Mindscape 234 | Tobias Warnecke on Cellular Structure and Evolution

Patreon: / seanmcarroll
Blog post with audio player, show notes, and transcript: www.preposterousuniverse.com/...
Eukaryotic cells manage to pull off a number of remarkable feats. One is packing quite a long DNA molecule, with potentially billions of base pairs, into a tiny central nucleus. A key role is played by histones, proteins that provide scaffolding for DNA to wrap around. Histones also appear in archaea (one of the other domains of life), but until recently there wasn't evidence for them in bacteria (the final of the three domains). Todays guest, Tobias Warnecke, is an author on a recent paper that claims to provide such evidence. We discuss this new result, as well as background questions of how cells evolved and what their current structure can teach us about their histories.
Tobias Warnecke received his Ph.D. in biology from the University of Bath. He is currently a Programme Leader and MRC Investigator at the London Institute of Medical Sciences. He is a co-author on A. Hochner et al. (2023), "Histone-Organized Chromatin in Bacteria."
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[@zack_120]

This channel now is my The go-to place for learning about this Universe. Sean's super abilities of instantaneously capturing every statement of the guests and raising probing questions, along with his crystal clear spoken English, are the main factors attracting my attention to here. 👍👍👍

[@Life_42]

I love this channel so much!!!

[@GeoffryGifari]

this sounds wild, but if we put a particular archaea and bacteria together in the lab, is it possible to engineer endosymbiosis?

[@osman2k]

thank you both, great podcast!

[@ballbalot]

Thank you for this, super interesting, great job!

[@glennmiller9759]

Interesting podcast for sure! I might have missed it somehow, but I was waiting for your guest to clarify that animal cells do not possess cell walls. I know that people will sometimes casually refer to an animal cell wall when what they really probably mean is cell membrane. Plant cells have both a cell membrane and a cell wall.

[@TobiasWarnecke-qo2cj]

True. Also interesting when looking beyond eukaryotes. Most archaea have a cell wall (although they can vary a lot in terms of their composition), but some archaea do not, including one we have worked on in the past, Thermoplasma acidophilum.

[@pragmaticcrystal]

Thank you 💛

[@nowhereman8374]

I wish Dr. Carroll would have leveraged knowledge from his William Ratcliff podcast. Since now they can culture these candidate acrehea in the lab, they can do evolutionary experiments and maybe one day recreate endosymbiosis (eukaryogenesis). A breakthrough akin to the holy grail!

[@adriancook9742]

Great show as usual. I did sit and wait for the hopefully inevitable word entropy or thermodynamics. Glad I didn't hold my breath. Come on Sean that was your bit of the show and it was a no show 😂.

[@GeoffryGifari]

and.. is it possible for the 3D configuration of DNA (and the proteins) inside the nucleus to reflect which genes are activated at which moment in which type of cell?

[@TobiasWarnecke-qo2cj]

Yes, that is now well documented in a variety of organisms, and manifest in a variety of ways. In mammalian eukaryotic cells, for example, genes that are silenced and then get activated often move from a repressed state located at nuclear periphery/lamina to a more central position (e.g. shown here: pubmed.ncbi.nlm.nih.gov/15361872/)

[@GeoffryGifari]

@@TobiasWarnecke-qo2cj oh, its you!

[@ExsoLam]

Yes, that's one way epigenetic information is encoded/transmitted. Histone acetylation changes DNA packing and influences expression (the DNA has to be unpacked to be expressed) and acetylation/histone modification patterns can likely be transmitted (although only relevant for at most a few generations as far as I know)

[@GeoffryGifari]

@@ExsoLam wait... DNA needs to be unpacked to expressed? how can this unpacking and repacking done (and controlled) by the cell? i've heard of none of these in my compulsory intro to bio course for science majors lol

[@GeoffryGifari]

@@ExsoLam do you work on this kind of problem?

[@zack_120]

28:00- 'multicellular vs ...', as a discipline at least as, if not more, complex as cosmology, it's extremely hard to establish clear cut rules in biology to separate the three kindoms for many features. Many of the so-called rules read in textbooks are not exclusive often with exceptions, especially when taking the time domain into consideration where new discoveries often disprove existing rules. Actually, this probably applues to many other disciplunes as well: the Universe is too complex to define everything clearly.

[@joshuapayne3937]

How much tension do you think DNA is under when it's wrapped up?

[@byronaburns5937]

Does the DNA ever get torn when the molecular engines are making it? Packaging it

[@TobiasWarnecke-qo2cj]

Not as a result of packaging, at least not directly. When it comes to replicating DNA, yes, sometimes the DNA breaks. This can be for several reasons. One is that replication requires separation of both strands of the DNA and single-stranded DNA is more fragile. A second one is that - sometimes the replication machinery screws up and this replication stress can give rise to DNA breaks. Finally, breaking the DNA is often a programmed part of the replication process, for example when the new copy has to be separated from the old copy in bacteria, or during recombination (e.g. between maternal and paternal copies of your DNA).

[@andanssas]

@@TobiasWarnecke-qo2cj Rare and pleased to find a guest answering questions. Enjoyed hearing the knowledge you shared and thank you for the simple/understandable explanation! 🙏

[@CraigMCox]

Wait , so what is his area of expertise?

[@Raydensheraj]

PhD in Biology.

[@TobiasWarnecke-qo2cj]

Don't really have one, to be fair (unless you go really specific...). More of a jack-of-all-trades-master-of-none kind of researcher

[@mman6283]

I hate when I’m watching something and a channel like this pops up but I’ve never asked to watch

[@Raydensheraj]

You should maybe check your channel subscriptions, goofy.

[@renaultr17]

Schrödinger managed both physical science and biological science expertise. Just saying.

[@jhernan9639]

I'm your horse barrol bonds