Big news for the Yeung Lab: Our paper on biological oxygen cycling and clumped isotopes was published in Science Magazine. It's a proof-of-principle set of observations that demonstrates a new type of biosignature—how rare isotopes are clumped together—that can be used to trace biogeochemical cycles in nature. We have our sights set on oxygen cycling in the oceans.
The phenomenon is important because up until now, the ideas surrounding clumped isotopes have primarily been about the temperatures at which molecules are formed, rather than the mechanisms through which they are formed. We, along with David Wang et al. at MIT showed that rare-isotope clumps are indeed sensitive to formation pathways. Rather than go further into the findings here, however, I will point you to some press releases and Ben Passey's excellent News & Views piece. Today, I'll focus on the story behind the paper:
Where did the scientific idea come from? How did it make its way, intellectually?
If you ask me, I think we are still in the "good ol' days" of clumped isotope geochemistry. There are so many things we still don't know. How are rare-isotope clumps made in nature? How are they transformed by biological cycles? The answers to these basic questions still elude us, and they will be the foundation for an entire industry of research.
The experiment and its result, in a nutshell. In many respects, it is a throwback to "classic" science; it's actually not so different from the experiments Joseph Priestley conducted back in the late 1700s that led to the realization that plants produced oxygen.
Of course, my perspective was much narrower at the beginning. I started looking for biological and atmospheric signals in oxygen-isotope clumps a couple years ago, but I hadn't yet realized the larger context. I didn't think the isotope-pairing idea was a big conceptual leap perhaps because my primary work in clumped isotopes up to that point had revolved around kinetic effects in the atmosphere; temperature hardly played a role. When I started developing the techniques to measure isotope clumps in oxygen, my goal was to carve out something in the field that was my own, intellectually.
I was a bit single-minded, you could say: I wanted to know clumped-isotope signatures of individual biological pathways. We had to do controlled, enzymatic experiments. Luckily, Boaz Luz, a much wiser scholar, implored me to start with something simpler. "Do a terrarium experiment first," he told me at a conference. "It's a lot easier. And you're bound to learn something interesting no matter what." My postdoc advisor Ed Young had told me as much, too, but stubborn young investigators often require a second (or third) opinion before they start listening to their senior colleagues.
Acquiring water hyacinths in Sunland-Tujunga.
Jeanine Ash actually got the experiment off the ground. My first attempt had failed, gloriously, turning into what we eventually called "the poop chest" (too much soil, not enough water; Ed still bugs me about how bad the box smelled when we finally opened it). I had been discouraged by this earlier failure, and had decided to spend my time running atmospheric samples. When Jeanine joined Ed's group, though, her enthusiasm was just what the project needed. She put together a box that didn't turn into poop (not immediately, at least) and voluntarily pulled the twelve-hour shifts necessary to get the analyses done over many, many months. I pulled twelve-hour shifts as well.
There were many red-eye nights for the both of us.
We sat on the data for a while. There were parts that made sense and parts that didn't (some are still puzzling), and I had wanted something neat and tidy. Modeling the data left us with still more questions. We were stuck with a mountain of experiments in front of us to clear up some of these questions, with limited funding and expertise to do them.
The life (and eventual death) of the terrarium.
A turning point came when Ed noticed that nobody was thinking beyond clumped-isotope thermometry outside of the community of isotope-clumping experts. Even then, there were not many of us. He argued that the basic result (photosynthesis does NOT yield oxygen clumps expressing formation temperatures) was both timely and important, even if the experiment was incompletely explained. There were many arguments between us; did the value of the observation extend beyond this one system enough to justify its publication? I imagine we all grapple with this question at one level or another with any project we're working on.
Publish or perish, as they say.
In the end, Ed prevailed, convincing me to write the darn manuscript despite our collective reservations. The timing was fortuitous, too: the MIT group had submitted their paper not long before us. Luckily, Nick Wigginton, our editor at Science, decided to publish both papers in the same issue. Our papers, with Ben Passey's kind commentary, will probably have more impact than either paper could ever have had on its own.
It is clear to me now that our success depends on those around us in ways we cannot predict. By chance, you meet the just the right people who tell you just the right things at just the right time. Luck is being around those who help you—the sages, the rabble-rousers, the supporters, and the taste-makers—when you don't know you need the help. Writing may be the stuff of science, but people are its heart and soul.
Jeanine Ash, myself, and Ed Young by the UCLA sample preparation line. Photo by Doug Rumble.