Ghost band (was Re: How to get a single stranded DNA as long as 2-3kb?)

Jose de las Heras via methods%40net.bio.net (by josenet from tiscali.co.uk)
Tue Jun 12 16:31:50 EST 2007


"peter" <peter.ianakiev from gmail.com> wrote in message 
news:1181593924.822581.168770 from q75g2000hsh.googlegroups.com...
> On Jun 11, 4:22 pm, Nick Theodorakis <nick_theodora... from hotmail.com>
> wrote:
>> ChenHA wrote:
>>
>> [...]
>>
>>
>>
>> > Perhaps I misremember, was it XL1 blue cells that produces the ghost
>> > band of ssDNA instead?
>>
>> I seem to remember a discussion about NaOH irreversibly altering the
>> plasmid conformation to generate a ghost band during alkaline preps, but
>> perhaps there is more than one kind of ghost band.
>>
>> Nick
>>
>> --
>> Nick Theodorakis
>> nick_theodora... from hotmail.com
>> contact form:http://theodorakis.net/contact.html
>
> Guys keep it focussed ... the original poster asked a specific
> question - 2-3 kb ssDNA out of a plasmid with 3 kb insert. There is no
> such thing like "ghost" bands. If the culture is overgrown the plasmid
> does not have time to separate and you have occasionally  concatenates
> -  thats all.
> my2c


actually, "ghost" bands do exist.

They do seem to be related to a change in conformation of the plasmid DNA 
under alkaline conditions.
I remember vaguely an old paper, from the 70s, describing what conformation 
circular DNA can take, and it was defined as "type V" DNA, or something like 
that...
I might be able to fish it out...

Jose




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