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pider venom research has so far focused
on a relatively narrow area. Now, a group of scientists in Switzerland has dug
a little deeper to find out exactly how deadly it is.
Could the secrets of spider venom
help design new drugs?
Animal
venom has long been used in medicine. While the industry used to focus on snake
venom, spiders are now under intense examination.
The
two types work in very different ways; snake venom targets the cardiovascular
system, while spider venom aims for the nervous system.
Understanding
precisely how spider venom works could lead to effective treatment methods for
the likes of epilepsy and stroke.
Scientists
already know that arachnid venom causes a breakdown in the function of ion
channels. These channels must be able to open and close at specific times in
order to control muscles and other critical bodily processes.
When
spider venom enters a body, it disrupts the usual ion channel flow, resulting
in paralysis and sometimes death. Focusing on the relationship between these
channels and venom could be the ticket to a revolutionary new treatment.
Research
into spider venom has been ongoing for the past few decades, but much of it has
revolved around the effects of neurotoxins. This has contributed to the
development of successful insecticides, but drug-related uses are still being
investigated.
Venom's double hit
Using
spider venom to treat diseases of the human nervous system requires a deeper
understanding of the venom's components. A new study from the University of
Bern's Institute of Ecology and Evolution (IEE), in Switzerland, combines years
of such research to prove just how complex the venom really is.
The
venom of Cupiennius salei —
more commonly known as the tiger wandering spider — is the study's prime focus.
It is a relatively large spider with a leg span of around 10 centimeters and is
usually found in Central America. When it catches prey, it does so by ambushing
and releasing venom, rather than spinning a web.
In
the study, published in Toxins,
researchers looked at how the venom's various ingredients interact to paralyze
prey. They call it the dual prey-inactivation strategy, so named for the two
parts that make up the process.
One
part is decidedly neurotoxic, and the other part aims to disturb stability
within the body. "Both parts of the strategy interact very closely,"
explains lead study author Lucia Kuhn-Nentwig, Ph.D.
"The venom targets not only the
muscles and the nervous system of the prey — the internal homeostasis, the
physiological balance of an organism, is also disrupted by the blockade of ion
channels and various metabolic pathways."
Lucia
Kuhn-Nentwig, Ph.D.
In
short, the neurotoxins target muscles and the nervous system, resulting in
paralysis. Tissue death allows the venom to spread throughout the body, while
the metabolic part causes a blood sugar spike, leading to significant damage to
bodily functions.
Kuhn-Nentwig
describes this particular spider's venom strategy as "very effective. [It]
reduces the risk of the spider losing the prey, as well as the risk of
potential prey developing a resistance to spider venom in the long run."
More than just a toxin
But
the researchers weren't done there. To further understand the deadliness of the
spider's venom, the IEE scientists studied every single RNA molecule found in
the venom glands. They discovered that a protein called alpha-amylase was the
main protein in the venom.
"Based
on this, we were in a position to understand the existence of many other
peptides and proteins contributing to the toxic effect of spider venom,"
Kuhn-Nentwig states.
Summing
up the team's conclusions, she notes, "Spider venom is more than just a toxin
— it is an entire armada of substances that attack, paralyze, and kill an
organism in a maximum of many different ways."
Insight
into how a nontoxic element develops into a toxic one may support the future
medicinal use of spider venom. Scientists believe that the venom strategy used
by the tiger wandering spider is also used by the majority of other spider
species, making this discovery even more important.
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