DNA balls

My feature on Spherical Nucleic Acids (SNAs) - a kind of assembly in which short nucleic acid strands stick out radially from a nanoparticle core - is out in the September issue of Chemistry & Industry:

DNA plays ball
Chemistry & Industry 2013, No. 9, pp28-31

This is premium content with restricted access to the full text, but I may get pdf reprints.

Image source: Wikipedia - Adapted from Cutler, J. I., et al., Spherical Nucleic Acids. J Am Chem Soc 2012, 134 (3), 1376-1391. Copyright 2012 American Chemical Society.

PS - as punishment for making fun of people for publishing DNA helices the wrong way round, I've been hit by another inverted helix in the illustrations for this article, which I didn't get to check. Fortunately, it's a detailed ball-and sticks model where the chirality is very hard to verify, so it won't mislead anybody who doesn't know already which way the helix is supposed to turn.

apps with inverted helices

After my recent blog post on DNA double helices that twist the wrong way (inverted helices), a reader (who prefers to remain anonymous) submitted a few examples of apps featuring such mirror-world DNA. Following the example set in that previous post, I'm showing the corrected versions here:

I'm sure you can still read the text to work out who the culprits were ...

the curse of the inverted helix

I've now figured out what to do with DNA double helices of the wrong chirality, which I frequently see in print and online. Earlier I started compiling a hall of shame, but that might reinforce the wrong image (eg by adding to the already considerable proportion of wrong helices that show up in google searches for double helix).

Instead, I'm now going to flip the images that also contain text, such that the DNA will be the right way round and the text will be mirrored. This way, I can signal-boost the correct structure while also exposing the error.

So, for example, a poster I received yesterday now looks like this:

much better, huh?

The same treatment for the historic blunders of Nature and Science yields:

inverted moons

Love the story about the inverted moons on christmas cards: Your moons are rubbish, astronomer tells Christmas card artists

I should just add that one doesn't need to know about waning moons and what time they rise - it is completely sufficient to know that both Sun and Moon move from left to right in the sky (seen from the Northern hemisphere outside the tropics) and that the bright side of the moon points towards where the Sun is. So in the wrong xmas card, the bright side points to the left, so the Sun is trailing the Moon and will rise in a couple of hours, so it must be early morning. For an evening scene, you want a Sun that has recently set, so bright side of the Moon must point to the right. Simples.

Are these artists the same people who insist on putting inverted helices on the covers of books and magazines, I wonder ...

Oxford Today relaunch

Oxford Today, the alumni magazine of Oxford University, has a new publisher and a new editor, so the first issue of the academic year was celebrated as a "relaunch" today with champagne, canapees, and speeches. Even the vice chancellor (organic chemist Andrew Hamilton) put in an appearance, and for me it was an opportunity to put faces to email addresses.

I've been writing science features for Oxford Today since 2004, and have now also taken over the science findings page which compiles very short news items on scientific results emerging from research conducted here (open the PDF version of the magazine and scroll down to page 11).

My latest feature, about data sharing in genetics, appears on pages 30 to 32 of the magazine and online here. As punishment for my recent rant on inverted helices I've been served with a wrong helix as well. Intriguingly, the same illustration also contains a correct (but much smaller) image of the double helix, on the 2-pound coin, so it can't be because someone flipped the image. Very pleased however that the spiral staircase appearing in the portrait of HELEX director Jane Kaye has the correct chirality.

We were told that not only the printed magazine has been spruced up, the website is also being relaunched in an improved format, with added content, including even music videos. I'll have to check those out.

PS I have been assured that links to earlier online content of Oxford Today will remain functional, so my previous pieces, such as this one on multiple sclerosis and epigenetics are still accessible via my website and blog.

the inverted helix

It is a fact widely ignored by people who design covers for science books and journals, but let me say it loud and clear, the normal version of the DNA double helix is RIGHT-HANDED, i.e. it is like an ordinary screw in that if you look down the axis and follow the ridge clockwise, the movement will lead away from you (see this example from the Ashmolean Museum's collection of glassware).

If, however, you take a picture of a DNA double helix and mirror it, you end up with something blatantly WRONG like the examples below:







PS in order to inject some scientific method into my rant, I've just done a Google image search for "DNA" and checked the first 30 double helix images shown. Giving those where the chirality isn't easy to see the benefit of the doubt, I have spotted three images with left-handed helices, so the error rate seems to be around 10%, even on websites that get high PageRank.