To prevent contamination from holes near, but you can do it or not, always that you work careful
To prevent contamination from holes near, but you can do it or not, always that you work careful
If you are re-using the tank buffer for subsequent electrophoresis, then the blank well lets you know if any DNA from previous runs has contaminated your running buffer or not.
to keep blank is totally optional, If you are good at handling sample then it's not necessary to keep blank. I also agree with Felix Moran, it's pretty difficult to know if there any spilled over of the sample from neighbor holes. It just prevents any contamination due to spilled over of samples. Thanks
Yes, I agree with the comments given above. Although it is optional, leaving a well without sample may help to detect any contamination, particularly from non-fresh running buffers. If you need to use the running buffer for other batch of analysis, it is good to leave a well empty to check whether the buffer is contaminated by previously loaded samples or not.
I never leave a well empty on purpose as a sort of control. If you don't overload the wells with too much PCR product and you don't spill between wells, then you don't need to worry about cross-contamination between samples.
I tendd to put my controls like postive.. then negative. . Then ladder... on into samlpes. I added an example of an early running gel.
To buffer from an over loaded well en empty well will save you from false results, or contaminates, always load with great caution.
if you plan to cut out the dna for futher work not a screen, i would buffer enpty wells on both sides and have ladder also on both sides, and you can extract dna inside the gel fast to limit uv damage, and be precise with just an straight edge razor blade.
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To me.. he is.
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I think that Charles is correct , When you look at a picture eof a gel and one well is negative it is not because no sample was loaded. The space was probably where the negative control sample was loaded. This is a sample with no added template to test if there is any contamination present in the reaction mixture, It should always read blank and when it is positive there is a posr pcr contamination issue
Hi Hassan Nima,
From your question, it can have several reasons the empty well was left:
1. Frist of all, people call them 'wells', instead of 'holes'.
2. I have seen some labs recycles unused gel portions (gel section without DNA samples run on), and re-melt it for re-use in the future. To make sure there is no DNA-contaminated gel blocks have been recycled, leave an empty well can help to check whether there is no unintended bands present. Since I always make new gels, I don't leave an empty well for this purpose.
3. Leave an empty well can check whether the amount/volume of sample added is adequate, and not overflow into the neighboring wells.
4. When 'positive control' and 'negative control' are used, I usually leave an empty well in-between them. So, I will be sure that no 'positive control' DNA samples will overflow into the well with 'negative control' sample
5. If the numbers of your samples are less than the numbers of wells, you will have empty wells left (sometimes, 1 well)
6. You leave an empty well because the well is cracked during removing the comb, so the well(s) will be left out
The appropriate word is well and not hole, kindly take note. The reason is to avoid contamination of DNA in one affecting the other especially if you are not careful enough while removing the comb.
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