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double helix

Zooming In on Meiosis

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Credit: Simone Köhler, Michal Wojcik, Ke Xu, and Abby Dernburg, University of California, Berkeley

Meiosis—the formation of egg and sperm cells—is a highly choreographed process that creates genetic diversity in all plants and animals, including humans, to make each of us unique. This kaleidoscopic image shows cells from a worm exchanging DNA during meiosis.

You can see a protein-based polymer tether (green) from what’s called the synaptonemal complex. The complex holds together partner chromosomes (magenta) to facilitate DNA exchange in nuclei (white). Moving from left to right are views of the molecular assembly that progressively zoom in on the DNA, revealing in exquisite detail (far right) the two paired partner chromosomes perfectly aligned. This is not just the familiar DNA double helix. This is a double helix made up of two double helices!

Copy-editing the Genome: Extreme Personalized Medicine?

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COOL TOOL. See how the TALE protein (rainbow colored) recognizes the target DNA site and wraps around the double helix. When this TALE protein is fused to a nuclease (the scissors), creating a TALEN, the hybrid protein will clip the DNA at the target site. Credit: Jeffry D. Sander, Massachusetts General Hospital

If I made a spelling mistake in this blog, and you were my copy editor, you’d want to fix it quickly. You’d delete the wrong letter and insert the correct one. Well, DNA is a language too, with just four letters in its alphabet; and disease can occur with just one letter out of place if it’s in a vulnerable position (think sickle cell anemia or the premature aging disease, progeria). Wouldn’t it be great for tomorrow’s physicians to be able to do what the copy editor does? That is, if they could fix a genetic mutation quickly and efficiently, without messing up the rest of the text?