8 replies to this topic

[fzhang]

Hi, everyone. I am extracting some genomic DNA from some soil samples. But I found some white stuff in the bottom of the mirco tube imediately after adding NaAc to it, but I had not yet added cold ethanol. When I votex the tube, the white stuff disappeared.

Can anyone tell me how did this all come out?

Thanks.

[swanny]

fzhang, on Sep 10 2009, 07:31 PM, said:

Hi, everyone. I am extracting some genomic DNA from some soil samples. But I found some white stuff in the bottom of the mirco tube imediately after adding NaAc to it, but I had not yet added cold ethanol. When I votex the tube, the white stuff disappeared.

Can anyone tell me how did this all come out?

Thanks.

Exactly how far through the protocol were you. For that matter, exactly what was your protocol?

[fishdoc]

fzhang, on Sep 10 2009, 04:31 AM, said:

Hi, everyone. I am extracting some genomic DNA from some soil samples. But I found some white stuff in the bottom of the mirco tube imediately after adding NaAc to it, but I had not yet added cold ethanol. When I votex the tube, the white stuff disappeared.

Can anyone tell me how did this all come out?

Thanks.

I have that happen as well. I don't know what the cause of it is. I do know that swirling or inverting it causes it to disappear.

[fzhang]

can anyone help?

[swanny]

fzhang, on Sep 12 2009, 02:16 AM, said:

can anyone help?

What's your protocol please?

[fzhang]

swanny, on Sep 14 2009, 01:18 PM, said:

fzhang, on Sep 12 2009, 02:16 AM, said:

can anyone help?

What's your protocol please?

After adding one volume of chloroform isoamyl alcohol (24:1) to my crude DNA solution, I pipette the upper aqueous phase to another tube. Then I added 0.1 volume of 3M sodium acetate to this solution. Right then some white stuff like precipiation appeared in the lower part of the volume. If I inverted the tube, this white stuff would readily vanish.

Thanks a lot, swanny.

[gebirgsziege]

is your NaAcetate ice cold AND you are using CTAB in one of the previous steps? If yes: you should keep your samples on ice before removing the supernatant. CTAB preciptiates at low temps (lower than app. 10-15°C).  Therefore it will vanish again, when warm enough.
Keeping you samples cold will allow you to remove the CTAB from your DNA...good for PCR, as CTAB is a strong inhibitor.

[fzhang]

gebirgsziege, on Sep 14 2009, 02:50 PM, said:

is your NaAcetate ice cold AND you are using CTAB in one of the previous steps? If yes: you should keep your samples on ice before removing the supernatant. CTAB preciptiates at low temps (lower than app. 10-15°C).  Therefore it will vanish again, when warm enough.
Keeping you samples cold will allow you to remove the CTAB from your DNA...good for PCR, as CTAB is a strong inhibitor.

Thanks. But neither did I use CTAB nor put my samples on the ice. It's wierd, right?

[gebirgsziege]

lot of polysaccarides or glycoproteins?