That's the problem with PCR. My students can't just write "We followed
the methods of Author (year)." because everyone does PCR slightly
differently. Times and temperatures and number of cycles
vary--sometimes by miniscule amounts--but they vary.
PCR really is about following a cookbook, but the recipe constantly gets
tinkered with to improve results for the particular species, primers,
whatever. So, standardizing times and temperatures in my examples below
have probably confused things. Those temperatures and times and number
of cycles vary. Well, 94*C and 72*C are used in many studies, as are 35
cycles.
CL
malcolm McCallum wrote:
Just write "We Followed the PCR methods of AUTHOR (year)."
Malcolm
On Fri, Jun 5, 2009 at 9:28 AM, Cara Lin Bridgman<[email protected]> wrote:
One of my students did a quick survey of 18 papers from 9 journals and found
a total of four ways of describing conditions for PCR reactions. I’ve tried
to standardize these examples for temperatures and times.
Ten papers used this formula: “All PCR reactions included an initial
denaturation of 94*C for 30 s, 35 cycles of 94*C for 30 s,
58*C for 45 s, and 72*C for 2 min, followed by a final elongation step at
72*C for 7.”
Five papers used this formula: “30 s denaturation at 95*C, 45 s annealing at
58*C and 2 min extension at 72*C, a final extension step of 7 min at 72*C.”
Two papers used this formula: “PCR cycling conditions of an initial
denaturation step (94*C, 30 s), followed by 35 cycles at 94*C (30 s), 58*C
(45 s), 72*C (2 min) and a final extension step of 7 min at 72*C.”
One paper used this formula: “The reaction was cycled 35 times with 94*C (30
s), 58*C (45 s) and 72*C (2 min).”
The question is this: When writing your own paper, does using (or copying)
one of these four ways constitute plagiarism?
If it does constitute plagiarism, then are these papers plagiarizing each
other? Also, how does one go about describing methods for PCR reactions
without commiting plagiarism? My students and I agree that the ways are
rather limited--especially since there is not much diversity in these 18
published papers. This is a real dilemma, because these conditions have to
be described in each paper that uses PCR--the details in terms of times,
temperatures, and cycle number change with every study and every experiment.
If it does not constitute plagiarism, then how much of the descriptions for
other methods (statistical analysis, definitions for formula, figure
legends, table titles, etc.) can be copied before it constitutes plagiarism?
(My students and I can see a slippery slope here...)
When writing her own PCR methods, my student tried going around this problem
by finding a paper that came close to doing the same things she did, citing
that paper, and adding a sentence to explain the changes in times or
temperatures to describe what she actually did. We do not find this a very
satisfactory solution because my student did not use the cited paper when
actually deciding how to do her PCR reactions or in any other part of her
thesis. In other words, citing that paper gives it undue credit for helping
her with her methods.
Finding ourselves in an impasse, I told my students I'd ask you here at
Ecolog what you think and how you cope with these sorts of dilemmas.
Thanks,
CL
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Cara Lin Bridgman [email protected]
P.O. Box 013 Shinjhuang http://megaview.com.tw/~caralin
Longjing Township http://www.BugDorm.com
Taichung County 43499
Taiwan Phone: 886-4-2632-5484
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Cara Lin Bridgman [email protected]
P.O. Box 013 Shinjhuang http://megaview.com.tw/~caralin
Longjing Township http://www.BugDorm.com
Taichung County 43499
Taiwan Phone: 886-4-2632-5484
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