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[Music]

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hi everyone

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um I'm Claire and so I'm going to talk a

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little bit about respiration oxygen

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sensing

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um and this idea that there might be a

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really close relative to the ancestor of

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Proto mitochondria in modern oxygen

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um so I think a lot of people here are

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familiar with eukaryogenesis it's this

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idea that an archaea and a bacteria a

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very long time ago decided to be best

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friends forever and now we're here

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um so there's lots of different

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hypotheses over how this might have

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happened

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um and kind of the main point I want to

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make here is that one there's always a

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bacterial host and that's generally

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thought of as an alpha proteobacteria

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and there's also a lot of or has been a

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lot of talk historically about is this

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obligately aerobic does it have to have

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oxygen is it facultatively aerobic where

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it could use oxygen or not or is it kind

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of

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um an anaerobic partnership that turned

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so a lot of more quantitative Recent

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research so kind of this triangulation

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method suggests that this new clade of

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marine Alpha proteobacteria from marine

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oxiclines and these are really related

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to a group called iodidemonus This is an

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iodide using bacteria might be the

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closest living relative to

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protomitochondria

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um and so like I said Alpha

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proteobacteria for a while have been

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thought of as that sort of bacterial

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component of eukaryogenesis and what I'm

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going to showing you really quick right

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here is that these are some anaerobic

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traits that are thought of really

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essential when you're looking at the

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criteria for this ancestor and so most

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of these are alpha proteobacteria and

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when we're looking at the heat map what

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we want to focus on is this green

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highlighted here that's this new clade

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so they hit all of these criteria for

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anaerobic traits when we're thinking

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and then when we're thinking more about

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the aerobic side of this these

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facultative aerobics we want to think

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about the terminal electron chain so

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what's interesting is that this is

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comprised of four complexes and these

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complexes actually have this really

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phenomenal history of the evolution of

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respiration inside of it so from complex

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one to complex four we can kind of track

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as the Earth went from anoxic to the

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great oxidation event to kind of what we

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experience now and so I'm really looking

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more at complex four because

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um within it um this is that last step

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that important uh reduction step so if

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we're thinking about proto-mitochondria

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they would need to have this complex for

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um so that can be divided up even more

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into this a to c family we have an

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a-type lots of oxygen we don't have to

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bind it super well it's there but the

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sea family is thought of these as the

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oldest terminal or complex four of the

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terminal electron chain and that's

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because it's capable of binding oxygen

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so for this new clade I had two main

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questions looking at sort of data mining

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which is what kind of genes do they have

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for respiration is it

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um entirely aerobic or is there

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anaerobic as well are they able to sense

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oxygen and are they moving along

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gradients in response to that and then

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on top of that are these genes actually

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um so I did a lot of data mining in the

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uh with this nice big data set from the

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sandwich Inlet that's in British

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Columbia it's a seasonally hypoxic area

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but it's an oxygen minimum Zone and that

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just means that very quickly we'll lose

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oxygen very high up in the water column

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and it's you can see how like seasonally

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variable it is but overall there's a

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and so the two really interesting points

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I saw was one there are c-type aerobic

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oxidases associated with this Alpha Pro

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newclate Alpha proteobacteria and its

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transcription or the amount that it was

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being used potentially increased Into

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the anoxic Depths and that there are two

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chemotaxis proteins so that's an

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aerotaxis protein

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maybe maybe not it might be responding

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to something else

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um they were both being transcribed

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really highly into these anoxic depths

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um so my main takeaway is we should look

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at omz's more we're thinking about

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protomitochondria

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um because there are some really

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interesting Alphas there that only exist

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right now as metagenomic assembled

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genomes

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um and it would be really interesting to

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really look at the full genomic uh

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capabilities of them

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um so I'd like to thank the glass Lab at

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Georgia Tech

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um my funding the NSF grad and then the