
First detailed microscopy evidence of ‘nanobacteria’ - ca98am79
http://www.kurzweilai.net/irst-detailed-microscopy-evidence-of-nanobacteria-at-the-lower-size-limit-of-life?utm_source=KurzweilAI+Daily+Newsletter&utm_campaign=8d0828414b-UA-946742-1&utm_medium=email&utm_term=0_6de721fb33-8d0828414b-281895037
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bayesianhorse
"As small as life can get" is an interesting claim. Without reading the paper
I am wondering if life before bacteria wouldn't have to be smaller. Maybe even
devoid of membranes. At the very beginning there should even have been
molecules which catalyzed (=enhanced) their own synthesis, first a little,
then progressively more until you had something like an RNA replication
machine...

And then these bacteria come pretty close to virus and cell organelles,
raising questions of when to call a parasite "life" or "not life".

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TheSpiceIsLife
Prions self replicate, but require the host to have the correctly folded
protein.[1] Of course there's viruses too, which are self replicating but need
to infect some other organism.

Maybe crystals? Now we're getting in to the potentially wonky question of
'what is life?'

1\. [http://en.wikipedia.org/wiki/Prion](http://en.wikipedia.org/wiki/Prion)

Edit: grammar for clarity.

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fabian2k
Prions are not considered alive under any reasonable definition of life.
They're infectious, but you can't really call it replication as they just
trigger a conformational change in the correctly folded prion protein

~~~
TheSpiceIsLife
Yes, that's true. I should not have included the word 'self' with regard to
prions.

Are viruses considered 'alive'?

~~~
lepton
No. Viruses require a live host in order to replicate. That sounds
tautological, but I'm not sure how else to say it briefly.

~~~
xkcd-sucks
It's begging the question... every 'living' organism also requires a favorable
environment in order to replicate

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pbhjpbhj
Couple of things stood out:

The DNA has been sequenced but the article reports that "The bacterial cells
have densely packed spirals that are probably DNA". To me it seems strange not
to know the gross anatomy but to be able to sequence the DNA; I can see how it
could happen.

Also "The images revealed dividing cells, indicating the bacteria were healthy
and not starved to an abnormally small size." but the write up says they
appear to need other bacteria to function properly - and suggests the pili are
involved in that. If they can stay healthy and divide in an environment
without other bacteria then what do they need the other bacteria for,
entertainment??

These parts appear to be based on the asbtract viz. " _Ultrastructural
features potentially related to cell and genome size minimization include
tightly packed spirals inferred to be DNA, few densely packed ribosomes and a
variety of pili-like structures that might enable inter-organism interactions
that compensate for biosynthetic capacities inferred to be missing from
genomic data._ "

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TeMPOraL
> _To me it seems strange not to know the gross anatomy but to be able to
> sequence the DNA; I can see how it could happen._

As far as I understand, DNA sequencing is about breaking target into pieces
and using clever tricks to fish out nucleotydes and determine their order. It
seems to me that you don't need to know where and how DNA is exactly located
to be able to brute-force its sequence.

~~~
pbhjpbhj
That's what I meant by "I can see how it could happen". I guess I imagined
that they would have confirmed the major features with further microscopy
prior to publication; perhaps that's harder than I imagined but once you've
seen STM images of atoms it _seems_ like recognising DNA in a sample should be
easy.

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ajarmst
Mimivirus
([https://en.wikipedia.org/wiki/Mimivirus](https://en.wikipedia.org/wiki/Mimivirus)),
a virus which is actually twice the size of these nanobacteria has already
prompted some debate about the relationship of viruses to the kingdoms of
"life" and, for some, a reevaluation of what we mean by "life". These bacteria
are likely to add to that debate.

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superfx
Genetically these bacteria are apparently not that small--on the order of a
million DNA bases. We already know of smaller bacteria with just a few hundred
thousand bases (e.g. M. genitalium.) And so from the perspective of "minimal
life", these may not be all that special.

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pjgomez
Midiclorians... finally!

