Re: natural and un-natural radiation

["Bjorn Cedervall" <bcradsafers@hotmail.com>]

>>These repair reactions occur at varying rates, thus the 30 - 40 minutes is 
>>not meaningful.

One aspect is the degree of misrepair. Another one is the repair kinetics. 
What I found for DSBs is that there seems to be a strong correlation between 
fast DSB rejoining and radioresistance. My interpretion (=guess) is that 
this reflects the probability that the right DNA ends will be rejoined 
(rather than having chromosomal rearrangements occur).

For UV damage different enzyme systems are involved as comapred to for DSBs.

>For 50% DNA repair it took 12 hrs.
This can depend strongly on whether the cells are cycling or not. Some cells 
may keep their damage for weeks or longer if they aren't forced to divide. 
They can still maintain their other functions (like metabolic machinery).

>My question is how did they measure 100,000 vs 30,000?
I don't know. I got the 100 000 number from two professors who are into 
SSBs. I may have read that number somewhere but can't recall it at the 
moment.

Bjorn Cedervall    bcradsafers@hotmail.com

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html