Difference between revisions of "Richard Lenski"

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'''Richard Lenski''' is an American biologist best known for his long term study of the evolution of E. coli.
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'''Richard Lenski''' is a professor of microbial ecologybiologist at Michigan State University who holds a doctorate from the University of North Carolina.
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Lenski is best known for his claim to have observed evolution of E. coli in a long-term laboratory study, insisting that it was not due to contamination.  His 2008 paper asserting his claims was peer reviewed in a mere 14 days, sparking questions about the thoroughness of the review.
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When Lenski received a public request for the data underlying for his published claims, he did not provide the actual data even though his study was taxpayer-funded.  No one else has reproduced Lenski's findings.
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Undisclosed data from the central claims in Lenski's 2008 paper are noted below (pp. 2-3 from paper, superscripts omitted):
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:Evolution of Cit Function in Population Ara-3. The LTEE populations are transferred daily into fresh medium, and the turbidity of each is checked visually at that time. [DATA ON THESE OBSERVATIONS?] Owing to the low concentration of glucose in DM25 medium [DATA ON SPECIFIC CONCENTRATIONS USED?], the cultures are only slightly turbid when transferred. Occasional contaminants that grow on citrate have been seen over the 20 years of this experiment. [DATA?  WHEN AND HOW MANY?] These contaminated cultures reach much higher turbidity owing to the high concentration of citrate in the medium, which allows the contaminants to reach high density. (When contamination occurs, the affected population is restarted from the latest frozen sample.) [DATA FOR WHEN THAT OCCURRED, AND HOW OFTEN?] After 33,127 generations, one population, designated Ara-3, displayed significantly elevated turbidity that continued to rise for several days (Fig. 1).[HIGHER RESOLUTION DATA UNDERLYING FIGURE NOT PROVIDED DESPITE REQUEST] A number [DATA? HOW MANY? STATISTICALLY SIGNIFICANT?] of Cit clones were isolated from the population and checked for phenotypic markers characteristic of the ancestral E. coli strain used to start the LTEE: all [DATA? HOW MANY? STATISTICALLY SIGNIFICANT?] were Ara, T5-sensitive, and T6-resistant, as expected (2) [DATA ABOUT THESE AND OTHER CHARACTERISTICS?]. DNA sequencing also showed [DATA?] that Cit clones have the same mutations in the pykF and nadR genes as do clones from earlier generations of the Ara-3 population, and each of these mutations distinguishes this population from all [DATA?] of the others (30). Therefore, the Cit variant arose within the LTEE and is not a contaminant [MEANINGFUL PEER REVIEW FOR THIS CONCLUSION MAY NOT HAVE OCCURRED IN THE ASTOUNDINGLY SHORT 14-DAY PEER REVIEW PERIOD]
  
 
==See Also==
 
==See Also==

Revision as of 10:34, 28 June 2008

Richard Lenski is a professor of microbial ecologybiologist at Michigan State University who holds a doctorate from the University of North Carolina.

Lenski is best known for his claim to have observed evolution of E. coli in a long-term laboratory study, insisting that it was not due to contamination. His 2008 paper asserting his claims was peer reviewed in a mere 14 days, sparking questions about the thoroughness of the review.

When Lenski received a public request for the data underlying for his published claims, he did not provide the actual data even though his study was taxpayer-funded. No one else has reproduced Lenski's findings.

Undisclosed data from the central claims in Lenski's 2008 paper are noted below (pp. 2-3 from paper, superscripts omitted):

Evolution of Cit Function in Population Ara-3. The LTEE populations are transferred daily into fresh medium, and the turbidity of each is checked visually at that time. [DATA ON THESE OBSERVATIONS?] Owing to the low concentration of glucose in DM25 medium [DATA ON SPECIFIC CONCENTRATIONS USED?], the cultures are only slightly turbid when transferred. Occasional contaminants that grow on citrate have been seen over the 20 years of this experiment. [DATA? WHEN AND HOW MANY?] These contaminated cultures reach much higher turbidity owing to the high concentration of citrate in the medium, which allows the contaminants to reach high density. (When contamination occurs, the affected population is restarted from the latest frozen sample.) [DATA FOR WHEN THAT OCCURRED, AND HOW OFTEN?] After 33,127 generations, one population, designated Ara-3, displayed significantly elevated turbidity that continued to rise for several days (Fig. 1).[HIGHER RESOLUTION DATA UNDERLYING FIGURE NOT PROVIDED DESPITE REQUEST] A number [DATA? HOW MANY? STATISTICALLY SIGNIFICANT?] of Cit clones were isolated from the population and checked for phenotypic markers characteristic of the ancestral E. coli strain used to start the LTEE: all [DATA? HOW MANY? STATISTICALLY SIGNIFICANT?] were Ara, T5-sensitive, and T6-resistant, as expected (2) [DATA ABOUT THESE AND OTHER CHARACTERISTICS?]. DNA sequencing also showed [DATA?] that Cit clones have the same mutations in the pykF and nadR genes as do clones from earlier generations of the Ara-3 population, and each of these mutations distinguishes this population from all [DATA?] of the others (30). Therefore, the Cit variant arose within the LTEE and is not a contaminant [MEANINGFUL PEER REVIEW FOR THIS CONCLUSION MAY NOT HAVE OCCURRED IN THE ASTOUNDINGLY SHORT 14-DAY PEER REVIEW PERIOD]

See Also

Conservapedia:Lenski dialog