Necessity of Carrier DNA?

[Han Li]

Hello DIY Bio Community!

My name is Han. I am a student who's been interested in DIY Bio, and I wanted to undergo my own project. I have recently been following the JHU 2011 VitaYeast IGEM project (http://2011.igem.org/Team:Johns_Hopkins) in an attempt to recreate their yeast transformation as a fun way to get started. Electroporation systems have been a little out of my budget for a beginner procedure, so I'm sticking with a lithium acetate transformation instead. 

However, I have had a bit of trouble searching for salmon sperm DNA that I can use, and I was wondering if you all had any cheap sources for to find it or ideas for replacement materials? I was also wondering how necessary it is to include in the transformation, and if I can simply continue on with just DMSO instead? 

Thank you in advance, and best of luck in your own projects,

Han

[Mega [Andreas Stuermer]]

I bet human source instead of salmon should be ok as well. DNA extraction with detergent and ethanol?

[Koeng]

Human source is... nasty.

Just don't use it. I've forgotten to use it in the past, and haven't had too of significant difference in efficiency.

-Koeng

[Patrik D'haeseleer]

We've talked about extracting strawberry DNA for use as carrier DNA in our Vegan Cheese project, just because it's such an easy and abundant DNA source. Haven't gotten around to experimenting with it though.

As far as I know, there is nothing special about salmon sperm DNA. You just want a heterologous DNA source that does not crossreact with and is easily distinguishable from the other DNA you're working with. That typically rules out human, mammalian, E. coli, yeast DNA, etc. Fish DNA fits the bill, but so does plant DNA.

Sperm cells are very small, so you actually get a lot of DNA per volume of cells. And fish sperm (often herring sperm in Europe) is a cheap and abundant source anywhere there's a fishery industry.

The use of salmon sperm DNA in molecular biology actually dates back all the way to the discovery of DNA by Friedrich Miescher. He was originally working with pus from bandages (neutrophils - another good source of DNA), but eventually switched to using salmon sperm from the large-scale salmon fisheries along the Rhine.

So the answers to "why salmon sperm DNA?" are: (1) at least it's not pus DNA, and (2) that's what we've used since the 1870's - if it ain't broke, don't fix it...

Patrik

[Josiah Zayner]

Hey Han,

     I have worked with Yeast a bunch. The SS DNA definitely helps with transformation efficiency but is definitely not required, you will just get less transformants. If you need some Yeast Transformation buffer with SS DNA you can find some here: https://www.the-odin.com/yeast-transformation-buffer/

Thanks,

     JZ

On Tuesday, January 10, 2017 at 8:26:55 PM UTC-8, Han Li wrote: