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Talk:Flaws in Richard Lenski Study (view source)
Revision as of 23:19, July 14, 2008
, 23:19, July 14, 2008→Richard Lenski incorrectly included generations of the E. coli already known to contain Cit+ variants in his experiments.[3] Once these generations are removed from the analysis, the data disprove Len
:Just a correction: The Cit+ cells didn't dominate the cultures at generations 32,000 & 32,500. Cit+ mutants represented 12% and 19% of the population at these times points, respectively. Replica plating is definitely one means of identifying Cit- and Cit+ clones but because the Cit+ cells represented a fraction of the total, it is simple enough to streak the samples to individual colonies (founded by single cells) and test each colony individually. Otherwise, a nice description of replica plating (a technique developed by Joshua Lederberg that allowed him do the research for which he was awarded one of the 1958 Nobel Prizes in Medicine)--[[User:Argon|Argon]] 18:38, 14 July 2008 (EDT)
:Just a correction: The Cit+ cells didn't dominate the cultures at generations 32,000 & 32,500. Cit+ mutants represented 12% and 19% of the population at these times points, respectively. Replica plating is definitely one means of identifying Cit- and Cit+ clones but because the Cit+ cells represented a fraction of the total, it is simple enough to streak the samples to individual colonies (founded by single cells) and test each colony individually. Otherwise, a nice description of replica plating (a technique developed by Joshua Lederberg that allowed him do the research for which he was awarded one of the 1958 Nobel Prizes in Medicine)--[[User:Argon|Argon]] 18:38, 14 July 2008 (EDT)
::Oops, you're right, Argon. Cit+ wasn't dominant at generation 32,000, so replica plating might not be the best option. Still, in the case of almost 20% Cit+, I think replica plating might be labor reducing. I'm a biochemist by training, not a microbiologist, but I'm sure there are other methods that could be used. For example, Christensen's agar appears to provide a sensitive, colorimetric method of identifying even weakly citrate-utilizing colonies, so one might be able to plate cells on a Christensen's agar plate and pick uncolored colonies. Again though, I'm no microbiologist so I don't know the best method. However, there are ways to easily pick Cit- clones from later generations in this case. That said, I think that this specific "flaw" cited in Lenski's paper should be removed from the main article. Clearly, Cit+ were not used in the replays from later generations, so Conservapedia's objection is totally baseless.[[User:Gerlach|Gerlach]] 19:19, 14 July 2008 (EDT)
== 1. Lenski's "historical contingency" hypothesis, as specifically depicted in Figure 3, is contradicted by the data presented... ==
== 1. Lenski's "historical contingency" hypothesis, as specifically depicted in Figure 3, is contradicted by the data presented... ==