Hi,
we have a new project in our lab where we take sediment samples from river systems, extract DNA and then sequence the samples by 454 or Illumina. We are taking several samples per day from different locations. The sampling and DNA extractions are done by a single person right now. Because of that, sometimes, samples sit in the freezer for a few days before the DNA is extracted. The problem that we are experiencing is that samples for which DNA is not extracted right away degrade very rapidly and in some cases, the DNA fragments that we are getting are only a few hundred bp long. It is simply not possible for us to do the DNA extraction for all samples right after sampling, so I'm wondering if anybody has any suggestions for us on what we could do to prevent degradation from happening even if the samples are stored for a while prior to DNA extraction. Any help would be greatly appreciated!
Here is some more information about the sampling:
At the site where samples are taken, samples are placed on ice and taken to the lab where they are stored at -20C in a freezer until DNA extraction. Samples are typically stored in the freezer for 12h to 2 days prior to DNA extraction. After DNA extraction, DNA extracts are kept at 4C in the fridge. 260/280 ratios are usually between 1.5-1.9. 260/230 ratios tend to be very low (usually well below 1).
Thanks in advance,
Daniela
we have a new project in our lab where we take sediment samples from river systems, extract DNA and then sequence the samples by 454 or Illumina. We are taking several samples per day from different locations. The sampling and DNA extractions are done by a single person right now. Because of that, sometimes, samples sit in the freezer for a few days before the DNA is extracted. The problem that we are experiencing is that samples for which DNA is not extracted right away degrade very rapidly and in some cases, the DNA fragments that we are getting are only a few hundred bp long. It is simply not possible for us to do the DNA extraction for all samples right after sampling, so I'm wondering if anybody has any suggestions for us on what we could do to prevent degradation from happening even if the samples are stored for a while prior to DNA extraction. Any help would be greatly appreciated!
Here is some more information about the sampling:
At the site where samples are taken, samples are placed on ice and taken to the lab where they are stored at -20C in a freezer until DNA extraction. Samples are typically stored in the freezer for 12h to 2 days prior to DNA extraction. After DNA extraction, DNA extracts are kept at 4C in the fridge. 260/280 ratios are usually between 1.5-1.9. 260/230 ratios tend to be very low (usually well below 1).
Thanks in advance,
Daniela
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