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The DNA of life at its limits:
Scientists have unraveled the complete genome of the tomato russet mite, which is considered one of the smallest animals on our planet and known as a destructive agricultural pest. The genome is the smallest reported to date for an arthropod and offers intriguing new insights into the organization of the tiniest lifeforms on Earth. The international consortium of European and American researchers, including UvA biologist Merijn Kant, now published their findings in the scientific journal eLife.
[...] The researchers sequenced the genome of A. lycopersici because it belongs the Eriophyoidea, a group of about 4,000 highly derived miniaturized animal species for which no representative genome was yet available. [...] "The tomato rust mite genome is much smaller than that of any other arthropod sequenced until today," says last author Merijn Kant from the UvA Institute for Biodiversity and Ecosystem Dynamics. "Its size is in the same range as that of fungal genomes." The consortium discovered that the mite's genome contains most of the gene families one would expect for an animal, although these are extremely reduced and several genes believed to be essential for animals were found to be absent.
Especially noteworthy in the russet mite genome is that 80% of its genes have no introns. "Introns are the dark matter of our genomes," Kant says. "These are chunks of non-coding DNA littered in large quantities across genes. No one knows why they are there or where they came from."[...]
Journal Reference:
Robert Greenhalgh, Wannes Dermauw, Joris J Glas, et al. Genome streamlining in a minute herbivore that manipulates its host plant, (DOI: 10.7554/eLife.56689)
(Score: 0) by Anonymous Coward on Tuesday November 24 2020, @11:02AM (1 child)
I wonder how many mites we eat per 250 ml of tomato sauce.
(Score: 0) by Anonymous Coward on Tuesday November 24 2020, @07:10PM
My guess is the number is higher than most people would ever care to know.
(Score: 2) by Taibhsear on Tuesday November 24 2020, @11:56AM (3 children)
This is absolute nonsense. Even back when it was called "junk DNA" it was nonsense. We know exactly where they came from (mutations: insertions, deletions, point mutations, crossing over events) and why they are there (alternative splicing and error correction for non-functional RNA/introns, gene regulation, replication, transcription, translation, and more for functional RNA).
From wikipedia [wikipedia.org]:
tRNA was hypothesized back in the 50's (when genetics essentially first became a field of study), primary structure studied in the 60's, and the xray crystallography for the structure performed in the 70's.
(Score: 1) by shrewdsheep on Tuesday November 24 2020, @12:17PM (1 child)
That's debatable, to say the very least. Having a possible explanation does not imply knowing the actual mechanism. Reconstructing genetic events is usually impossible in any outbred population, only studying parents and offspring sometimes allows to do so.
Even if we are talking about principles and possible events, a lot of things remain unexplained. Whey are the introns so much larger than exons in most eucaryotes? What is the function of repetitive/ highly repetitive DNA if any? How about their amount (>50% of human DNA is repetitive)? What determines genome size (the article contains some speculation)? The list goes on, but I will stop here (starting is easy, stopping is what's hard).
(Score: 2) by Taibhsear on Tuesday November 24 2020, @12:53PM
Alternative splicing variants. Of the organisms we've studied for alternative splicing, humans have the highest percentage of genome pertaining to it.
If you mean repetition of genes, increase of gene product or a "backup" gene in case one is non-functional. In the case of directly repeating nucleotides, well there's plenty of research on that. Off the top of my head, for structural elements (histones, telomeres, etc). https://www.sciencedirect.com/topics/medicine-and-dentistry/repetitive-dna [sciencedirect.com]
The data is out there. There's certainly things we still don't fully understand yet and are actively researching but all this "mysterious hand wavy woo who knows dark pseudo esoteric" nonsense that always gets reported has always instigated a Neil DeGrasse-Tyson eye roll from me.
(Score: 2) by Muad'Dave on Tuesday November 24 2020, @02:06PM
I came here to say this. Such hubris back then to call them 'junk' when they had no clue that they were actually there for a reason.
(Score: 2) by Mojibake Tengu on Tuesday November 24 2020, @12:04PM (1 child)
Never seen padding in code/data/filesystem for proper periodic alignment?
The edge of 太玄 cannot be defined, for it is beyond every aspect of design
(Score: 0) by Anonymous Coward on Tuesday November 24 2020, @07:12PM
Maybe Mother Nature is paid per line of code?
(Score: 1, Insightful) by Anonymous Coward on Tuesday November 24 2020, @07:44PM (1 child)
The "extra" DNA is encoded alien porn images inserted into Earth life when it was created and seeded here by the aliens. All life on Earth is an alien's porn backup archive.
Hmm, I may have just started a new religion...
(Score: 0) by Anonymous Coward on Tuesday November 24 2020, @10:06PM
All the better if you indoctrinate your female disciples with porn and DNA worship. Another soupy DNA specimen coming right up!
(Score: 0) by Anonymous Coward on Tuesday November 24 2020, @08:11PM
"Padding" is a good analogy for introns, as far as i know...
But i think that current understanding of mathematics/logic and computation is... not enough to even begin to describe the glorious deep dark waters of co-evolving systems of systems.
Present day humans are too stupid to design their machines like that, so they just call all these nameless design principles that cells used to terraform worlds successfully - "evolution".
The human thingies also like for things to have function, for there to be a boundary between parts, for parts being distinguishable, for there being things at all...
They're used to imaginary, socially-invented stuff like beginnings and ends, durations and distances...
Is it a surprise that self-created processes without unchanging form or function or even separate identity from the whole (like life or Boltzmann brains) puzzle them?