[ECOLOG-L] life that uses Arsenic in place of phosphorus
Regarding arsenic life - this work is currently under question due to methods. The central methodological issues seem to be a lack of controls and sloppy DNA extraction. I recommend you read Carl Zimmer's piece in slate and the links therein, especially Rosie Redfield's critique http://blogs.discovermagazine.com/loom/2010/12/08/of-arsenic-and-aliens-what-the-critics-said/ Best, Hannah Waters http://culturingscience.wordpress.com/
Re: [ECOLOG-L] life that uses Arsenic in place of phosphorus
In response to Malcolm McCallum's post on the NASA-funded study on bacteria that live off arsenic in place of phosphorus, I agree that the media has greatly hyped up its conclusions. Furthermore, I want to bring attention to the strong criticisms of the study among many microbiologists, one scientist from the University of Colorado going as far as to say that the paper should never have been published (see http://www.slate.com/id/2276919/pagenum/all/). Among several issues identified with the study, a couple notable ones are: 1. When the authors stopped feeding phosphorus to the bacteria and replaced it with arsenic, the bacteria kept growing, implying that the bacteria were living off the arsenic. However, they were also feeding the bacteria a salt that had been contaminated with phosphorus. Granted, it was a very tiny amount of phosphorus, but many other bacteria species have been known to live off so little phosphorus, so this bacterium could have been eking out a living from the contaminated salts. 2. The study gives evidence for the bacteria incorporating arsenic compounds in their DNA. Arsenic compounds break down in water, so if there was arsenic in the DNA, when submerged in water the DNA should have broken into many small fragments. Instead of this, however, the DNA remained in a small number of large chucks, suggesting that the DNA was composed of more stable phosphorus compounds. Rosie Redfield, a microbiologist at the University of British Columbia, posted a much more extensive and detailed review of the arguments against the study's findings at: http://rrresearch.blogspot.com/2010/12/arsenic-associated-bacteria-nasas.html Regards, Briana Abrahms
Re: [ECOLOG-L] life that uses Arsenic in place of phosphorus
Ecolog, Malcolm: In digging around the Internet, I unearthed the following references. I hope that y'all will help me to further understand the importance of this discovery, and any possible lines of relevance to evolution in general and arsenic use in other organisms and how those uses differ and resemble each other. Transmission electron microscopy revealed large vacuole-like regions in +As/-P grown cells that may account for this increase in size (Fig. 1E). These experiments demonstrated arsenate-dependent growth, morphological differences in GFAJ-1 driven by AsO4 3- in the growth medium, and the fact that the level of PO4 3- impurities in the medium was insufficient to elicit growth in the control (-As/-P). A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus Felisa Wolfe-Simon,1,2* Jodi Switzer Blum,2 Thomas R. Kulp,2 Gwyneth W. Gordon,3 Shelley E. Hoeft,2 Jennifer Pett-Ridge,4 John F. Stolz,5 Samuel M. Webb,6 Peter K. Weber,4 Paul C. W. Davies,1,7 Ariel D. Anbar,1,3,8 Ronald S. Oremland2 1NASA Astrobiology Institute, USA. 2U.S. Geological Survey, Menlo Park, CA, USA. 3School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA. 4Lawrence Livermore National Laboratory, Livermore, CA, USA. 5Department of Biological Sciences, Duquesne University, Pittsburgh, PA, USA. 6Stanford Synchrotron Radiation Lightsource, Menlo Park, CA, USA. 7BEYOND: Center for Fundamental Concepts in Science, Arizona State University, Tempe, AZ, USA. 8Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ, USA. *To whom correspondence should be addressed. E-mail: felisawolfesi...@gmail.com http://lqma.ifas.ufl.edu/PUBLICATION/Lombi-02.pdf X-ray microanalyses also revealed that As was localized in the central intracellular portion of cut cells. Since the majority of this area is occupied by the vacuole, this suggests that As was mainly contained in the vacuoles (Fig. 4). This is supported by the differences between the distribution of Si and As (Fig. 3). Both elements are mainly concentrated in the epidermal cells but Si appears to be localized in the external cell walls whereas As is more evenly distributed in the epidermal cells. This finding is in agreement with observed distributions of heavy metals in hyperaccumulating plants and indicates that compartmentalization of both metals and metalloids in cell vacuoles plays a key role in terms of metal/metalloid tolerance in these plants. Thank you for your generosity in sharing your knowledge freely with the world through Ecolog. WT - Original Message - From: malcolm McCallum malcolm.mccal...@herpconbio.org To: ECOLOG-L@LISTSERV.UMD.EDU Sent: Thursday, December 02, 2010 4:56 PM Subject: [ECOLOG-L] life that uses Arsenic in place of phosphorus For those who have not heard NASA today announced that research done through their exobiology program discovered a that a bacterium living in Mono Lake, California can use Arsenic in place of phosphorus. This is being pretty hyped in the news as a new form of life. I think the aspect regarding its impact on extraterestrial life is over-hyped and frankly a stretch. We are not looking at an organism THAT USES Arsenic instead of phosporus. We are looking at an organism that CAN OPPORTUNISTICALLY USE Arsenic in place of phosphorus. This is pretty cool, and a huge scientific finding. however, I guess our anti-intellectual society would find it very difficult to appreciate that this is a big deal, so we have to promote the least interesting component of the study, the most speculative, and frankly the part that is hardly related to these findings,...that extraterrestrial life could use Arsenic. In fact, this DOES NOT REDEFINE our understanding of life, it REAFFIRMS our understanding!!! This is another adaptation that evolved from species with normal phosphorus-based physiology that resides in a high-arsenic environment. We long believed that organisms should be able to do this, and now they found one that could. Also, they have not established whether these organisms do this in the environment, only that they can do it in the lab. Understand, I am not taking away from the extreme importance of their findings, I just wish we would actually revel in their findings instead of speculation that has not been established. Here is a link to the NASA announcement: http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html -- Malcolm L. McCallum Managing Editor, Herpetological Conservation and Biology Peer pressure is designed to contain anyone with a sense of drive - Allan Nation 1880's: There's lots of good fish in the sea W.S. Gilbert 1990's: Many fish stocks depleted due to overfishing, habitat loss, and pollution. 2000: Marine reserves, ecosystem restoration, and pollution reduction MAY help restore populations. 2022: Soylent Green is People! Confidentiality Notice: This e-mail message,
Re: [ECOLOG-L] life that uses Arsenic in place of phosphorus
Ecolog: I hope that Malcolm will continue to help us/me understand the details of this paper. As a non-member of AAAS, I do not have access to it . . . [24 hours access to this Science article for US $15.00 from your current computer. [Why Don't I Have Access? [The content you requested requires a AAAS member subscription to this site or Science Pay per Article purchase. To find out what content you currently have access to - view your access rights. If you would like to recommend that your institution subscribe to this content, please visit our Recommend a Subscription page.] . . . and I'll be damned if I will pay $15 or more (or less?) for access to it, particularly as my tax money supports NASA, and the sources of funding for the paper are not cited. Neither can I, or any other unaffiliated person afford to pay for every paper I might like to review (I/we unwashed untouchables used to go to the library and read the clay-paper version, then pay $00.15 per page for a Thermofax(R) copy). Now the UnAmerican Dissociation for the Retardation of Science has not only cloistered itself even more, along with certain rapacious foreign publishers of prestigious journals, which even very large libraries like the University of California library can't afford. Not only have the bean-counters in charge of academic institutions decided to shit-can the time-honored custom of dissemination of knowledge at the lowest possible cost if not free, they now obviously consider that dissemination to be just one more profit center, now that a few clicks is all it takes to upload a research paper to a web site, meaning profits far out of proportion to any previously realized in the old days. And AAAS (not to mention other organizations that just happen to be largely supported by my taxes) want my support? They may get it, but it is growing more grudging by the millisecond. Beyond this, these pound-of-flesh bureaucrats apparently do not even understand fundamental pricing theory, much less morality, fairness, nay, noblesse oblige and intellectual tradition. Do you who are affiliated and can thus get this paper for free (even though your institution's library must pay a huge ransom to provide it to you) believe that there will be no ripple-effect upon you, your research, your institution? Guess again. You who complain that the public is anti-science, ill-informed, and anti-intellectual if not plain stupid, must, then, strongly desire to have your ivory tower image enhanced in the view of we, the untouchables. Do you wonder, then, that you are resented, even if you are blameless? Now, back to the issue. I must resort to speculation, puny abstracts, and Tee-Vee publicity, so my basic ignorance will be magnified, but may I ask a few ignorance-based questions? 1. Malcolm, why don't you post your comment to the NASA site? (I think I know the answer, but just in case I'm jumping to unwarranted conclusions, I would like to hear it from you; however, if you choose not to answer, I fully understand and do not want to put you on the spot.) 2. Has the genome been done on this organism (GFAJ-1 of the Halomonadaceae)? 3. Have the genomes from similar organisms been done? 4. How, specifically, do they compare? 5. Has the same experiment been replicated with other organisms under the same conditions with negative results for arsenic? 6. If the extra-terrestrial hook is always considered necessary to appeal to the anti-intellectual public, is that not an act of further dumbing it down? Who's to blame for the public's attitude? Do you see the relationship here to the opening rant? I have other questions, but I'll hold 'em. WT - Original Message - From: malcolm McCallum malcolm.mccal...@herpconbio.org To: ECOLOG-L@LISTSERV.UMD.EDU Sent: Thursday, December 02, 2010 4:56 PM Subject: [ECOLOG-L] life that uses Arsenic in place of phosphorus For those who have not heard NASA today announced that research done through their exobiology program discovered a that a bacterium living in Mono Lake, California can use Arsenic in place of phosphorus. This is being pretty hyped in the news as a new form of life. I think the aspect regarding its impact on extraterestrial life is over-hyped and frankly a stretch. We are not looking at an organism THAT USES Arsenic instead of phosporus. We are looking at an organism that CAN OPPORTUNISTICALLY USE Arsenic in place of phosphorus. This is pretty cool, and a huge scientific finding. however, I guess our anti-intellectual society would find it very difficult to appreciate that this is a big deal, so we have to promote the least interesting component of the study, the most speculative, and frankly the part that is hardly related to these findings,...that extraterrestrial life could use Arsenic. In fact, this DOES NOT REDEFINE our understanding of life, it REAFFIRMS our understanding!!! This is another adaptation that evolved from
[ECOLOG-L] life that uses Arsenic in place of phosphorus
For those who have not heard NASA today announced that research done through their exobiology program discovered a that a bacterium living in Mono Lake, California can use Arsenic in place of phosphorus. This is being pretty hyped in the news as a new form of life. I think the aspect regarding its impact on extraterestrial life is over-hyped and frankly a stretch. We are not looking at an organism THAT USES Arsenic instead of phosporus. We are looking at an organism that CAN OPPORTUNISTICALLY USE Arsenic in place of phosphorus. This is pretty cool, and a huge scientific finding. however, I guess our anti-intellectual society would find it very difficult to appreciate that this is a big deal, so we have to promote the least interesting component of the study, the most speculative, and frankly the part that is hardly related to these findings,...that extraterrestrial life could use Arsenic. In fact, this DOES NOT REDEFINE our understanding of life, it REAFFIRMS our understanding!!! This is another adaptation that evolved from species with normal phosphorus-based physiology that resides in a high-arsenic environment. We long believed that organisms should be able to do this, and now they found one that could. Also, they have not established whether these organisms do this in the environment, only that they can do it in the lab. Understand, I am not taking away from the extreme importance of their findings, I just wish we would actually revel in their findings instead of speculation that has not been established. Here is a link to the NASA announcement: http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html -- Malcolm L. McCallum Managing Editor, Herpetological Conservation and Biology Peer pressure is designed to contain anyone with a sense of drive - Allan Nation 1880's: There's lots of good fish in the sea W.S. Gilbert 1990's: Many fish stocks depleted due to overfishing, habitat loss, and pollution. 2000: Marine reserves, ecosystem restoration, and pollution reduction MAY help restore populations. 2022: Soylent Green is People! Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.
