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The relative contribution and timing of different mechanisms that expanded the genome between FECA and LECA are illustrated, loosely based on the branch length-based estimates from single gene trees. They comprise the contributions to both the nuclear and mitochondrial genomes. The red bar indicates the gain of proto-mitochondrial genes upon endosymbiosis. The timing estimates of de novo gene inventions correspond to a minimal estimate of their age based on the earliest duplications they underwent. The black line illustrates the total number of genes in the composite genome, including only those genes that were still present in LECA. The loss of proto-mitochondrial and FECA genes before LECA cannot be timed. EGT, endosymbiotic gene transfer; HGT, horizontal gene transfer. To comment: the evidence shows that eukayogenesis relies very heavily on transferred genes. The de novo ones also likely came by transfer (what else?) How genes transerred from prokaryotes or viruses acquired their eukaryotic programming is a huge, unanswered question. The puzzle is at least equal (the reliance on transfer is complete) for evolution strictly among prokaryotes. It makes no neo-darwinian sense at all. A radical rethink is needed. "The emerging view on the origin and early evolution of eukaryotic cells," by Vosseberg, J., van Hooff, J.J.E., Köstlbacher, S. et al, Nature, 11 Sep 2024. Truly novel eukaryotic genes that originated de novo through gene genesis from non-coding DNA are arguably the most enigmatic. Previous work indicated that a substantial fraction... do not exhibit discernible homology to prokaryotic sequences.De Novo Genes has updates for this subject. 07 May 2015: example ef Eukaryotic signature proteins (ESPs) in archaea. 10 Mar 2021: New genes can be acquired only via HGT..., among prokaryotes, an analysis and updates.
Life on Europa, Other Moons, Other Planets?... has related links.
Photographic Evidence of Panspermia: 30-minute interview by Brian Cory Dobbs, YouTube, 24 Aug 2024. ...Analysis of Interstellar Dust and Chandra Wickramasinghe have background.
Astrobiology: Biomolecules and Life on Earth and in Icy Moons, Comets and Asteroids: 100-minute lecture by Richard B. Hoover for Eco Astronomy, Sri Lanka, 18 Aug 2024, on YouTube. 11 Jan 2013: A carbonaceous meteorite that fell in Sri Lanka..., with links to followup research and reactions. Richard Hoover: collected articles.
The heart of the book is its very close look at more than a hundred images from four Mars rovers, Opportunity, Spirit, Phoenix and Curiosity. Forms that, on Earth, would certainly be recognized as stromatolites, get close scrutiny and reasoned argument. Various other forms of microbial life are also convincingly visualized in the Mars images, with helpful comments. The discussion of bluberries and "newberries" is unconventional and enlightening. Skeptics will likely compare some of their suggestions to the sighting of canals on Mars by Giovanni Schiaparelli, later championed by Percival Lowell. That would ignore the careful quantitative and statistical analysis also provided. The subject deserves to be considered by the broadest range of experts, especially sedimentologists, with open minds and genuine curiosity. This book is an excellent new resource for the question of past life on Mars. Compelling Evidence of Fossils and Microbialites on Ancient Mars, edited by Vincenzo Rizzo and Giorgio Bianciardi, [poster], ISBN:978-1-0364-0827-5, Cambridge Scholars Publishing, coming Sep 2024.Thanks for an advance copy, Vincenzo Rizzo and Cambridge Scholars Publishing. "Why should geological criteria used on Earth not be valid also for Mars? Evidence of possible microbialites and algae in extinct Martian lakes," by Vincenzo Rizzo, International Journal of Astrobiology, 02 Mar 2020. "The Case for Past Life on Mars Gets Stronger," by Dirk Schulze-Makuch, Smithsonian Magazine, 13 Apr 2020. Life on Mars! has history and updates.
"Community Report from the Biosignatures Standards of Evidence Workshop" arXiv:2210.14293, Oct 2022.
"Liquid water in the Martian mid-crust," by Vashan Wright et al, doi:10.1073/pnas.2409983121, PNAS, 12 Aug 2024. Life on Mars! has lots about water there, but this much buried water is a newsworthy.
"Ship Brings Rocky Clues to Life's Origins Up From Ocean's 'Lost City'," by William J. Broad, The New York Times, 08 Aug 2024; re:
The RNA World: and Other Origin-of-Life Theories has discussion and history.
"Convergent evolution of plant prickles by repeated gene co-option over deep time," by James W. Satterlee et al, doi:10.1126/science.ado1663; and commentary by Elizabeth A. Kellogg, Science, 02 Aug 2024. "How Did Roses Get Their Thorns?" by Carl Zimmer, The New York Times, 01 Aug 2024. Each time prickles [thorns] arose, plants did not evolve an entirely new way to make them. They just borrowed the same gene again and again.
Convergent evolution puzzled Charles Darwin and remains puzzling. One simple explanation could be that, in each instance, the same genetic program is responsible for the phenomenon. A close analysis of the convergent evolution of thorns supports this suggestion.
Thanks, Jim Powers. Life on Europa, Other Moons, Other Planets?... has related links. Search for Venus.
"Perseverance rover discovers rock with potential signs of ancient life," NASA via PhysOrg, 25 Jul 2024. "NASA ...Very Excited About This Rock," by Kenneth Chang, The New York Times, 25 Jul 2024. Life on Mars! cites lots of existing evidence, beginning with Viking in 1976.
"Evidence of dark oxygen production at the abyssal seafloor," by Sweetman, A.K., Smith, A.J., de Jonge, D.S.W. et al, doi:10.1038/s41561-024-01480-8, [link], Nat. Geosci., 22 Jul 2024; and commentary: "Mystery oxygen source discovered on the sea floor – bewildering scientists," by Davide Castelvecchi, [link], Nature, 22 Jul 2024. Thanks, Google Alerts. However it is produced, if oxygen is available without light, it would permit oxygen-dependent metazoan life to live in the dark, ice-covered oceans of bodies like Europa. Life on Europa, Other Moons, Other Planets? has more about ice-covered oceans. 21 Jul 2023: another study suggests that oxygen can accumulate without photosynthesis.
"Bdelloid rotifers deploy horizontally acquired biosynthetic genes against a fungal pathogen," by Nowell, R.W., Rodriguez, F., Hecox-Lea, B.J. et al, doi:10.1038/s41467-024-49919-1, Nat Commun, 18 Jul 2024. "Small animals acquire genes from bacteria that can produce antibiotics," Marine Biological Laboratory via EurekAlert!, 18 Jul 2024. "These microscopic animals fight off infection using genes 'stolen' from bacteria," Science, 18 Jul 2024. Viruses and Other Gene Transfer Mechanisms has links to hundreds of examples of HGT. ... these data suggest that cross-kingdom HGT events shape the metabolic capabilities and interactions between plants and bacteria. "Widespread horizontal gene transfer between plants and bacteria," ISME Communicatins, 01 Jan 2024. Thanks, Google Alerts.
"Found with Webb: a potentially habitable world," University of Montreal +PhysOrg, 08 Jul 2024; re: "Transmission Spectroscopy of the Habitable Zone Exoplanet LHS 1140 b with JWST/NIRISS," by Charles Cadieux et al, arXiv:2406.15136 [astro-ph.EP] 21 Jun 2024. Life on Europa, Other Moons, Other Planets? has related links.
An international team has sequenced the genomes of 24 species of "bonnet" mushrooms as part of the 1000 Fungal Genomes project. They found that the genomes of three Arctic ones were especially large. Gene duplications, TE insertions, HGT and de novo and orphan genes all apparently contributed to the genome expansions. Many of the extra genes, although conserved across several species, are silent, and most of them are unrecognized. To explain these surprises, new corrolaries to neo-Darwinian theory are considered.
In cosmic ancestry, unnecesary genes, genes-in-waiting, unfamiliar, orphan and de novo genes are expected. Evolution can make significant steps when robust software management "tinkers" with existing, available programming such as that. This latter suggestion even gets inferential support in the new study: TE insertions were seen to be especially active around transcription factors, which can turn genes on-or-off. The study is comprehensive and very deep.
"The Mysterious, Deep-Dwelling Microbes That Sculpt Our Planet," by Ferris Jabr, The New York Times, 24 Jun 2024. Gaia and James Lovelock are well endorsed by Jabr. Bacteria... discusses their surprising range and engineering capability..
"Is dimethylsulfide a good biomarker?" by Nora Hänni et al. [abstract], EGU General Assembly 2024, 14-19 Apr 2024. Thanks, Richard B. Hoover.
Their reaction leaves me dumbfounded. Before the evience is in, they already know where life is and isn't: But what if this biomarker is present in the completely abiotic cometary matter? ...Our detailed analysis of the sulfur-bearing hydrocarbon signals detectable in 67P's coma yields strong evidence for the presence of DMS and thus provides the basis to argue that this molecule might not be a robust indicator of extraterrestrial life.
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