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- 12 December 2013 1:00 pm , Vol. 342 , #6164
- About Us
Exclusive Interview: Discoverer of Arsenic Bacteria, in the Eye of the Storm
20 December 2010 4:19 pm
Three weeks ago, Felisa Wolfe-Simon, 33, a former performance oboist with a doctorate in oceanography and a NASA fellowship in astrobiology, published a paper online in Science about bacteria that can use arsenic instead of phosphorus in DNA and other biomolecules. Four days before the publication, NASA sent out a media advisory that it would hold a press briefing "to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life." That led to wild speculations on the Web about extraterrestrial life, and when the paper was published, many headlines made the most of the "alien" nature of the discovery by Wolfe-Simon and her colleagues at the U.S. Geological Survey in Menlo Park, California.
Then came a torrent of criticism by scientists. A highly critical blog post by Rosie Redfield, a microbiologist at the University of British Columbia, Vancouver, quickly drew hundreds of comments, many also finding fault with the study. Wolfe-Simon and her co-author Ronald Oremland then came under attack by journalists when they declined to respond to media calls for a response to these comments. On 16 December, the authors posted responses to some of the issues, and Science will publish technical comments and responses in early 2011. In the meantime, Wolfe-Simon agreed to share some of her thoughts in an interview with Science's news department, which covered the original finding in early December. The following has been edited for brevity.
Q: How would you characterize your life since the press conference?
F.W.-S.: Since the press conference, my life has been really busy and stressful. When the paper was accepted for publication, we told the Astrobiology Program and NASA, ... and when they asked me to come in and talk about the paper, I said, "Sure." I was obliged. It had been 2 months or so, and the paper had been accepted for a while, so I thought this would be great, I'll bring the information to the public.
Q: So, NASA approached you about doing a press conference, and you thought that was a good idea?
F.W.-S.: I wouldn't say I thought it was a good or bad idea. I'd never been to a press conference, but it made good sense to me that my mom should know what I'd been up to, and I love teaching. So, it made sense to me at that level, in terms of, again, bringing what we did to the public. But we weren't clearly prepared, in terms of understanding how it might be, again, with the new types of media that are really rather amazing, what was exactly going to happen.
Q: So you did expect your finding to be controversial. Why?
F.W.-S.: We expected some questions and challenges. Our paper, what does it suggest? It suggests that there's a potential exception to what we would say is a fundamental axiom of biology, so it's kind of a two-fold thing. We thought that our findings would generate some discussion, but we didn't anticipate the reaction we saw.
Q: Why do you think you got the reaction that you did?
F.W.-S.: I think maybe it has something to do with that there was some hype generated around it. I was receiving a lot of inquiries from all sorts of people, science journalists and scientists and other sorts of reporters, even before the paper went out under embargo.
So, in terms of understanding what generated the interest, I'm not exactly sure, but I think it was remarkable. What I did know is that on Monday, NASA had sent out the media advisory and it seemed to have people talking. And I thought, "Oh, we're all talking about science." You know, as a science communicator and a person, what I'd like to communicate is how passionate I am about science and understanding these fundamental properties and principles of nature and my small contribution to that understanding. If fifth-graders in Iowa and retirees in Buenos Aires are talking about it, well, that's fantastic.
We, as scientists and other science communicators moving forward, need to understand how the Internet gives voice to things we can't necessarily anticipate, and I think that that's something I will think a lot more about.
Q: You answered questions at the press conference, but then after that, when did you stop talking to the press?
F.W.-S.: This is a difficult question. Well, no, I guess it's very straightforward. For the press conference, I was prepared to talk about our findings reported in the paper. I did not show any data, nor did I describe the study as definitive. I was not giving a scientific talk, so I was really not prepared to engage in a scientific debate on that spot. Had I given a professional scientific talk, where I would go to the details—and, again, I think this was not the point of the press conference, as I understood it. I was explicit, and my co-authors included were explicit in that the point, as we understood it, was communicating in a way that could be understood what the results were and could suggest the implications. If I were to be giving a [scientific] talk, we could have a scientific discussion with my data in front of everyone, so we could actually look at the graphs and look at, well, what is this actually saying, rather than talking in the abstract. I think that's part of the difference.
Q: So, in other words, you avoided questions that related specifically to the data, even at the press conference?
F.W.-S.: I did address it a little bit. But, again, since I didn't show the data, and it was [a] complicated sort of situation where we didn't have enough time, it was really about, as I understood it and my co-authors understood it, it was really about representing this is what we found, this is the observations we made, in a way that a community could understand.
Q: So, after Saturday when Redfield's blog came out, at least some journalists took a look at the paper again and wanted to talk to you. If my information is correct, that's when you and NASA declined to talk to reporters anymore about this. Is that right?
F.W.-S.: There are two issues. One is that, well, we wanted to be able to have that discourse in the scientific community as a record. That's the record, the literature record that we go back to or has been up until now. So that was the one issue, and the other issue was the rapidness. So, we spent a lot of time really crafting our paper and crafting the SOM [supplemental online material] and crafting all the data, in terms of trying to show it as clearly as we thought. We wanted to give voice to that, in responses to these queries and some of the questions and issues brought up in the press, and we didn't want to answer it in a way, or respond to it in a way, that we thought would not give us the opportunity to think as deeply as we might need to. I was under a lot of pressure, and I'll be honest, I was exhausted. I really wanted to get back home and back into the lab. A lot of friends started contacting me to ask if I was okay, and I started to get concerned, "Should I be okay?" I felt a lot of pressure to respond. But I really needed to just get back in the lab, that was always clear. We presented our findings to the community in a peer-review journal, and to the broader public in that press conference, and I would really be lying if I told you that the barrage of criticism that followed didn't hurt. It did. I know my colleagues in the community aren't thrilled or happy about this delay, but, again, I'm really doing my best.
Q: Some researchers have suggested that it would be very easy to conclusively tell whether the arsenic is in DNA using different techniques. One was the cesium chloride density gradient ultracentrifugation? Did you do those tests, and if you didn't do those tests, why not?
F.W.-S.: We're aware of all these other techniques you mentioned. In fact, I have done a cesium chloride gradient experiment [that's density gradient], and it showed what my gel showed: something unusual that we couldn't quite explain.
We could have waited until we did a really exhaustive selection of all of these alternative techniques, many requiring collaborations with groups well outside of our field, but, instead, I and my co-authors, we wanted to provide a strongly suggestive and convincing argument to our community to initiate these new collaborations and really inspire other people to go out and do this totally in de novo. So, while we're familiar with many of these alternative techniques, a number of them really require access to tools we did not have within reasonable reach, given the time. I can't reiterate enough that we wanted to bring this to the community, as a phenomenon, to initiate those direct collaborations, or for us to help another group, with their tool, like different types of mass spectrometry, get to that goal.
Q: Has anybody asked to collaborate or for your samples?
F.W.-S.: Yes, absolutely. People have asked for cells, which we had been already working on getting to make available. Yes, and we're really thrilled with not just individual or individual labs or professors with techniques from around the world but also the variety of different companies that said, "Hey, we have this new, interesting technique, it could be useful." So, yes, those are absolutely coming in, and we are hot on that.
Q: Have you been able to send anything out yet?
F.W.-S.: No, not yet, and part of why I've been trying to concentrate, myself and Ron Oremland, we're really trying to get focused back on the science. We can talk about a variety of different issues, and, again, we welcome this discussion. We expected there to be discussion, as there should be in science, about different aspects of the data. But, coping with that has slowed down; it takes bandwidth, in terms of being able to push forward with the next set of experiments, either in collaboration or in our own group. So, no, unfortunately, we have not yet. But, let's look at the timeline, and this was December 2nd and today's the 15th, and I have been traveling. It's myself and my co-authors, and we're not a company of 300, 400 people. It's funny, there have been two comments to me about either my study was incredibly fast, or I should have done all these other things. And I think on the orders of weeks to months is pretty fast. So, we're trying to pursue it. That was the goal—to stimulate the discussion and [have] somebody say, "Hey, we have this technique, could we help you?"
Q.: But, do you have the capability of sending stuff out?
F.W.-S.: We're currently working to submit the bacteria to two culture collections so that they are available to all interested scientists. Our lab is not currently equipped to provide the cells at the scale needed to ensure fair access for everyone. So we hope to be able to grow enough to supply the culture collection. These are slow-growing cells that a scientist hopefully would recognize from our growth curves that we published, and the volume you need, the physical amount of bacteria, is a lot. Some of the collaborations we had started a bit before, who knew about the work, and those we're hoping to pursue soon. But, in terms of how fast you get it to everybody, it's difficult. We got requests from a lot of people.
Q: About how many? Dozens? Hundreds?
F.W.-S.: Oh, in the dozens, I'd say.
Q: What are the questions you want to answer right away?
F.W.-S.: I'd love to know the structure. There are the questions of NMR [nuclear magnetic resonance], there are options of crystallography, and we have collaborations we set up, actually before the paper came out, to do that. I think that we'd love to know if this is happening in the environment. That's a great question. We'd love to understand the amount of substitution. We do see substitutes, what level of substitution, we're not sure; we're not clear about that. Also, not just level of substitution, but all of our evidence is in what we call stationary growth, which I hesitate to say, it's a bit like old age, something like that, but it's in maintenance phase. What is the level of substitution in mid-log or late-log? Maybe it's much higher, maybe it's much lower—it's a great question. There are so many questions this opens up. I think what we're trying to do, next in line, is really provide additional evidence to support this paper and the observations the paper points out, in particular, using x-ray spectroscopy on the cell fractions but also pursuing genome sequencing.
Q.: It's also been suggested that you didn't wash the DNA of any arsenic that may be stuck to the DNA. What's your comment on that?
F.W.-S.: First, we take the cells, and we collect them by centrifugation, and we wash them very well. We did a standard DNA-extraction protocol, multiple phenol chloroform steps to remove all the impurities, including things like any free arsenic, which the washing will have removed. So, after that point, we ran the DNA in a gel, further separating the DNA from the impurities. Any arsenic from the media would have been removed by the washing before this extraction, and, in theory, would have been partitioning into the aqueous phase of the extraction. But, if the arsenic was incorporated into a lipid or protein, it would have partitioned into the phenol, or phenol chloroform. The arsenic would not have stuck. We have no reason to believe—nor do we understand anything in the data—to really have shown that arsenic will stick to DNA in the final aqueous fraction. One reason that we thought it was pretty consistent is that the DNA fraction that was used for further analyses, including things like PCR, would require highly purified DNA. So any of those contaminants, if indeed they were there, would have been a problem. So, we really don't feel it's a valid concern.
Q: Do you think the other researchers are overstating how easy it is going to be to resolve this matter?
F.W.-S.: I would immediately say, "If we're lucky, it's going to be very easy," but I don't think so. The cells are not easy to deal with. They're kind of soft and fluffy, and they're different. And so testing with the alternative techniques will fill in more pieces to the puzzle, and, again, no doubt will open up new questions.
Q: What would be the easy test, if it worked?
F.W.-S.: I'd say it would depend on who you speak to. [For] a microbiologist, there's very little other way to explain the figure 1, the growth. To many chemists, that's not clear to them. So, I think it depends on who you are. So crystallography—we have a collaborator who we already had begun the collaboration, but that takes time. Magnetic resonance may be the smoking gun for others to see arsenic, but each of these techniques has its own challenges. I think what's important to realize is it's not just about which technique, there's sample prep that's involved for each technique that could pose challenges we don't know yet, as well as interpretation of the data when we get it.
Q: So, were you surprised by the personal tone of some of the criticism?
F.W.-S.: I'll be honest. Of course, I was disturbed by the personal attacks, and I can only speak for myself right now. I've worked really hard on this project. I've solicited the advice and assistance from the top scientists across a variety of different fields—not just my co-authors, but many, many individuals. They've been incredibly generous with their time and expertise, and I'm deeply grateful to everyone who's helped, both many of the people that we identify in our thank- you's, but also at meetings, and I really can't thank other scientists who've helped myself, in particular, along the way. One lesson that I'm learning from this whole experience is that as I proceed with my career, hopefully, in science, I want to really ensure that I maintain collegial relations with my fellow scientists and always take time to help out the newcomers to the field.
Q: So much of the criticism has centered on whether NASA or your group has inappropriately put forward this work as relevant to the search for extraterrestrial life. Do you regret that?
F.W.-S.: I can speak a little to this. Our findings, we think, are relevant to the astrobiology community—that is, the study of the origin, evolution, and distribution of life in the universe. So, any of our contribution to understanding the fundamental principles of life here on Earth can aid in understanding whether and how life begins inside or outside our own solar system, and you're finding life here or elsewhere that was really different from life as we knew it, but that we could recognize would give us greater insight into our own molecular underpinnings, and also speak to that eternal question—are we alone, and how did we get here? The scientific community is hard at work on finding answers to these questions, and I'll be honest, I'm glad to be a part of this endeavor
Q: So, do you think you've weathered this well?
F.W.-S.: Do I think I've weathered this well? Well, it's been really difficult for my co-authors and I, and I guess maybe I should punt and answer that in 6 months from now.
Q: Have you, by any chance, contacted or tried to talk to Redfield, the woman who wrote the blog that sort of fueled the whole thing?
F.W.-S.: I have not. I've had a deluge, as you might imagine, of e-mails. I'm only a single person, and I've been focused on getting in the lab and getting more evidence, and hopefully helping collaborators and other folks, having the opportunity, either from us or in their own group, collecting alternative evidence.
Q.: Are you going to start taking media calls again, or are you going to lay low for a while?
F.W.-S.: That's a hard question because, definitely, in talking to my co-authors, we want to get to work. We're scientists, and it's hard if all your time is taken up talking. I'm happy to explain the results, but there's one thing, I think, to explain the results, and there's another thing to be under what feels like an attack; it's hard to do that. There's only so many hours in a day, you've got to prioritize and time-block.
Q: It sounds like what you want to do is not really spend much time with the media right now.
F.W.-S.: What we would want to iterate is that we're thrilled that the public is talking about science. I think the media is an important part of the process. We absolutely don't want to come off as evasive. We wanted the time to think. I think the physical volume at which questions and comments were coming in; I don't know how others would respond. I mean, it was so much and so quick. In fact, during the press conference, I had a couple hundred, at least, e-mails coming in. I'm still on stage. I didn't have my PDA with me. When I checked my e-mail later, they're demanding, "Answer all my questions right now." It's really hard.
I still haven't answered your question, I suppose.
Q.: Well, you sort of have, I think.
F.W.-S.: I will say, on the record, I really appreciate you giving myself personally and my co-authors this opportunity, and I am really doing the best I can. I don't know if you've picked up from what you may have read from my background, but I'm an oboist, which is a particularly rigorous instrument. It's not a "take out by the campfire" sort of instrument, but I do have an oboe that I take into the field made of plastic.
And what can I tell you, I understand rigor and getting in there and wood shedding, that's how we put it, to practice, play it again, play it again. You think it's right? Play it again. So, in science, if you're lucky enough to put one peg into trying to help all of us understand a big question, just one little peg, that's really important. I think in music, that's what I liken it to, raising what we do to a level much beyond us.
As a musician, first and foremost—and getting back to what I'm saying about communication and the media, and why I think it's very important—part of bringing music, playing in front of other people, it's the joy and the interest you get. So, I don't think any of us would want to look like we don't respect that communication.
I think the media is changing, and I think that we're all learning, and I think you've got to navigate the best you can.