other envenomation influencing factors.

There exist two types of toxins in snakes – Neurotoxin, which employs toxic peptides and amino acids, and Hemotoxin, the effects of which are mediated by enzymatic constituents of the venom. Some of the components in the venom may not be toxic by themselves, but they help in the toxicity of other compounds. For instance, hyaluronidase helps spread the toxins within the tissue and increase the damage caused by proteolytic or any other enzymes.

The Viper’s venom being hemotoxic, contains compounds such as antifibrinolysin which interferes with the clotting mechanism. This causes symptoms of blood loss from the wound, internal bleeding etc. Further, several other reactions take place in tandem if left untreated – the antiprothrombic factor induces blood haemorrhage, antithromboplastic factor and fibrinolysin cause cardiovascular damage, complement (C-3) inhibitor prevents complement activities and interferes with the immune mechanism, thereby weakening the body’s immune mechanism, DNAase denatures the DNA, exopeptidase and lipase destroy proteins and cause tissue damage along with hydrolysing lipids in the cell wall respectively, there by showing myotoxic (myo-muscle) properties, and so on. It is therefore, not just one aspect that is targeted and damaged by veno rather a spectrum of damages that ensues.

To be more specific, venom creates havoc in the molecular level by altering and blocking biological cycles that are necessary in the survival of an individual, and even by arresting ATP synthesis, causing oxidative stress etc. Effective treatment of a venomous snake bite is therefore only possible when the person is given appropriate medical assistance within recommended time limit, the sooner being the better. Some of the DOs after a snake bite include washing the bite under running water as soon as possible to prevent the venom on the skin from entering the wound, immobilising the affected limb, staying calm, and most importantly, getting medical aid.  Contrary to media portrayals and hear-say, never attempt to make cuts or lacerations at the bite site and sucking at the bite site, as the venom may enter into the oral cavity and cause further complications. The basic rationale behind, being that venom doesn’t stay at the place of bite, but mixes with the blood stream spreads to other parts of the body. It is therefore very important not to excite the bite victim in any manner, as this would result in an increased heart beat which translates to faster distribution of venom in the blood stream. The first aid in the event of a snake bite can be illustrated as below:

 

Deepak Tarun

Deepak Tarun is a post graduate in Zoology. Not one to embrace anything at its face value, Deepak believes in really digging to the roots, before arriving at a decision. A budding wildlife biologist and passionate knowledge seeker, Deepak likes to read, and watch stand-up comedy in his spare time.