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At Esquire
Could future humans evolve to have poison glands? In new research, scientists are closing a long-open door by causally linking early salivary glands to what eventually became venom glands in many animals.
Because saliva is the common denominator, that means anyone with salivary glands could potentially develop venom – from mice in the new experiment to humans.
First, the facts. In this study, scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) and the Australian National University set out to answer an old question in evolutionary biology: How did venom glands evolve in animals?
“Oral venom systems have evolved repeatedly in many vertebrates, allowing the exploitation of unique predatory niches. However, how and when they evolved remains poorly understood ”, explain the researchers.
To narrow the field of possible responses, the scientists studied the cluster of several thousand genes that express themselves in tandem with the release of venom in animals with venom glands. They found that the same genes and physical mechanisms were at work in old, simple salivary glands in other animals:
“We found that the general expression of the venom gland genes was surprisingly well preserved compared to the salivary glands of other amniotes. We characterized the “metavenom network”, a network of ∼3,000 nonsecreted housekeeping genes which are strongly coexpressed with toxins and which are mainly involved in protein folding and modification. “
Basically, the salivary glands serve as empty bowls and the venom glands serve as bowls filled with poison. The missing piece is not in the genes or the mechanism, but in the content of what is released by the glands: special proteins.
Why is venom such a mystery? It’s mainly just that scientists haven’t studied it en masse, and that’s partly because the venom is surprisingly common and eclectic. “While many snakes use an oral venom system to secure their prey, there are also mammals, such as shrews and solenodons, which have developed oral venom systems (based on the salivary glands) for capture or defense of prey, ”say scientists. There are thousands of poisonous animal species.
This widespread nature is one of the reasons a common genetic ancestor is so exciting. In this case, the researchers highlighted the shared link between, in particular, mammals and reptiles. There are only a handful of poisonous mammals, and the actual venom they secrete is different. The researchers explain:
“For example, the salivary tissues of most mammals produce large volumes of very dilute mixtures, while snake venom glands produce highly concentrated mixtures of various toxins.”
All of this helps explain why the link has not been explored before – the poisonous animal pool was just too large for a link to suggest at first glance.
“In poisonous snakes, gene families underwent larger expansions and evolved at a significantly higher rate than in other lineages like mammals,” scientists say, which is why these snakes spit venom out. high octane number compared to aqueous venom of mammals having the same genetic profile of expression.
But knowing that it all goes back to the earliest salivary glands, there’s a better place to start exploring the commonalities, as well as the differences.
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