The Physics Police

The Physics Police

Tuesday, January 8, 2013

The Myth of Russian Milk-frogging

Recently, the science news media has been abuzz with reports that an old Russian tradition of putting a frog in a bucket milk to stave off spoilage had been vindicated by science. As it turns out, this tradition is a myth, and was never practiced by any sane people. What's more, it played absolutely no part in any scientific discovery!

This science news fiasco started on December 12th, 2012, when the headline Frog-in-bucket-of-milk folklore leads to potential new antibiotics appeared on a ACS News Service Weekly press release. The article included an interview with one Albert Lebedev of Moscow State University. He is the contact author on a paper published on November 5th, 2012 in the Journal of Proteome Research. Lebedev seems to be showboating during this interview, when he mentions:
These peptides could be potentially useful for the prevention of both pathogenic and antibiotic resistant bacterial strains while their action may also explain the traditional experience of rural populations.
Nowhere in the paper is this milk-frogging myth even mentioned. In fact, the true motivation for this line of research is clearly explained by the same team in an earlier paper published on December 22nd, 2010 in the Journal of Analytical Chemistry:
It is known that the peptide profile of the skin secretion of amphibians characterize not only a certain species but also different populations inside it. Therefore, we expected that the set of the skin peptides (peptidome) of the species of Rana temporaria from Zvenigorod population can differ from the one typical for European population which was composed in our group on the basis of the compilation of literature data.
 I found one source which explains the thinking behind the Russian myth:
Most likely, the people believed that the milk with the frog will be colder and so long did not go sour.
So the myth seems to infer a refrigeration benefit via the observation that frogs are cold to the touch. It has nothing to do with the antibiotic properties of the frog's secreted peptides, and so could never have inspired a this biochemical search! The statement that milk-frogging "lead to" or "inspired" this research is nothing more than a LIE fabricated by the headline writer for ACS News Service Weekly. Lebedev never said that the traditional experience of rural populations lead to his team's research. He said the research may also explain the traditional experience of rural populations. The reporter misunderstood, or deliberately lied in the headline.

It seems this silly story was next picked up in a December 17th editorial by David Schultz of NPR entitled Scientists Look For New Drugs In Skin Of Russian Frog. The NPR article continues the campaign of misinformation with this wonderful caption, which just about gave me the biggest citation needed headache of my life:
For centuries, Russians believed putting a brown frog in their milk would keep it fresh.
Obviously, no Russian ever put a real frog in their milk, and later thought it had been a good idea! The poor creature would immediately defecate, eventually drown, then defecate some more, releasing toxic salmonella into your milk. It would quickly rot without refrigeration, causing your ruined milk to further putrefy in a matter of hours. Any antimicrobial advantage of it's skin secretions is negated by the fact that it would SHIT AND DIE. This is common sense to all but the most glorious of fools, no matter the century or country of origin. This myth probably exists as a sort of trolling meme; a joke, where the goal is to fool people into trying it out. I mean, you don't have to be Alton Brown to know that frog-shit milk isn't good eats.

So why would so many news outlets repeat the same lie, despite its obvious falsehood? This is another example of the media just making shit up to create a false sense of mystical ancient wisdom. Their goal is to entertain; not to inform. I don't mean to say all ancient knowledge is worthless. You know what they call ancient knowledge that survives to this day? Science.

Actually, the truth, in this case, happens to be a lot more interesting than media-generated fiction! Allow me to explain:

This work by Lebedev's team is based on work begun with the publication of the paper published on September 29th, 1998 by John Conlon et al. This team went on to publish many papers about frog antimicrobial peptides, in 1999, 2000, 2002, 2004, etc. Where was the news buzz back then? Hmm, I guess the whole world's media just happened to miss all those papers... somehow. Or, they might have not have sounded all that important at the time, because they had nothing to do with the traditional experience of rural populations...

Anyway, in 2008 and 2009 that Lebedev et al. got into the game. But what have they been up to in the intervening years? Well, now we get into the actual, fun science.

The chemicals in question, which ooze out of frog skin are called peptides. That's just the fancy word for a short protein; a sequence of less than 50 amino acids. Scientists figure out peptide composition by a process called mass spectrometry.  This process works by ionizing the peptide to generate charged molecules or molecule fragments and measuring their mass-to-charge ratios. So, like putting together a puzzle, you can piece together the sequence of amino acids in the peptide. Mass spectrometry has also been used to sequence DNA. In their previous work, Samgina et al. used something called Fourier transform mass spectrometry. But in this new work, they used different technique called Electrospray ionization. This technique is better for organic molecules, like peptides, because it doesn’t break them apart too much. The longer bits are easier to put together, just like a puzzle is easier to solve when cut into bigger pieces. So, the team managed to identify a lot of new peptides.

Cool, huh?

[UPDATE] January 2nd, 2013: Ed Yong over at The Scientist posted this article explaining why the decade of research hasn't yielded much promise for medicinal application.

[UPDATE] January 10th, 2013: It seems at least one blogger was so confused, they thought the outcome of this research was a new method of pasteurization! Louis Pasteur is probably rolling in his grave.
The best new way to save your nasty curdled dairy from spoiling? Just mix in some good old frog slime.
Um, no thank you.

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