Hello everyone, please help: how to detect low abundance gene expression? Now I use 1 ug of RNA per 20 ul cDNA reaction, then I use 1 ul of the cDNA. For beta-Actin, the qPCR picks up the signal at around 15 cycles in linear range. But my target gene (I used 2.5 ul per reaction) can only be picked up at around 35 cycles (1 or 2 out of triplicated reactions), where it is already out of the linear range!! How to enhance the signal?? Please help! Thank you very much!! So frustrated...
do not force it, the gene is simply not expressed.
. up
【在 a*****s 的大作中提到】 : Hello everyone, please help: how to detect low abundance gene expression? : Now I use 1 ug of RNA per 20 ul cDNA reaction, then I use 1 ul of the cDNA. : For beta-Actin, the qPCR picks up the signal at around 15 cycles in linear : range. But my target gene (I used 2.5 ul per reaction) can only be picked up : at around 35 cycles (1 or 2 out of triplicated reactions), where it is : already out of the linear range!! How to enhance the signal?? Please help! : Thank you very much!! So frustrated...
you need to have no-RT controls. If no-RT control has a much higher Ct (say 45) then you are fine. If no-RT is also 35, then forget it. Just say your gene is not detectable under the condition.
. up
【在 a*****s 的大作中提到】 : Hello everyone, please help: how to detect low abundance gene expression? : Now I use 1 ug of RNA per 20 ul cDNA reaction, then I use 1 ul of the cDNA. : For beta-Actin, the qPCR picks up the signal at around 15 cycles in linear : range. But my target gene (I used 2.5 ul per reaction) can only be picked up : at around 35 cycles (1 or 2 out of triplicated reactions), where it is : already out of the linear range!! How to enhance the signal?? Please help! : Thank you very much!! So frustrated...
a*s
7 楼
No-RT controls have no amplifications until 45 cycles... so I believe the gene is expressed... Thanks for more suggestions!
say
【在 m**********2 的大作中提到】 : you need to have no-RT controls. If no-RT control has a much higher Ct (say : 45) then you are fine. If no-RT is also 35, then forget it. Just say your : gene is not detectable under the condition. : : . : up
r*8
8 楼
What's No-RT controls ?Is the RNA without reverse-transcription?
【在 a*****s 的大作中提到】 : No-RT controls have no amplifications until 45 cycles... so I believe the : gene is expressed... : Thanks for more suggestions! : : say
l*y
9 楼
pre-amp your sample for 10-15 cycles, that will bring down the Ct of your gene to 20ish, but you might need to find a different housekeeping gene to normalize to because Ct of actin will be below 10.
. up
【在 a*****s 的大作中提到】 : Hello everyone, please help: how to detect low abundance gene expression? : Now I use 1 ug of RNA per 20 ul cDNA reaction, then I use 1 ul of the cDNA. : For beta-Actin, the qPCR picks up the signal at around 15 cycles in linear : range. But my target gene (I used 2.5 ul per reaction) can only be picked up : at around 35 cycles (1 or 2 out of triplicated reactions), where it is : already out of the linear range!! How to enhance the signal?? Please help! : Thank you very much!! So frustrated...
m*2
10 楼
in this case I'd suggest you do a few 2x dilutions of the cDNA and see if you get a linear curve with the Ct. If that is good then pretty convincing to me.
【在 a*****s 的大作中提到】 : No-RT controls have no amplifications until 45 cycles... so I believe the : gene is expressed... : Thanks for more suggestions! : : say