Turns out, they are even less like other eukaryote genomes:
A striking finding was that the genes in the genome tended to be organized in alternating unidirectional blocks. “That’s really, really different to what you see in other organisms,” says Octavio Salazar, a postdoc in Manuel Aranda’s group at KAUST and one of the lead authors of the study. The orientation of genes on a chromosome is usually random. In this case, however, genes were consistently oriented one way and then the other, with the boundaries between blocks showing up clearly in the chromatin interaction data.
This organization is also reflected in the three-dimensional structure of the genome, which the team inferred comprises rod-shaped chromosomes that fold into structural domains at the boundaries where gene blocks converge. Even more intriguingly, this structure appears to be dependent on transcriptional activity. When the researchers treated cells with a chemical that blocks gene transcription, the structural domains disappeared.
This unusual link is consistent with another strange fact about dinoflagellates — they have very few transcription factors in their genome and do not seem to respond to environmental changes by altering gene expression. They may use gene dosage to control expression and adapt to the environment by losing or gaining chromosomes or perhaps via epigenetic structural modifications. The researchers plan to explore all of these questions.
Octavio Salazar, “Coral symbionts have a genome like no other” at KAUST Discovery (April 29, 2021)
The paper is open access.
So how did all this originate randomly, different from what all the other life forms do — and still work?
See also: Dinoflagellate genome structure is unique. So, in other words, these plankton evolved (randomly, so we are told) a highly successful genome that’s entirely different from the type that most life forms have. Well, if you are skeptical of Darwinian claims that it all happened randomly but just once, how about (at least) twice?
” do not seem to respond to environmental changes by altering gene expression. ”
Note how epigenetics has become the default norm.
Lysenko wins.
Polistra, you seem to be well educated. I have an off topic question, perhaps you can help.
I am an engineer and don’t have a formal education in biology. I was always wondering, the DNA is a very long molecule, how the cell knows, where to look for the right DNA sequence during DNA transcription. I know that there are so called start/end codons, but this is not what i mean. Humans have approx. 20,000 genes, so how the cell know where to look for the particular gene in order to transcript it … in other words, how the cell finds the proper DNA sequence in this vast storage space ? I hope my question does not sound too silly, but i tried to google it, i could not find any answer. Perhaps you can navigate me … thank you.
Martin_r – I know you’re asking Polistra, but his answer in 1 demonstrates he doesn’t understand the subject (in case you’re wondering, yes I am a biologist).
Anyway, the simple answer to your question is – it’s complicated. Genes don’t just have start and end codons, they also have promoters – DNA sequences near the start codon that say ” a gene starts here”, and allow RNA polymerase to bind to them to start transcription. There’s more on Wikipedia.
Incidentally, I can recommend this book if you want a basic introduction to genetics.
BobOH, anybody can answer my question … however, this is not what i have asked. Perhaps my question is not clear enough (English is not my first language).
Like i mentioned above, i am aware of start/stop codons, i heard of promoters, but does promoters answer my question ? How the cell knows where to look for the particular gene which needs to be transcribed ? I can imagine, that there are genes that are transcribed all the time… the same genes again and again… but, for example under some stress, a particular gene needs to be transcribe which is usually turned off. How the cell knows, where to look for this particular gene DNA sequence ? Start/stop-codon only tells where to start /stop the DNA transcription of the particular gene. But how the cell knows the exact position in whole DNA molecule of this particular gene?
BobOH, anybody can answer my question … Perhaps my question is not clear enough (English is not my first language). Let me clarify:
Like i mentioned above, i am aware of start/stop codons, i heard of promoters, but do promoters answer my question ? How the cell knows where to look for the particular gene which needs to be transcribed ? I can imagine, that there are genes that are transcribed all the time… the same genes again and again… but, for example under some stress, a particular gene needs to be transcribed. How the cell knows, where to look for this particular gene DNA sequence ? Start/stop-codon only tells where to start /stop the DNA transcription of the particular gene. But how the cell knows the exact position on chromosome(s) of this particular gene?
Martin_r – promoters are more than just start/stop codons. They are where the RNA polymerase binds. There are also sequences around them that are specific to the gene, and other transcription factors can bind to them. This provides the basic mechanism – there is a lot more (of course).
Are you asking about how genes are regulated?
Way to totally miss the point, Bob O’H. How did blind and mindless processes cobble all of that together, Bob?
Martin_r you asked Bob, “But how (does) the cell know the exact position on (the) chromosome(s) of (any) particular gene?”
Contrary to what Bob implied, Bob does not know, nor does anyone else know, exactly how the cell ‘knows’ the exact position of any particular gene on the chromosome(s).
In fact, “cell-intelligence’ is, in direct contradiction to a central assumption of Darwinian evolution, “turning our ideas of genetic causation inside out.”
Stephen Talbott has an excellent article detailing just how amazing it is for the cell to ‘know’ where a gene is.
Talbott states, “You may recall from my earlier article, “Getting Over the Code Delusion” (Talbott 2010), that packing DNA into a typical cell nucleus is like packing about 24 miles of very thin, double-stranded string into a tennis ball, with the string cut up (in the normal human case) into 46 pieces, corresponding to our 46 chromosomes.
To locate a protein-coding gene of typical size within all that DNA is like homing in on a one-half-inch stretch within those 24 miles.
BobOH, no, you still dont get it.
I know about stop/start codons and promoters. What i dont understand is, how the cell knows the location/position on chromosomes of particular gene … chromosomes are pretty huge storage space, how the cell knows where to look …
Let me quote the following
“Geneticists use maps to describe the location of a particular gene on a chromosome. One type of map uses the cytogenetic location to describe a gene’s position. “
Does the cell use a map? This is what i meant…
BobOH,
meanwhile BA77 posted the following:
Talbott states, “You may recall from my earlier article, “Getting Over the Code Delusion” (Talbott 2010), that packing DNA into a typical cell nucleus is like packing about 24 miles of very thin, double-stranded string into a tennis ball, with the string cut up (in the normal human case) into 46 pieces, corresponding to our 46 chromosomes.
To locate a protein-coding gene of typical size within all that DNA is like homing in on a one-half-inch stretch within those 24 miles.
This is exactly what i meant…. How does the cell know, what is the position of that ‘half-inch stretch’ within those 24 miles… I understand, that you Darwinists never think about these things, because in your fantasy world, you don’t have to … in your fantasy world works everything flawlessly, no thinking needed, no design needed, just chance and lots of lucky accidents …
PS: BA77 thank you for your post, actually, i am not surprised that nobody knows… this is what i have expected … but this is pretty serious question if Darwinists want to rule out design…
Martin_r – here we were having a perfectly nice conversation, and i was trying to help you understand better. But then you write this:
You are asking an interesting question, so I would have been prepared to dig deeper (e.g. I did see a comment about how promoters tended to be physically located on the outside of the chromosome), but now I don’t see why I should bother.
Bob O’H… i apologize, you are right. From my end, it was not necessary. I am just angry when i see all this, and when a Darwinist (not you) calls me ‘you stupid creationist’. I apologize. Any rational person (the more a scientist) should see a creation/design behind these things – to believe anything else is like to believe in miracles…to say “we don’t know yet / god of the gaps” is not enough. Anyway, when you could look deeper into it, that would be great. I won’t check for your update on this in this post, but you can contact me anytime using my contact details at my blog. Just click my UD nickname, it will redirect you to my blog where you will find my contact details/form. Thanks.
PS: i doubt you will find any answer. Because, it is like with DNA proofreading & repair subject. I tried to learn how something like that can evolve, i did not find a thing, i even contacted some geneticists in DNA repair research, NOBODY KNOWS (they also said, that i am asking interesting questions)
Nobody will ever find an answer how these things ever evolve. Because this can’t be evolved. It only can be created/designed by an intelligent agency. The good thing is, that you finally understand my question on gene position.