The New York Times has a brief one page article in the Sunday Magazine on “The Forensic Humanitarian” In the article, Jim Giles describes the work of Patrick Ball, a statistician working on searching for evidence for war crimes. The work is clearly important. But what caught my attention was his method. Basically, he uses a form of mark-release-recapture statistics taken from ecology studies. In the article, Giles writes
To understand Ball’s accomplishments, you might start with the problem of counting rattlesnakes.
And then he goes on to describe how one can estimate how many rattlesnakes are in a population by marking ones that you find and then counting how many times you refind one you have marked previously. This is a method generally known as mark-release-recapture (e.g., see the Wikipedia entry here, which seems OK but I have not read too carefully).
Apparently, Ball uses a similar type of statistic to estimate the number of murders and/or deaths in particular areas, by looking for overlap among different reports of deaths.
What you say does this have to do with microbial ecology? Well, everything. Because one of the most common methods for estimating the number of microbial species in a sample is to use a gene survey method where one isolates DNA from environmental samples and then one looks in the DNA for multiple versions of a gene found in all species (the gene most commonly used is known as small subunit rRNA). The gene survey method is needed because appearance is not a robust method of identifying microbial species.
From the gene sampling data, one then compares each version of the gene to the others and counts how many times one sees the same form of the gene (suggesting that one has found two different cells of the same species). If one keeps seeing the same forms of the gene even with only a few samples, one would estimate there are few species in the sample. If one keeps seeing different forms of the gene, one would estimate there are many species in the sample.
Things that seem to be hidden – be the murders or populations of rattlesnakes or microbes – can still be studied with what the Times perfectly refers to as
“A statistical sleight of hand”
Well, it is the time of year for everyone to hunker down and watch some good ads on TV in between football plays (I am a football fan, but most years, the ads are better than the game).
And in the spirit of microbiology education I have created a my list of some of the fun roles microbes will play in the superbowl.
- Can anyone say HGH? Sure you can get it from grinding up cadavers, but it is a bit easier to get it from engineered bacteria.
- Cleanliness is next to Godliness.With all the blood, grass, sweat, and other stuff from the Championship games, cleaning those uniforms is going to be tough. Better use some detergents with extra enzymes like these.
- Victory celebration. To the victor goes the bubbly. And boy, that bubbly would really rot without microbes.
- Making a good football. Without some serious processing, a cowhide or pigskin is not something you would want to throw around. Enzymes are a key part of most leather processing. And hey – who makes most of the best enzymes on the planet. That’s right, microbes.
- Obesity epidemic. Sure, pumping iron and taking steroids will get you big. But maybe those linemen just have a health dose of some of Ruth Ley’s gut bacteria.
- Avoid double dipping. MSNBC (and everyone else) is reporting this story. MSNBC says “Keep an eye on the salsa this Super Bowl Sunday: A researcher inspired by a famous “Seinfeld” episode has concluded that double dipping is just plain gross.” Not just gross. “They found that three to six double dips transferred about 10,000 bacteria from an eater’s mouth to the remaining dip sample.”
- Football transmits bacteria much like STDs. Yes that is right. Tara Parker-Pope in a blog via the New York Times is reporting about a Salon.Com discussion of MRSA (methicillin resistant Staphylococcus aureus). Salon was weighing in on a recent study that focused on transmission of MRSA among gay men. Salon dug out an New England Journal of Medicine article about MRSA transmission among football players. And Salon says “When it comes to spreading the bacteria, it is not homosexuals we have to worry about….The medical researchers were not studying gays, they were studying the St. Louis Rams. That is correct: football players; in particular, linebackers.”