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Boiled single strand DNA (salmon sperm derived)
ssDNA is used as a supplement during chemical transformations of yeast as an additive (called a "carrier").
The function of it is (probably) threefold:
- To keep the nucleases in the yeast cells busy which might give the plasmid or fragment of interest a bigger change to make it to the nucleus without being degraded. 
- To keep our plasmid or DNA fragment from sticking to the yeast's cell wall. The extra added DNA (which is added before) will interact with the cell wall and fill some of the interacting surfaces. 
- To induce the repair and with that homologous recombination machinery(?)
Working with ssDNA:
- Thaw on ice (or shortly in the waterbath)
- Keep on ice
- Don't use for more than 4-6 transformations!
Make stock solution 10 μg/μl
- weigh 10 mg salmon sperm in a sterile 50ml duran bottle
- add 10ml sterile MQ water
- dissolve by stirring
- boil for 10min in a waterbath
- aliquote into 100 μl tubes (we only use 2μl/transformation, so these go a long way!).
- Store at -20°C
Stock solutions are kept in the top drawer of freezer 7.