Friday, December 18, 2015
DNA Sequence found in Human Gut with Significant Difference to any Known Life Form
In the end it is something new and we simply do not know. It is just unexpected. It also means that we never quite searching. Far too many biota are specific to an exact niche and unless someone goes many extra miles it will never get discovered.
I recall checking off all plant species on my farm. A couple of plants remained undiscovered. Reading the description carefully i discovered that they liked cool rocks and rock piles.
I went immediately to our rock pile and discovered a specimen. That alone shows us just how a rare plant may not be rare at all but its preferred domicile may well be.
DNA sequence found in human gut with significant difference to any known life form
Stories broke across the Internet recently that researchers in France had discovered an entirely new microbial life form, living in the human digestive system.
Is this the movie “Alien” coming to life? Are we doomed?
No. It turns out the headlines like “Scientists think a whole new type of life form could be living in our guts” were running well ahead of the facts.
There is, as of now, no new observed and captured living thing swimming around in your stomach.
But there is some odd, unidentified DNA. And that alone is a really cool story.
“What we’re trying to do is to identify a very strange gene in the environment – strange with respect to genes that we understand are related to known organisms,” says Eric Bapteste, an evolutionary biologist at Pierre and Marie Curie University in Paris.
“The research is in a very preliminary first step. The conclusion is not yet reached.”
Bapteste and his colleagues were examining what he calls a “soup” of DNA from the human gut. There are already three known families of life there – bacteria, archaea, and eukaryotes.
Then up pops this bizarre outlier of a DNA sequence that is a full 40 per cent different from any known form.
“The average similarity between sequences belonging to organisms from two distinct domains of life – one being a bacteria and one being an archaea – is about 60 per cent,” says Bapteste.
“So if you are less similar than that, then you are very divergent.”
By comparison, human beings share about 75 per cent of our DNA with mice, and 60 per cent with fruit flies.
“We try to match every sequence to something that looks somehow like it,” he explains.
“Say you have a picture of your grandfather and your father, and you try to connect them to yourself. You might be able, eventually, to connect your dad’s picture to your picture. Maybe you might be able to connect your grandfather to your dad, but maybe you’re not able to connect your grandfather to yourself directly, because you are too dissimilar."
At this point, no organism has been found that corresponds to this rogue DNA. Bapteste is intrigued with the possibilities, however.
“I’ll be excited to test it, because truly, I don’t know. And I don’t want to be making assumptions or big claims, because that’s not what we want to do as scientists. Either it’s something that was there forever and we’ve just never seen it before, or it’s been carried in a different organism that we still haven’t observed and cultured.
“We don’t yet know if there are weird organisms in our gut. But we know that there are weird genes. And so it’s really just the first step, because now that we know the genes are there, eventually we could try to capture organisms that carry these strange genes.”
Scientific research is always conducted along the ragged, shifting line between what we know, and what we don’t. Many enticing clues emerge, but ultimate discovery frequently remains elusive.
“I think the reason it’s exciting is because if we dream about what it could mean, then we could start imagining a whole new world of microbial diversity,” Bapteste says.
“We now have a way to imagine that maybe there is more. If we hadn’t found these divergent sequences, we would have no way to dream further.”