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today I'm going to talk about a very

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interesting behavior of those solving

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microbes and then well before I started

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I would like to thank all my

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collaborators my lab mates or the grants

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support this project particularly AB

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grant committee to give me the chance to

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present here so this story besides the

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original of life it's more than like how

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life could adapt to beyond the earth

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particularly we already have the

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evidence that on Mars we have found the

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liquid water in the brine deposit so

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make this so loving microbes could be

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the very promising candidate to survivor

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clients are like for example Mars so on

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the earth actually we already are simple

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der study this micro communities all all

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over the world and then we call this if

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you're not familiar hello files so the

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whole group of microbes called and here

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is an example what are this kind of

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habitat looks like so this area connect

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to the sea water with relative low

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concentration of the salinity and this

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area is a red color area have a high

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salt concentration and this color is

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meaning because of those microbes living

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this region and this small area is

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artificial source and pan so evaporate

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the liquid water to extract salt so

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normally those region will have the

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concentration gradient in some of those

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pant or have a really high concentration

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you can see they already started to

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crystallize the crust all those

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concentration gradient

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the hell file communities have been fund

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so one of the challenge for those

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microbes survive in this type of

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environment is resource limitation okay

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however ah there's a one potential

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resources might be available for them

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which is the extracellular DNA molecule

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so if we think about DNA molecules we

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first will think they are genetic

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information carrier but actually as the

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large organic molecules there are also

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very nutrition to see that and then

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where it come from it could from in all

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the organisms those individual they die

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and those DNA materials or release from

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the cell so basically it exists in all

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type of ecosystem and kind of abundant

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and it has been found that some microbes

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species will take this ed na as

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nutritional supply so the question is is

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the hell file could do this so the

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answer is yes so this experiment is

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performed in dr. Parker slab showing by

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fitting this species health Eric's

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bikini I which is model species of how

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hello files so it can grow on IDI na but

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the thing is depends on where the

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stealing Eden income from its

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selectively picking for example here

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health Eric's will grow on the E DNA

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from itself but it won't grow on the DNA

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from hearing or e coli so this results

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we want to ask like okay what type of

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look II DNA they prefer what's the

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characteristic of those consumed DNA

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molecules right so talk about DNA

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molecules so here our many

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using two while you used characters to

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describe the features of DNA why is this

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GC content so DNA molecules have four

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bases a tgc so GC content basically

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calculate the percentage of GC in

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certain region could be genome

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chromosome or any region were interested

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in another thing is the DNA modification

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pattern specifically is a methylation

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pattern so here this three figures show

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three type of methylation for bacteria

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and nakia so what type of methylation

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will happen or generate here depends on

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the methylation enzymes this species

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have or carry and then different

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methylation enzyme normally have a

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specific recognition motif which is

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small DNA regions for example later

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we'll talk about the methylation enzyme

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of Health erics which using this CTA GC

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tag motif as a recognition region so to

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exam what type of a DNA they prefer to

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take we design this experiment so first

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extract the community DNA from certain

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pound and then part of it directly being

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sequenced so we obtain this pre fitting

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meta-genome dead data another part used

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as edu a source to fit the health erics

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and after feeding treatment or sequence

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the post feeling same how to obtain the

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post feeding meta-genome then we'll

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compare is pre fitting and post feeding

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sample to check like DNA features or DNA

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future changes of those groups so here

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is the summary of the results to this

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purple pink circle is the pre feeding

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sample blue

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Circle is the post feeding sample so the

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overlap area is those DNA occur in both

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samples so they're like basically

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haven't been consumed so we call the

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leftover group and then this area is

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particularly interesting is the only

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occurred in pre feeding sample but

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disappear in post feeding samples so

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potentially being consumed so we call

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the eaten group then things where we

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repeat that experiment twice so

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eventually we obtain two replicates and

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then the results are pretty consistent

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are there about eight point three eight

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point five percent of the DNA have been

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consumed then next about the GC content

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of those groups are this purple curve is

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the leftover group which is pretty

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similar to this black curve is the GC

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content distribution of the total

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community sample however the eaten group

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which is this red orange curve showing

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they have the bias towards the lower GC

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content indicate the health Eric's

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prefer to take the DNA with lower GC

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cannon and since the GC content of

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genome when we talk about that it's it

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has it's basically species-specific so

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different species normally have

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different GC content our average for

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their genome so we want you a check if

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this load GC content is contribute to by

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specific species so next we do a

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taxonomy analysis to analyze the

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composition of our sample so here is the

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compensation of the total community

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sample different color represents

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different than general settings this

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taxonomy is in genus level and then the

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leftover groups showing a very similar

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pattern to the entire community sample

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however this eatin group are

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significantly different and I check all

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the species in those general and haven't

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found no specific species abundance

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pieces in this group have low GC content

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so is this suggests this low GC content

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bias could maybe just from like some

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region of the genome or have lower GC

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content and they take that next about

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the methylation pattern so already

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mentioned hello ferrets have this

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methylation enzyme using seatac motif so

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with then if the other species in this

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eating group also share this gene then

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eventually you will generate similar

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methylation pattern so here we exam the

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presence absence status of those of this

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gene in all those species in the eating

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group and then if all the species in

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this genus have this gene we color in

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dark purple if none of the species in

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genus have this gene then we'll color in

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white so to map the status here we can

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show or we can see a lot of genus or

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species in this eating group actually

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share this methylation enzyme and we

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also connect this presence/absence

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status of this gene to this bundles

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change changes of those group so here

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this green arrow connect the genus if

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their proportion increased in Eden group

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compared to the proportion in the entire

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community sample and then the orange

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arrow connect the opposite so if this

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genus the proportion decreased

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in the Ealing group compared to the

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proportion in an entire community sample

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anyways can see there is a a very strong

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correlation pattern here is almost all

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the green error eral have a cross 12

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dark purple dot here or the orange arrow

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they have like white dot so meaning they

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don't have this gene so this results

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might suggest the sharing the similar

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methylation pattern could be a signal

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for to determine if health Eric's will

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pick this gene or not so a quick summary

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here so health Eric's makini I prefer to

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take the e DNA with lower GC content and

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similar methylation pattern and with

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this information we wonder if we put

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those species sharing this stimulant

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methylation pattern together to form a

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community and then my former our

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resource recycling system then this

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might be a really nice strategy to adapt

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the inning source limited environment

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which you know if this system can work

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then I guess hello file commit whom we

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work better okay so with that I would

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thank you sing oh yeah I was wondering

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if you looked for the that specific

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motif in the not eaten organisms as well

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and found that it wasn't present ah

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didn't do you know what I mean yeah but

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because the well if we see they actually

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are so those groups are actually pretty

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similar to the total community structure

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to the committee samples so basically we

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already check if they did if those

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groups share that gene his you know in

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the Eden group they actually have more

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general stand out compared to the

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community symbol so we did check those

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so they are already included sort of

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included in this group thank you um so I

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was wondering I is there any other kind

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of DNA that the hayloft Eric's likes to

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eat more than its own or does it it

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doesn't always go for its its own kind

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of DNA first and then things that are

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similar ah yeah all we have some before

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we do they will have some hypotheses

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like if they take DNA from you know the

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taxonomy resources saying if they're

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from like clothes related species but it

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turns out it determined by the

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methylation pattern but sharing the

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similar methylation pattern doesn't

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necessarily mean they are closed related

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species so yes so like those are species

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in those chilling those general they

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they sharing this method similar

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methylation pattern but on the phylogeny

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fellow genetic tree they are not really

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clustering together or they don't have

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those kind of pattern they just widely

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alright one last question okay so

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obviously you haven't done this here but

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has anybody looked into how much of the

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DNA that's eaten is actually

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incorporated into the bacterial

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chromosome ah you mean like map them to

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the back to that yeah like you'd have to

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do it with a monoculture and not like

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this community like you did here um you

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know because this group is now first

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it's not just from one species so well

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it definitely could try to yeah I

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haven't done that yet but I have those

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like all the DNA because this is I have

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those metagenomic samples from all those

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generals

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okay no I was just asking if anybody has

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done it with like a monoculture of one

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representative of one of these species

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that eats DNA oh yeah I haven't heard

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that because for the hell files those

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are all the all those are most most of

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them except this one thing most of them

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are archaea and i think as i know

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besides health eric's bikini I their

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only few species are successfully cut

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you know and can culturing the lab and a