7 ms·

Scientists learn more about enigmatic archaea (2021)

56 points by Hooke 5y ago

pugworthy 5y ago
Archaea strike me as the kind of thing we'd find on Mars. I didn't realize it until doing some searching, but some archaea are methanogenic (they generate methane), which has been detected on Mars.
- emmelaich 5y ago
  Look into Panspermia if you're not aware already. Hoyle and Wickramasinghe wrote a lot on this. I don't know how seriously it's regarded in the science world.
  - reubenswartz 5y ago
    If life somehow hitched a ride from one planet to another, it seems far more likely that it would have gone from earth to Mars, than the other way around. ;-)
julienchastang 5y ago
"Duggin studies cell division in the archaeon Haloferax volcanii. It’s a lover of salty conditions, such as those in the Dead Sea, and not of volcanoes, as the species moniker suggests. (It was named after microbiologist Benjamin Elazari Volcani.)" Indeed.
wombatmobile 5y ago
Fascinating research into the question of how the first eukaryotic cells arose from prokaryote antecedents. The ancestors of the mitochondria organelles you see today in every cell in your body were once free swimming bacteria, in a world where there were no animals, and no eukaryotic cells. Planet earth then, and for its first 2 billion years, was populated exclusively by bacteria, or single celled organisms. These cells were about one hundredth the size of the cells in your body. How did life on earth become more complex? Billions of years before the Cambrian explosion, when the number of animal species exploded into the millions, something much more basic happened at the cellular level. Cells became more complex. How? Maybe cells engulfed other cells, and the engulfed cells survived, forming a partnership or a colony. Or maybe different types of cells hung out in close proximity, in colonies, which eventually merged into a network of DNA exchanging nodes that keep growing in complexity and interdependency. We don't know. This new effort to grow and study archea in vitro gives us something to study and experiment with.
- blacksmith_tb 5y ago
  Chloroplasts are also thought to have been engulfed and recruited to stay on as organelles[1], mind-boggling stuff. 1: https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolution https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolu...
  - wombatmobile 5y ago
    This made perfect sense to Lyn Margulis, an evolutionary biologist who was once married to astronomer Carl Sagan. She put up with decades of skepticism and derision from older scientists before Woese and Doolittle identified the genetic data in chloroplasts that confirmed the theory. The History of Evolutionary Thought → 1900 to present → Endosymbiosis: Lynn Margulis https://evolution.berkeley.edu/the-history-of-evolutionary-thought/1900-to-present/endosymbiosis-lynn-margulis/ https://evolution.berkeley.edu/the-history-of-evolutionary-t... Lynn Margulis and the endosymbiont hypothesis: 50 years later https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/
    - estaseuropano 5y ago
      Already said in another comment, but I recommend the book "Sex, power, suicide" which explores the history of mitochondria and their evolutionary and todays role. The author also discusses Lyn's theories and partially absolves her (in particular on the symbiosis) but also highlights where her further theories don't hold up.
- emmelaich 5y ago
  > mitochondria organelles ... were once free swimming bacteria Maybe same goes for cilia, centrioles, golgi body, nerve cells ..
  - estaseuropano 5y ago
    No, these are cell organs that also exist in simpler lifeforms, and they don't hold DNA. Key is that mitochondria have their own DNA and multiply independently of the host cell.
andrewflnr 5y ago
My understanding is that the really interesting thing about eukaryotes is their complexity, especially of their genomes and all the machinery needed to maintain them. Eukaryotic cells are just really complex overall compared to bacteria, tons of weird organelles all over the place. The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not special. I'll grant my view is mainly driven by the question of how much complex life exists off of Earth, and therefore how hard/unlikely it was for Earth life to reach its current complexity. If it happened a bunch of times on Earth it's probably not a blocker, and therefore not relevant to my interests. :D Anyway, the evolutionary gradient that drove complexity in the genome is what I'd really like to know about. How it works, how it got started, why it apparently only happened once, etc.
- wolverine876 5y ago
  My (limited) understanding is that eukaryotes had (and still have!) a nucleus that can split into sex cells, changing the potential for evolution ... It took only 2 billion years from that to the Cambrian Explosion!
- reubenswartz 5y ago
  > The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not special. The arrival of mitochondria, or the "merger" of the bacterial ancestors of mitochondria and the archea "host" was pivotal. Bacteria and archea have been around for billions of years, ~a billion years longer than eukaryotes. Only once, as far as we know, did they blossom into the complexity of the eukaryotic cell, via a very specific endosymbiotic event. Most of the bacterial DNA ended up in the (newly developed) nucleus, where, in addition to coding proteins for the mitochondria, it could also take on lots of new functions. We don't have a bunch of intermediate states between prokaryotes and eukaryotes-- it's a huge gulf that suggests a one time event that left most offspring unable to reproduce. Whether we are talking about life on earth or other worlds, this seems very, very lucky, and very relevant to your interests-- it is why we got the big complexity gradient, and why, even billions of years later, you don't have "complex" bacteria or archea.
thadk 5y ago
If you enjoyed this article but your biology background is from the 1990's or early 2000's, you might check out The Tangled Tree (2018) by Quammen https://bookshop.org/books/the-tangled-tree-a-radical-new-history-of-life/9781476776637 https://bookshop.org/books/the-tangled-tree-a-radical-new-hi... It traces how we got to some of these new ideas from pre-Darwin, through Lynn Margulis, to present day nanopore sequencers via the guy who discovered Archea.

56 points by Hooke 5y ago

Archaea strike me as the kind of thing we'd find on Mars. I didn't realize it until doing some searching, but some archaea are methanogenic (they generate methane), which has been detected on Mars.

emmelaich 5y ago
Look into Panspermia if you're not aware already. Hoyle and Wickramasinghe wrote a lot on this. I don't know how seriously it's regarded in the science world.
- reubenswartz 5y ago
  If life somehow hitched a ride from one planet to another, it seems far more likely that it would have gone from earth to Mars, than the other way around. ;-)

julienchastang 5y ago

"Duggin studies cell division in the archaeon Haloferax volcanii. It’s a lover of salty conditions, such as those in the Dead Sea, and not of volcanoes, as the species moniker suggests. (It was named after microbiologist Benjamin Elazari Volcani.)" Indeed.

wombatmobile 5y ago

Fascinating research into the question of how the first eukaryotic cells arose from prokaryote antecedents. The ancestors of the mitochondria organelles you see today in every cell in your body were once free swimming bacteria, in a world where there were no animals, and no eukaryotic cells. Planet earth then, and for its first 2 billion years, was populated exclusively by bacteria, or single celled organisms. These cells were about one hundredth the size of the cells in your body. How did life on earth become more complex? Billions of years before the Cambrian explosion, when the number of animal species exploded into the millions, something much more basic happened at the cellular level. Cells became more complex. How? Maybe cells engulfed other cells, and the engulfed cells survived, forming a partnership or a colony. Or maybe different types of cells hung out in close proximity, in colonies, which eventually merged into a network of DNA exchanging nodes that keep growing in complexity and interdependency. We don't know. This new effort to grow and study archea in vitro gives us something to study and experiment with.

blacksmith_tb 5y ago
Chloroplasts are also thought to have been engulfed and recruited to stay on as organelles[1], mind-boggling stuff. 1: https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolution https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolu...
- wombatmobile 5y ago
  This made perfect sense to Lyn Margulis, an evolutionary biologist who was once married to astronomer Carl Sagan. She put up with decades of skepticism and derision from older scientists before Woese and Doolittle identified the genetic data in chloroplasts that confirmed the theory. The History of Evolutionary Thought → 1900 to present → Endosymbiosis: Lynn Margulis https://evolution.berkeley.edu/the-history-of-evolutionary-thought/1900-to-present/endosymbiosis-lynn-margulis/ https://evolution.berkeley.edu/the-history-of-evolutionary-t... Lynn Margulis and the endosymbiont hypothesis: 50 years later https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/
  - estaseuropano 5y ago
    Already said in another comment, but I recommend the book "Sex, power, suicide" which explores the history of mitochondria and their evolutionary and todays role. The author also discusses Lyn's theories and partially absolves her (in particular on the symbiosis) but also highlights where her further theories don't hold up.
emmelaich 5y ago
> mitochondria organelles ... were once free swimming bacteria Maybe same goes for cilia, centrioles, golgi body, nerve cells ..
- estaseuropano 5y ago
  No, these are cell organs that also exist in simpler lifeforms, and they don't hold DNA. Key is that mitochondria have their own DNA and multiply independently of the host cell.

andrewflnr 5y ago

My understanding is that the really interesting thing about eukaryotes is their complexity, especially of their genomes and all the machinery needed to maintain them. Eukaryotic cells are just really complex overall compared to bacteria, tons of weird organelles all over the place. The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not special. I'll grant my view is mainly driven by the question of how much complex life exists off of Earth, and therefore how hard/unlikely it was for Earth life to reach its current complexity. If it happened a bunch of times on Earth it's probably not a blocker, and therefore not relevant to my interests. :D Anyway, the evolutionary gradient that drove complexity in the genome is what I'd really like to know about. How it works, how it got started, why it apparently only happened once, etc.

wolverine876 5y ago
My (limited) understanding is that eukaryotes had (and still have!) a nucleus that can split into sex cells, changing the potential for evolution ... It took only 2 billion years from that to the Cambrian Explosion!
reubenswartz 5y ago
> The arrival of mitochondria is kind of a red herring by comparison, in my view; we know cellular endosymbiosis has happened a bunch of times so it's not special. The arrival of mitochondria, or the "merger" of the bacterial ancestors of mitochondria and the archea "host" was pivotal. Bacteria and archea have been around for billions of years, ~a billion years longer than eukaryotes. Only once, as far as we know, did they blossom into the complexity of the eukaryotic cell, via a very specific endosymbiotic event. Most of the bacterial DNA ended up in the (newly developed) nucleus, where, in addition to coding proteins for the mitochondria, it could also take on lots of new functions. We don't have a bunch of intermediate states between prokaryotes and eukaryotes-- it's a huge gulf that suggests a one time event that left most offspring unable to reproduce. Whether we are talking about life on earth or other worlds, this seems very, very lucky, and very relevant to your interests-- it is why we got the big complexity gradient, and why, even billions of years later, you don't have "complex" bacteria or archea.

thadk 5y ago

If you enjoyed this article but your biology background is from the 1990's or early 2000's, you might check out The Tangled Tree (2018) by Quammen https://bookshop.org/books/the-tangled-tree-a-radical-new-history-of-life/9781476776637 https://bookshop.org/books/the-tangled-tree-a-radical-new-hi... It traces how we got to some of these new ideas from pre-Darwin, through Lynn Margulis, to present day nanopore sequencers via the guy who discovered Archea.