6 ms·

Largest bacterium ever discovered has unexpectedly complex cells

128 points by amichail 5y ago

adrian_b 5y ago
The complete research article: https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1 https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1
sva_ 5y ago
The article seems to imply that this organism is single-cellular: > Its threadlike single cell is visible to the naked eye, growing up to 2 centimeters—as long as a peanut—and 5000 times bigger than many other microbes. The study[0] however speaks of "cells" in plural, and "daughter cells". It would've really surprised me if that really had been a single cell - unless I'm misunderstanding something here. edit: I stand corrected. Misunderstood it. [0] from other comment: https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1.full.pdf https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1....
- stdbrouw 5y ago
  First subheading of the study: "Thiomargarita magnifica is a centimeter-long, single bacterial cell". They apparently stick together, but do constitute individual organisms.
- R0b0t1 5y ago
  There is precedence for cells being that large. I can't remember the organism name, but there is actually some macroscopic single cell organism. It cheats by having multiple nuclei, among other things.
  - throwamon 5y ago
    You may be thinking of Valonia ventricosa (bubble algae), though I believe there are others.
  - bochoh 5y ago
    Chicken and ostrich eggs are both single cells that are quite large as well
    - bayindirh 5y ago
      But it's an eukaryote cell. Not prokaryote.
  - sva_ 5y ago
    Yeah, but the cell of such single-celled organisms are usually round or in one segment. This one looks like it has several segments, and still be a single cell, which is fascinating. Perhaps it is blurring the line between single cellular and multi cellular a bit, which might be the point that the article was trying to make.
  - adrian_b 5y ago
    What is new here is that this is a bacteria, not a nucleate cell. Large eukaryote cells, even over 10 cm (4 inches), are well known. Almost all normal bacteria have a diameter under 100 micrometer, usually much less. The article explains that the huge size for a bacteria seems to be enabled by 2 features, first a large water-filled vesicle inside, so that the living part of the cell is around the periphery of the cell, within short distances from the cell membrane, and second, a special compartment for DNA which provides some of the functions of a nucleus in an eukaryote (nucleate) cell.
- jessriedel 5y ago
  No, they claim that most of the filament is a single cell, albeit with compartmentalized DNA: > Strikingly, all techniques consistently showed that each filament was one continuous cell for nearly its entire length with no division septa, including the partial constrictions towards the apical pole. Only the most apical few buds were separated from the filament by a closed constriction and represented daughter cells "Apical" means the apex of the filament. In other words, toward the end of the filament the cell starts pinching off ("budding") to create daughter cells as part of its reproductive cycle. But the away from the end, the cell is contiguous. Fig. S2 is highly recommended.
- actually_a_dog 5y ago
  Believe it or not, that's not even close to the largest unicellular organism. One of the largest is Valonia ventricosa, a species of algae that has spherical or ovoid cells "with a diameter that ranges typically from 1 to 4 centimetres (0.4 to 1.6 in) although it may achieve a diameter of up to 5.1 centimetres (2.0 in) in rarer cases." [0] --- [0]: https://en.wikipedia.org/wiki/Valonia_ventricosa#Physiology_and_reproduction https://en.wikipedia.org/wiki/Valonia_ventricosa#Physiology_...
  - bayesian_horse 5y ago
    Point being those algae are eukaryotic. The article is about an unusually large bacterium (prokaryotic) which has some eukaryotic features.
  - undersuit 5y ago
    My favorite large unicellular organisms are Xenophyophorea. They have multiple nuclei probably because the diffusion of transcription processes over an 8 inch diameter cell would be just too slow with a single central nucleus. https://en.wikipedia.org/wiki/Xenophyophorea https://en.wikipedia.org/wiki/Xenophyophorea
tombert 5y ago
How is complexity measured in this case? I'm not disagreeing, I'm just curious.
- unfocussed_mike 5y ago
  It's largely based on the bacterium's nuanced views on late nineties experimental electronica.
- Kichererbsen 5y ago
  Disclaimer: I am not a biologist or whatever someone who studies this stuff is called. But from what I've been able to gather, actually having the RNA be in it's own membrane (an "organelle" they're calling it in the article) is not something you'd usually expect in a bacterium. If I remember correctly, they're more "soupy" inside.
deleted 5y ago
[deleted]
catlifeonmars 5y ago
From further down in the article: > Furthermore, that cell includes two membrane sacs, one of which contains all the cell’s DNA, Volland and colleagues report in their 18 February preprint on bioRxiv. Volland calls that sac an organelle and that’s “a big new step” that implies the two branches of life are not as different as previously thought, Carvalho says. “Perhaps it’s time to rethink our definition of eukaryote and prokaryote!” agrees Petra Levin, a microbiologist at Washington University in St Louis. “It’s a supercool story.” IMO, they really buried the lede on this one by focusing on the size of the bacterium and not on the convergent evolution of an apparent nucleus in a prokaryote.
Karawebnetwork 5y ago
I am wary to bring the topic up but I wonder if this might have some degree of connection with what people call morgellons disease. The bactarium shown in the video looks very similar to what people describe. My understanding is that morgellons is largely seen as psychosomatic or "fake". I now wonder if some people might have similar bacteria on them and that it might explain some of the symptoms.
- danachow 5y ago
  The problem with this theory, despite lobbied funding for the Morgellons foundation with very extensive testing including histological and biochemical, no evidence of an organism has been found associated with it. It’s not like nobody has looked.
- likpok 5y ago
  It would be easy to determine if Morgellons was caused by a bacteria or some other physical thing: you can take samples and look at them under the microscope. When the CDC did just that (looked at samples of the fibers), they found them to be likely cotton. If this were the cause of morgellons then their result would be "morgellons caused by infestation with unknown large bacteria" not "people with morgellons have no physical evidence of infestation".
- unfocussed_mike 5y ago
  Nope. There is some fringe theory about a bacterium but Morgellons is almost certainly delusional parasitosis and the fibres are just that - fibres from clothes. It emerged from an odd nexus of Munchausens, Munchausens by proxy, internet diagnosis and schizophrenia. So it's not "fake" but it might be faked. Morgellons is a really fascinating mini model of Qanon, in a way; it now "exists" as a "thing" that has to be discussed, even though it doesn't exist as a thing.
  - bayesian_horse 5y ago
    Delusional parasitosis is quite the opposite of "Munchhausen's". Sufferers can't even be described as hypochondriac. It's a psychiatric disorder, and they seek help because they suffer. In "Munchhausen's" people seek suffering to get help, to oversimplify by a few magnitudes. But it's really not the same thing. And QAnon-followers are in their majority not suffering from psychotic delusions.
maxk42 5y ago
Why would they call these the largest when things like this [0] exist? It's my understanding that even these large cells aren't the largest. [0] https://www.australiangeographic.com.au/blogs/creatura-blog/2019/04/this-bizarre-bubble-creature-is-a-single-living-cell/ https://www.australiangeographic.com.au/blogs/creatura-blog/...
- flobosg 5y ago
  That’s an eukaryotic alga, not a bacterium.
  - maxk42 5y ago
    Perhaps I am misinformed but I was taught bacteria come in both prokaryotic and eukaryotic varieties. Are algae not bacteria?
    - flobosg 5y ago
      Bacteria are always prokaryotes since they lack nucleus and membrane-bound organelles. Algae (both single-celled and multicellular ones) are more complex and thus eukaryotic. That being said, photosynthetic bacteria (cyanobacteria) do exist and were known as “blue-green algae” in the past, but that term has fallen out of use.
Jiro 5y ago
It apparently has thousands of copies of the same DNA. That makes it sound like calling it a single cell is a technicality based on how the multiple copies of DNA aren't separated from each other, but it isn't necessarily a single cell in an interesting way.

128 points by amichail 5y ago

The complete research article: https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1 https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1

sva_ 5y ago

The article seems to imply that this organism is single-cellular: > Its threadlike single cell is visible to the naked eye, growing up to 2 centimeters—as long as a peanut—and 5000 times bigger than many other microbes. The study[0] however speaks of "cells" in plural, and "daughter cells". It would've really surprised me if that really had been a single cell - unless I'm misunderstanding something here. edit: I stand corrected. Misunderstood it. [0] from other comment: https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1.full.pdf https://www.biorxiv.org/content/10.1101/2022.02.16.480423v1....

stdbrouw 5y ago
First subheading of the study: "Thiomargarita magnifica is a centimeter-long, single bacterial cell". They apparently stick together, but do constitute individual organisms.
R0b0t1 5y ago
There is precedence for cells being that large. I can't remember the organism name, but there is actually some macroscopic single cell organism. It cheats by having multiple nuclei, among other things.
- throwamon 5y ago
  You may be thinking of Valonia ventricosa (bubble algae), though I believe there are others.
- bochoh 5y ago
  Chicken and ostrich eggs are both single cells that are quite large as well
  - bayindirh 5y ago
    But it's an eukaryote cell. Not prokaryote.
- sva_ 5y ago
  Yeah, but the cell of such single-celled organisms are usually round or in one segment. This one looks like it has several segments, and still be a single cell, which is fascinating. Perhaps it is blurring the line between single cellular and multi cellular a bit, which might be the point that the article was trying to make.
- adrian_b 5y ago
  What is new here is that this is a bacteria, not a nucleate cell. Large eukaryote cells, even over 10 cm (4 inches), are well known. Almost all normal bacteria have a diameter under 100 micrometer, usually much less. The article explains that the huge size for a bacteria seems to be enabled by 2 features, first a large water-filled vesicle inside, so that the living part of the cell is around the periphery of the cell, within short distances from the cell membrane, and second, a special compartment for DNA which provides some of the functions of a nucleus in an eukaryote (nucleate) cell.
jessriedel 5y ago
No, they claim that most of the filament is a single cell, albeit with compartmentalized DNA: > Strikingly, all techniques consistently showed that each filament was one continuous cell for nearly its entire length with no division septa, including the partial constrictions towards the apical pole. Only the most apical few buds were separated from the filament by a closed constriction and represented daughter cells "Apical" means the apex of the filament. In other words, toward the end of the filament the cell starts pinching off ("budding") to create daughter cells as part of its reproductive cycle. But the away from the end, the cell is contiguous. Fig. S2 is highly recommended.
actually_a_dog 5y ago
Believe it or not, that's not even close to the largest unicellular organism. One of the largest is Valonia ventricosa, a species of algae that has spherical or ovoid cells "with a diameter that ranges typically from 1 to 4 centimetres (0.4 to 1.6 in) although it may achieve a diameter of up to 5.1 centimetres (2.0 in) in rarer cases." [0] --- [0]: https://en.wikipedia.org/wiki/Valonia_ventricosa#Physiology_and_reproduction https://en.wikipedia.org/wiki/Valonia_ventricosa#Physiology_...
- bayesian_horse 5y ago
  Point being those algae are eukaryotic. The article is about an unusually large bacterium (prokaryotic) which has some eukaryotic features.
- undersuit 5y ago
  My favorite large unicellular organisms are Xenophyophorea. They have multiple nuclei probably because the diffusion of transcription processes over an 8 inch diameter cell would be just too slow with a single central nucleus. https://en.wikipedia.org/wiki/Xenophyophorea https://en.wikipedia.org/wiki/Xenophyophorea

tombert 5y ago

How is complexity measured in this case? I'm not disagreeing, I'm just curious.

unfocussed_mike 5y ago
It's largely based on the bacterium's nuanced views on late nineties experimental electronica.
Kichererbsen 5y ago
Disclaimer: I am not a biologist or whatever someone who studies this stuff is called. But from what I've been able to gather, actually having the RNA be in it's own membrane (an "organelle" they're calling it in the article) is not something you'd usually expect in a bacterium. If I remember correctly, they're more "soupy" inside.

deleted 5y ago

[deleted]

catlifeonmars 5y ago

From further down in the article: > Furthermore, that cell includes two membrane sacs, one of which contains all the cell’s DNA, Volland and colleagues report in their 18 February preprint on bioRxiv. Volland calls that sac an organelle and that’s “a big new step” that implies the two branches of life are not as different as previously thought, Carvalho says. “Perhaps it’s time to rethink our definition of eukaryote and prokaryote!” agrees Petra Levin, a microbiologist at Washington University in St Louis. “It’s a supercool story.” IMO, they really buried the lede on this one by focusing on the size of the bacterium and not on the convergent evolution of an apparent nucleus in a prokaryote.

Karawebnetwork 5y ago

I am wary to bring the topic up but I wonder if this might have some degree of connection with what people call morgellons disease. The bactarium shown in the video looks very similar to what people describe. My understanding is that morgellons is largely seen as psychosomatic or "fake". I now wonder if some people might have similar bacteria on them and that it might explain some of the symptoms.

danachow 5y ago
The problem with this theory, despite lobbied funding for the Morgellons foundation with very extensive testing including histological and biochemical, no evidence of an organism has been found associated with it. It’s not like nobody has looked.
likpok 5y ago
It would be easy to determine if Morgellons was caused by a bacteria or some other physical thing: you can take samples and look at them under the microscope. When the CDC did just that (looked at samples of the fibers), they found them to be likely cotton. If this were the cause of morgellons then their result would be "morgellons caused by infestation with unknown large bacteria" not "people with morgellons have no physical evidence of infestation".
unfocussed_mike 5y ago
Nope. There is some fringe theory about a bacterium but Morgellons is almost certainly delusional parasitosis and the fibres are just that - fibres from clothes. It emerged from an odd nexus of Munchausens, Munchausens by proxy, internet diagnosis and schizophrenia. So it's not "fake" but it might be faked. Morgellons is a really fascinating mini model of Qanon, in a way; it now "exists" as a "thing" that has to be discussed, even though it doesn't exist as a thing.
- bayesian_horse 5y ago
  Delusional parasitosis is quite the opposite of "Munchhausen's". Sufferers can't even be described as hypochondriac. It's a psychiatric disorder, and they seek help because they suffer. In "Munchhausen's" people seek suffering to get help, to oversimplify by a few magnitudes. But it's really not the same thing. And QAnon-followers are in their majority not suffering from psychotic delusions.

maxk42 5y ago

Why would they call these the largest when things like this [0] exist? It's my understanding that even these large cells aren't the largest. [0] https://www.australiangeographic.com.au/blogs/creatura-blog/2019/04/this-bizarre-bubble-creature-is-a-single-living-cell/ https://www.australiangeographic.com.au/blogs/creatura-blog/...

flobosg 5y ago
That’s an eukaryotic alga, not a bacterium.
- maxk42 5y ago
  Perhaps I am misinformed but I was taught bacteria come in both prokaryotic and eukaryotic varieties. Are algae not bacteria?
  - flobosg 5y ago
    Bacteria are always prokaryotes since they lack nucleus and membrane-bound organelles. Algae (both single-celled and multicellular ones) are more complex and thus eukaryotic. That being said, photosynthetic bacteria (cyanobacteria) do exist and were known as “blue-green algae” in the past, but that term has fallen out of use.

Jiro 5y ago

It apparently has thousands of copies of the same DNA. That makes it sound like calling it a single cell is a technicality based on how the multiple copies of DNA aren't separated from each other, but it isn't necessarily a single cell in an interesting way.