New findings show that ancestral single-celled organisms were “amazingly complex”

6 Replies to “New findings show that ancestral single-celled organisms were “amazingly complex””

1. 1
   OLV says:

   July 18, 2019 at 7:33 pm

   Pluripotency and the origin of animal multicellularity
   Shunsuke Sogabe, William L. Hatleberg, Kevin M. Kocot, Tahsha E. Say, Daniel Stoupin, Kathrein E. Roper, Selene L. Fernandez-Valverde, Sandie M. Degnan & Bernard M. Degnan 

   Nature   volume 570, pages519–522 (2019)
   DOI:  10.1038/s41586-019-1290-4

   A widely held—but rarely tested—hypothesis for the origin of animals is that they evolved from a unicellular ancestor, with an apical cilium surrounded by a microvillar collar, that structurally resembled modern sponge choanocytes and choanoflagellates1,2,3,4. Here we test this view of animal origins by comparing the transcriptomes, fates and behaviours of the three primary sponge cell types—choanocytes, pluripotent mesenchymal archaeocytes and epithelial pinacocytes—with choanoflagellates and other unicellular holozoans. Unexpectedly, we find that the transcriptome of sponge choanocytes is the least similar to the transcriptomes of choanoflagellates and is significantly enriched in genes unique to either animals or sponges alone. By contrast, pluripotent archaeocytes upregulate genes that control cell proliferation and gene expression, as in other metazoan stem cells and in the proliferating stages of two unicellular holozoans, including a colonial choanoflagellate. Choanocytes in the sponge Amphimedon queenslandica exist in a transient metastable state and readily transdifferentiate into archaeocytes, which can differentiate into a range of other cell types. These sponge cell-type conversions are similar to the temporal cell-state changes that occur in unicellular holozoans5. Together, these analyses argue against homology of sponge choanocytes and choanoflagellates, and the view that the first multicellular animals were simple balls of cells with limited capacity to differentiate. Instead, our results are consistent with the first animal cell being able to transition between multiple states in a manner similar to modern transdifferentiating and stem cells.
2. 2
   OLV says:

   July 18, 2019 at 7:38 pm

   Emergence of diverse life cycles and life histories at the origin of multicellularity
   Merlijn Staps, Jordi van Gestel & Corina E. Tarnita 

   Nature Ecology & Evolution (2019)
   DOI: 10.1038/s41559-019-0940-0

    

   The evolution of multicellularity has given rise to a remarkable diversity of multicellular life cycles and life histories. Whereas some multicellular organisms are long-lived, grow through cell division, and repeatedly release single-celled propagules (for example, animals), others are short-lived, form by aggregation, and propagate only once, by generating large numbers of solitary cells (for example, cellular slime moulds). There are no systematic studies that explore how diverse multicellular life cycles can come about. Here, we focus on the origin of multicellularity and develop a mechanistic model to examine the primitive life cycles that emerge from a unicellular ancestor when an ancestral gene is co-opted for cell adhesion. Diverse life cycles readily emerge, depending on ecological conditions, group-forming mechanism, and ancestral constraints. Among these life cycles, we recapitulate both extremes of long-lived groups that propagate continuously and short-lived groups that propagate only once, with the latter type of life cycle being particularly favoured when groups can form by aggregation. Our results show how diverse life cycles and life histories can easily emerge at the origin of multicellularity, shaped by ancestral constraints and ecological conditions. Beyond multicellularity, this finding has similar implications for other major transitions, such as the evolution of sociality.
3. 3
   PaV says:

   July 19, 2019 at 10:54 am

   Looking at the abstract of the Nature article that prompted this Quanta article, one would have to say this: Darwnism is dead!

   What were looking at, plain and simple, is what has been called “front-loading” for the 15 years I’ve been here at UD. We’re vindicated. Darwinism is defeated. There’s no other way of understanding these results—only rationalizations (or should we call them “epicycles”!?)
4. 4
   john_a_designer says:

   July 19, 2019 at 12:17 pm

   Genetic comparisons between simple multicellular organisms and their single-celled relatives have revealed that much of the molecular equipment needed for cells to band together and coordinate their activities may have been in place well before multicellularity evolved.

   This suggests pre-planning, preadaptation or some kind of genetic pre-programming. In other words, a guided, directed, teleological form of evolution. That’s not exactly what Darwin had in mind.

   You can’t salvage Darwinian evolution by arbitrarily smuggling in teleology where ever and whenever you need it. “Pre-adaptation” is evidence of intelligent design.

   Single cell Choanoflagellates for some reason are protozoa which have signaling proteins that are necessary in higher multicellular animals including human beings.

   Choanoflagellates, or at least their ancestors, have long been suspected as being the bridge between microorganisms with only one cell and metazoan, or multi-cellular organisms…

   By analyzing the recently-sequenced choanoflagellate genome, the researchers discovered another similarity between choanoflagellates and most metazoans–their genetic code caries the markers of three types of molecules that cells use to achieve phospho-tyrosine signaling proteins.
   Animals depend on tyrosine phosphorylation to conduct a number of important communications between their cells, including immune system responses, hormone system stimulation and other crucial functions. These phospho-tyrosine signaling pathways utilize a three-part system of molecular components to make these communications possible.

   Tyrosine kinases (TyrK) ‘write’ messages between cells by adding phospho-tyrosine modifications, protein tyrosine phosphatases (PTP) are molecules that modify or ‘erase’ these modifications, and Src Homolgy 2 (SH2) molecules ‘read’ these modifications so the recipient cell gets the message.

   Without these three molecules to help our cells ‘write,’ ‘read’ and ‘erase’ chemical messages between them, our bodies would never be able to conduct the complex tasks needed to survive such as reproduction, digesting food or even breathing.

   Other genome analysis showed that some microorganisms contain some of these molecules in small levels, but never all three. This makes sense considering these organisms don’t need the tools to communicate between cells since they are made up of only one cell. What makes choanoflagellates unique, however, is that they have all three of these molecules. What’s more, they have relatively large quantities of them in amounts commonly seen in larger metazoan organisms.

   https://www.sciencedaily.com/releases/2008/07/080701165050.htm

   Frankly this undermines neo-Darwinism. What is the Darwinian explanation for a single celled organism evolving a function that they do not need? From an ID perspective, on the other hand, this looks like a case of pre-planning or pre-adaptation. NS + RV is non-teleological it cannot anticipate or look ahead. Darwinism has to rely on lucky accidents that sometimes happened millions of years in the past. How do you prove that these lucky accidents (and there has to be a long series of them) ever occurred?
5. 5
   Silver Asiatic says:

   July 19, 2019 at 2:55 pm

   How did they just happen to get to be amazingly complex if there is no design in nature?

   They never seem to ask that kind of question. Reading the article and the few comments, nobody questions the Darwinian narrative as a result of this. They use the new finding as a means of explaining what comes after, not as a means of wondering about how the new finding originated.
6. 6
   OLV says:

   July 20, 2019 at 3:21 am

   Baluška F, Witzany G. At the dawn of a new revolution in life sciences. World J Biol Chem 2013; 4(2): 13-15

   Article

   the most relevant scientific revolution in biology at his time was the breakthrough of the role of “information” in biology. The fundamental concept that integrates this new biological “information” with matter and energy is the universal Turing machine and von Neumann’s self-reproducing machines.

   in contrast to Turing/von Neumann machines living cells can really reproduce themselves. Additionally current knowledge on the roles of non-coding RNAs indicates a radical violation of the central dogma of molecular biology and opens the way to a new revolution in life sciences.

    biology and life is not only physics and digital information encoded in DNA sequences. In order to understand life in its whole complexity, the top-bottom processes such as occurs in epigenetics and non-coding RNA regulations leads to a new revolution in life sciences.

    

    Key Levels of Biocommunication
   PDF

   DOI: 10.1142/Q0013
   In book: BIOCOMMUNICATION: SIGN-MEDIATED INTERACTIONS BETWEEN CELLS AND ORGANISMS, Chapter: 2, Publisher: World Scientific, Editors: Richard Gordon, Joseph Seckbach, pp.37-61

   Organisms actively compete for environmental resources. They assess their surroundings, estimate how much energy they need for particular goals, and then realize the optimum variant. They take measures to control certain environmental resources. They perceive themselves and can distinguish between ” self ” and ” non-self. ” Current empirical data on all domains of life indicate that unicel-lular organisms such as bacteria, archaea, giant viruses, and protozoa as well as multicellular organisms such as animals, fungi, and plants coordinate and organize their essential life functions through signaling processes. Signaling allows for real life coordination and organization and is a communicative action in which species-specific behavioral patterns and sign repertoires are used. Cells, tissues, organs, and organisms that communicate share several key levels that are essential to all life forms and which serve as a uniform tool for investigating biocommunication. Complementary to this, active biocommunication depends on the deoxyribonucleic acid (DNA) storage medium and the agents that generate coherent content of nucleic acid sequences.