Monday, December 13, 2010

Pesky little bacteria as meance, machine, and metaphor (Books - Microcosm by Carl Zimmer)

Carl Zimmer's 2008 book Microcosm is like the microbiology he writes about. He takes the pesky little bacterium Escherichia coli, and cultures it - that is, he has it reproduce under controlled conditions, and then studies the process that we have come to call life. He then hijacks those processes to produce useful things. In this case, he makes of e coli an eloquent narrative that focuses the reader on two main topics 1- how the bacteria has been studied to help us understand how genes participate in the functions cells carry out: reproduction, architecture of components for mobility and immunity, and eventual destruction, as well as how they effect their own processes of replication and mutation and 2- how e coli can be employed in biotechnology to produce insulin, antibiotics, growth hormone, cheap drugs for malaria, and photosensitive biological circuitry. As the title suggests, Zimmer takes e coli as a prototype of the entire biological world and, with his rich store of knowledge, and, often, elegant sentences, help you to better understand this world.

Every science book makes choices about its starting point. Although Zimmer builds his story about e coli itself from the ground up, he assumes a certain amount of knowledge in his reader. For example, it helps if one comes to Microcosm understanding how DNA participates in the production of proteins. I appreciated this choice in that it helped make for a more flowing narrative however, it may leave one or two lay-readers with a few trips to the library or wikipedia to look things up. Or he may assume that it is some basic knowledge in science that will make most readers interested in a book such as Microcosm in the first place. My idealist's mind says that's a shame, since the strongest sections of the book provide such a well-structured primer in the work done in a lab setting on evolution. It is amazing to me how many people, including some working in the social sciences or mental health (for example), will tell you that the replication of DNA, its random mutation, and the "selection" of adaptations useful to passing on a species' genome in a given environment, that is, the process of evolution, is one of design, that it is "only a theory," or that it cannot be tested in the lab. Scientists such as Richard Lenski, for example, have spent years testing the process in the lab.
when Lenski looked at a flask of E. coli, he saw a mountain. It was an ecosystem filled with billions of individual organisms. Like his beetles, E. coli searched for food and reproduced. They were preyed upon by viruses rather than by salamanders. E. coli's ecosystem might be simple than the Blue Ridge Mountains, but simplicity can be a virtue in science. A researcher can precisely control every variable in an experiment to see the effect of each one.

Best of all, E. coli is the sort of creature that can, in theory, evolve very fast. Mutations may occur only rarely, but with millions of microbes in a single flask, a few mutations will arise in every generation. And because E. coli can reproduce in as little as twenty minutes, a beneficial mutation may let a mutant overtake a colony in a matter of days...

Lenski's students continue to nurture his dynasty of E. coli from one generation to the next, and other scientists have used similar methods to run experiments of their own. Some have watched E. coli adapt to life at the feverish temperature of 107 degrees Fahrenheit. Others have unleashed viruses on the bacteria and observed them become resistant, only to have the viruses evolve ways to overcome their resistance, starting the cylce all over again...
The work done in the laboratory on evolution of species has allowed scientists to observe natural selection, has shown experimentally that mutations arise randomly, and has even "rewound the tape" of evolution, as Stephen Jay Gould's Wonderful Life put it (Zimmer tells us). This way one can "let the tape run again and see if the repetition looks at all like the original." It would be useful for us all to understand mutation and adaptation a bit more thoroughly as it provides the basis of nearly every experimental hypothesis tested in biology and its related fields, is the process by which so many people access drugs to treat once mortal illnesses, and so that we can make better decisions about the presence of antibiotics in our food supply and as medicine for diseases it cannot effectively treat, as this has the potential to produce dangerous antibiotic-resistant illnesses.

I would like to wax on more about Microcosm but as I have two final exams tomorrow, I'm going to bring this appreciation to a close. Zimmer is an effective storyteller about science, focusing his story tightly, framing its relevance to his life (and by extension to our's), and employing fresh metaphors as, for example, in envisioning the genome not as the hackneyed blueprint, but instead as a palimpsest - a manuscript from which text has been scraped off and used again, as it is full of
...mutations, duplications, deletions, and insertions. Yet traces of those older layers of text survive in E. coli's genome, like vestiges of Archimedes.
Microcosm is involving, informative, and fluidly written and I recommend it if you are looking for a better understanding of microbiology as it is relevant to our lives or for excellent writing on the science of evolution.

1 comment:

Willa said...

"Every science book makes choices about its starting point"

Very true! :-)