More on Asgards:

https://www.livescience.com/asgard-archaea-striking-new-images

" Now, for the first time, scientists have grown a large enough quantity of these microbes in the lab to study their internal structure in detail,

"Researchers grew an organism called Lokiarchaeum ossiferum, which belongs to a group of microbes known as Asgard archaea, according to a new report, published Wednesday (Dec. 21) in the journal Nature(opens in new tab). Asgard archaea are thought by some scientists to be the closest evolutionary relatives of eukaryotes, cells that package their DNA in a protective bubble called a nucleus.

"On the evolutionary tree of life, Asgards often appear as a "sister" of eukaryotes or as their direct ancestor, Jan Löwe, leader of the Bacterial Cytoskeleton and other Molecular Machines research group at the Medical Research Council, wrote in a commentary about the new study. Asgards don't carry nuclei themselves, but they do contain a suite of genes and proteins that were once thought to be unique to eukaryotes. Researchers have a variety of theories as to how Asgards may have gained primitive nuclei and thus birthed the first complex cells, which later gave rise to plants, animals and humans.

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"Compared with other Asgards, L. ossiferum grows relatively fast, doubling its number of cells in seven to 14 days, Löwe noted. In comparison, P. syntrophicum replicates every 14 to 25 days. Note that the familiar bacterium Escherichia coli replicates every 20 minutes or so. (The slow growth of these archaea is one factor that makes them incredibly difficult to culture.)

"Gathered from mud in a canal on the coast of Piran, Slovenia, the L. ossiferum specimens have funky tentacles that extend from the body of each cell; odd bumps and bulges appear along the length of each appendage. These "surface protrusions" may support the idea that, at some point in evolutionary history, an Asgard grabbed a passing bacterium using similar extensions of its membrane and sucked the bacterium into its cell body, and this led to the development of the nucleus, Löwe wrote. The protrusions support the idea that such an interaction could have occurred, he explained.

"L. ossiferum also carries tiny, lollipop-like structures on its surface, which "look like they come from another planet," Thijs Ettema(opens in new tab), an environmental microbiologist at Wageningen University in the Netherlands who wasn't involved in the work, told Science. The microbe also contains structural filaments that closely resemble those seen in the cytoskeleton, or supporting scaffold, of eukaryotic cells, Löwe wrote.

More evidence:

https://www.science.org/content/article/strange-tentacled-microbe-may-resemble-ancestor...

"Additional evidence came earlier this year when Victoria Orphan, a geobiologist at the California Institute of Technology and her colleagues isolated enough of two other Asgard species—from rock collected from a hydrothermal vent in the Gulf of California—to sequence their complete genomes. The genes in those genomes bolstered the case that these genes really did arise in archaea. Moreover, the genomes harbored mobile pieces of DNA that contained bacterial genes involved in metabolism, suggesting these elements played a role in transferring genes among life’s major branches, Orphan and her colleagues reported on 13 January in Nature Microbiology.

"By comparing the proteins encoded by Asgard archaea and eukaryotes, researchers including Ettema, Baum, and Mohan Balasubramanian, a cellular microbiologist at the University of Warwick, recently connected the two domains in another way. They focused on the interacting protein complexes eukaryotic cells use to bend, cut up, and stitch together their membranes to link internal compartments. To that point, only two of those protein complexes had been found in archaea. But Asgard genomes contain instructions for making four of them, the team reported on 13 June in Nature Communications.

"After predicting the proteins’ structures, the group synthesized some of the molecules in the lab and showed they work similarly to the eukaryotic versions. To the scientists, that suggests this membrane-manipulating machinery predates the evolution of eukaryotes.

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"Its genome is larger and has more eukaryotic genes than the other cultured Asgard, and its DNA includes four genes for the protein actin, a key component of a eukaryotic cell’s internal skeleton, Schleper’s team reports. That skeleton extends throughout the cell and into the tentacles, and it varies from cell to cell, suggesting it’s capable of being rearranged. “We show that the ‘eukaryotic’ cytoskeleton—which is crucial for eukaryotes—was an invention within archaea, meaning it evolved before the emergence of the first eukaryotic cells,” Schleper explains.

“'This study further strengthens that our ancestor is archaea,” agrees Nobu’s collaborator, Hiroyuki Imachi, a microbiologist at the Japan Agency for Marine-Earth Science and Technology.

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"Some scientists now believe the most likely scenario for the emergence of eukaryotes, some 2 billion years after bacteria and archaea arose, is that an Asgard-like microbe enveloped an oxygen-using bacterium, turning it into an extra energy producer for its host. The archaea may have also acquired other bacteria to make the combined cell that comprise eukaryotes."

Comment: More evidence our ancestors are Archaea.

More research on how they release their DNA. Like all viruses they lack RNA and cannot replicate without it:

https://www.livescience.com/triggers-for-giant-virus-infection.html?utm_source=Selligen...

"Viruses, giant or otherwise, lack the machinery required to make copies of their DNA; the microbes are essentially just a coil of genetic material tucked inside an envelope, called a capsid. In order to survive, viruses must sneak inside a host cell, hijack the machinery within and set up a so-called viral factory to produce new viruses. Giant viruses have a special portal for this job: the stargate.

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"Since their initial discovery, giant viruses have been recovered from melting permafrost in Siberia, the depths of the Antarctic ocean and highly alkaline soda lakes, as well as less exotic environments, said Chantal Abergel, research director of the Structural and Genomic Information laboratory at the French National Centre for Scientific Research, who was not involved in the study. The viruses have mostly been found to infect amoebas and phytoplankton, but laboratory studies suggest that they can also infect animal cells, including rodent and human cells. However, "no direct link between GVs and human disease has yet been established," the authors noted.

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"For example, Parent and her coauthors studied several giant viruses that look like 20-sided dice, including the mimivirus, Antarctica virus, Samba virus and Tupanvirus. The structure and outer shells of these viruses "are very complex, as never seen before in the virosphere," Jônatas Abrahão, an associate professor of virology at the Universidade Federal de Minas Gerais in Brazil, told Live Science in an email. The stargate found on the surfaces of these viruses particularly fascinates scientists "due its beauty and symmetry," and the fact that no smaller viruses contain such a structure, said Abrahão, who was not involved in the study.

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"Before the stargate opens, giant viruses get "gobbled up by cells" in a process called phagocytosis, Parent said. While small viruses like influenza fuse their fatty membrane with that of the cell they're infecting, giant viruses enter cells by being swallowed whole, hard outer shell and all.

"Once inside, the giant viruses open their stargates and release their infectious "seed," Abergel said. "This is an entire structure that is downloaded from the plasmid," or circular ring of viral DNA, into the cytoplasm, or the water solution of proteins and salts that surrounds the organelles in eukaryotic cells. This process jumpstarts infection, she said."

Comment: The complex parts of the giant virus suggest it is a more evolved form of virus.

Do they have a metabolism?:

https://www.newscientist.com/article/2258107-viruses-have-been-shown-to-produce-their-o...

"A few giant viruses appear to generate their own energy, which viruses are not supposed to be able to do. Viruses usually consist of RNA or DNA wrapped in a protein coat or membrane, and rely on host cells to copy themselves. Giant viruses, first discovered in 2003, can be larger than bacterial cells and some have their own machinery for processes like copying DNA into RNA. Now researchers have found that some giant viruses known as pandoraviruses somehow generate an electrical voltage across their outer membrane. It takes energy to do this, which means these giant viruses must have a metabolism, but why they do so is still unclear. The finding will fuel an already fierce debate about whether giant viruses really are viruses, and if they are alive or not."

Comment: No real answers as yet