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TWiM 76 Letters

Geoffrey writes:


I just got around to listening to episode 12 “Photothermal Nanoblades and Genome Engineering”. Your comment that it would need to be scaled up before it was practical for some of you to use intrigued me. I did a quick Google search and I didn’t see any recent articles addressing scaling up the process though I’m sure that there are groups working on it. In my own amateur fashion, I’d like to suggest an approach to such a process.

I believe that technology applying microfluidic flow cells to single cell streaming is reasonably well-developed currently and improving all the time. If you installed the insertion capillary tube into a microfluidic flow cell and added a photo-sensitive trigger to the capillary tube, then it should be fairly practical to mass insert bubbles of materials into cells fed through the flow cell and collected on the other side. Although flow cells would, most likely be tailored to particular cell sizes, it might be possible to make the insertion point slightly generic (i.e., slightly larger) by using laser forceps to automatically direct and immobilize the cells during insertion.

The main restriction would likely be finding a cell culture that would support the microbe in question with sufficiently low viscosity so as to flow through the cell with ease while prevented undesirable cellular effects (such as clumping or lysing) while the cells are waiting to inject. High cell density at the input reservoir could probably be achieved by centrifuging the initial culture then micro-diluting up the resulting pellet.

Although this may not prove to be the most efficient way to mass-process cells, I do see another potential advantage in using a microflow cell. With additional solvent input channels before and after the insertion point it might be possible to chemically manipulate the cell’s immediate environment for periods of milliseconds to seconds in such a way as to make them momentarily more amenable to insertion without long-term consequences to cell survival. Such manipulations would be easy to study, cell species by species in these flow cells until a manual of cells and optimum manipulation conditions could be generated.

Anyway, thanks again for the fascinating look at research that I don’t get a chance to look at very closely often (or understand).


Tarwin writes:

25c in Palo Alto, California.

I think humans (us) are so enthralled by the idea and stories of symbiosis because we see it as unusual. Even though our world is full of symbionts, life relies on symbiosis, we are blind to it most of the time until extraordinary examples are pointed out to us. These make great examples of the "precision", depth and complexity of evolution and of life.

It's easiest to make a headline in our mind when we see "small" examples of tightly woven systems than to keep the whole ecosystem of metabolism in our minds.

Thanks as always for the amazing education and entrainment,

Tarwin - Developer / Designer

Jacob writes:

Hi all,
Just wanted to make a point about organelles vs symbionts.
You suggested that the difference might be that if all cells in the organism have it then it is an organelle; however not all plant cells have chloroplasts.
Might the difference be just how high up the taxonomic tree the symbiosis goes?
Sydney, Australia.

Marion writes:

TWIM 74, about 26 minutes in.
the difference between enbosymbionts and organelles is:
1. WHEN it happened and
2. how much it increased fitness.

the endosymbioses that resulted in mitochondria and chloroplasts happened many billion years ago and apparently conferred selective advantage to recipients cells (future eukaryotes) over nonrecipients (future prokaryotes). we only have to wait a few billion years to see if the same is true for the endosymbionts discussed.

Bernadeta writes:

Dear Twim team,
Thank you for all the great episodes; I'm loving every single one of them!

I'm very pleased to hear more discussions on fungi-related subjects, being from Lithuania myself, I wait every year for the mushroom season, so that I could go and collect them. We even have national competitions for who can collect the largest number of mushrooms or find the biggest variety of them :)

On the mushroomy note, I would like to draw your attention on a recent paper describing the first fully sequenced genome of arbuscular mycorrhizal fungus, I think it's worth discussing.
"Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis" .

The second paper that caught my eye, was describes how S. aureus "intentionally" induces pain through neurone stimulation, in order to suppress immune system's response to the infection. I think it very much makes one think about systemic control of the immune system and, as ever, the unexpected ways that bacteria have evolved to evade it.

"Bacteria activate sensory neurons that modulate pain and inflammation"

Best wishes,



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American Society for Microbiology