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Genetic changes that crop up in an organism's DNA may not be completely random, new research suggests. That would upend one of the key assumptions of the theory of evolution.
Researchers studying the genetic mutations in a common roadside weed, thale cress (Arabidopsis thaliana), have discovered that the plant can shield the most "essential" genes in its DNA from the changes, while leaving other sections of its genome to build up more alterations.
"I was totally surprised by the non-random mutations we discovered," lead author Grey Monroe, a plant scientist at the University of California, Davis, told Live Science. "Ever since high-school biology, I have been told that mutations are random."
"DNA is a fragile molecule; on average, the DNA in a single cell is damaged between 1,000 and 1 million times every day," Monroe said. "DNA also has to be copied each time a cell divides, which can introduce copying errors."
Luckily for humans and all other organisms, our cells can counteract a lot of this damage. "Our cells are working constantly to correct DNA and have evolved complex molecular machines, DNA repair proteins, to search for mistakes and make repairs," Monroe said.
The new finding does not disprove or discredit the theory of evolution, and the researchers said randomness still plays a big role in mutations. But the study does show that these genetic alterations are more complex than scientists previously believed.
The non-random pattern in mutations between gene and non-gene regions of DNA suggests that there is a defensive mechanism in place to prevent potentially disastrous mutations.
"In genes coding for proteins essential for survival and reproduction, mutations are most likely to have harmful effects, potentially causing disease and even death," Monroe said. "Our results show that genes, and essential genes in particular, experience a lower mutation rate than non-gene regions in Arabidopsis. The result is that offspring have a lower chance of inheriting a harmful mutation."
Researchers found that to protect themselves, essential genes send out special signals to DNA repair proteins. This signaling is not done by the DNA itself but by histones, specialized proteins DNA wraps around to make up chromosomes.
"Based on the result of our study, we found that gene regions, especially for the most biologically essential genes, are wrapped around histones with particular chemical marks," Monroe said. "We think these chemical marks are acting as molecular signals to promote DNA repair in these regions."
The idea of histones having unique chemical markers is not new, Monroe said. Previous studies into mutations in cancer patients have also found that these chemical markers can affect whether DNA repair proteins fix mutations properly, he added.
However, this is the first time these chemical markers have been shown to influence genome-wide mutation patterns and, as a result, evolution by natural selection.
However, more research into animal genomes is needed before researchers can tell if the same non-random mutations occur in humans. "Our discoveries were made in plants and do not give rise to new treatments," Monroe said, "but they change our fundamental understanding of mutation and inspire many new research directions."
originally posted by: TzarChasm
From the attached article:
The non-random pattern in mutations between gene and non-gene regions of DNA suggests that there is a defensive mechanism in place to prevent potentially disastrous mutations.
"In genes coding for proteins essential for survival and reproduction, mutations are most likely to have harmful effects, potentially causing disease and even death," Monroe said. "Our results show that genes, and essential genes in particular, experience a lower mutation rate than non-gene regions in Arabidopsis. The result is that offspring have a lower chance of inheriting a harmful mutation."
Researchers found that to protect themselves, essential genes send out special signals to DNA repair proteins. This signaling is not done by the DNA itself but by histones, specialized proteins DNA wraps around to make up chromosomes.
"Based on the result of our study, we found that gene regions, especially for the most biologically essential genes, are wrapped around histones with particular chemical marks," Monroe said. "We think these chemical marks are acting as molecular signals to promote DNA repair in these regions."
The idea of histones having unique chemical markers is not new, Monroe said. Previous studies into mutations in cancer patients have also found that these chemical markers can affect whether DNA repair proteins fix mutations properly, he added.
However, this is the first time these chemical markers have been shown to influence genome-wide mutation patterns and, as a result, evolution by natural selection.
However, more research into animal genomes is needed before researchers can tell if the same non-random mutations occur in humans. "Our discoveries were made in plants and do not give rise to new treatments," Monroe said, "but they change our fundamental understanding of mutation and inspire many new research directions."
Don't you think that bolded text might have been useful to include in your title? And how do you know the not entirely random mutation didn't originally manifest as a random but helpful mutation?
originally posted by: TzarChasm
a reply to: neoholographic
Environment drives adaptations, not mutations. Mutations are largely incidental whether they assist or don't assist.
Explain how the environment causes changes in the genome at the exact point where the organism needs it to survive?
The fact is, this is fiction but to be fair to Darwin he lacked the knowledge we have today. The people who still believe this fantasy are doing so to support their belief system.
When we look at the fossil record and the genome, we see no evidence that random mutations are behind adaptations in any way. We see a one to one correspondence. The organism needs x traits to survive in an environment and x traits evolve.
If this isn't the case, what's natural selection selecting???
Show me evidence that mutations are controlled but still VERY random. That's just nonsense.
originally posted by: TzarChasm
a reply to: neoholographic
Environment drives adaptations, not mutations. Mutations are largely incidental whether they assist or don't assist.
Did you even watch the video?
Natural selection is blind and random