Q: LCR and isothermic amplification

Zophonias O. Jonsson zjons at vetbio.unizh.ch
Tue May 2 01:55:11 EST 1995

In article <mgrebus.35.2FA01427 at postbox.acs.ohio-state.edu>,
mgrebus at postbox.acs.ohio-state.edu (Marcy Grebus) wrote:

> Hey folks,
> 	Anyone have experience with or an understanding of LCR [ligase chain 
> reaction] technology or isothermal amplification techniques?  I'm reading a 
> review [Henson & French, Annu. Rev. Phytopathol 1993 31:81-109] that touts 
> these procedures as potential alternatives to PCR for DNA amplification.  
> 	Specifically, I would like an explanation [&/or pointers to refs. if 
> possible] of how these techniques work.  And... if they're as good as PCR, why 
> haven't I heard more about them?  

  Yes I have done LCR!  The principle is quite simple, and under the right
circumstances it works quite well but it will hardly replace PCR except for
two purposes, the detection of well defined point mutations, insertions or
deletions and detecting viruses/bacteria in samples.  LCR does not amplify
DNA in the same way as PCR.  What you see is simply a shift of bands from
say 25 bp to 50 bp upon ligation, if a correctly matching template is
present.  Francis Barany has written a number of reviews where he describes
the techique.  Take a look at Barany F. (1991) PNAS 88:189-193 for a
desctiption of the methodology.
  Actually the most interesting applications I have seen for LCR lately
have used it together with PCR to detect pathogens in various samples, e.g.
Listeria monocytogenes in food.  The advantage is that you can use PCR
primers that recognize a wide range of species or strains to amplify a well
known stretch of DNA ( e.g. 16S rDNA) and then you can use strain specific
LCR primers for further characterization.  This is probably the niche that
holds most promise for LCR.


Zophonias O. Jonsson
Institut fur Veterinarbiochemie               Tel: (41-1)-257-54-75
Universitat Zurich-Irchel                     Fax: (41-1)-362-05-01
Winterthurerstrasse 190
CH-8057 Zurich

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