Intro and Evolution of Toxins Flashcards
What is the difference between a toxin and a toxicant?
Toxin is something that is naturally derived and a toxicant is something that is man made
What are the characteristics of a poison?
small molecule toxins, only one toxin present, must be consumed or contacted and used to deter predators
What are the characteristics of venom?
mix of proteinaceous toxins, result in severe pain, incapacitation or death, must be injected and is used for prey capture of defence
What are some examples of poisonous organisms?
Bacteria, blue-green algae, fungi, plants, arthropoda, aquatic vertebrates, marine invertebrates, terrestrial vertebrates and birds
What are some examples of venomous organisms?
marine invertebrates, arthropoda, and reptiles
What are the two most basic reasons to produce a toxin?
To eat and to avoid being eaten
What is meant by the term exochemical and why are toxins considered this?
Exochemical is a substance that performs outisde the producing organisms body
What genetic process had a major role in toxin development? Describe why.
Gene duplication- one gene is able to keep its original function while the other gene can be subject to mutations without disrupting the original process encoded by the gene.
Why are duplicated genes subject to more mutations and what is this process referred to as?
Escaping negative selection-removes the force that protects the gene from harmful mutations
What are the three types of toxin resistance and explain
Predator resistance: where predator is resistant to the toxins of its prey
Prey resistance: where the prey is resistant to the toxins of a predator
Autoresistance: where an animal is resistant to its own toxins
What are three evolutionary mechanisms that contribute to toxin resistance?
Target modification: gene sequence changes so that affinity for toxin reduces
Off-target repurposing: when an allosteric site has a higher affinity for the toxin than the receptor, causing a non harmful effect of toxin
Toxic scavenging: serum based components that inhibit the activity of enzymatic toxins
What is a real world example of toxin resistance and the toxin then becoming more potent to counteract this issue?
Squirrels becoming resistant to snake venom metalloproteinases (SVMPs) and the snake venom then having higher activity of SVMP
What are some theories that explain the phenomenon of tetrodotoxin?
Convergent evolution- all organisms with no evolutionary relationship all developed this
Bacterial Symbiosis: all organisms that produce this toxin have the same bacteria that produce this toxin (more likely)
What two organisms have developed the same resistance to TTX without having any evolutionary similarities?
Pufferfish and newts have mutations in their sodium channels to reduce sensitivity TTX so they are unable to be poisoned by it
Why do cyanobacteria produce toxin?
Protection against grazers and competition
