Michal,

DNA damage has been achieved with a 405 laser on a laser scanning  
confocal (such as in Bergink et al, Genes Dev 20: 1343-1352, 2006).  
People have also had success with a Photonic Instruments Micro-Point  
laser (Ayoub et al, Nature 453, 682-686, 2008). A FRAP of  
photokinesis laser module from a variety of vendors will also work  
fine. If you check the literature, you will see that different  
wavelengths may induce different types of DNA damage, also depending  
on which sensitizers you add to your cells, so doing a review of the  
literature would be a good idea. A PubMed search for " laser DNA  
damage" or similar will give you plenty to read. One review on  
different laser irradiation methods was published recently (Kong et  
al, NAR 37(9): e68-2009). Exact conditions will depend on your  
samples and experiment... as usual for this type of work, I would  
recommend using the most gentle settings that allow you to see a  
response.

--
Julio Vazquez
Fred Hutchinson Cancer Research Center
Seattle, WA 98109-1024

http://www.fhcrc.org/


On Jun 21, 2010, at 9:20 AM, Michal Jarnik wrote:

> Listers,
>
> We would need to perform experiments including controlled DNA  
> damage to cells in culture. One idea was to use the LSCM and expose  
> an area in a way similar to the bleaching part of a FRAP  
> experiment. We do have a LED 405 nm laser (I would assume that  
> would be the right wavelength, we do not have any really UV laser),  
> Nikon C1 can do quite a lot of zooming to concentrate the energy in  
> a small area. I have no idea, though, about the power necessary/ 
> available and other conditions. Any recommendations would be very  
> much appreciated.
>
> Thanks, M.
>
> -- 
>
> Michal Jarnik, Ph.D.
> Cell Imaging Facility
> Electron Microscope Facility
> Fox Chase Cancer Center
> 333 Cottman Ave.
> Philadelphia, PA 19111
> 215-728-5675 (v.)
> 215-728-2770 (v.)
> 215-728-2412 (f.)