Breaking point: not unlike a slab of cooling rock, DNA "cracks" under pressure in roughly predictable patterns.(BIOMECHANICS)

Publication: Natural History

Publication Date: 01-SEP-05

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COPYRIGHT 2005 Natural History Magazine, Inc.

It's said that the legendary Finn MacCool created the Giant s Causeway--thousands of steplike stones on Ireland's northeast coast--in order to reach Scotland and thrash an upstart rival. As a child living in Dublin, I was fascinated by this myth. As an adult, I am intrigued by the true origin of this geologic formation: black basaltic rock that cracked into uniform columns after a volcanic eruption, 60 million years ago. And as a biomechanist, I am delighted that the same physical phenomena that led to the Giant's Causeway can also explain information exchange at the opposite end of the size spectrum, across strands of DNA.

DNA does not remain quietly coiled in the nucleus of a cell. Instead, it goes through cycles of unraveling and compaction, most dynamically during the process of meiosis. Meiosis is a kind of cell division that produces gametes--sperm cells and egg cells--from germ-line cells; no topic brings on cold sweats in biology students quite...

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