Crosswords21 mins ago
Retro-Transponons. The Difference Generator?
Bar one article in Nature which by the way stopped me breathing when I considered that scientists now believe that only once, a billion or so years ago did a tiny creature now known as a mitochondria collide with a eukariote cell making the evolutionary path that led to us possible did I ever read anything more amazing than this.
At a certain point in the embryonic development of the cells that go on to form the human brain our ancient molecular defences against what we consider to be one of the most primitive forms of life the retro-transposon appear to back off and let it go.
When they looked for evidence of this in other organs of the body they realised it was only in the brain that this happens.
It's a few years ago when I learned this. I just wanted an update. Is it one of the enigmatic phenomena that lends itself to outlandish speculative theories concerning the origins of individuality, creativity and our capacity for independent thought?
At a certain point in the embryonic development of the cells that go on to form the human brain our ancient molecular defences against what we consider to be one of the most primitive forms of life the retro-transposon appear to back off and let it go.
When they looked for evidence of this in other organs of the body they realised it was only in the brain that this happens.
It's a few years ago when I learned this. I just wanted an update. Is it one of the enigmatic phenomena that lends itself to outlandish speculative theories concerning the origins of individuality, creativity and our capacity for independent thought?
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In plain English, you appear to be suggesting that the brain is vulnerable to retroviruses for a short time, early in its development.
I am given to uderstand that the fully-formed brain lacks any and all immune cell activity because the "blood-brain barrier" is structured such tha macrophages cannot squeeze between cells, as they do in normal capillaries. Bacteria and even viruses cannot get through it either. However, I do not know what stage of embryo development the barrier reaches completion.
The deeper level of your question revolves around whether and how an embedded piece of DNA from a virus could influence anything, ranging from cell function to how cells 'wire themselves up', to more complex levels, like behaviour characteristics or nebulous things like personal preferences, personality and so on (higher level behaviours I would tend to say are multifactiorial and with a tendency to be in reaction to external stimuli and accumulated experience).
I am given to uderstand that the fully-formed brain lacks any and all immune cell activity because the "blood-brain barrier" is structured such tha macrophages cannot squeeze between cells, as they do in normal capillaries. Bacteria and even viruses cannot get through it either. However, I do not know what stage of embryo development the barrier reaches completion.
The deeper level of your question revolves around whether and how an embedded piece of DNA from a virus could influence anything, ranging from cell function to how cells 'wire themselves up', to more complex levels, like behaviour characteristics or nebulous things like personal preferences, personality and so on (higher level behaviours I would tend to say are multifactiorial and with a tendency to be in reaction to external stimuli and accumulated experience).
A transposon is not a virus. They are far more primitive than that. They are formally classified as 'Transposable Elements' or 'jumping genes' as they would be referred to in the popular press.
They survive, such as they are, by encorporating themselves into the genome of their host. As I understand it, it seems intra-nuclear molecular defence mechanisms have evolved to control them-proof reading etc. What is amazing was what I said; In the developing human brain they are allowed to let rip!
Does it mean that every neuron has an individual identity corresponding to -who knows. Let the speculations begin!
They survive, such as they are, by encorporating themselves into the genome of their host. As I understand it, it seems intra-nuclear molecular defence mechanisms have evolved to control them-proof reading etc. What is amazing was what I said; In the developing human brain they are allowed to let rip!
Does it mean that every neuron has an individual identity corresponding to -who knows. Let the speculations begin!
Actually, Colm //our capacity for independent thought// is worth a thread in its own right. It is as difficult to generate thoughts without prior input of knowledge of the world as it is to create a novel object without the basic building blocks (try to resist thinking of Lego, at this point. I failed. (grin))
No sooner does one come up with a supposedly original thought, if you google it, it will probably be out there. Just look at the way song titles you thought were too famous to re-use are being shamelessly appropriated by the youngest generation.
No sooner does one come up with a supposedly original thought, if you google it, it will probably be out there. Just look at the way song titles you thought were too famous to re-use are being shamelessly appropriated by the youngest generation.
Thanks for the correction, Colm. It sounds reminiscent of the 'randomiser' portion of the genes which code for antibodies.
If the transposon has no actual gene product, then it is hard to see how it would have any outward effect other than to assure its own replication and continuance. In extremis maybe it could jam up the works of transcribing the genes either side of it. In other words it can have an impact on the cell without actually coding for a peptide product.
If the transposon has no actual gene product, then it is hard to see how it would have any outward effect other than to assure its own replication and continuance. In extremis maybe it could jam up the works of transcribing the genes either side of it. In other words it can have an impact on the cell without actually coding for a peptide product.
I'm out of my field now. I'm just a country vet that loves science (not just that branch of it that I do every day).
The thing about transposons as I understand them is that they are capable of spontaneously disrupting the ordering in which chromosomal genes are transcripted such that some will be non-functional and others hypothetically could be promoted.
I would love to hear more about this. Could our much vaunted intelligence be overplayed when our African breakout was 'just a stroke of luck' in terms of the interglacial period that has allowed us to flourish.
Humanity needs to finally understand itself if we are to survive. My granddaughter needs us all to try our best.
The thing about transposons as I understand them is that they are capable of spontaneously disrupting the ordering in which chromosomal genes are transcripted such that some will be non-functional and others hypothetically could be promoted.
I would love to hear more about this. Could our much vaunted intelligence be overplayed when our African breakout was 'just a stroke of luck' in terms of the interglacial period that has allowed us to flourish.
Humanity needs to finally understand itself if we are to survive. My granddaughter needs us all to try our best.
:-D @jno
DNA has so many levels of sophistication that TV dare not let loose on the general public that it is no wonder we end up with these creationist standpoints where the attitude is "how can all this sophistication emerge from the simple workings of non-sentient molecules?" It has taken decades for them to get as far as admitting that genes code for proteins and *nothing else*.
Not ability to play a musical instrument, not oratorical skill, not a golf swing and so on. Explaining how traits beyond skeleton, musculature, motor skills, coordination and raw mental capacity pass down the generations is impossible at the genetic level (see the (rejected) theory of Lamarckianism, for more details). The required thought-experiment would be "braniac deposits their newborn with a fovela family and returns, 18 or more years later, to collect their little genius".
Increasingly I view DNA as being like sheet music except that it is also capable of being the conductor of the orchestra, changing tempo, volume, expression, the mix of banks of instruments and so on. It is a symphony, rather than a flat piece of prose.
Better still, it's a music collection and the person deciding what tracks to play. It even responds to the presence of chemicals in its immediate environment. Elevated levels of ethanol? Crank up the dehydrogenase gene and signal nearby liver cells to do likewise. (Non liver cells, please ignore this message).
Hic!
DNA has so many levels of sophistication that TV dare not let loose on the general public that it is no wonder we end up with these creationist standpoints where the attitude is "how can all this sophistication emerge from the simple workings of non-sentient molecules?" It has taken decades for them to get as far as admitting that genes code for proteins and *nothing else*.
Not ability to play a musical instrument, not oratorical skill, not a golf swing and so on. Explaining how traits beyond skeleton, musculature, motor skills, coordination and raw mental capacity pass down the generations is impossible at the genetic level (see the (rejected) theory of Lamarckianism, for more details). The required thought-experiment would be "braniac deposits their newborn with a fovela family and returns, 18 or more years later, to collect their little genius".
Increasingly I view DNA as being like sheet music except that it is also capable of being the conductor of the orchestra, changing tempo, volume, expression, the mix of banks of instruments and so on. It is a symphony, rather than a flat piece of prose.
Better still, it's a music collection and the person deciding what tracks to play. It even responds to the presence of chemicals in its immediate environment. Elevated levels of ethanol? Crank up the dehydrogenase gene and signal nearby liver cells to do likewise. (Non liver cells, please ignore this message).
Hic!
Hypognosis //The deeper level of your question revolves around whether and how an embedded piece of DNA from a virus could influence anything,... //
It should be no surprise as it is becoming increasingly evident that a considerable part of our DNA comes to us from viral infections. Left to react in the survivors and their descendants over millions of generations these genes were incorporated into the code for complex structures.
Structures that include what is evidently viral DNA include the mammalian uterus.
It should be no surprise as it is becoming increasingly evident that a considerable part of our DNA comes to us from viral infections. Left to react in the survivors and their descendants over millions of generations these genes were incorporated into the code for complex structures.
Structures that include what is evidently viral DNA include the mammalian uterus.
Yes but retrotransposons are thought to be even more primitive than viral or chromosomal DNA. They are viewed as disruptive ancestors of the more organised DNA structures that enabled life-forms such as our selves to exist and reproduce.
As I understand it their DNA makes no direct contribution to the function of the cell but indirectly by randomly interfering with the sequence of codons that are the structure of genes they are capable of disrupting gene expression.
Their impact is normally curbed by the innate immune system that includes 'proof reading' error correcting genes.
It was simply breathtaking to learn that for some as yet unknown reason, during the development of the brain this protection is turned off, while continuing to be active in every other cell in the body according to the researchers.
There must be some kind of advantage gained from this unleashing of the 'jumping genes' but what could it be? 'Brain-specific genetic mosaicism' is proposed, suggesting perhaps that for our brains to do what they do every neuron has to be genetically distinct from every other. There are around 100 billion of them!
http://
As I understand it their DNA makes no direct contribution to the function of the cell but indirectly by randomly interfering with the sequence of codons that are the structure of genes they are capable of disrupting gene expression.
Their impact is normally curbed by the innate immune system that includes 'proof reading' error correcting genes.
It was simply breathtaking to learn that for some as yet unknown reason, during the development of the brain this protection is turned off, while continuing to be active in every other cell in the body according to the researchers.
There must be some kind of advantage gained from this unleashing of the 'jumping genes' but what could it be? 'Brain-specific genetic mosaicism' is proposed, suggesting perhaps that for our brains to do what they do every neuron has to be genetically distinct from every other. There are around 100 billion of them!
http://
They want £22 for the full-length article?
I think you can by Lewin's Genes (what numeral is it up to X, XI?) for around £15 (500+pages) and you're going to need it to understand the jargon and concepts.
You mentioned codons and that triggered my recall of the way some genes are extensively scattered and have to be spliced and reassembled before its product can be made. DNA can be like a fragmented hard-drive (but we didn't have the luxury of that analogy when I was at uni; home computing went mainstream later).
Speculation-wise, I suppose a random variation in the behaviour of neurons would be useful. When you are stuck on a problem, you have to "try" various strategies before you can learn what is the best solution. The act of trying things must require some degree of randomness to kickstart the mental processes, otherwise all individuals would try the exact same strategies in the exact same order because their brains were wired up in identical ways.
Which ain't so.
I think you can by Lewin's Genes (what numeral is it up to X, XI?) for around £15 (500+pages) and you're going to need it to understand the jargon and concepts.
You mentioned codons and that triggered my recall of the way some genes are extensively scattered and have to be spliced and reassembled before its product can be made. DNA can be like a fragmented hard-drive (but we didn't have the luxury of that analogy when I was at uni; home computing went mainstream later).
Speculation-wise, I suppose a random variation in the behaviour of neurons would be useful. When you are stuck on a problem, you have to "try" various strategies before you can learn what is the best solution. The act of trying things must require some degree of randomness to kickstart the mental processes, otherwise all individuals would try the exact same strategies in the exact same order because their brains were wired up in identical ways.
Which ain't so.
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