DNA/RNA/Protein Extraction – Isolate pure DNA from the cell. There are a wide variety of protocols available for isolating pure DNA from all sorts of material. But they all involve the same four basic steps: lysis, adsorption, washing and elution. The details vary, depending on the source material and the concentration of DNA expected.
Hudson provides components that support each of the commonly encountered variations of these steps. In particular, the recent introduction of our FilterPress extraction system means we can support all possible methods of adsorbing nucleic acids from the lysis mixture: vacuum filtration, pressure-based filtration, magnetic bead adsorption, and centrifugation. The latter method is frequently the most difficult to automate, but is frequently required due to the lack of force produced by the vacuum-based methods.
The pressure-based FilterPress makes it possible to eliminate the centrifuge step in many situations. The pressure-based method also greatly improves the ability to run extractions on a partially filled microplate without the need to cover the unused wells. Vacuum nests are notorious for their inability to maintain an equal flow rate when some wells are empty.
Below is a simple DNA extraction system with each of the Hudson components labeled. A simple system like this can be used to carry out plasmid preparation and a wide variety of other DNA/RNA or protein isolations.
In this example, the samples are in Matrix tubes sitting in a shaker nest. Lysing reagents are drawn from the deep-well reservoir on the SOLO automated pipettor and mixed with the samples. The mixture is then adsorbed on the filter plates, sitting on the upper nest of the FilterPress. At this stage, there wouldn’t be a collection plate in the lower nest so that a series of wash buffers can be added by the Micro10x reagent dispenser. A 4-way valve controls which buffer is added, and the lines are automatically emptied and primed as necessary.
In the final step, a collection plate is placed into the lower nest of the FilterPress and the elution buffer is added to the filter plate. This separates the pure DNA from the filter and releases it into the collection plate.
This system can be fully automated and additional features can be included by adding the right equipment. For example, the following image shows a more complex system that includes a PlateCrane for moving microplates, a UV reader for measuring DNA yields, and a thermocycler for amplifying the final product. The thermocycler can also be used in protocols that require amplification as part of the isolation procedure, such as the 16S RNA isolation protocol, commonly used in microbiome research.
