IUBio

Storage of dry DNA? Any experience?

Robert Hartley rh at mblab.gla.ac.uk
Thu Mar 11 12:59:20 EST 1999


In article <36e7ff7e.27317058 at news>, alejaconeja at hotmail.com (alexandra
hiller) wrote:

> Hello. 

> How would it be possible to store DNA when a -20° C refrigerator
> is not immediately at hand for up to one week (because of  a
> field project in a tropical country)? 

OK Alexandra. Here is how I made my desktop -70 freezer for 6 pounds 
(about 15 Dm).

What you need is a 30x30x30cm (approx) polystyrene box that enzymes come
in. (free)
you need a gilson tip box (the 1ml blue tips) and a thermometer(not
esential as the temp usually goes to -70) and dry ice(solid CO2). (tip-box
free. thermometer 6 poundds)

Use a screwdriver to extract the white tip-cradle from the inside of the
blue tip-box. 
Take a scalpel and remove the small plastic grips on the side of the
cradle. This allows easy extraction of the cradle.

Then insert the cradle back upside down into the tip box. This will hold
0.5 and 1.5ml epindorph tubes. (for 1.5's you need to scrape the hole
bigger)

Place in the polystyrene box and suround with C02 (this usually comes free
with all enzymes).

Fill the tip box with 95% ethanol (mp of 100% = -112C so 95% is probably
about -100celcius) leave for a couple of hours and you have a -70C
enviroment. :-)
The heat transfer for solid CO2 is 85% and the gas 15% therefore you can
regulate the temp depending on the CO2 depth. Here in scotland the depth
is the top of the tip box but you can fill it higher since you are going
tropical.
Now all you need is a supply of Dry-ice or a big thermos container.

Come to think of it why not have your samples in a thermos filled with
dry-ice or with a little liquid nitrogen at the bottom.

I know my wee freezer may not be Ideal for you, but I am sure that it will
be usefull to a lot.

Cheers
Bob (Motto: if you cant buy it on a grant for 3,000 make it for free)
 Only joking. :-)

-- 
Robert Hartley BSc(Hons)                                    
Centre for Cell Engineering,                        
IBLS Division of Infection & Immunity,           
Joseph Black Building,                                
University of Glasgow,                                  
Glasgow.                                               
G12 8QQ                                               
Web: http://www.gla.ac.uk/Inter/CellEngineering          
E-Mail rh at mblab.gla.ac.uk                             
Tel: +44 (0)141 3398855 Ext 2074                      
Fax: +44 (0) 141 330 3730   



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