Wondering if anyone can help me.
I'm trying to preare some samples for 454 sequencing. The DNA template is made up of various organisms but PCR primers are designed to amplify a only a 500bp of the 18s rDNA from all these different organisms (it does I've checked on individual organisms). So I get a strong 500bp band (50ng/ul and load 25ul), cut it gel extract and then run a 1ul sample to check quantity and I get two bands! One 500 and one 350bp. I've tried reducing the amount of PCR product I load before I get extract and PCR purification before I run the gel but I still get the same problem.
Hope you can help,