Oct 20, 2021 06:47 PM
So-called junk DNA plays critical role in mammalian development
https://www.sciencedaily.com/releases/20...140504.htm
INTRO: Nearly half of our DNA has been written off as junk, the discards of evolution: sidelined or broken genes, viruses that got stuck in our genome and were dismembered or silenced, none of it relevant to the human organism or human evolution.
But research over the last decade has shown that some of this genetic "dark matter" does have a function, primarily in regulating the expression of host genes -- a mere 2% of our total genome -- that code for proteins. Biologists continue to debate, however, whether these regulatory sequences of DNA play essential or detrimental roles in the body or are merely incidental, an accident that the organism can live without.
A new study led by researchers at University of California, Berkeley, and Washington University explored the function of one component of this junk DNA, transposons, which are selfish DNA sequences able to invade their host genome.
The study shows that at least one family of transposons -- ancient viruses that have invaded our genome by the millions -- plays a critical role in viability in the mouse, and perhaps in all mammals. When the researchers knocked out a specific transposon in mice, half their mouse pups died before birth.
This is the first example of a piece of "junk DNA" being critical to survival in mammals... (MORE)
Humans did not cause woolly mammoths to go extinct -- climate change did
https://www.eurekalert.org/news-releases/932061
EXCERPTS: For five million years, woolly mammoths roamed the earth until they vanished for good nearly 4,000 years ago – and scientists have finally proved why [...] the hotly debated question about why mammoths went extinct has been answered - geneticists analysed ancient environmental DNA and proved it was because when the icebergs melted, it became far too wet for the giant animals to survive because their food source – vegetation – was practically wiped out.
The 10-year research project, published in Nature today (20 October 2021), was led by Professor Eske Willerslev, a Fellow of St John’s College, University of Cambridge, and director of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen.
The team used DNA shotgun sequencing to analyse environmental plant and animal remains – including urine, faeces and skin cells – taken from soil samples painstakingly collected over a period of 20 years from sites in the Arctic where mammoth remains were found. The advanced new technology means scientists no longer have to rely on DNA samples from bones or teeth to gather enough genetic material to recreate a profile of ancient DNA. The same technique has been used during the pandemic to test the sewage of human populations to detect, track and analyse Covid-19.
Professor Willerslev said: “Scientists have argued for 100 years about why mammoths went extinct. Humans have been blamed because the animals had survived for millions of years without climate change killing them off before, but when they lived alongside humans they didn’t last long and we were accused of hunting them to death.
“We have finally been able to prove was that it was not just the climate changing that was the problem, but the speed of it that was the final nail in the coffin – they were not able to adapt quickly enough when the landscape dramatically transformed and their food became scarce.
“As the climate warmed up, trees and wetland plants took over and replaced the mammoth’s grassland habitats. And we should remember that there were a lot of animals around that were easier to hunt than a giant woolly mammoth – they could grow to the height of a double decker bus!” (MORE - missing details)
https://www.sciencedaily.com/releases/20...140504.htm
INTRO: Nearly half of our DNA has been written off as junk, the discards of evolution: sidelined or broken genes, viruses that got stuck in our genome and were dismembered or silenced, none of it relevant to the human organism or human evolution.
But research over the last decade has shown that some of this genetic "dark matter" does have a function, primarily in regulating the expression of host genes -- a mere 2% of our total genome -- that code for proteins. Biologists continue to debate, however, whether these regulatory sequences of DNA play essential or detrimental roles in the body or are merely incidental, an accident that the organism can live without.
A new study led by researchers at University of California, Berkeley, and Washington University explored the function of one component of this junk DNA, transposons, which are selfish DNA sequences able to invade their host genome.
The study shows that at least one family of transposons -- ancient viruses that have invaded our genome by the millions -- plays a critical role in viability in the mouse, and perhaps in all mammals. When the researchers knocked out a specific transposon in mice, half their mouse pups died before birth.
This is the first example of a piece of "junk DNA" being critical to survival in mammals... (MORE)
Humans did not cause woolly mammoths to go extinct -- climate change did
https://www.eurekalert.org/news-releases/932061
EXCERPTS: For five million years, woolly mammoths roamed the earth until they vanished for good nearly 4,000 years ago – and scientists have finally proved why [...] the hotly debated question about why mammoths went extinct has been answered - geneticists analysed ancient environmental DNA and proved it was because when the icebergs melted, it became far too wet for the giant animals to survive because their food source – vegetation – was practically wiped out.
The 10-year research project, published in Nature today (20 October 2021), was led by Professor Eske Willerslev, a Fellow of St John’s College, University of Cambridge, and director of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen.
The team used DNA shotgun sequencing to analyse environmental plant and animal remains – including urine, faeces and skin cells – taken from soil samples painstakingly collected over a period of 20 years from sites in the Arctic where mammoth remains were found. The advanced new technology means scientists no longer have to rely on DNA samples from bones or teeth to gather enough genetic material to recreate a profile of ancient DNA. The same technique has been used during the pandemic to test the sewage of human populations to detect, track and analyse Covid-19.
Professor Willerslev said: “Scientists have argued for 100 years about why mammoths went extinct. Humans have been blamed because the animals had survived for millions of years without climate change killing them off before, but when they lived alongside humans they didn’t last long and we were accused of hunting them to death.
“We have finally been able to prove was that it was not just the climate changing that was the problem, but the speed of it that was the final nail in the coffin – they were not able to adapt quickly enough when the landscape dramatically transformed and their food became scarce.
“As the climate warmed up, trees and wetland plants took over and replaced the mammoth’s grassland habitats. And we should remember that there were a lot of animals around that were easier to hunt than a giant woolly mammoth – they could grow to the height of a double decker bus!” (MORE - missing details)