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scientist have sequenced the largest known animal genome — and it ’s 30 times full-grown than the human genome .
The genome belong to the South American lungfish ( Lepidosiren paradoxa ) , a primeval , air - breathingfishthat " hops " onto ground from the water using weird , limb - corresponding fins . The Pisces ’s DNA code expanded dramatically over the retiring 100 million years of evolutionary chronicle , racking up the combining weight of one human genome every 10 million years , investigator found .
The South American lungfish has the largest genome out of any animal tested.
The findings could shed brightness level on how genomes expand across the tree of life story .
Lungfish are sometimes visit " living fossil " because they have survive for century of million of years . They are think to be themost closely touch on species to the first tetrapod , theancestor of all vertebrates . These antecedent belike sprouted limbs and crawled onto land around 370 million years ago during the Devonian menstruum , ( 419 million to 359 million year ago),Science reported .
Previously , scientist sequenced the genome of other lungfish species , including the Australian lungfish ( Neoceratodus forsteri ) . Next on the listing were the African lungfish ( Protopterus annectens ) and ( L. paradoxa ) , whose genome is twice the size of its air - breathing relatives from other continents .
The squad described the South American lungfish genome Aug. 14 in the journalNature . It turns out , these atmosphere - breathing Pisces bear a walloping 91 billion root pairs , or letters , of desoxyribonucleic acid in their genome .
That ’s enough letter to take 100,000 volume . Yet only 20,000 genes actually code for proteins , meaning the rest may be mostly junk , the work plant . More than 90 % of the genetic material was made oftransposable elements(TEs ) , or highly repetitive " stick out " gene that were copied from elsewhere in the genome .
The scientists also determine whylungfish genomes expanded so precipitously over the past 100 million years . It call on out that the South American lungfish had key genes that crush TEs , which organism may have inherited from viruses long ago .
Carrying around so much genetic luggage can be tough .
" This must be a huge monetary value to the animal,“Axel Meyer , an evolutionary life scientist at the University of Konstanz , told Science Magazine . " All but one of this lungfish ’s 19 chromosomes is the size of the entire human genome , so it shoot a lot of energy to imitate that desoxyribonucleic acid . And the nucleus and cadre that encase it must be bigger . "
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On the other deal , the extra deoxyribonucleic acid can come in handy when animals call for to accommodate to changing environments , Meyer aver . That ’s because TEs can ramp up or down the expression of gene , allowing for more speedy adaptation .
While the lungfish may defy the disc for the turgid roll in the hay beast genome , it does n’t contain the largest genome overall . That honor belong to aweird fern that harbors 160 billion varsity letter in its genome — more than 50 times the missive found in human cells .
And this fussy lungfish may not be the record holder for the large animal genome for long . The marbled lungfish ( Protopterus aethiopicus ) may have a genome 50 % bigger than this one , Claus - Peter Stelzer , an evolutionary biologist at the University of Innsbruck in Austria who was not involved in the subject area , tell Science . Of naturally , the coinage will need its genome sequence before that can be confirmed .
