Showing posts with label homochirality. Show all posts
Showing posts with label homochirality. Show all posts

Tuesday, May 1, 2012

Same (Space) Science, Different (Dino) Day

"Five Acids" -  Duplicated in five papers
(PNAS, OLEB, IJC,  TL, JACS)
For those new to the Breslow #spacedino saga, Paul's collection of links back at ChemBark might be the best place to start. Long story short: a tongue-in-cheek press release proclaiming "Dinosaurs from Space!" drew much (unwanted) attention to a prebiotic homochirality review by Columbia University chemistry professor Ronald Breslow. Astute readers and blog commenters noted that the review text strikingly resembled that of earlier papers by the same author.

Well, just how similar were they? Not to incite a flame-war over "least publishable units" (LPUs), but, inspired by ChemBark's commentary on the matter, I've dug through the last six years of Breslow origin-of-life (OOL) publications, and summed up my findings below (Thanks to Paul, Stu, Chemjobber, Ash, Mark, Unity, Martyn, 'Anon,' and everyone else who provided source material for this post!)


"Transamination" - Duplicated in five papers
(TL, OL, OLEB,  IJC, JACS)
Over the last 6 years, I count nine papers that involve, in some fashion, the following topics: homochirality, prebiotic chemistry, enantiomeric amplification, meteorites, or OOL. Here's a list, with full titles, journals, and authorship:

2006Tet. Lett. - "Partial transfer of enantioselective chiralities from alpha-methylated amino acids, known to be of meteoric origin, into normal amino acids." Breslow, Levine
2006 - PNAS - "Amplification of enantiomeric concentrations under credible prebiotic conditions." Breslow, Levine
2008 - Org. Lett. - "Enantioselective Synthesis and Enantiomeric Amplification of Amino Acids under Prebiotic Conditions." Breslow, Levine
2009 - PNAS - "On the origin of terrestrial homochirality for nucleosides and amino acids." Breslow, Cheng
2010 - Org. Life Evol. Biosph. - "Imitating Prebiotic Homochirality on Earth." Breslow, Levine, Cheng
2010 - PNAS - "L-amino acids catalyze the formation of an excess of D-glyceraldehyde, and thus of other D sugars, under credible prebiotic conditions." Breslow, Cheng
2011 - Isr. J. Chem. - "Formation of L Amino Acids and D Sugars, and Amplification of their Enantioexcesses in Aqueous Solutions, under Simulated Prebiotic Conditions." Breslow
2011 - Tet. Lett. - "The origin of homochirality in amino acids and sugars on prebiotic earth." Breslow
2012 - JACS - "Evidence for the Likely Origin of Homochirality in Amino Acids, Sugars, and Nucleosides on Prebiotic Earth." Breslow

"Formose" - Duplicated in four papers
(OLEB, IJC, TL, JACS)
*So, for those keeping count at home, that's "Prebiotic" = 7, "Amino Acids" = 7, "Origin" = 4, "Chirality" = 4, "Sugars" = 4...and we're not yet past the titles!

(Throughout the post, I've also compared similar Figures, a task Paul and other bloggers had started tackling. I've examined each one in the context of the other eight.)

Poring over the text, many of the papers fall into similar thematic traps. First, Breslow poses a "big question" or concept (OOL, homochirality, etc.), then discusses the Murchison "carbonaceous chondritic meteorite." Breslow references the work of Cronin and Pizzarello, and discusses circularly polarized light, white dwarf stars, and synchrotron radiation. The Breslow "formose reaction" paper (Tet. Lett., 1959, 22-26) sets the stage for the D sugars, and the group's transamination / amplification work for the L-AA papers.

"Nucleosides" - Duplicated in five papers
(TL, OLEB, IJC, PNAS, JACS)
Dead-center in the most recent four papers (OLEB, TL, IJC, JACS), one finds the Morowitz equation, which explains enantiomeric amplification from tiny initial excesses of single enantiomers. Unfortunately, one also finds the most glaring piece of self-plagiarism: the kinetics paragraph. As noted by Stuart Cantrill and several others, full pages are duped among the separate articles - TL p. 4229 is identical to JACS p. 5-6, IJC from 992-993, and (almost) OELB from 20-21.

Even the dinosaur joke, that witty aside that brought all the attention to the paper in the first place, was repeated three times! (IJC, TL, JACS). This inclusion almost begs the question . . .did Breslow wish to be caught?

Obligatory dinosaur image
Source: stegosaurus.com
Nonetheless, the offending paper has been removed from the JACS website, and further editorial action likely awaits him. I remain puzzled, however. How could an academic legend, a chemical pioneer, a man whose research has launched quite a few stelllar professorships (Gellman, Schepartz, Groves, Grubbs, among others), simply reissue the same science, over and over again, in different journals? Breslow continually mentions "credible" conditions; was this because the papers were less so? There's also the puzzling publication order, from 'worst to first.' Breslow re-publishes tenuous material from TL (Impact Factor = 2.6) in JACS (I.F. = 9.0), where visibility no doubt increases? Generally, high-impact research starts out in high-impact journals, and later trickles down.

Time will tell what will happen to the #spacedino paper. My final hope would be that aspiring academics and graduate students watch the situation unfold, and take care against any similar publishing behavior.

Wednesday, April 11, 2012

Space Dinos! Prebiotic Chemistry Meets Paleozoic Commentary

Source: Columbia Giving
When I open Google News, I usually expect to see trade agreements, protests, car shows, or sports quotes. But, when I read a title like Dinosaurs from Space! (Smithsonian), or Do Intelligent Dinosaurs Really Rule Alien Worlds? (Discovery) I'm admittedly drawn in.

Ready for the real shocker? It's a paper published in JACS! No joke - here's the ACS presser. Bonus: the paper's written by a well-respected research lion - Ron Breslow, long a veteran of Columbia's chemistry department (Aside: I couldn't recall if ChemBark had seen Breslow's professorial "portrait," (right), courtesy of Columbia's University Giving Office).

The paper, a Perspective, reads fairly well: Breslow muses about the origin of homochirality on the early Earth, a subject near and dear to researchers such as Robert Shapiro, Albert Eschenmoser, Jack Szostak - and #1 on Philip Ball's list of chemical "grand challenges." Breslow recalls that scientists measured small enantiomeric excesses in amino acids, from 2-15% of the S (also called "L-") form, found in several meteorites that fell to Earth in the last 50 years. He then demonstrates, using a clever mix of solvation energies and autocatalytic reactions, some possible prebiotic setups leading to enrichment of single-enantiomer sugars and amino acids. 

Sound good? Well, it's all fine up until the closing paragraph - again, no exaggeration on my part:
"An implication of this work is that elsewhere in the universe there could exist life forms based on D amino acids and L sugars...Such life forms could even be advanced versions of dinosaurs,  if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth. We would be better off not meeting them."
Artist's Representation: Life Elsewhere
Source: fanpop.com
I'm actually both horribly amused, and somewhat embarrassed by that conclusion. It's playful and exciting, yes, but, as others have pointed out, it sounds suspiciously like bait to draw sensationalist reviews and lure more casual readers. 

Well, two can play at this game! Without further ado, I'd like to offer a few novel O.O.L. speculations of my own: 
- On "Earth 2," in a far-off galaxy, a preference for body hair, muscles, and heavy brows favored Neanderthals over modern humans. 

- Life on distant planets proven to be highly evolved amoebas, who had the good fortune never to form into any multi-cellular critters.

D-amino acids + L sugars = Luck Dragons?
Source: Kristen Lamb
- In the land of Fantasia, a young boy named Atreyu must find the Nothing killing his world (wait, no, that's the Never Ending Story...).


- On Planet 2G, slightly different rules of gravity and lack of water, combined with a preponderance of slightly chiral amino acids led to...really beautiful crystal gardens, but not much life. (sorry, everyone!)