Well, the biological community is finally starting to wake up to the fact that circular DNA may have some valid reason for more rigorous study because it comes in all different sizes, packed with (guess what?) chromosomal genes! These circles appear abundant in cancer cells, but apparently, they are having a hard time finding them in normal cells. They call them “circulomes”. Fine by me. It only took them 20+ years to catch up to what I have been saying all along. Better late than never, I guess. Here is a summary of the work:
Are geneticists ready for the circulome? At a recent Biology of Genomes meeting, a biologist showed off a new method to extensively survey human cells for mysterious, sometimes gene-filled loops known as extrachromosomal circular DNA (eccDNA). These genetic rings, which come in varying sizes, are gaining new respect as researchers find more evidence that eccCDNA plays roles in health and disease, particularly in cancer. Recent work shows the biggest ones are abundant in many cancer cells but not healthy cells and that these circles may aid the cancer’s evolution and recurrence. Another new paper even suggests the DNA loops are released to influence distant cells.
I too, found circles in mouse L-1210 cancer cells. However, I had to dislodge them from the chromosomes before I could see them and I very much doubt that the researchers recovered the level and size rang of circles that I did. My circles can do “tricks”. They can fuse together. They can also form intricate geometric patterns. I also discuss how apoptosis prevents such kinds of DNA from entering adjacent healthy cells, thereby, preventing corruption of the genetic machinery which could lead to cancer (see last sentence in the above summary).
So the obvious question to answer here is why these researchers cannot find circles in normal cells? Perhaps they need to ask somebody who could show them how.