LIGHT CYCLER

Dr. Duncan Clark Duncan at nospam.demon.co.uk
Wed Oct 18 04:54:33 EST 2000


In article <8sj1tj$ntp$1 at slb6.atl.mindspring.net>, the eminent theLabRat
at MindSpring Enterprises wrote
>The advantages are:
>
>(1) It gives you "real" realtime results - meaning you can monitor it while
>the experiment is running (unlike Taqman, which you need to wait until it is
>done).

By Taqman I think you mean the ABI7700 machine. There are other real-
time machines that allow monitoring in real-time i.e. RotorGene from
Corbett Research, I-Cycler from Biorad etc. 

>(2) It is much faster per reaction (although this can be a problem if you
>are doing high-throughput.

Very fast.

>(3) It allows you much more flexability in the reaction:  altering the
>melting curve profile, etc. than the exonuclease activity of the Taqman
>instrument.

Depends upon what you are doing. Sybr Green is good for some things but
it does detect any ds DNA i.e. dimers. A Taqman reaction, in it's true
sense using the 5-3 exo. Activity of the Taq pol to cleave the
fluorescent molecule off the probe, you never see dimers. They may well
be there but they do not show up as a false positive on an amplification
trace.  

>
>Disadvantages:
>
>(1) If you are doing high throughput it is not as good, since you need to
>load the cappilaries.  There is an automated process for that, but still
>doesn't make up for the difficulty if you are doing several runs a day.

Capillaries are also expensive, UKP284 for 768 capillaries. 

Glass messes up the PCR reaction conditions i.e. you won't get very far
using standard PCR reaction buffers in glass capillary PCR, regardless
of adding BSA. 

Corbett's machine accepts standard 0.2ml polypropylene microtubes,
others (bar the Cepheid) take 96 well plates.

>
>IMHO it is a far superior research instrument than the Taqman...

I think it really depends upon the application you require the machine
for. I would look very closely at the optics, in particular
discrimination between different channels, and check out literature from
the following manufacturers of real-time machines. 

ABI 7700
Cepheid
Corbett Research
Biorad
Stratagene
Roche Diagnostics

I would also make no decision until after you have played, if at all
possible, with the machines yourself.

Duncan

-- 
The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
GeneSys Ltd.
Tel: +44(0)1252376288
FAX: +44(0)8701640382
http://www.dnamp.com
http://www.genesys.demon.co.uk






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