A Species of Lungfish Claims Title of World's Largest Animal Genome (science.org) 20
sciencehabit shares a report from Science Magazine: A species of lungfish found in South America has claimed the title of the animal with the biggest genome sequenced so far. The DNA of Lepidosiren paradoxa comprises a staggering 91 billion chemical letters or "bases," 30 times as many as the human genome, researchers report today in Nature. However, those 91 billion bases of DNA only contain about the same number of genes that humans have -- roughly 20,000 -- with the rest consisting of noncoding, perhaps even "junk" DNA. By comparing this genome with those of other lungfishes, the researchers determined that L. paradoxa adds the equivalent of a human genome to its DNA every 10 million years.
So what you are saying ... (Score:3, Interesting)
... is that code bloat [wikipedia.org] is natural.
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It's a kind of stenographic note instead of putting a big black monolith for us to find on the Moon.
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Stenographic wouldn't need 90 billion bases. Maybe steganographic.
oops my bad (Score:2)
The 󠁯future 󠁯belongs 󠁰to 󠁳those 󠀠who 󠁭believe 󠁹in 󠀠the 󠁢beauty 󠁡of 󠁤their dreams. -Eleanor Roosevelt
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An important discovery, although less celebrated, is that more than half the human genome is derived from mobile pieces of DNA called transposable elements (colloquially known as “jumping genes”). Transposable elements were discovered in corn by Barbara McClintock more than 60 years ago,5 but few people would have guessed that the aggregate length of these sequences exceeds that of protein-coding exons by a factor greater than 40 (Fig. 1).1 Although the bulk of transposable element–derived DNAs are remnants of their former selves and cannot transpose, some retain the ability to mobilize.11,12 The insertion of mobile elements into the DNA of gametes or the early embryo can disrupt genes, leading to sporadic cases of disease,13 and their insertion into the DNA of somatic cells may contribute to cancers and neuropsychiatric disease.
In the late 1980s, Kazazian and colleagues discovered that LINE-1 elements can cause disease.
Retroviruses and HERVs “jump” by means of a rather complicated mechanism. First, their viral RNA is reverse-transcribed into DNA within a virus like particle in the cytoplasm of the cell. The full-length viral DNA is then transported into the nucleus and integrated into the genome.8,30 In contrast, LINE-1 retrotransposition (also known as target-site–primed reverse transcription) occurs through a somewhat simpler process (Fig. 3).31,32 Active LINE-1 elements contain two open reading frames, ORF1 and ORF2; an endonuclease encoded by ORF2 nicks one strand of DNA at the site of the new integration.39 The reverse-transcriptase enzyme (also encoded by LINE-1 ORF2) then copies LINE-1 RNA, beginning at the chromosomal integration site. It is not yet clear how the second strand of LINE-1 DNA is made, although it probably involves the LINE-1 reverse transcriptase
LINE-1 retrotransposition occurs in various cancers.73–83 Studies have shown that somatic LINE-1 insertions primarily occur in epithelial cancers (e.g., those in the gastrointestinal tract); that the number of LINE-1 insertions varies among epithelial tumors (with some having >50 somatic insertions and others having none); that certain clonal somatic insertions in esophageal and gastric tumors are present at low frequencies in normal tissue, suggesting that a normal cell harboring a somatic LINE-1 insertion may be clonally expanded in the cancer https://www.ncbi.nlm.nih.gov/p... [nih.gov]
We have a lot of 'junk' dna https://www.ncbi.nlm.nih.gov/p... [nih.gov]
Is the driver pollution?
L1 and Alu elements are among the most active retroposons (mobile elements) in the human genome. Several human diseases, including certain forms of breast cancer and leukemia, are associated with L1 and Alu insertions in functionally important areas of the genome. We present data demonstrating that environmental pollutants, such as heavy metals, can stimulate L1 retrotransposition in a tissue culture system using two different types of assays.
Reproducible results showed that mercury (HgS), cadmium (CdS), and nickel (NiO) increase the activity of L1 by an average of three (3) fold p 0.001. This observation is the first to link several carcinogenic agents with the increased retrotransposition activity of L1 as an alternate mechanism of generating genomic instability contributing to the process of carcinogenesis.
https://www.mdpi.com/1660-4601/2/1/14
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I think better term for junk DNA is "dead code" as it doesn't have a functional purpose (or so is assumed). Code bloat is more about using 5 genes and 4 extra proteins just to make one protein when you could just use one gene to make the target protein directly.
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So lots of retroviruses or mutations? (Score:2)
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Probably because the word "junk" is journalist for "clickbait"
It quite likely still serves a vital function, either as a contingency against environmental instability or as a control mechanism which sticks around to suppress specific, deliterious, mutations.
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Probably because the word "junk" is journalist for "clickbait"
It quite likely still serves a vital function, either as a contingency against environmental instability or as a control mechanism which sticks around to suppress specific, deliterious, mutations.
Or it's waiting to be activated [wikipedia.org] by environmental factors.
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Probably because the word "junk" is journalist for "clickbait"
No, it's a scientific term for DNA doesn't have a function [wikipedia.org].
It quite likely still serves a vital function, either as a contingency against environmental instability or as a control mechanism which sticks around to suppress specific, deliterious, mutations.
How is a bunch of extra non-coding DNA supposed to suppress mutations? I think you're misunderstanding a fairly fundamental point about evolution.
Evolution isn't some ruthless optimizer guaranteeing perfect efficiency.
It's a mathematical process by which beneficial mutations are more likely to propagate than harmful mutations. That's why serious genetic disorders on a dominant gene are rare (really harmful, hard to pass on) but recessive ones are mo
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Pot. Kettle
Unlike humans with their womb hack, and much like frogs, lungfish live in a fairly chaotic environment and therefore require contingencies for handling wildly fluctuating variables in the environment, pH/contaminants/etc.
Calling this "junk" ignores the important part played by the so called "junk".
But do keep schooling us. It's fascinating to see google spam masquerading as knowledge
Ok... so what's the mechanism by which junk DNA does this? Where's the publication or reputable website that talks about this? I'm not a biologist so it's possible that I'm missing some extra functions that junk DNA does, but from what I understand most biologists would be astonished if the majority of junk DNA was doing something useful.
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The purpose of junk DNA is to ensure that chromosomes bundle correctly inside the cell's nucleus. If you remove junk DNA you can end up with a mess in your cells, which will kill you.
https://www.lsi.umich.edu/news... [umich.edu]
Hyperbole (Score:2)
I talked with the fish, he said he didn't claim anything.
Comment removed (Score:3)
So a Lepidosiren paradoxa lungfish has 30 times... (Score:1)
I bet I could STILL kick its ass.