Scientists Discover First Nitrogen-Fixing Organelle (phys.org) 25
In two recent papers, an international team of scientists describes the first known nitrogen-fixing organelle within a eukaryotic cell, which the researchers are calling a nitroplast. Phys.Org reports: The discovery of the organelle involved a bit of luck and decades of work. In 1998, Jonathan Zehr, a UC Santa Cruz distinguished professor of marine sciences, found a short DNA sequence of what appeared to be from an unknown nitrogen-fixing cyanobacterium in Pacific Ocean seawater. Zehr and colleagues spent years studying the mystery organism, which they called UCYN-A. At the same time, Kyoko Hagino, a paleontologist at Kochi University in Japan, was painstakingly trying to culture a marine alga. It turned out to be the host organism for UCYN-A. It took her over 300 sampling expeditions and more than a decade, but Hagino eventually successfully grew the alga in culture, allowing other researchers to begin studying UCYN-A and its marine alga host together in the lab. For years, the scientists considered UCYN-A an endosymbiont that was closely associated with an alga. But the two recent papers suggest that UCYN-A has co-evolved with its host past symbiosis and now fits criteria for an organelle.
In a paper published in Cell in March 2024, Zehr and colleagues from the Massachusetts Institute of Technology, Institut de Ciencies del Mar in Barcelona and the University of Rhode Island show that the size ratio between UCYN-A and their algal hosts is similar across different species of the marine haptophyte algae Braarudosphaera bigelowii. The researchers use a model to demonstrate that the growth of the host cell and UCYN-A are controlled by the exchange of nutrients. Their metabolisms are linked. This synchronization in growth rates led the researchers to call UCYN-A "organelle-like." "That's exactly what happens with organelles," said Zehr. "If you look at the mitochondria and the chloroplast, it's the same thing: they scale with the cell."
But the scientists did not confidently call UCYN-A an organelle until confirming other lines of evidence. In the cover article of the journal Science, published today, Zehr, Coale, Kendra Turk-Kubo and Wing Kwan Esther Mak from UC Santa Cruz, and collaborators from the University of California, San Francisco, the Lawrence Berkeley National Laboratory, National Taiwan Ocean University, and Kochi University in Japan show that UCYN-A imports proteins from its host cells. "That's one of the hallmarks of something moving from an endosymbiont to an organelle," said Zehr. "They start throwing away pieces of DNA, and their genomes get smaller and smaller, and they start depending on the mother cell for those gene products -- or the protein itself -- to be transported into the cell."
Coale worked on the proteomics for the study. He compared the proteins found within isolated UCYN-A with those found in the entire algal host cell. He found that the host cell makes proteins and labels them with a specific amino acid sequence, which tells the cell to send them to the nitroplast. The nitroplast then imports the proteins and uses them. Coale identified the function of some of the proteins, and they fill gaps in certain pathways within UCYN-A. "It's kind of like this magical jigsaw puzzle that actually fits together and works," said Zehr. In the same paper, researchers from UCSF show that UCYN-A replicates in synchrony with the alga cell and is inherited like other organelles.
In a paper published in Cell in March 2024, Zehr and colleagues from the Massachusetts Institute of Technology, Institut de Ciencies del Mar in Barcelona and the University of Rhode Island show that the size ratio between UCYN-A and their algal hosts is similar across different species of the marine haptophyte algae Braarudosphaera bigelowii. The researchers use a model to demonstrate that the growth of the host cell and UCYN-A are controlled by the exchange of nutrients. Their metabolisms are linked. This synchronization in growth rates led the researchers to call UCYN-A "organelle-like." "That's exactly what happens with organelles," said Zehr. "If you look at the mitochondria and the chloroplast, it's the same thing: they scale with the cell."
But the scientists did not confidently call UCYN-A an organelle until confirming other lines of evidence. In the cover article of the journal Science, published today, Zehr, Coale, Kendra Turk-Kubo and Wing Kwan Esther Mak from UC Santa Cruz, and collaborators from the University of California, San Francisco, the Lawrence Berkeley National Laboratory, National Taiwan Ocean University, and Kochi University in Japan show that UCYN-A imports proteins from its host cells. "That's one of the hallmarks of something moving from an endosymbiont to an organelle," said Zehr. "They start throwing away pieces of DNA, and their genomes get smaller and smaller, and they start depending on the mother cell for those gene products -- or the protein itself -- to be transported into the cell."
Coale worked on the proteomics for the study. He compared the proteins found within isolated UCYN-A with those found in the entire algal host cell. He found that the host cell makes proteins and labels them with a specific amino acid sequence, which tells the cell to send them to the nitroplast. The nitroplast then imports the proteins and uses them. Coale identified the function of some of the proteins, and they fill gaps in certain pathways within UCYN-A. "It's kind of like this magical jigsaw puzzle that actually fits together and works," said Zehr. In the same paper, researchers from UCSF show that UCYN-A replicates in synchrony with the alga cell and is inherited like other organelles.
So, diving into this whole nitroplast thing (Score:5, Interesting)
This is wild because it's not just about nitrogen anymore. It's about how life evolves in the most unexpected ways. Think about it – this little organelle, the nitroplast, is proof that nature has more tricks up its sleeve than we thought. The coolest part - It could help us grow food in a more eco-friendly way, cutting down on pollution from synthetic fertilizers.
Biology just got a new plot twist.
Re: (Score:2)
Finding an efficient source of non-liquid fertilizer would help prevent runoff. The whole problem with synthetics is that they are a liquid that easily washes away in rain. A more efficient pre-season cover crop that fixes nitrogen would be way better. Your link shows legume fixation as one of the complements to synthetic. Here where I live, that's a rotation between soybeans and corn from year to year.
The big problem is that if it gets a huge chunk of its nutrients from the air, it can be really invasi
Amazing discovery (Score:3)
Looks like they discovered the early stage evolution of an organelle, and also a new type of organelle, and also something that could revolutionize agriculture.
Re: (Score:2)
Agreed, but the thing with agriculture is that the very thing that has the potential to revolutionize it also has the potential to nuke it.
So now what? (Score:2)
Or add it to a corn plant so that doesn't require fertilizer?
Or something different?
Re: (Score:3)
Brew ammonia? Why, when I can buy Michelobe Ultra in the store?
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SIR, that is NOT ammonia YET-- That is a can of salty piss, sure, but that requires room temperatures and access to air to get ammonia!
Re: (Score:3)
Use CRISPR to add this to a yeast cell so you can brew ammonia?
That could be interesting, if the yeast cell escapes, for instance into natural soils. Given the way industry operates, it probably will escape at some point.
Re: (Score:2)
You use a needle to add this into a yeast cell. It's not produced by the host DNA. You'd use CRISPR to add the genes that facilitate symbiosis. Like mitochondria, this is an organelle with its own DNA and reproduces independently, even if simultaneously.
Re: (Score:2)
As an organelle, it should be carrying enough DNA (and replication biochemistry) to duplicate itself, but will probably have transferred some of the genes it needs to prepare some of it's precursor materials to the enclosing organism. Which means that it then becomes an obligate endosymbiont (it is obliged to live in a host with those biochemical tricks).
So, you'd need to identify the sections of host genome that the organelle depends on, copy them (for which CRISPR may well be appropriate) into
The Slashdot effect in action (Score:5, Funny)
Re: (Score:2)
UC Santa Cruz (Score:2)
Must be fucking nice. Uh, yeah I'm not hanging out on the beach all day .. I'm looking for nitrogen fixing organelles.
How do I enroll?
Re: UC Santa Cruz (Score:2)
The researcher took 300+ trips on a boatâ¦
Re: (Score:2)
Knights of Sidonia anime (Score:2)
So maybe we could have in future photosynthesizing humans and associated, uhm, ray-taking sessions eh eh..
Isn't this a big deal for soil? (Score:2)
Re: (Score:2)
Not QUITE correct.
the issue, is that adding nitrogen to soil causes rapid CARBON depletion. This has been observed in agri-science literature since at least the 30s.
https://grist.org/climate-ener... [grist.org]
"Fully Automating" nitrogen addition, without a commensurate increase in carbon addition, will result in destruction of soils, not improvements.
Not that this little factoid would in any way dissuade the big agribiz folks for even an attosecond. They will just slap an "ENVIRONMENTALLY FRIENDLY! NOW CARBON NEUTRAL
Re: (Score:3)
This is one reason why manure is still needed. High carbon content. If you don't replace the carbon, you eventually get just desert sand. Tilled under cover crops add carbon and nitrogen. But when most of your carbon in the soil is rotting plants, you are also getting methane. Farming ecology is kind of a mess. I wonder if any earthworms even survive these conditions.
I've always wondered what desert cities do with the sludge from wastewater treatment. I have to imagine it could be used for de-deserti
Why should I care? (Score:1)
Re: Why should I care? (Score:2)
Re: (Score:2)
Huh? It is important cause it's fucking cool, it's interesting. The fact that it's useful is not what makes people who like science giddy. The fact that it's a different and unusual thing is what is important about it. We're only forced to contrive uses for things so that we can get funding. Utility is secondary to usage. Galileo spent many hours every night at his telescope with no idea of any sort of utility .. in fact it only brought him hell. The excitement of finding and doing something new is what tri
Suddenly aquarists... (Score:2)
...switch from fighting cyanobacteria in their tanks to embracing it.
Lynn Margulis waving from her grave ... (Score:2)
Which she did, in the early 1970s, with the then-controversial suggestion that chloroplasts and mitochondria came into existence as separately achieved symbioses between bacteria (with particular biochemical tricks) and multiple strains of bacteria without those tricks. Then later, the symbiotic bacteria lost DNA and cytoplasm to become "organelles". In at least one case, it happened twice (yielding mitochondria and chloroplasts within plant cells - hardly unsuccessful!)
So