I am technically an author on this manuscript, if anyone has any specific questions. I probably can't answer them, but I can text the first author. (Was not expecting to see this on HN today)
throwup238 9 minutes ago [-]
How do these bacteria compare to hydrozoans like the man o' war? Is the similarity just superficial or do they exhibit some form of differentiation?
> In the new study, scientists have revealed even more complexity in the relationships between MMB cells. First, contrary to long-held assumptions, individual cells within MMB consortia are not genetically identical, they differ slightly in their genetic blueprint. Further, cells within a consortium exhibit different and complementary behavior in terms of their metabolism.
Does that mean there's mutation when they multiply or do these MMBs exhibit some crude form of sexual reproduction - two MMBs with separate genetics merging? What's their life cycle look like when they reproduce?
Have you guys managed to identify any genetic clocks that can help estimate when they broke off from their closest relative? The MMB sounds so much like a hydrazoan (~540 MYa) that I'm curious if there's an evolutionary connection there.
linguistbreaker 3 hours ago [-]
Love the writing as well as the content here.
Especially fascinated by the coordinated replication.
Also curious about magnetotactics - why would such a small scale organism need to orient to such a large scale phenomenon (the earth's magnetic field)? Wouldn't it make more sense for this electromagnetic sense to be used for smaller scale orientation in their environment?
gschaible 34 minutes ago [-]
Magnetotaxis in bacteria (and some protist) is passive. The organism will biomineralize a ferromagnetic mineral, such as magnetite or greigite, and in a magnetic field they will passively orientate. This is not active orientation, meaning that even when the organism is dead it will still orientate in the field.
Their movement in the magnetic field is however active. The theory behind the magnetotaxis is that it allows them to know what direction is up. In the northern hemisphere, the magnetic poles come in from above and go down. So to a bacterium, North is down.
Why care what direction North is? if you are sensitive to oxygen, which MMB are, and oxygen diffuses in from the atmosphere above, your magnetotaxis would tell you the direction to swim to get away from toxic levels of oxygen. Wild how evolution works!
guelo 3 hours ago [-]
Since these bacteria can't live on their own I don't understand what differentiates them from true multicellular organisms.
gschaible 41 minutes ago [-]
Hi there, first author of the paper here. We would argue that they are a true multicellular organism, which is rather unconventional for Bacteria. They do indeed have some level of genomic heterogeneity between individual cells within a single consortium but it appears this is actually purposefully maintained by the organism, likely to facilitate their evolution. They have a large genome (8 Mb) compared to E. coli (4 Mb) and have duplicate genes that are under higher rate of evolution (dN/dS) compared to the rest of the genome.
linguistbreaker 2 hours ago [-]
The article says "individual cells within MMB consortia are not genetically identical, they differ slightly in their genetic blueprint."
"a Portuguese man o' war constitutes a single organism from an ecological perspective, but is made up of many individuals from an embryological perspective."
Rendered at 23:19:56 GMT+0000 (Coordinated Universal Time) with Vercel.
> In the new study, scientists have revealed even more complexity in the relationships between MMB cells. First, contrary to long-held assumptions, individual cells within MMB consortia are not genetically identical, they differ slightly in their genetic blueprint. Further, cells within a consortium exhibit different and complementary behavior in terms of their metabolism.
Does that mean there's mutation when they multiply or do these MMBs exhibit some crude form of sexual reproduction - two MMBs with separate genetics merging? What's their life cycle look like when they reproduce?
Have you guys managed to identify any genetic clocks that can help estimate when they broke off from their closest relative? The MMB sounds so much like a hydrazoan (~540 MYa) that I'm curious if there's an evolutionary connection there.
Especially fascinated by the coordinated replication.
Also curious about magnetotactics - why would such a small scale organism need to orient to such a large scale phenomenon (the earth's magnetic field)? Wouldn't it make more sense for this electromagnetic sense to be used for smaller scale orientation in their environment?
Their movement in the magnetic field is however active. The theory behind the magnetotaxis is that it allows them to know what direction is up. In the northern hemisphere, the magnetic poles come in from above and go down. So to a bacterium, North is down.
Why care what direction North is? if you are sensitive to oxygen, which MMB are, and oxygen diffuses in from the atmosphere above, your magnetotaxis would tell you the direction to swim to get away from toxic levels of oxygen. Wild how evolution works!
"a Portuguese man o' war constitutes a single organism from an ecological perspective, but is made up of many individuals from an embryological perspective."