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Long PCR problem - Product smaller than expected size (Jan/29/2003 )

I have been using the Roche Expand Long PCR kit (system 3) and keep getting a product about half my expected size (`9000bp vs ~15000bp); I am trying to amplify the entire mitochondrial genome of Orthopteran insects. In the course of my experiments, I also often get what appear to be very large pieces of DNA hung up in the wells of theagarose gels that I run to screen my products. Any ideas?


if u have long well platform to run ur amplified products then use it
size of the well should be 5 cm .
i also had the same probs but then i used 5cm well and solved


You might want to try software designed for picking primers for long PCR or high-low GC contents:



I also had the same problems. Has your problem been rectified? If yes, please let me know the key. Thanks.