Genome complexity: Mavericks (Introduction)

by David Turell , Thursday, August 03, 2023, 18:16 (268 days ago) @ David Turell

In horizontal transfer:

https://www.quantamagazine.org/selfish-virus-like-dna-can-carry-genes-between-species-2...

"In new research published in Science, researchers have identified a unique class of genetic elements as the agents responsible for shuttling certain genes between multiple species of simple invertebrates called roundworms. A jump from one worm to another may not sound like much, but the worms in question diverged many millions of years ago, making them as different at the molecular level as fish and humans. The genetic elements, called Mavericks, have been detected in a wide range of animals, both invertebrates and vertebrates, and they display many features found in the genomes of viruses. Given those properties, researchers suspect that Mavericks — and similar elements, including some not yet discovered — may have mediated horizontal gene transfers throughout the history of life.

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"The complete picture of the genome revealed that the shuttled gene was embedded within a set of virus-like genes and a transposon, all of which Burga recognized as making up a Maverick.

"Mavericks are an ancient and fragmented class of jumping genes prevalent in the genomes of protists, fungi and animals, including humans. These massive mobile elements were initially assumed to be inactive, mutated relics of obsolete genes. But later research revealed that Mavericks can be reactivated, and that they can mediate horizontal gene transfer between some species of protists. Complete, intact Mavericks had never been characterized in a multicellular organism. The roundworms therefore presented a rare opportunity to study them.

"The Maverick in one of these roundworms, however, had an additional gene — one encoding a protein called a fusogen that enables a virus to fuse with a cell and transfer its genome into it. “Without fusogen, there would be no way for the virus to transfer its genes,” said Sonya Angeline Widen, a postdoctoral researcher in Burga’s laboratory and co-lead author with Bes of the new study. The discovery of the protein strongly suggested that this Maverick had the ability to form a virus-like particle and invade different cell types.

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"There is reason to believe that gene transfer using massive transposons may be more common in nature. Recent research led by Aaron Vogan of Uppsala University in Sweden has found massive mobile genetic elements called Starships that shuttle genes around in multiple species of fungi. Vogan suspects that Starships transferring key genes between fungal pathogens may have created the new strains that cause rolling epidemics of wheat diseases, such as tan spot (yellow leaf spot). (my bold)

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Researchers have come to appreciate that transposon-like genetic elements are “key drivers of genome evolution,” Zanders said. To really understand genomes, we must understand these “selfish elements” that can jump between species, she added. (my bold)

Comment: the bolds above are perhaps the way a designer would have managed recoding genomes.