Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: scientizscht on 21/12/2018 17:56:21
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What is this analysis?
How is it performed?
What are its benefits and applications?
It is supposed to be revolutionary, but I don't understand what it is about.
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Early DNA/RNA reading techniques were not very sensitive, and required collection of DNA/RNA from many cells in order to read it.
However, there are cases where different cells have different DNA, and/or different RNA expression.
- It is useful to be able to pick up the differences between cells instead of getting an "average" across many cells
- Modern DNA/RNA reading techniques are much more sensitive, to the point where you can get enough DNA/RNA from a single cell that you can read the sequence with fair confidence
Examples include:
- Studying complex tissues like the brain, kidney and even heart, where there are many cell types with specialised functions. These functions are controlled by epigenetic markers on the DNA, which control which RNA gets produced in that cell (type). It is important to just read the DNA/RNA from just one cell (type), not an average across the entire organ.
- Gang rape, where police need the DNA of individual offenders, not an average
- Cancer, where there are many mutations in different cells of a cancer, and oncologists want a single treatment that will attack all the cancer cells. If they just treat a sub-population of cancer cells, the cancer will rebound, and the original treatment will be ineffective. This requires reading a representative sample of individual cancer cells, not an average across the entire cancer.
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Early DNA/RNA reading techniques were not very sensitive, and required collection of DNA/RNA from many cells in order to read it.
However, there are cases where different cells have different DNA, and/or different RNA expression.
- It is useful to be able to pick up the differences between cells instead of getting an "average" across many cells
- Modern DNA/RNA reading techniques are much more sensitive, to the point where you can get enough DNA/RNA from a single cell that you can read the sequence with fair confidence
Examples include:
- Studying complex tissues like the brain, kidney and even heart, where there are many cell types with specialised functions. These functions are controlled by epigenetic markers on the DNA, which control which RNA gets produced in that cell (type). It is important to just read the DNA/RNA from just one cell (type), not an average across the entire organ.
- Gang rape, where police need the DNA of individual offenders, not an average
- Cancer, where there are many mutations in different cells of a cancer, and oncologists want a single treatment that will attack all the cancer cells. If they just treat a sub-population of cancer cells, the cancer will rebound, and the original treatment will be ineffective. This requires reading a representative sample of individual cancer cells, not an average across the entire cancer.
Thanks very helpful.
But how they actually do it? What's the process?
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Heard the name,didnt know he came from Glasthule. Great man doing really good work.
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Reading RNA starts with converting it into DNA.
Reading DNA starts with multiplying the 2 copies of each gene in a single cell into millions of copies, to provide enough genetic material to sequence.
- There have been some improvements in the traditional Polymerase Chain Reaction which create more, longer copies
- But this step will result in millions of copies of some sequences, and only thousands of copies of other segments, so coverage is not even
- Extreme care must be taken with sterilisation of the equipment and collection of samples, as any contamination will also be multiplied by millions
Once there is enough genetic material, traditional sequencing machines can be used.
See: https://en.wikipedia.org/wiki/Single_cell_sequencing
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A recent announcement of a whole new kingdom of single-celled life (ie not an animal, plant, fungus, protists or archaea) was enabled by these new, more sensitive decoding methods.
Most microorganisms are impossible to cultivate in the lab, so it is hard to get a big enough DNA sample for traditional sequencing. Hemimastigotes had previously been described in the literature, but not much was known about them.
However, newer DNA sequencing machines were able to sequence this microorganism from a soil sample in Nova Scotia, which showed that it was not part of any of the existing kingdoms of life.
See: https://www.scientificamerican.com/article/what-a-newfound-kingdom-means-for-the-tree-of-life