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Marine bacteria genus may hold mitochondria's closest relatives
- borissk 3y agoThe origin of eukaryotes is an amazing story. The chances of survival of the original combined organism were 0.0000000001%. All the bacterial RNA and DNA that the bacteria produced during life and death were surely messing up with the archaea inner workings, as bacteria and archaea have different genetic code "dialects". The archea had to evolve a nucleus instantly to keep the bacterial RNA away from it's ribosomes. The survival of eukaryotes may be so unlikely as to even partially explain Fermi paradox.
- __loam 3y agoThe theory that eukaryotic cells are just a bunch of bacterial subsystems that happened to start cooperating is one of the cooler points in the biology iceberg. Up there with chickens descended from the T Rex for me.
- bonzini 3y ago> Up there with chickens descended from the T Rex for me. Archaeopteryx lived in the Jurassic, so it's not really possible that chicken descended from the T Rex. They're cousins though.
- euroderf 3y agoThe Great Chicken God decries your heresy!
- isaacfrond 3y agoActually, Archaeopteryx is not an ancestor to chickens either... Archaeopteryx is offshoot in the evolutionary path leading to birds. It shares a common ancestor with modern birds but branched off in a direction that did not lead directly to them.
- culi 3y agoYou'd love the highly influential 2015 paper, Major evolutionary transitions in individuality https://www.pnas.org/doi/full/10.1073/pnas.1421402112 https://www.pnas.org/doi/full/10.1073/pnas.1421402112 > The evolution of life on earth has been driven by a small number of major evolutionary transitions. These transitions have been characterized by individuals that could previously replicate independently, cooperating to form a new, more complex life form. For example, [...]
- treyd 3y ago> The archea had to evolve a nucleus instantly to keep the bacterial RNA away from it's ribosomes. I heard another theory that it was actually the archea that engulfed the pre-mitochondria rather than the it accidentally finding itself inside an archea. There's some kinds of archea that occasionally grow some extracellular "appendages" and it's conjectured that it may have had some kind of more typical symbiotic relationship with the two kinds of microbes living in near physical contact. What could have happened is that the archea gradually came to fully engulf the protomitochonria with the appendages evolving into being the full body of modern eukaryotes with the nucleus evolving from the functions that were part of the main archean cell body. Some functions got shuffled between the three compartments as this became more of an obligate relationship.
- deleted 3y ago[deleted]
- gravelc 3y agoSceptical of this. Where did that number come from? What's the uncertainty? Yes, it's an extremely unlikely event, but unlikely events happen all the time. There's just as good an argument that given the advantages conferred by the union, it's bound to be successful given enough iterations.
- vikramkr 3y agoI mean, it happened again with chloroplasts and there's a bunch of other cases of endosymbiosis too it's not that rare
- bonzini 3y agoMaking it happen once is harder than doing it a second time. Plant cells have both mitochondria and chloroplasts.
- vikramkr 3y agoI'm unfamiliar with research into the difficulty of the second endosymbiotic event that no humans were present to measure and analyze being reduced by the existence of a first endosymbiotic event that has also not been replicated in a lab yet, resulting in another n=1 data point
- favoritecolor 3y agoI think this might count as endosymbiosis replicated in a lab: https://pubmed.ncbi.nlm.nih.gov/30373839/ https://pubmed.ncbi.nlm.nih.gov/30373839/
- vikramkr 3y agoIt's a system to measure endosymbiosis in an organism that's already undergone endosymbiosis so not directly applicable for the entirety of gp's hypothesis, but there's definitely a ton of research into it. There'll always remain a question of if we engineer a system does that work the same way as the evolutionary path since we have the benefit of being non-random/guided by intelligence. It's like with abiogenesis, if we ever figure out a system that lets us reproducibly create life within the timespan of a couple years so we can replicate it and study it reasonably that system almost certainly isn't the original way it happened, but it'll give us good insights into the concepts hopefully
- a_bonobo 3y agoNick Lane wrote some amazing popular science books on the history of mitochondria; - Power, Sex, Suicide for a general overview and history of mitochondria (did you know that Lynn Margulis, main proponent of the endosymbiont theory, was once married to Carl Sagan?!?) - The Vital Question on restraints on life due to the biochemistry of mitochondria Both highly, highly recommended.
- jmcqk6 3y agoEvery single one of his books is amazing and mind blowing. His latest "Transformers" on the krebb cycle is a must read if you're interested in the origins of life.
- Qem 3y ago> The chances of survival of the original combined organism were 0.0000000001%. It was surely an experiment attempted many times, as countless bacteria infected countless protoeukaryotes. Probably doesn't explain Fermi paradox, as it succeeded at least twice here on Earth. One for mitochondria, another for chloroplasts.
- borissk 3y agoThe symbiosis with chloroplasts was a lot easier, as the host already had a nucleus.
- beeforpork 3y ago> All eukaryotes have mitochondria. To be picky: that's only 99.9...% true, because some have lost them again, like Monocercomonoides and Henneguya zschokkei. And they lost the mitochondria by two different mechanisms! https://en.wikipedia.org/wiki/Monocercomonoides https://en.wikipedia.org/wiki/Monocercomonoides https://en.wikipedia.org/wiki/Henneguya_zschokkei https://en.wikipedia.org/wiki/Henneguya_zschokkei EDIT: typo
- Angostura 3y agoFascinating. I had no idea, thank you.
- oboes 3y agoRelatedly, some animals can steal chloroplasts. https://en.wikipedia.org/wiki/Kleptoplasty https://en.wikipedia.org/wiki/Kleptoplasty
- a_bonobo 3y agoand to complete the circle, many plants - usually the parasites and the carnivorous plants - have lost some or most of their chloroplasts. Rafflesia (a parasite) might have lost the entire chloroplast: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3969568/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3969568/ Here's one 'in the middle' that lost a bunch of genes from the chloroplasts: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058747 https://journals.plos.org/plosone/article?id=10.1371/journal...
- culi 3y agolet's keep it going because "parasites" are fascinating. Dodder plants are usually generalized obligate plant parasites. Dodders have "stolen" at least 108 genes from various plants its parasitized. Bonus, dodder plants also seem to be able to double as a sort of above-ground mycorrhizal network, allowing plants (even across species) to communicate with each other and send warning signals about pests/stressors/etc
- phito 3y ago
- Qem 3y agoI wonder, if antibiotics kill bacteria, and mitochondria are just ancient atrophied bacteria hiding inside other cells, does that mean antibiotics cold be able to kill mitochondria too.
- loa_in_ 3y agoAntibiotics is a category defined pragmatically by the end effect they achieve, killing biological things selectively. They have nothing in common structurally or chemically. So I guess I want to say that you're asking the wrong question.
- deleted 3y ago[deleted]
- andsoitis 3y ago> Antibiotics is a category defined pragmatically by the end effect they achieve, killing biological things selectively. They have nothing in common structurally or chemically. To illustrate, here's a list of different classes of antibiotics, examples, and how they work: https://arpsp.cdc.gov/resources/OAU-Antibiotic-Class-Definitions.pdf https://arpsp.cdc.gov/resources/OAU-Antibiotic-Class-Definit... And here is a visualization: https://i0.wp.com/www.compoundchem.com/wp-content/uploads/2014/09/A-Guide-to-Different-Classes-of-Antibiotics-Aug-15.png?ssl=1 https://i0.wp.com/www.compoundchem.com/wp-content/uploads/20...
- bigbillheck 3y agoIt was almost as fast to google as it would have been to ask: https://www.sciencedirect.com/science/article/abs/pii/S1567724913002705#:~:text=Fig.-,1.,side%20effect%20of%20the%20antibiotics https://www.sciencedirect.com/science/article/abs/pii/S15677....
- Qem 3y agoNice. Thank you. If iodidimonas can be cultured in lab, I bet the researchers that conducted the study posted by OP can try to corroborate their hypothesis by testing if antibiotics more effective against iodidimonas are correlated to those that harm mitochondria the most, when compared to other bacterial groups.
- mailund 3y ago[flagged]
- chiefalchemist 3y agoPardon me but I have to ask, as someone here might know... Over this past weekend on Saturday afternoon (ET, NYC + PHL markets)[1] on an NPR station (in the car) I heard what I presume was a rebroadcast of a show on a theory about the creation of the first multi-cell organism. Typically, I pick up the name of the show and who the featured guest was, but this time I missed both. It was fascinating stuff and would like to listen to it in full. Does this ring a bell with anyone? [1] I realize each NPR station has its own schedule so this clue might not be helpful.
- tambourine_man 3y agoNPR has most of their programs in podcast form. It might be easier to search this way
- bigbillheck 3y agoSend the station an email and ask.
- chiefalchemist 3y agoDone. Thanks. I've done that in the past. But given this post on HN I figured someone looking in would know WTF I was talking about :)
- PawgerZ 3y agoPerhaps this one: https://www.npr.org/2011/08/10/139345519/scientists-explore-why-single-cells-band-together https://www.npr.org/2011/08/10/139345519/scientists-explore-...
- chiefalchemist 3y agoThanks. Close. That's the same topic / idea, but the bit I heard for definitely longer than 3 minutes. Might have been a 20 mins segment out of 1 hour show. Still. Thanks. The whole concept is ridiculously beyond comprehension.
- gadders 3y agoI've never really understood the story of mitochrondria. It's like "This cell absorbed another type of cell [ok so far] but then every future generation of this cell includes the absorbed cell. [<-- How does that bit work?]"
- deleted 3y ago[deleted]
- LordKeren 3y agoCan you elaborate on the part that seems unintuitive? Eukaryotic cells have multiple copies of their mitochondria, not one. When the cell divides, the mitochondria (roughly) split between the two daughter cells then carry on
- Karawebnetwork 3y ago> Can you elaborate on the part that seems unintuitive? For me, the intuitive part is how mitochondria can be created by the body if it's an external structure that's been found. If I take a coin and put it in my pocket, my children don't have any coins at birth. They have to find one themselves. Why is it different for mitochondria?
- myfavoritetings 3y agoMitochondria are self replicating. When the cell splits some of the mitochondria are present in each new cell.
- gadders 3y agoYeah, this was how I was thinking as well. But to continue the analogy, it's more like you split yourself into two smaller "you"s, and in the process each new "you" gets half a coin in the pocket of each new "you".
- LordKeren 3y agoTo clarify, it would be more like you have a group of 10 coins and each of your offspring get 5, but grow back to having 10 during development
- blindriver 3y agoThe idea that mitochondria is somehow external organisms that cells co-opted, and somehow became an integral part of every single organism on Earth is one of the most absurd, science fictional things I've ever seen in my life. And yet people just accept this as almost-fact. It's like believing in magic, there's no real explanation as to how something like this occurred, or even what the basic mechanism is, except for one person's speculation that it happened and the idea has spread virally and now it shows up as a fact in articles like this.
- me_me_me 3y ago"mitochondria is a powerhouse of our cells" its most banal summary used widely of what you aptly summarized. A legacy code of complex life that we cannot get rid of :D
- mvuijlst 3y agoIt might seem far-fetched but the theory is not based on speculation. It's supported by a substantial body of scientific evidence.
- stevenjgarner 3y agoEndosymbiotic theory is supported by a wealth of evidence, including: 1) Mitochondria have their own DNA, which is circular and similar to bacterial DNA. This DNA is distinct from the DNA in the nucleus of the eukaryotic cell. 2) Mitochondria have their own ribosomes, which are smaller and structurally different from cytosolic ribosomes. These ribosomes are responsible for translating mitochondrial DNA into proteins. 3) Mitochondria have their own mechanism for protein import, which is different from the protein import machinery of the eukaryotic cell. This suggests that mitochondria were once independent organisms. 4) Mitochondria share many similarities with alpha-proteobacteria, a group of bacteria. This includes the structure of their inner membranes, the arrangement of their genes, and the way they generate energy. 5) Mitochondria reproduce by binary fission, similar to bacteria. This suggests that mitochondria once replicated independently of the eukaryotic cell. 6) The endosymbiotic theory is also supported by the fact that mitochondria are found in all eukaryotic cells, with only a few rare exceptions. This suggests that mitochondria were acquired by an ancestral eukaryotic cell and have since been passed down to all of its descendants.