DNA pellet (?) floats in CTAB precipitation - (May/23/2005 )
Hi,
I have just got a problem in the CTAB extraction. I used high salted CTAB buufer to extract seaweed samples with PVPP added. After two rounds of Chloroform::isoamly alcohol invertion, I got ppt (presumabily is DNA) when I lowered the concentration of NaCL. However after centrifugation, the pellet didn't get to the bottom. It floats!! Is there anyone know whether the pellet I saw is really DNA? I succeeded in geting the sank DNA quite a number of times. Ocasionally, the pellet floats. I just can't figure out why it is so. Hope that someone can help. Thanks in advance.
Regards,
Frank
I have had occasions when the DNA 'pellet' stubbornly floats!
On all these occasions it has been due to the incorporation of tiny air bubbles that get trapped in the pellet during the precipitation phase. The problem is usually resolved when the pellet is dried and redisssolved in water or TE.
So rest assured it is DNA!!
I have just got a problem in the CTAB extraction. I used high salted CTAB buufer to extract seaweed samples with PVPP added. After two rounds of Chloroform::isoamly alcohol invertion, I got ppt (presumabily is DNA) when I lowered the concentration of NaCL. However after centrifugation, the pellet didn't get to the bottom. It floats!! Is there anyone know whether the pellet I saw is really DNA? I succeeded in geting the sank DNA quite a number of times. Ocasionally, the pellet floats. I just can't figure out why it is so. Hope that someone can help. Thanks in advance.
Regards,
Frank
hi frank!
previously i also used the same method as u did in extracting DNA (CTAB method) but in fungus. but firstly may i asked u what color is the pellet u got after chloroform::isoamly alcohol invertion?coz if u got a very white yellowish pellet,basically it is not the DNA pellet.DNA pellet should be more transparent but yellowish.somehow, i already overcome the floating pellet problem myself,which was i rechanged my lysis buffer coz may be in ur sample still contain protein and other polysaccharide contamination .so how many times u do the chloroform::isoamly alcohol invertion?coz mybe u can repeat it more than 3 times..so really hope u can overcome ur problem.
