In one of the traditional experiments to detect the presence of DNA in some different samples during the study, using Gel Electrophoresis. When tested under UV, this light appears in some samples (1-2) as shown in the picture below. The samples were as follows: 1. DNA from bacteria (I do not remember the method of isolation where it was from a long time but it was a traditional way). 2-Plasmid of the same bacteria (Isolation Using Alkaline Lysis). 3-DNA of plant (CTAB method of DNA isolation). 4-DNA of blood (Using Kit).
In your opinion, What are the reasons for this?
I'm guessing you co-extracted a negatively charged fluorescent molecule from your bacteria which was largely removed using your plasmid extraction protocol. Wasn't a Pseudomonas was it?
Hi there,
It has already happen to me to observe this kind of fluorescent spots into gels when using Quiagen loading buffer from miniprep kit... What is the apparent size of this spot?
Hi,
it indeed appears to be some kind of fluorescent contamination, as suggested earlier. The fact that it seems to be limited to the gel lanes indicates that it comes into the gel via sample loading. Try running sample-less loading buffer diluted to 1x concentration with ddH20 along with your samples, excessive loading dye in the wells sometimes leads to similarly shaped clouds, although they usually appear darker than background (shadow-like), not brighter, but this may depend on the composition of the buffer.
Also, negatively charged fluorescent proteins (either endogenous or probably originating from a strain engineered to express fluorescent proteins) not completely removed during DNA prep may also explain this.
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