As shown in the figures to the left and right, most DNA of living things on the earth twists as a "right-hand screw". This is the same direction as a regular wood or metal screw. Many artists will flip a picture of DNA over and reverse the twist. Although left-handed Z-DNA has been demonstrated by X-ray crystallography and scanning tunnel microscopy (STM), it only recently was established that it occurs in vivo (Schwartz et al Science 1999 Jun 11;284(5421):1841-5, New York Times, June 29, 1999).

Thanks to Boris Steipe for this figure.

See the figure to the right, which compares normal B-DNA found in cells to the rare Z-DNA, which is the same molecule twisted the other way. Furthermore, the structure of this left-handed Z-DNA is quite different from a mirror image of B-form DNA. So most of these inverted twist pictures are incorrect. This error has become so pervasive that even well-known scientists, major scientific journals and institutes make it. For several years I was collecting these cases by tossing them into a file. On 1996 February 14, I was stunned and embarrassed that my file had grown enormous, so I created this page to alert people to the problem. (Thanks to Eric Putz at my alma mater CU's MCDB for permission to use the rotating DNA.)

See the Right Handed DNA Hall of Fame and my home page on molecular information theory too!

For your first visit to the Left Handed Hall of Fame page I suggest that you follow the story over all of the years. After that you can look at each year individually from the table below. Note: just because a year has gone by does not mean we haven't found more examples for that year!

1997 and 1998 were bumper crop years
and 1999 beat them more than 2 fold. 2000 was a record year, thanks to help from friends around the world (60 of the 97 cases, 63%!). 2001 exceeded even that record! 2002 was lower - are we making headway?

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2009

version = 1.11 of leftyear2009.html 2009 Jul 02

Our Story So Far: The story line, if you have not had time to follow the previous 694 or so entries (!) is my slow realization that earth is being invaded by left handed DNA people ... NOTE: I am currently NOT adding entries with images - too much else to do!! Please enjoy a visit to my web site and read my papers.

1. host building of the National Institute of Genomic Medicine - Mexico has a nice 5 story left handed DNA. First reported on 2009 Jan 9, as of 2009 Jan 9 (Thanks to S. Derkins, PhD, dyctiostelium@gmail.com, for pointing this one out!)
   
2. Sándor Kaba has created a left handed Double Helix model for Mathematica. Now you too can make these models! First reported on 2009 Feb 12, as of 2009 Feb 12 (Thanks to cherstvy andrey, a.cherstvy@googlemail.com, for pointing this one out!)
   
3. Darwin's Legacy: Evolutionary Approaches to World Challenges is a symposium to celebrate 200 years of left handed DNA evolution! First reported on 2009 Feb 17, as of 2009 Feb 17 (Thanks to Fungi for pointing this one out!)
   
4. Web of Life, a T-shirt will sportingly show that you are a superior Left Handed DNA Man. First reported on 2009 Mar 03, as of 2009 Mar 03 (Thanks to James A. Perkins, japfaa@rit.edu, for pointing this one out!)
   
5. 'For White Hill' by Joe Haldeman in A Separate War and Other Stories (pp 77-123) is a science fiction story by Joe Haldeman in which people have left handed DNA! "Our DNA winds backwards, as was the case with many people born or created after that stage of the war." (page 78). (google) (Some interesting discusssion, For White Hill Notes is not very readable in its current form.) First reported on 2009 Mar 24, as of 2009 Apr 05 (Thanks to Blake Sweeney for pointing this one out!)
   
6. Resolved: This house believes that the handedness of people's DNA is their business, and nobody else's. a blog by Ronald Bailey (March 24, 2009, 1:34pm). Previous work by Bailey can be found in 2005 (#27). First reported on 2009 Mar 25, as of 2009 Mar 26 (Thanks to Dmitri Sobolev, dmitri.sobolev@jsums.edu, for pointing this one out!)
   
7. Touche pas à mon ADN. At first I thought this was an example of a flat DNA, but the person who alerted me to it points out that the DNA strand in front is thicker, so it is a perspective view. (For more perspective on the issue shown on the web page, see Tests ADN : "Pseudoscientific Bigotry in France" Sauvons la recherche, 23 octobre 2007) First reported on 2009 Apr 12, as of 2009 Apr 12 (Thanks to an anonymous contributor for pointing this one out!)
   
8. On Being a Scientist: Third Edition by the Committee on Science, Engineering, and Public Policy, National Academy of Sciences, National Academy of Engineering, and Institute of Medicine tells how scientists with left handed DNA run the scientific enterprise. (A large image is available.) First reported on 2009 Apr 24, as of 2009 Apr 24 (Thanks to Shoji Nakayama, Nakayama.Shoji@epamail.epa.gov, for pointing this one out!)
   
9. Doonesbury 4/27 finally discusses molecular biology, showing first a left handed DNA (first panel) that turns into a right handed one by the second panel. What a great way to hedge one's bets! First reported on 2009 Apr 27, as of 2009 Apr 27 (Thanks to Frank Deis, deis@rci.rutgers.edu, and Rachel Rodman, rrodman@biochem.wisc.edu, for pointing this one out almost simultaneously!)
   
10. theLabRat.com will sell you rats that have either left or right handed DNA. New special: combined rats! First reported on 2009 May 01, as of 2009 May 03 (Thanks to Rachel Rodman, rrodman@biochem.wisc.edu, for pointing this one out!)
    
11. Psst, Bob . . . you're left-handed!. This cartoon also appeared in Nature Genetics 22, 123 (1999). First reported on 2009 May 01, as of 2009 May 03 (Thanks to Rachel Rodman, rrodman@biochem.wisc.edu, for pointing this one out!)
    
12. The symbol of the journal Genes & Development has a subtle left handed DNA on it. This is most visible between the n and the e of the icon. First reported on 2009 Jun 10, as of 2009 Jun 10 (Thanks to cherstvy andrey, a.cherstvy@googlemail.com, for pointing this one out!)
    
13. Left Handed DNA Tobacco Stops Smokers First reported on 2009 Jul 02, as of 2009 Jul 02 (Thanks to Dmitri Sobolev, dmitri.sobolev@jsums.edu, for pointing this one out!)
    

Coda

None of the statements on this page are intended to endorse or favor any product over other equivalent products on the market.

When a source can be identified, permission has been requested to reproduce all graphics. If someone knows who made that cute mouse (which I picked up from somewhere on the net), please tell me.

Contributions

It helps if you check through the previous entries to see if you have been scooped, as I do not repeat (even for really egregious cases). To do this please use the Left Handed DNA Google search engine. ( as of 2003 Feb 25)

DO NOT SEND IMAGES BY EMAIL!!! If you would like to contribute examples that are on the web, please send me precise evidence that documents the case, along with all reference materials that are available. Precise web pointers are appreciated as it saves me time. If there is an image on the web just tell me where it is, please NEVER send me images that I can get from the web! I have to check them anyway and I use wget to grab them. Let me put that another way: I cannot use graphics sent to me. I only use ones I can verify from the web.

Finally, NEVER NEVER NEVER SEND ME DOC FILES!

Also please indicate whether you would like to be acknowledged on this page. Your name will be listed with your email address if you do not tell me. Since I don't want to have to recall previous rules for people, please tell me how you would like to be listed each time. You may pick an alias such as Gorilla Guerilla (which is already taken).

Web Sites: For web sites, it helps a lot if you email to me three URLs:

• The web site page where you found the image.
• The url of the image itself.
• The url of a page that gives the email address of the contact for obtaining permissions.

Printed Sources: If you would like to contribute examples that are not on the web, please send me hard physical evidence that documents the case, along with all reference materials that are available. The simplest address for sending physical evidence is:

Tom Schneider
NCI-Frederick Bldg 469. Room 144
P.O. Box B
Frederick, MD 21702-1201

Books: For books please send a photocopy of:

• the front cover
• the inside page that includes the ISBN and other publication details
• the pages you have found the examples on

Image Policy