First detailed microscopy evidence of ‘nanobacteria’
kurzweilai.net
kurzweilai.net
And then these bacteria come pretty close to virus and cell organelles, raising questions of when to call a parasite "life" or "not life".
Maybe crystals? Now we're getting in to the potentially wonky question of 'what is life?'
1. http://en.wikipedia.org/wiki/Prion
Edit: grammar for clarity.
Are viruses considered 'alive'?
But "as small as life can get" is a thing that has been studied, eg for Mars Sample-Return missions, they have to figure out a safe filter size (chapter 3): http://science.nasa.gov/media/medialibrary/2013/01/17/ESF_Ma...
An important distinction is whether these organisms can live 'independently' - a virus relies on a host. Quoting from the doc above: it is believed that theoretically a coccoid[1] cell with the minimum number of genes to be free living in an environment other than a living host would have a minimum cell diameter of approximately 0.15–0,2 μm. - which is around about the size of the beasties in the parent article.
They did consider smaller biological entities though, like gene transfer agents[2], and recommended filters such that nothing over 0.05μm is released under any circumstances, and that there's only a 1 in a million chance of anything smaller than 0.01μm escaping.
[1] Spherical. http://en.wikipedia.org/wiki/Coccoid
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."
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.
They're just looking at an image of the cell and seeing these unknown structures. They cannot be sure what it is. It is impossible to determine whether its DNA or not from the image.
Quite independent of this, we can take a sample containing the organism and sequence its DNA without knowing where it originated from in the source cell. DNA is purified for sequencing from other cell structures by chemical and mechanical methods.
I require food and water to function properly, but I'm not currently eating or drinking. These microbes were isolated using filteration, so presumably they were surrounded by other bacteria to leech from, right up to the point they were isolated.
The solution you proffer is the expected situation but then the images would be prior to isolation or they'd show _divided_ cells (which is entirely uninteresting and tautological I think).