Unlocking the mystery of the duck-billed platypus' venom (Australia)

American Chemical Society ^ | Jan 13, 2010 | Unknown

[decimon]

Abandon any notion that the duck-billed platypus is a soft and cuddly creature -- maybe like Perry the Platypus in the Phineas and Ferb cartoon. This platypus, renowned as one of the few mammals that lay eggs, also is one of only a few venomous mammals. The males can deliver a mega-sting that causes immediate, excruciating pain, like hundreds of hornet stings, leaving victims incapacitated for weeks. Now scientists are reporting an advance toward deciphering the chemical composition of the venom, with the first identification of a dozen protein building blocks. Their study is in the Journal of the American Chemical Society, a weekly publication.

Masaki Kita, Daisuke Uemura, and colleagues note that spurs in the hind limb of the male platypus can deliver the venom, a cocktail of substances that cause excruciating pain. The scientists previously showed that the venom triggers certain chemical changes in cultured human nerve cells that can lead to the sensation of pain. Until now, however, scientists did not know the exact components of the venom responsible for this effect.

To unlock its secrets, the scientists collected samples of platypus venom and used high-tech analytical instruments to separate and characterize its components. They identified 11 new peptides, or protein subunits, in the venom. Studies using nerve cells suggest that one of these substances, called Heptapeptide 1, is the main agent responsible for triggering pain. The substance appears to work by interacting with certain receptors in the nerve cells, they suggest.

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ARTICLE FOR IMMEDIATE RELEASE "Duck-Billed Platypus Venom Peptides Induce Ca2+ Influx in Neuroblastoma Cells"

DOWNLOAD FULL TEXT ARTICLE http://pubs.acs.org/doi/full/10.1021/ja908148z

CONTACT:

Masaki Kita, Ph.D. Graduate School of Pure and Applied Sciences University of Tsukuba Tsukuba, Japan Email: mkita@chem.tsukuba.ac.jp or

Daisuke Uemura, Ph.D. Department of Biosciences and Informatics Keio University Yokohama, Japan Email: uemura@bio.keio.ac.jp

[decimon]

Maybe a photoshop job of Nancy and Harry with those bills.

[SunkenCiv]

/bingo

[ransomnote]

Yeah....it’s like....that guy is watching me in an evil way too...and when I move from side to side, it looks like his eyes follow me...........

[Fire_on_High]

Friend had a boxer...all I can say is oh my.

There was a rather famous James Herriot story about a flatulent boxer who finally found a good home with a grizzled old farmer...who’d lost his sense of smell to a botched surgery some years before.

[JRios1968]

Curse you, Perry the Platypus!

[TheThirdRuffian]

It’s not an “assertion;” it’s a hypothesis.

But the basis for the hypothesis is the “island effect” or “island rule” where, because of isoltion pre-existing genetic tendancies tend to get exageratted on close ecosystems.

To see in another context, see Shetland ponies or some islands where rodents become huge.

Biologically, because of its isolation (and large desert areas that also restrict migration even on Australia itself), Australia is essentially a genetic island.

[1raider1]

What I wanted was the published source for your “hypothesis”.
It may be a hypothesis, but you asserted it.

[TheThirdRuffian]

The “island rule” is basic biology. Google it.

[1raider1]

You made the assertion. Prove it. Don’t patronize me by talking down to me. If it’s basic biology it should be easy for you to find and shut me up, otherwise I’ll just assume that your talking through your hat.

[allmendream]

Not exactly what TTR was alluding to, but goggling “island rule biology” showed me this interesting take on the general observation that on islands you see large species of (usually) small animals and small species of (usually) large animals.

http://rspb.royalsocietypublishing.org/content/275/1631/141.abstract

The island rule: made to be broken?
Shai Meiri1*, Natalie Cooper2,3 and Andy Purvis2

The island rule is a hypothesis whereby small mammals evolve larger size on islands while large insular mammals dwarf. The rule is believed to emanate from small mammals growing larger to control more resources and enhance metabolic efficiency, while large mammals evolve smaller size to reduce resource requirements and increase reproductive output. We show that there is no evidence for the existence of the island rule when phylogenetic comparative methods are applied to a large, high-quality dataset. Rather, there are just a few clade-specific patterns: carnivores; heteromyid rodents; and artiodactyls typically evolve smaller size on islands whereas murid rodents usually grow larger. The island rule is probably an artefact of comparing distantly related groups showing clade-specific responses to insularity. Instead of a rule, size evolution on islands is likely to be governed by the biotic and abiotic characteristics of different islands, the biology of the species in question and contingency.

[Jewbacca]

I’ve always seen “the island rule” called “Foster’s Rule,” but I was educated outside the USA.

Foster’s Rule is a specialized application of the Reproduction Isolation Rule -— which states that happenstance genetic variation (e.g., color, size, or in this case, venom) will become exagerated over time in an genetically isolated population, especially if it gives the species an “edge” -— but also regardless, simply by re-ocurrance of an otherwise recessive trait.

Foster’s Rule applied Reproduction Isolation Rule to island populations.

The classic example was a study of a wild horse herd that was divided by a railroad fence.

[Jewbacca]

Sorry, I meant to ping you to the previous post.

[Jewbacca]

I had to get my English dictionary:

“allopatric speciation”-— Speciation that depends on an external barrier to gene flow (such as geographic isolation) to begin or complete the process of speciation.

Is the concept being discussed.

Foster’s Rule is the first step in allopatric speciation.

[1raider1]

Your post was about size. TheThirdRuffian was saying that the island rule causes venomous animals to become more poisonous due to a feedback loop. Does the article that you refenced say anything about this?

[allmendream]

TTR also mentioned size (Shetland Ponies), and mentioned the “island effect” in the context of genetic isolation and mentioned (without naming it) the “Founder effect”.

Not sure if there is anything out there about poison, but the idea of an evolutionary “arms race” is well supported; although I am unsure how it is applicable to use of venomous compounds as a defense and/or prey gathering strategy without there being some native resistance to poisons in general having evolved among the relevant prey species such that a particularly nasty venom would be necessary.

I just wanted to google “island effect biology” and see what was going on with the subject.

I found the notion that some “clades” tend to get smaller and some “clades” tend to get bigger when isolated on an island to be interesting.

[1raider1]

Heren is TTR’s original post.

I could venture a guess: escallation.

Things that make venom tend to be resitant to venoms in general, so when you end up with a closed environment with more than average venomous creatures venoms get nastier, and nastier and nastier with each generation.

Do you see anything about size here? Also, you are making the same assertion he did. Give me the published evidence that creatures develop stronger and stronger poisons to cope with resistance by their prey, or admit that you are just making it up because it sounds good.

[allmendream]

Here is his second post on the subject wherein he DOES mention size.....

“It’s not an “assertion;” it’s a hypothesis.

But the basis for the hypothesis is the “island effect” or “island rule” where, because of isoltion pre-existing genetic tendancies tend to get exageratted on close ecosystems.

To see in another context, see Shetland ponies or some islands where rodents become huge.

Biologically, because of its isolation (and large desert areas that also restrict migration even on Australia itself), Australia is essentially a genetic island.” TheThirdRuffian

Me again......

Do you NOT see something about size there? Also, I am NOT making the same assertion. I said that without any evidence that the relevant prey species were growing more resistant to venom, I could see no need for a particularly nasty venom (in case you are from Rio Linda, that would be me NOT supporting TTR’s assertion). I also said that I didn't see any published works linking “the Island effect” with venom (also me not supporting TTR’s assertion, especially his assertion that all one had to do was “goggle it”.).

Are you just naturally contrary? Looking for a squabble when there isn't one?

[1raider1]

Yes, but he is using the island rule which is about size to justify his assumption about venom which was his original assertion.

[allmendream]

Yes, my point exactly, that when I (as suggested) “googled it” what I found was about animal sizes, as I remembered the “Island effect” to be about.

I did find this interesting abstract on the evolution of poison in a newt. Apparently a snake can spend almost an hour swallowing the thing before it makes the assessment that this is ‘good enough to go down’ or ‘too toxic to swallow’. Not sure what it has to do exactly with almost everything that is “the most poisonous in the world” showing up in Australia, but whatever.....

http://www.bioone.org/doi/abs/10.1655/0018-0831(2003)059%5B0155:CODTAP%5D2.0.CO%3B2

Deadly toxins and resistance to them are an evolutionary enigma. Selection for increased resistance does not occur if predators do not survive encounters with toxic prey. Similarly, deadly toxins are of no advantage to individual prey if it dies delivering the toxins. For individual selection to drive the coevolutionary arms race between resistant predators and lethal prey, the survivorship of individual predators must covary with their resistance. The extreme toxicity of the rough skinned newt Taricha granulosa appears to have coevolved with resistance in its predator, the common garter snake Thamnophis sirtalis, yet the mechanism by which individual selection can operate has been unclear in this and other lethal prey-predator systems. We show that individual snakes assess their own resistance relative to newt toxicity and reject prey too toxic to consume. Rejected newts all survived attacks and attempted ingestion by snakes that sometimes lasted over 50 min. Behavioral moderation of toxin exposure by snakes provides the association between individual resistance and fitness necessary for coevolution of lethal toxins and resistance to occur

[1raider1]

I forgot. All I meant in my whole rant was for people to not come here and make assertions when they have nothing to back them up. I’m not trying to disagree with you, but when you say things like (to paraphrase) “I couldn’t find anything to support TTR, but I found such and such and he may be on to something”. When it has nothing to do with the point. It made me think that you were supporting his assertion.