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Left-handed DNA challenge
) Measurement Science and Standards, National Research Council Canada
1200 Montreal Road, Ottawa, ON K1A 0R6
We would like to invite you to participate in the Analytical Challenge, a series of puzzles to entertain and challenge our readers. This special feature of Analytical and Bioanalytical Chemistry has established itself as a truly unique quiz series, with a new scientific puzzle published every other month. Readers can access the complete collection of published problems with their solutions on the ABC homepage at http://www.springer.com/abc. Test your knowledge and tease your wits in diverse areas of analytical and bioanalytical chemistry by viewing this collection. In the present challenge, DNA is the topic. And please note that there is a prize to be won (a Springer book of your choice up to a value of 100). Please read on Meet the left-handed DNA challenge (literally), most prominently so in his 1957-58 Butterfly Landscape. However, the left-handed DNA is abundant among the countless depictions featuring DNA. Strictly speaking, the helicity of DNA is not always right. Nucleotides rich with guanine and cytosine can indeed crystallize in a left-handed helix, known as the Z-DNA . This left-handed DNA was in fact featured on the cover of the 13 December 1979 issue of Nature. However, the rare left-handed Z-DNA is not the intended Mona Lisa of modern science and most depictions of the left-handed DNA likely reflect the artistic oversight.
Both our hands can be thought of as mirror images of
one another. Likewise, the DNA double helix can be
drawn as two mirror images: the right-handed DNA
and the left-handed DNA. Unlike our hands, however,
DNA does not easily come in equal amounts of both
varieties. It is the right-handed helix as Watson and
Crick announced it in 1953 that is largely responsible for
life on Earth  and is now often celebrated as the
Mona Lisa of modern science  (Fig. 1).
Odile Crick drew the first DNA sketch for the seminal 1953
Nature paper  and soon thereafter Salvador Dali was among
the first to depict DNA in his art. Dali got the DNA twist right
Published in the topical collection celebrating ABCs 13th Anniversary.
The widespread occurrence of left-handed DNA images has
its parallels. Representations of sharpened pencil tips or
galloping horses are frequently drawn unrealistically . All in
all, the depictions of left-handed DNA are much like an
upside-down hoisted British flag: both are widespread and
many of us never even notice that something is amiss. To
Fig. 1 Although the DNA occurs in nature almost exclusively as a
righthanded helix, it can also be drawn as a left-handed helix
those who can, in fact, spot the difference, this column invites
the reader to search for the infamous left-handed DNA in
unlikely places in a manner befitting the King Williams
College annual quiz.
Locate left-handed DNA:
We invite our readers to participate in the Analytical
Challenge by solving the puzzle above. Please send the correct
solution to by February 15,
2015. Make sure you enter Left-handed DNA challenge in
the subject line of your e-mail. The winner will be notified by
e-mail and his/her name will be published on the Analytical
and Bioanalytical Chemistry homepage at http://www.
springer.com/abc and in the journal (volume 407/issue12)
where readers will find the solution and a short
The next Analytical Challenge will be published in 407/7,
March 2015. If you have enjoyed solving this Analytical
Challenge you are invited to try the previous puzzles on the