Figure 1: Cryo-electron tomography provided insight into the cellular structure of a newly cultured Asgard archaeon illustrated here. Remarkable are the extensive actin cytoskeleton filaments (orange) in the cell bodies and cell protrusions, as well as the unique cell envelope (blue).
© Margot Riggi, The Animation Lab, University of Utah
For example, one absurd dogma is that it is impossible for complexity to increase by an evolutionary process because this needs an increase in genetic information and the Second Law of Thermodynamics [sic] forbids it. It does nothing of the sort, of course, as anyone who understands the 2LOT and genetics will tell you. The Creationist cults work hard to ensure their dupes understand neither.
A casual and unintentional refutation of these absurdities was provided a few days ago by a team of researchers at Universität Wien and Eidgenössische Technische Hochschule (ETH) Zürich, who cultivated a special archaeon, a member of the Asgard archaea, and examined it in microscopic details, noting that it contained unique cellular characteristics suggesting that it could be the evolutionary link to more complex forms such as animals and plants.
According to the Vienna University news release:
All life forms on earth are divided into three major domains: eukaryotes, bacteria and archaea. Eukaryotes include the groups of animals, plants and fungi. Their cells are usually much larger and, at first glance, more complex than the cells of bacteria and archaea. The genetic material of eukaryotes, for example, is packaged in a cell nucleus and the cells also have a large number of other compartments. Cell shape and transport within the eukaryotic cell are also based on an extensive cytoskeleton. But how did the evolutionary leap to such complex eukaryotic cells come about?
Most current models assume that archaea and bacteria played a central role in the evolution of eukaryotes. A eukaryotic primordial cell is believed to have evolved from a close symbiosis between archaea and bacteria about two billion years ago. In 2015, genomic studies of deep-sea environmental samples discovered the group of the so-called "Asgard archaea", which in the tree of life represent the closest relatives of eukaryotes. The first images of Asgard cells were published in 2020 from enrichment cultures by a Japanese group.Figure 2: Scanning electron micrograph of a Lokiarchaeum ossiferum cell showing the long and complex cell protrusions.
© Thiago Rodrigues-Oliveira, Univ. Wien
Figure 3: One of the currently most popular evolutionary theories assumes that eukaryotes (including animals, plants and fungi) arose from the fusion of an Asgard archaeon with a bacterium.
© Florian Wollweber, ETH Zürich
Asgard archaea cultivated from marine sediments
Christa Schleper's working group at the University of Vienna has now succeeded for the first time in cultivating a representative of this group in higher concentrations. It comes from marine sediments on the coast of Piran, Slovenia, but is also an inhabitant of Vienna, for example in the bank sediments of the Danube. Because of its growth to high cell densities, this representative can be studied particularly well.It was very tricky and laborious to obtain this extremely sensitive organism in a stable culture in the laboratory.
Dr. Thiago Rodrigues-Oliveira, co-first author
Department of Functional and Evolutionary Ecology
Archaea Biology and Ecogenomics Unit,
University of Vienna, Vienna, Austria.
Asgard archaea have a complex cell shape with an extensive cytoskeletonThis method enables a three-dimensional insight into the internal cellular structures.
Dr. Martin Pilhofer, co-corresponding author
Institute of Molecular Biology & Biophysics
ETH Zürich, Zürich, Switzerland.
The remarkable success of the Viennese group to cultivate a highly enriched Asgard representative finally allowed a more detailed examination of the cells by microscopy. The ETH researchers in Martin Pilhofer's group used a modern cryo-electron microscope to take pictures of shock-frozen cells. The cells also contain an extensive network of actin filaments thought to be unique to eukaryotic cells. This suggests that extensive cytoskeletal structures arose in archaea before the appearance of the first eukaryotes and fuels evolutionary theories around this important and spectacular event in the history of life.
The cells consist of round cell bodies with thin, sometimes very long cell extensions. These tentacle-like structures sometimes even seem to connect different cell bodies with each other
Dr. Florian Wollweber,c-first author
Institute of Molecular Biology & Biophysics
ETH Zürich, Zürich, Switzerland.Future insights through the new model organismOur new organism, called 'Lokiarchaeum ossiferum', has great potential to provide further groundbreaking insights into the early evolution of eukaryotes. It has taken six long years to obtain a stable and highly enriched culture, but now we can use this experience to perform many biochemical studies and to cultivate other Asgard archaea as well.
Dr. Christa Schleper, co-corresponding author
Department of Functional and Evolutionary Ecology
Archaea Biology and Ecogenomics Unit
University of Vienna, Vienna, Austria
In addition, the scientists can now use the new imaging methods developed at ETH to investigate, for example, the close interactions between Asgard archaea and their bacterial partners. Basic cell biological processes such as cell division can also be studied in the future in order to shed light on the evolutionary origin of these mechanisms in eukaryotes.
The scientists casualty confirm their acceptance of the TOE, and particularly the evolution of Eukaryotes by fusion of archaea and bacteria in the abstract to their open access paper in Nature:
Abstract
Asgard archaea are considered to be the closest known relatives of eukaryotes. Their genomes contain hundreds of eukaryotic signature proteins (ESPs), which inspired hypotheses on the evolution of the eukaryotic cell1,2,3. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated4,5,6, but never visualized. Here we describe a highly enriched culture of ‘Candidatus Lokiarchaeum ossiferum’, a member of the Asgard phylum, which thrives anaerobically at 20 °C on organic carbon sources. It divides every 7–14 days, reaches cell densities of up to 5 × 107 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain7. ESPs represent 5% of its protein-coding genes, including four actin homologues. We imaged the enrichment culture using cryo-electron tomography, identifying ‘Ca. L. ossiferum’ cells on the basis of characteristic expansion segments of their ribosomes. Cells exhibited coccoid cell bodies and a network of branched protrusions with frequent constrictions. The cell envelope consists of a single membrane and complex surface structures. A long-range cytoskeleton extends throughout the cell bodies, protrusions and constrictions. The twisted double-stranded architecture of the filaments is consistent with F-actin. Immunostaining indicates that the filaments comprise Lokiactin—one of the most highly conserved ESPs in Asgard archaea. We propose that a complex actin-based cytoskeleton predated the emergence of the first eukaryotes and was a crucial feature in the evolution of the Asgard phylum by scaffolding elaborate cellular structures.
Rodrigues-Oliveira, Thiago; Wollweber, Florian; Ponce-Toledo, Rafael I.; Xu, Jingwei; Rittmann, Simon K.-M. R.; Klingl, Andreas; Pilhofer, Martin; Schleper, Christa
Actin cytoskeleton and complex cell architecture in an Asgard archaeon
Nature(2022); DOI: 10.1038/s41586-022-05550-y
Copyright: © 2022 The authors.
Published by Springer Nature Ltd. Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
Fig. 4: Complex and variable architecture of ‘Ca. L. ossiferum’ cells.
a,b, SEM imaging of fixed ‘Ca. L. ossiferum’ cells showed small coccoid cells with extensive protrusions. Example micrographs from n = 2 independent cultures are shown. See also Extended Data Fig. 7d. For a and b, scale bars, 500 nm. c–f, Slices through cryo-tomograms (c,e; thickness, 9.02 nm) and the corresponding neural-network-aided 3D volume segmentations (d,f) of two different ‘Ca. L. ossiferum’ cells. The insets in c and e show 2D overview images of the two different target cells. Cell bodies (c,d) and networks of protrusions (e,f) both contained ribosomes (grey arrowheads), cytoskeletal filaments (orange arrowheads) and complex surface densities (blue arrowheads). Note that e and f show the same cell as in Fig. 3c. For c and e, scale bars, 100 nm (tomogram) and 1 µm (2D overview). g,h, Expanded views of slices from tomograms in c and e, showing ribosome chains, complex surface proteins and filaments (colour code as in c–f) in a junction of a cell bridge (g) and a constricted part of the protrusion network (h). For g and h, scale bars, 100 nm. i–l, Slices through cryo-tomograms showing a putative chemoreceptor array (i; indicated by a white arrowhead) and different types of connections between cell bodies and protrusions (j–l). The coloured arrowheads indicate filaments and surface structures as defined for c–f. The white arrowheads in j indicate weak densities at the neck of the junction. Slice thickness, 9.02 nm (j) or 10.71 nm (i and k–l). For i–l, scale bars, 100 nm.
a,b, SEM imaging of fixed ‘Ca. L. ossiferum’ cells showed small coccoid cells with extensive protrusions. Example micrographs from n = 2 independent cultures are shown. See also Extended Data Fig. 7d. For a and b, scale bars, 500 nm. c–f, Slices through cryo-tomograms (c,e; thickness, 9.02 nm) and the corresponding neural-network-aided 3D volume segmentations (d,f) of two different ‘Ca. L. ossiferum’ cells. The insets in c and e show 2D overview images of the two different target cells. Cell bodies (c,d) and networks of protrusions (e,f) both contained ribosomes (grey arrowheads), cytoskeletal filaments (orange arrowheads) and complex surface densities (blue arrowheads). Note that e and f show the same cell as in Fig. 3c. For c and e, scale bars, 100 nm (tomogram) and 1 µm (2D overview). g,h, Expanded views of slices from tomograms in c and e, showing ribosome chains, complex surface proteins and filaments (colour code as in c–f) in a junction of a cell bridge (g) and a constricted part of the protrusion network (h). For g and h, scale bars, 100 nm. i–l, Slices through cryo-tomograms showing a putative chemoreceptor array (i; indicated by a white arrowhead) and different types of connections between cell bodies and protrusions (j–l). The coloured arrowheads indicate filaments and surface structures as defined for c–f. The white arrowheads in j indicate weak densities at the neck of the junction. Slice thickness, 9.02 nm (j) or 10.71 nm (i and k–l). For i–l, scale bars, 100 nm.
Just another abysmal failure to support Creationism, like just about every scientific biology paper published in the last 160 years.
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