Tag Archives: musings on science

A Birthday Sonnet

This past weekend, I celebrated my 60th birthday with friends and family from all over. One of the roasters was Ben “The Bard” Kerr, a professor at the University of Washington and colleague in the BEACON Center for the Study of Evolution in Action.

Borrowing from another bard, Ben waxed poetic about one of the lineages in the long-term evolution experiment and raised a toast with this Shakespearean flask.

 

Ben Kerr's Skakespearean flask

ODE TO AN LTEE LINEAGE

Shall I compare Ara-3 to a summer’s day?

Thou start more humbly, but sure potentiate.

Rough spins do shake the darling bugs of Rich’s gaze,

And latecomer’s “fleece” hath all to port citrate.

One line’s long-shot passed by eleven lines,

And how was its controlled complex “skin” pinned?

Promoter capture, over some time refined.

By chance, with nature’s arranging force, trimmed.

But thy Cit-minus partner shall not fade

Nor gain possession of the flair of most

C4 shall Cit snag, now spawned by carbon trade

Then on it turns ‘til lines will species now boast

     So long these cells can achieve, so wise to see,

     So long lives this work- and awe is rife, Lenski.

 

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Another Birthday Haiku

As I said in my last post, I just celebrated my 60th birthday with lots of friends and family. Several folks produced new artistic works, including two lovely haikus that celebrate the E. coli long-term evolution experiment.

Here’s one from Mike Wiser, who did his doctoral research on the long-term lines. A highlight of his work was a paper showing that fitness trajectories in these populations tend to follow a power law, which has no upper bound, rather than an asymptotic rectangular, as I had previously assumed.

Living things adapt.
Evolution keeps going.
No peak yet in sight.

 

Power law prediction, 2013

[The power-law model (blue) predicts future fitness gains much more accurately than does the hyperbolic model (red).  Image modified from Wiser et al. (2013, Science 342: 1364-1367) and shown here under the doctrine of fair use.]

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Birthday Haiku

This past weekend I had my 60th birthday. I was delighted to celebrate it with wonderful colleagues, students, friends, and family.

At a dinner roast and toast, everyone sang When We’re Sixty Four (Thousand), a tribute from the E. coli in the LTEE to the People of the Lab. And several friends came up with new contributions at the intersection of science and culture.

This beauty is from Andy Ellington, a professor in the Center for Systems and Synthetic Biology at the University of Texas and a member of the BEACON Center. As background, Andy coauthored a recent paper that helps to elucidate how one LTEE population evolved the novel ability to use citrate.

Without further ado, here’s his haiku …

Citrate just beyond.

Acetate potentiates.

Glucose is all gone.

 

Citrate

[Image of citrate molecule from Wikimedia Commons]

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When We’re Sixty Four (Thousand)

From the E. coli in the LTEE to the People of the Lab

[To be sung along to this Beatles classic]

 

When we get older, losing our fimbriae,

Many years from now,

Will you still be sending us our thiamine,

Birthday greetings, Erlenmeyer wine?

If we were mutants, crazy and fit,

Would that make you snore?

Will you still feed us, will you still freeze us,

When we’re sixty-four?

 

You’ll be older too,

And if you say the word,

We’ll evolve with you.

 

We could be handy, helping your pubs,

When your grants are gone.

You can write a paper by the fireside,

Weekend days give no time to hide.

Colonies growing, dotting the plates,

Who could ask for more?

Will you still feed us, will you still freeze us,

When we’re sixty-four?

 

Every summer you can buy a freezer when the space gets tight,

If it’s not too dear.

Save our clonal mix,

Plus and minus progeny,

Ara One to Six.

 

Keeping the notebook, pipetting each drop,

Track trajectories.

Indicate precisely what you think will change.

Hypothesize, test, unlimited range.

Give us your data, sequence and store,

Evolving evermore.

Will you still feed us, will you still freeze us,

When we’re sixty-four?

 

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Bacterial Niche Finally Defined

The following scholarly contribution comes from my wife Madeleine Lenski after conversing with her “sister” (my former postdoc) Valeria Souza.

For those with an itch for criteria,

Scratch this: What’s a niche for bacteria?

Don’t take me to task

If I answer “a flask” –

It’s a bitch from warm broth to Siberia.

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January 19, 2016 · 9:08 pm

Representing Science to My Representative

My research is funded by the National Science Foundation, including the BEACON Center for the Study of Evolution in Action. BEACON is one of a dozen or so NSF Science and Technology Centers. Today, our Representative in the US Congress, Mike Bishop, came to BEACON for 40 minutes to discuss our center—what we do, what impacts our work has, and so forth.

It was something of a “fire hose” for Mr. Bishop, with several presenters trying to convey a lot of information very quickly.  However, he was engaged and asked thoughtful questions.  I think he left with an understanding of the importance of scientific and engineering research, including how fundamental curiosity-driven research can lead to applications.

I had 10 minutes to show him my lab and explain what we do and why.  When I make a short presentation like this one, I often write out a version in advance.  I don’t read it or memorize it by any means. However, writing it out helps get my thoughts in order—removing details that aren’t important, ordering ideas into a narrative, reminding me of what I most want to convey.

I’m sure I was not as clear or coherent as the text that follows.  I offer it here because it conveys the points I tried to make in the few minutes that I had as a representative of science speaking with a representative of the people.

~~~~~~~~~~~

I want to show you one of the experiments in my lab.  We call it the long-term evolution experiment. It’s an unusual experiment because it’s been running for over 27 years.  And we keep it going because it’s been a scientific goldmine leading to new discoveries about how bacteria change over time.

It’s important that we understand bacteria and how they evolve for many reasons. Bacteria are best known because some of them can cause dangerous infections. But many of them protect us against infections—if our guts were not filled with harmless bacteria, then the dangerous ones would have a much easier time getting established in our bodies. Some bacteria also provide nitrogen to plants and perform other essential functions in the environment, including degrading some of the wastes that we produce.  And some bacteria are the workhorses of biotechnology.

To give one example of why bacterial evolution is so important:  If bacteria didn’t evolve, we would have defeated nearly all the pathogenic bacteria on Earth with antibiotics.  But they do evolve and become resistant to our drugs, and so the pharmaceutical industry has to spend billions of dollars trying to keep up with the evolving bacteria and viruses by developing new drugs to treat infections.

It’s possible to see evolution-in-action in bacteria, like we do here, for several reasons.

  • Their populations are huge.  The number of bacteria in just one of these little flasks is comparable to number of people in the United States.
  • They grow really fast.  Every day, there are about 7 generations of bacteria in each of the flasks.  So each day we see the great-great-great-great-great grandkids, so to speak, of the bacteria that were in our flasks yesterday. After 27 years, the experiment has run for over 63,000 generations.
  • And one more important thing about bacteria. We can freeze them and bring them back to life, and so we’ve got a frozen fossil record of the experiment.

When I started the experiment in 1988, there was no human genome project, and not even a single bacterial genome had been sequenced.  Now we go into our freezers and sequence the bacterial genomes to see how their DNA is changing over time.

The work we’ve done in this curiosity-driven experiment has inspired others who are using similar ideas and approaches to understand the rates and mechanisms of how bacteria evolve.

I’ll give two quick examples that show how our NSF-supported fundamental science gets translated into applications that are important for security and health.

First, you remember the anthrax letter attacks on Congress that occurred right after the 9/11 attacks. In the first few days after the anthrax attacks, I was contacted by the Defense Threat Reduction Agency for advice on how to identify the source of the strain used in that bioterrorism, and how to distinguish it from other related strains. And in the months that followed, I was asked for and provided advice to the FBI and other agencies investigating the attacks. Tracking the source of microbes in outbreaks—whether natural or terroristic in origin—requires understanding how they change over time.

Second, my colleague Prof. Martha Mulks studies bacteria that colonize the lungs of people with cystic fibrosis (CF).  There are about 30,000 people with this disease in the US alone.  It’s an inherited disease that makes people susceptible to lung infections and, unfortunately, those infections kill many kids and young adults with CF.  Some of the bacteria that infect the diseased lungs are not pathogens to most of us—they’re bacteria that live in soil and on plants, but when they get into the lungs of CF patients they evolve and adapt to that new environment. They also evolve resistance to the antibiotics that are meant to get rid of them. How exactly the various bacteria change to become better adapted to the CF lung environment is not known. Luckily, though, Martha Mulks and other foresighted scientists and clinicians have kept frozen samples of these bacteria over the years—just like we’ve done with the long-term experiment I described a moment ago. Now the BEACON Center is supporting work by a graduate student, Elizabeth Baird, who will analyze the DNA from old and new samples and apply some of the same approaches and methods that we’ve used and developed for the laboratory experiment to see how the bacteria have changed—how they have become resistant to antibiotics and otherwise adapted to the environment of the lungs of people who suffer from cystic fibrosis.

The bottom line is that the fundamental, curiosity-driven research that the National Science Foundation supports is also an engine for future applications—often ones that we may not even have dreamed of—as well as a training ground for the talented and dedicated young people who you can see working all around us in this lab and throughout the BEACON Center.

~~~~~~~~~~~

Rep. Mike Bishop (MI-08) and me in the lab.  [Photo: Danielle Whitaker, MSU.]

Rep Mike Bishop and me in lab, 14 Oct 2015

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Lucky in Life, Prologue

I’ve been meaning to write for a long time about the role of chance … luck … whatever you want to call it … in life, from the grand sweep of evolution to our individual existence.

Well, just this morning, I came pretty close to demise by random genetic drift. Almost every weekday, I walk to and from work at Michigan State University. It’s a pleasant walk through pretty neighborhoods and the beautifully landscaped MSU campus.

Today was not much different from most other days. It had been sprinkling lightly, but no wind or anything out of the unusual.

I walked the route I usually take, crossing the streets by habit in more or less the same spots every time, I guess. The only moderately big road I cross is Grand River Avenue, where it intersects with Bogue Street. No problem on Grand River.

I walk down Bogue on the east side or the west side of the street depending on the traffic light, where cars are, on whimsy I guess. I was walking on the east side, though I would have to cross over to the west to get to the building where I work.

At this point in my walk, I’d guess that’s the side I’m still on maybe 80% of the time. Lucky today was one of those days. I heard a loud crack on the other side of the street. A tree limb snapped and crashed hard on the sidewalk.

Maybe half a second from snap to crash? And the limb was big and bifurcating, with two main branches, each maybe a foot in diameter. It came down straight, square and hard against the sidewalk. Even if you had an instant to react, it wouldn’t be clear which way to run to avoid one branch and not get smacked by the other.

I wasn’t the only lucky one. No one was there to get hit. A student was walking toward the spot, maybe 100 feet away. I called out something like “That was crazy, lucky you weren’t there.” He nodded and crossed to my side of the street.

It was only in walking the next couple hundred feet that I realized I had been lucky, too, to be walking this morning on the east side and not the west side of the road.

Indeed, each of us is incredibly lucky just to be here—the product of billions of generations of parents who were not only fit enough to survive and reproduce, but also lucky enough to have escaped the random drift of life and death.

The sidewalk

The break

[Both photos: Richard E. Lenski.]

Added November 1:  The second tree to come after me this autumn … or maybe I should say this fall.  This one was much smaller but fell just a few steps behind me on my morning run!

Me and tree 2

[Photo: Madeleine Lenski]

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