I agree with 2 prior answers regarding more sensitive techniques

Alternatively, increase the mass of starting material to try and obtain at least ng/ul of DNA. With concentrations of pg/ul I m not sure much is to be gained by precipitation/concentration. I suspect you have another problem you need to address at source

For what its worth if you do decide to ethanol precipitate your starting material to concentrate up you might want to add 1ul of 1mg/ml to 20mg/ml molecular grade glycogen: This will greatly increase your recovery, especially with such vanishingly small quantities of DNA

Remember though: you need a minimum of 10ng of genomic DNA for PCR to work reliably; Your quantities appear to fall well short of that: If you are in the 1ng or pg magnitude of materials you might want to think about qPCR (which is > 10x more sensitive) as mentioned above 

You can use real time PCR its more sensitive

Hi, first of all, if you can change your primer's, then do it. If you have to use the same primer set, increase the cycle number and see if any good comes out. If not, you can change to more sensitive Taq DNA Polymerase enzyme.  Best wishes!

• I tend to agree with the first commentator: your DNA could concentrations are very low indeed
• This could imply something awry with your extraction material or you are extracting from vanishingly small quantities of material: is it possible to extract from more starting material so that you end up with multiple ng quantities of DNA? 
• If this isn't possible you might want to try qPCR: ideally for PCR from genomic DNA you should not use less than 10ng fir reliable detection
• If that isn't possible subtle green qPCR will allow you to detect reliably from
  2 votes 1 thanks

Ethonal re-precipitation of dna sample to resuspend smaller volume to concentrate...

Boil/ heat  sample down to concentrate. ..also contaminates will concentrate.

Realtime pcr...more precise 

Larger pcr rxn add more dna less water to mix.. or 

Extend pcr cycles a few more times....

Hummmm,  

If your conteols worked its not the pcr rxn... mastermix or such...

Best of luck!

Hello Stella,

I agree--you have low concentration of DNA samples. How about doing Ethanol precipitation? I did it once and it really improved my DNA concentration. Good luck!

Regards,

NRB

As I can see, your sample is very important and you cannot lose anything. So I will not recommend you to precipitate your sample because you will lose material. You should use more sensitive techniques like full genome amplification (used in forensic samples for example), digital PCR, pyrosequencing, qPCR or nested-PCR. As I'm sure that you can do convetional PCR, so I would recommend nested-PCR. The main disadvantage of nested-PCR is that it is prone to contamination, but it can do miracles with bad samples.

I would also recommend to increase the cycle number and to do a nested-PCR. If not available more sensitive techniques as ddPCR, qPCR...Good luck!

I agree with 2 prior answers regarding more sensitive techniques

Alternatively, increase the mass of starting material to try and obtain at least ng/ul of DNA. With concentrations of pg/ul I m not sure much is to be gained by precipitation/concentration. I suspect you have another problem you need to address at source

For what its worth if you do decide to ethanol precipitate your starting material to concentrate up you might want to add 1ul of 1mg/ml to 20mg/ml molecular grade glycogen: This will greatly increase your recovery, especially with such vanishingly small quantities of DNA

Remember though: you need a minimum of 10ng of genomic DNA for PCR to work reliably; Your quantities appear to fall well short of that: If you are in the 1ng or pg magnitude of materials you might want to think about qPCR (which is > 10x more sensitive) as mentioned above 

Hi

I agree with Dr. Dawikins-Hall, increasing DNA concentration will be an appropriate approach to go ahead and a carrier molecule like glycogen works quite well. WE use it regularly in our lab for precipitating and concentrating low amount DNA.

I also think you should increase the number of cycles as mentioned earlier.

If you have very low concentration of DNA I would not recommend ethanol precipitation but beads purification. My experience with ethanol precipitation showed very poor efficiency. Moreover, playing with beads ratio you can optimize your purification by selecting size of the matrix you want.

Maybe you have contaminant in your samples leading to absence of results... Try applying RNAse for example...

Be strong and find a solution

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