'Useless Specks of Dust' Turn Out To Be Building Blocks of All Vertebrate Genomes (sciencealert.com) 30
An anonymous reader quotes a report from ScienceAlert: Originally, they were thought to be just specks of dust on a microscope slide. Now, a new study suggests that microchromosomes -- a type of tiny chromosome found in birds and reptiles -- have a longer history, and a bigger role to play in mammals than we ever suspected. By lining up the DNA sequence of microchromosomes across many different species, researchers have been able to show the consistency of these DNA molecules across bird and reptile families, a consistency that stretches back hundreds of millions of years. What's more, the team found that these bits of genetic code have been scrambled and placed on larger chromosomes in marsupial and placental mammals, including humans. In other words, the human genome isn't quite as 'normal' as previously supposed.
By tracing these microchromosomes back to the ancient Amphioxus, the scientists were able to establish genetic links to all of its descendants. These tiny 'specks of dust' are actually important building blocks for vertebrates, not just abnormal extras. It seems that most mammals have absorbed and jumbled up their microchromosomes as they've evolved, making them seem like normal pieces of DNA. The exception is the platypus, which has several chromosome sections line up with microchromosomes, suggesting that this method may well have acted as a 'stepping stone' for other mammals in this regard, according to the researchers. A tree chart outlining the presence of similar DNA in snakes, lizards, birds, crocodiles, and mammals. The study also revealed that as well as being similar across numerous species, the microchromosomes were also located in the same place inside cells. "It's not clear whether there's an evolutionary benefit to coding DNA in larger chromosomes or in microchromosomes, and the findings outlined in this paper might help scientists put that particular debate to rest -- although a lot of questions remain," adds ScienceAlert. "The study suggests that the large chromosome approach that has evolved in mammals isn't actually the normal state, and might be a disadvantage: genes are packed together much more tightly in microchromosomes, for example."
The findings have been published in the journal PNAS.
By tracing these microchromosomes back to the ancient Amphioxus, the scientists were able to establish genetic links to all of its descendants. These tiny 'specks of dust' are actually important building blocks for vertebrates, not just abnormal extras. It seems that most mammals have absorbed and jumbled up their microchromosomes as they've evolved, making them seem like normal pieces of DNA. The exception is the platypus, which has several chromosome sections line up with microchromosomes, suggesting that this method may well have acted as a 'stepping stone' for other mammals in this regard, according to the researchers. A tree chart outlining the presence of similar DNA in snakes, lizards, birds, crocodiles, and mammals. The study also revealed that as well as being similar across numerous species, the microchromosomes were also located in the same place inside cells. "It's not clear whether there's an evolutionary benefit to coding DNA in larger chromosomes or in microchromosomes, and the findings outlined in this paper might help scientists put that particular debate to rest -- although a lot of questions remain," adds ScienceAlert. "The study suggests that the large chromosome approach that has evolved in mammals isn't actually the normal state, and might be a disadvantage: genes are packed together much more tightly in microchromosomes, for example."
The findings have been published in the journal PNAS.
And we're all made of stardust. (Score:5, Funny)
And of course the platypus stands as an exception.
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But not the Echidna, so...?
Impossible (Score:1)
Everyone knows God made people and animals in their present form, only 6000 or so short years ago. The Bible says so!!
HAHAHAHAHAAHAHAAH! Just kidding.
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Yeah. You can read about the microchromosomes in 2 Leviticus 17:3-5. Turns out Moses was a big biologist fan.
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The correct way to bring sacrifice and offerings?
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No you got confused, you might have looked in 1 Leviticus. The reference is to its sequel, 2 Leviticus. It was a transitional time for Moses.
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My bad. I didn't know there was a sequel. Then again, I don't keep up with this stuff; stopped watching "Fast and Furious" after "Tokyo Drift".
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Re:Impossible (Score:4, Funny)
I personally knew (yes, past tense for a reason) one person that started going to church in his twenties and literally you could watch the actual scientific knowledge he had carried his whole life dropping out of his head. One day he showed up and started lecturing our little group of buds about how the dinosaurs were planted by god to test our faith and I finally just had to leave. Haven't seen him since.
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And the Hebrew "days" [wikipedia.org] of creation could more easily be interpreted as something like eras rather than 24 hour periods
My grandfather was a conservative protestant pastor who believed the Bible was literal truth, and even he didn't believe in a young earth.
People often believe religious things they are told at an early age that have no basis in their purported religious faith.
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My grandfather was a conservative protestant pastor who believed the Bible was literal truth
There's no "the bible" despite what it says on some of their covers. Which Bible did he think was literal?/snark
Re: Impossible (Score:2)
The Bible was written by a bunch of religious people (aka cultists)
Evolutionary Tradeoffs (Score:5, Insightful)
On the other hand, having smaller chromosomes means that if something does go wrong, there are potentially fewer genes affected by it so assuming the affected genes aren't super dosage sensitive, the resulting cells are more likely to be viable overall.
Evolutionary biology is always fascinating!
The closer we look... (Score:5, Interesting)
... the more complicated the machinery of life is revealed to be. Perhaps if designed from scratch there would be more efficient ways to achieve some of the same things (eg having blood vessels in front of the retina in mammals is definately suboptimal), but you can't fault evolution for some stunningly exquisite solutions to various problems.
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There are levels of complexity we have barely explored yet. For example the entire structure of the cell represents information that is not codes in DNA or RNA. To makes a Golgi Apparatus, you need a Golgi Apparatus as a template. They do not arise spontaneously through DNA or RNA directed protein synthesis, Most or all lipid structures in the cell are like that.
Also intracellular processes involve long range signalling between apparently unrelated parts of the cells. The inability to tie most observable c
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Certainly the basic structure of cells relies on the laws of physics for their shape rather than anything coded in DNA. Lipids will naturally form spheres in water , nothing more required.
Re: The closer we look... (Score:3)
Keep digging and we're going to find the biological equivalent of the gzip library in there.
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Keep digging and we're going to find the biological equivalent of the gzip library in there.
Inevitably. After all, we've already found the biological equivalent of systemd. We call it cancer.
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Certainly the basic structure of cells relies on the laws of physics for their shape rather than anything coded in DNA. Lipids will naturally form spheres in water , nothing more required.
This claim is extremely similar to observing the formation of nucleotides in reducing atmospheres (work done 70 years ago) and then shouting "SEE LIFE! IT'S ALL SO EASY!".
The lipid membranes in cells are very complex structures of many different types.
I even provided a specific example for the slightly educated "know if alls" (like yourself) of one such structure - the Golgi apparatus (or body) which all of human science cannot replicate from scratch - unlike genomes of moderate size which we can now. Golgi
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"But go back to your stunning ignorance that "makes you an expert". Dunning-Kruger and all that"
Says the clown who can't even read the subtext - to whit that the FIRST cells were just basic lipid spheres inside which chemical reactions could occur, and then things got more complex from there. No one is suggesting - other than morons like you with your straw men - current cell membranes could arise from scratch as is. However their spherical structure is still down to physics , not genetics.
"slightly educate
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No competent creator would have ever made the human back. It is the a terrible design for its purpose and any engineering student who proposed it would be failed immediately.
No competent sane creator, yes. After taking a look at the world I’ve come to the conclusion something about that god ain’t quite right.
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No competent creator would have ever made the human back. It is the a terrible design for its purpose and any engineering student who proposed it would be failed immediately.
No competent sane creator, yes. After taking a look at the world I’ve come to the conclusion something about that god ain’t quite right.
Well, he was created in the image of humans. What do you expect.
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The Old Testament god is 100% a vindictive psychopath with paedopile and incestual tendencies (how did adam and eves children procreate etc). Probably says rather a lot about the violent society and the social mores of the people who wrote it.
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Think of them as code snippets (Score:2)
Look, you can get down into the weeds about different RNA and DNA variants, but what we originally thought were non-coding segments in DNA and RNA, turn out to be circRNA, mRNA, cisRNA, and many other small segments.
Some of those become virii (the RNA snippets) sometimes - think of COVID being caused by the rogue code snippet that infects a cell and replicates to harm it.
Some of those are part of your cells and are expressed during certain conditions. Your DNA contains multiple biochemical pathways to react