Does UV light nick DNA?

[Frederik Intelmann]

In article <cbbccm2-2101971438500001 at cbb088.lubb.ttuhsc.edu>,
   cbbccm2 at tthsc6.lubb.ttuhsc.edu (Clinton MacDonald) wrote:
>Friends:
>
>   Does UV light "nick" or cut DNA? What effect does ethidium bromide have
>on this?

<snip>

About the first part:

"[...] Minimize the exposure time of the gel with DNA to be excised to =< 1 
minute of UV light. If possible, be sure the wavelength of the light is 
greater than 300 nm. Too long exposure, or the use of short wavelength light 
will result in photonicking and/or photodimerization of the DNA. [...]"