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?