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Rethinking biology: What role does physical structure play in the development of cells?

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That’s structuralism, in part. Further to Evelyn Fox Keller’s comment that the landscape of biological thought is being “radically reconfigured,” a cancer geneticist writes to say that a tumor’s physical environment fuels its growth and causes treatment resistance:

The forces of cancer

In vitro experiments showing that cancer cells actively migrate in response to fluid flow have supported the hypothesis that fluid escaping from the boundary of a tumor may guide the invasive migration of cancer cells toward lymphatic or blood vessels, potentially encouraging metastasis. There remains controversy over how the fluid forces induce the migration; the cells may respond to chemical gradients created by the cells and distorted by the flowing fluid,8 or the fluid may activate cell mechanosensors. Because of the potential for new therapeutic interventions, the transduction of mechanical fluid forces into biochemical signals by cell mechanosensors is an active area of investigation. In a more direct manner, the fluid flow can physically carry cancer cells to lymph nodes.

And fluid pressure is just one of the many forces in a tumor that can influence its development and progression. Tumors also develop increased solid pressure, as compared with normal tissue, stemming from the uncontrolled division of cancer cells and from the infiltration and proliferation of stromal and immune cells from the surrounding tissue and circulation. High-molecular-weight polysaccharides known as hydrogels found in the extracellular matrix (ECM) also add pressure on a tumor. The most well-studied of these hydrogels is hyaluronan; when the polysaccharide absorbs water, it swells, pressing on surrounding cells and structural elements of the tissue. More. (The Scientist, April 1, 2016)

and

May the Force be with you

The dissection of how cells sense and propagate physical forces is leading to exciting new tools and discoveries in mechanobiology and mechanomedicine.

Of course, mechanical properties and forces aren’t just important in disease, but in health as well. Almost all living cells and tissues exert and experience physical forces that influence biological function. The magnitudes of those forces vary among different cell and tissue types, as do cells’ sensitivities to changes in magnitudes, frequencies, and durations of the forces. Touch, hearing, proprioception, and certain other senses are well-known examples of specialized force sensors. But force detection and sensing are not limited to these special cases; rather, they are shared by all living cells in all tissues and organs. The underlying mechanisms of force generation and detection are not well understood, however, leaving many open questions about force dynamics; the distance over which a force exerts its impact; and how cells convert mechanical signals into biochemical signals and changes in gene expression (The Scientist, February 1, 2017)More.

We may come to understand evolution better if we see what can and can’t happen in physics terms.

See also: Keller: Landscape of biological thought is being “radically reconfigured”

Comments
Cichlids encompass one of the most diverse groups of fishes in South and Central America, and show extensive variation in life history, morphology, and colouration. [...] a key amino acid substitution present in some Central American cichlids accelerates the rate of decay of active rhodopsin, which may mediate adaptation to clear water habitats.
Accelerated Evolution and Functional Divergence of the Dim Light Visual Pigment Accompanies Cichlid Colonization of Central America. Hauser FE1, Ilves KL2,3, Schott RK1, Castiglione GM4, López-Fernández H1,2, Chang BSW1,4, Mol Biol Evol. 34(10):2650-2664. doi: 10.1093/molbev/msx192.
Fish remains fish? Isn’t this all about microevolutionary changes? Where’s the beef? Another example of the Embedded Variability Framework (EVF) designed within the biological systems. Complex functionally specified informational complexity.Dionisio
November 16, 2017
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@51-52 Isn’t this all about microevolutionary changes? Where’s the beef? Another example of the Embedded Variability Framework (EVF) designed within the biological systems. Complex functionally specified informational complexity.Dionisio
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[...] unique amino acid substitutions occur at sites under positive selection in high-altitude catfishes, located at opposite ends of the RH1 intramolecular hydrogen-bonding network. Natural high-altitude variants introduced into these sites via mutagenesis have limited effects on spectral tuning, yet decrease the stability of dark-state and light-activated rhodopsin, accelerating the decay of ligand-bound forms. As found in cold-adapted enzymes, this phenotype likely compensates for a cold-induced decrease in kinetic rates-properties of rhodopsin that mediate rod sensitivity and visual performance. Our results support a role for natural variation in enhancing the performance of GPCRs in response to cold temperatures.
Evolution of nonspectral rhodopsin function at high altitudes. Castiglione GM1,2, Hauser FE2, Liao BS1, Lujan NK2,3,4, Van Nynatten A1, Morrow JM2, Schott RK2, Bhattacharyya N1, Dungan SZ2, Chang BSW5 Proc Natl Acad Sci U S A. 114(28):7385-7390. doi: 10.1073/pnas.1705765114
Complex functionally specified informational complexity.Dionisio
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High-altitude environments present a range of biochemical and physiological challenges for organisms through decreases in oxygen, pressure, and temperature relative to lowland habitats. Protein-level adaptations to hypoxic high-altitude conditions have been identified in multiple terrestrial endotherms; however, comparable adaptations in aquatic ectotherms, such as fishes, have not been as extensively characterized. In enzyme proteins, cold adaptation is attained through functional trade-offs between stability and activity, often mediated by substitutions outside the active site. Little is known whether signaling proteins [e.g., G protein-coupled receptors (GPCRs)] exhibit natural variation in response to cold temperatures. Rhodopsin (RH1), the temperature-sensitive visual pigment mediating dim-light vision, offers an opportunity to enhance our understanding of thermal adaptation in a model GPCR.
Evolution of nonspectral rhodopsin function at high altitudes. Castiglione GM1,2, Hauser FE2, Liao BS1, Lujan NK2,3,4, Van Nynatten A1, Morrow JM2, Schott RK2, Bhattacharyya N1, Dungan SZ2, Chang BSW5 Proc Natl Acad Sci U S A. 114(28):7385-7390. doi: 10.1073/pnas.1705765114
Complex functionally specified informational complexity.Dionisio
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Like many aquatic vertebrates, whales have blue-shifting spectral tuning substitutions in the dim-light visual pigment, rhodopsin, that are thought to increase photosensitivity in underwater environments. We have discovered that known spectral tuning substitutions also have surprising epistatic effects on another function of rhodopsin, the kinetic rates associated with light-activated intermediates. [...] killer whale rhodopsin is unusually resilient to pleiotropic effects on retinal release from key blue-shifting substitutions (D83N and A292S), largely due to a surprisingly specific epistatic interaction between D83N and the background residue, S299.
Epistatic interactions influence terrestrial-marine functional shifts in cetacean rhodopsin. Dungan SZ1, Chang BS2,3,4. Proc Biol Sci. 284(1850). pii: 20162743. doi: 10.1098/rspb.2016.2743.
Isn't this all about microevolutionary changes? Where's the beef? Did somebody say 'surprising'? Did somebody say 'surprisingly'? Complex functionally specified informational complexity.Dionisio
November 16, 2017
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Biological systems are complex and consist of many proteins and other molecules. Genes are the sections of DNA that provide the instructions needed to produce these molecules, and some genes encode proteins that can bind to DNA to control whether other genes are switched on or off. [...] the nature of the interaction between mutations can be explained through biophysical laws, combined with the basic knowledge of the logic of how genes regulate each other’s activities. The interaction between individual mutations – epistasis – determines how a genotype maps onto a phenotype [...]
On the mechanistic nature of epistasis in a canonical cis-regulatory element Mato Lagator,1,† Tiago Paixão,1,† Nicholas H Barton,1 Jonathan P Bollback,1,2 and C?lin C Guet1,* eLife. 2017; 6: e25192. doi: 10.7554/eLife.25192
Complex functionally specified informational complexity.Dionisio
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Understanding the relation between genotype and phenotype remains a major challenge. The difficulty of predicting individual mutation effects, and particularly the interactions between them, has prevented the development of a comprehensive theory that links genotypic changes to their phenotypic effects. [...] a predictive theory for the effects of cis-regulatory mutations is possible from first principles, as long as the essential molecular mechanisms and the constraints these impose on a biological system are accounted for.
On the mechanistic nature of epistasis in a canonical cis-regulatory element Mato Lagator,1,† Tiago Paixão,1,† Nicholas H Barton,1 Jonathan P Bollback,1,2 and C?lin C Guet1,* eLife. 2017; 6: e25192. doi: 10.7554/eLife.25192
Complex functionally specified informational complexity.Dionisio
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Despite now a days wealth of structural data in the Protein Data Bank (Bermanetal.,2000) and decades of protein studies, some of the very fundamentals of protein structure are still under intense discussion. [...] the exhaustive catalogs with detail description of all relevant characteristics are yet to be produced. The catalog will be instrumental in the high-throughput annotation / prediction of protein function on the basis of its building blocks - elementary functions [...] Further development of the concept of descriptor of elementary function (Goncearenco and Berezovsky,2015;Zheng et al.,2016), construction of the comprehensive library of descriptors, and implementation of the computational protocol for descriptor - based design of required catalytic functions are also the first priority, future tasks.
Basic units of protein structure, folding, and function Igor N. Berezovsky a, b, Enrico Guarnera a, Zejun Zheng a Progress in Biophysics and Molecular Biology ScienceDirect Volume 128, Pages 85-99 DOI: https://doi.org/10.1016/j.pbiomolbio.2016.09.009
Complex functionally specified informational complexity.Dionisio
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Study of the hierarchy of domain structure with alternative sets of domains and analysis of discontinuous domains, consisting of remote segments of the polypeptide chain, raised a question about the minimal structural unit of the protein domain. Generalized descriptors of the elementary functions are proposed to be used as basic units in the future computational design.
Basic units of protein structure, folding, and function Igor N. Berezovsky a, b, Enrico Guarnera a, Zejun Zheng a Progress in Biophysics and Molecular Biology ScienceDirect Volume 128, Pages 85-99 DOI: https://doi.org/10.1016/j.pbiomolbio.2016.09.009
Complex functionally specified informational complexity.Dionisio
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The 20 naturally occurring amino acids have different environmental preferences of where they are likely to occur in protein structures. Environments in a protein can be classified by their proximity to solvent by the residue depth measure. Since the frequencies of amino acids are different at various depth levels, the substitution frequencies should vary according to depth. To quantify these substitution frequencies, we built depth dependent substitution matrices. Further developments in these substitution matrices could help in improving structure-sequence alignment for protein 3D structure modeling.
Depth dependent amino acid substitution matrices and their use in predicting deleterious mutations Nida Farheen a, 1, Neeladri Sen a, 1, Sanjana Nair a, Kuan Pern Tan b, c, M.S. Madhusudhan a, b Progress in Biophysics and Molecular Biology Volume 128, Pages 14-23 DOI: https://doi.org/10.1016/j.pbiomolbio.2017.02.004
Complex functionally specified informational complexity.Dionisio
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Complete maps of PPI networks annotated with biological pathway and protein structural information, will provide a platform from which to understand the molecular nature of PPI networks, in turn guiding predictions of the impacts of mutations on disease biology. Structural understanding and quantification of effects of mutations at PPIs will enable the design of better PPI inhibitors and stabilisers that can target specific disease states, and address cases where further interface mutations lead to drug resistance.
Mutations at protein-protein interfaces: Small changes over big surfaces have large impacts on human health Harry C. Jubb a, b, 1, Arun P. Pandurangan a, 1, Meghan A. Turner a, c, 1, Bernardo Ochoa-Montaño a, 1, Tom L. Blundell a, David B. Ascher a, d Progress in Biophysics and Molecular Biology Volume 128, Pages 3-13 DOI: https://doi.org/10.1016/j.pbiomolbio.2016.10.002
Work in progress... stay tuned. Complex functionally specified informational complexity.Dionisio
November 16, 2017
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Interactions between proteins mediate many biological processes, especially with respect to cell regulatory events requiring high signal-to-noise ratios to transduce information within and between cells [...] Understanding how mutations modulate protein interactions and thus biological functions raises potential for developing therapeutic interventions targeting interaction mutants. Protein interactions impart selectivity and sensitivity to biological processes, and may occur either through the co-operative assembly of specific multi-protein assemblies or through the co-operative folding and binding of one binding protomer onto another.
Mutations at protein-protein interfaces: Small changes over big surfaces have large impacts on human health Harry C. Jubb a, b, 1, Arun P. Pandurangan a, 1, Meghan A. Turner a, c, 1, Bernardo Ochoa-Montaño a, 1, Tom L. Blundell a, David B. Ascher a, d Progress in Biophysics and Molecular Biology Volume 128, Pages 3-13 DOI: https://doi.org/10.1016/j.pbiomolbio.2016.10.002
Complex functionally specified informational complexity.Dionisio
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Many essential biological processes including cell regulation and signalling are mediated through the assembly of protein complexes. Changes to protein-protein interaction (PPI) interfaces can affect the formation of multiprotein complexes, and consequently lead to disruptions in interconnected networks of PPIs within and between cells, further leading to phenotypic changes as functional interactions are created or disrupted. [...] a better understanding of how these mutations affect the structure, function, and formation of multiprotein complexes provides novel opportunities for tackling them, including the development of small-molecule drugs targeted specifically to mutated PPIs.
Mutations at protein-protein interfaces: Small changes over big surfaces have large impacts on human health Harry C. Jubb a, b, 1, Arun P. Pandurangan a, 1, Meghan A. Turner a, c, 1, Bernardo Ochoa-Montaño a, 1, Tom L. Blundell a, David B. Ascher a, d Progress in Biophysics and Molecular Biology Volume 128, Pages 3-13 DOI: https://doi.org/10.1016/j.pbiomolbio.2016.10.002
Complex functionally specified informational complexity.Dionisio
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[...] the follicular epithelium represents a beautiful example of how the combination of diverse signalling pathways creates cell diversity by using morphogen gradients. These gradients initiate spatially restricted gene expression domains that become stabilized by negative cross-regulation of their downstream targets. Finding out how the temporal- and spatial-specific information provided by these signalling pathways converge on their downstream targets and particularly how their activating and repressing inputs are integrated on the target gene enhancers is a fundamental area of research [...]
Cell Signalling: Combining Pathways for Diversification and Reproducibility James Castelli-Gair Hombría, Acaimo González-Reyes Current Biology Volume 26, Issue 21, pR1153–R1155 DOI: http://dx.doi.org/10.1016/j.cub.2016.08.070
Complex functionally specified informational complexity.Dionisio
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[...] posterior follicle cells with an activated STAT pathway signal back to the oocyte, reorganizing its £cytoskeleton [...]. The nature of this signal from the posterior follicle cells to the oocyte is unknown [...]
Cell Signalling: Combining Pathways for Diversification and Reproducibility James Castelli-Gair Hombría, Acaimo González-Reyes Current Biology Volume 26, Issue 21, pR1153–R1155 DOI: http://dx.doi.org/10.1016/j.cub.2016.08.070
Complex functionally specified informational complexity.Dionisio
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Intriguingly, the EGFR pathway is responsible for setting both the A–P and D–V axes. [...] it is the combination of the EGFR pathway with either the JAK/STAT or the BMP pathways that ultimately determines different follicle cell fates.
Cell Signalling: Combining Pathways for Diversification and Reproducibility James Castelli-Gair Hombría, Acaimo González-Reyes Current Biology Volume 26, Issue 21, pR1153–R1155 DOI: http://dx.doi.org/10.1016/j.cub.2016.08.070
Complex functionally specified informational complexity.Dionisio
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How a given signalling pathway can generate diverse outcomes is an open question. A new study shows that EGFR signalling in combination with JAK/STAT or BMP pathways induces different cell fates. Antagonistic interactions between downstream targets further stabilizes epithelial patterning.
Cell Signalling: Combining Pathways for Diversification and Reproducibility James Castelli-Gair Hombría, Acaimo González-Reyes Current Biology Volume 26, Issue 21, pR1153–R1155 DOI: http://dx.doi.org/10.1016/j.cub.2016.08.070
Complex functionally specified informational complexity.Dionisio
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What coordinates the internal leading and trailing edges in collectively migrating cells is largely unknown.
Fat2 and Lar Dance a Pas de Deux during Collective Cell Migration Qiyan Mao 1, Jules Lavalou 1, Thomas Lecuit Developmental Cell Volume 40, Issue 5, Pages 425-426 DOI: https://doi.org/10.1016/j.devcel.2017.02.025
Complex functionally specified informational complexity.Dionisio
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Collective migration of epithelial cells underlies diverse tissue-remodeling events, but the mechanisms that coordinate individual cell migratory behaviors for collective movement are largely unknown. [...] the cadherin Fat2 and the receptor tyrosine phosphatase Lar function in a planar signaling system that coordinates leading and trailing edge dynamics between neighboring cells. Fat2 signals from each cell's trailing edge to induce leading edge protrusions in the cell behind, in part by stabilizing Lar's localization in these cells. Conversely, Lar signals from each cell's leading edge to stimulate trailing edge retraction in the cell ahead. Fat2/Lar signaling is similar to planar cell polarity signaling in terms of sub-cellular protein localization; however, Fat2/Lar signaling mediates short-range communication between neighboring cells instead of transmitting long-range information across a tissue. This work defines a key mechanism promoting epithelial migration and establishes a different paradigm for planar cell-cell signaling.
Fat2 and Lar Define a Basally Localized Planar Signaling System Controlling Collective Cell Migration Kari Barlan 1, Maureen Cetera 2, 3, Sally Horne-Badovinac Developmental Cell Volume 40, Issue 5, Pages 467-477.e5 DOI:0https://doi.org/10.1016/j.devcel.2017.02.003
Did somebody say 'coordinate'? Complex functionally specified informational complexity.Dionisio
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Basement membranes (BMs) are specialized types of extracellular matrix (ECM) that coat the basal side of epithelial and endothelial tissues, surround muscles and fat cells, and play an active role in tissue and organ morphogenesis [...] [...] the specific functions of the different BM components during morphogenesis remain uncertain. [...] our knowledge of the molecular details behind the initiation of collective cell migration is scarce. [...] the finding that collective migration is regulated by linked cellular and environmental properties broadens our understanding of the cellular basis of development and disease.
Laminin Levels Regulate Tissue Migration and Anterior-Posterior Polarity during Egg Morphogenesis in Drosophila María C. Díaz de la Loza 1, 4, Alfonsa Díaz-Torres 1, Federico Zurita 2, Alicia E. Rosales-Nieves 1, Emad Moeendarbary 3, 5, Kristian Franze 3, María D. Martín-Bermudo 1, Acaimo González-Reyes Cell Reports Volume 20, Issue 1, Pages 211-223 DOI: https://doi.org/10.1016/j.celrep.2017.06.031
Complex functionally specified informational complexity.Dionisio
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Epithelial structures are foundational for tissue organization in all metazoans. Sheets of epithelial cells form lateral adhesive junctions and acquire apico-basal polarity perpendicular to the surface of the sheet. Epithelial follicle cells progress through tightly choreographed phases of proliferation, patterning, reorganization and migrations, before they differentiate to form the elaborate structures of the eggshell. Distinct structural domains are organized by differential adhesion, within which lateral junctions are remodeled to further shape the organized epithelia. During collective cell migrations, adhesive interactions mediate supracellular organization of planar polarized macromolecules, and facilitate crawling over the basement membrane or traction against adjacent cell surfaces. Technological advances will keep this tissue at the leading edge for interrogating the precise spatiotemporal regulation of normal epithelial reorganization events [...]
The repertoire of epithelial morphogenesis on display: Progressive elaboration of Drosophila egg structure Juan Carlos Duhart, Travis T. Parsons, Laurel A. Rafters Mechanisms of Development DOI: https://doi.org/10.1016/j.mod.2017.04.002
Did somebody say 'tightly choreographed'? Did somebody say 'elaborate structures'? Did somebody say 'precise spatiotemporal regulation'? Complex functionally specified informational complexity.Dionisio
November 15, 2017
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Understanding the mechanisms driving tissue and organ formation requires knowledge across scales. How do signaling pathways specify distinct tissue types? How does the patterning system control morphogenesis? [...] The Drosophila egg chamber, where EGF and BMP signaling intersect to specify unique cell types that construct epithelial tubes for specialized eggshell structures, has provided a tractable system to ask these questions. Work there has elucidated connections between scales of development [...]
Epithelial Patterning, Morphogenesis, and Evolution: Drosophila Eggshell as a Model Author links open overlay panel Miriam Osterfield 1, Celeste A. Berg 2, Stanislav Y. Shvartsman 3 Developmental Cell Volume 41, Issue 4, Pages 337-348 DOI: https://doi.org/10.1016/j.devcel.2017.02.018
Complex functionally specified informational complexity.Dionisio
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How confident could we be on the validity of the rationale for the origins of the metabolic maze? The path from simple to complex is not to be considered ‘the’ paradigm of evolution, but it is appealing in view of having been reached here as a result, not having been taken as a premise or assumption. [...] In this possibly highly conflictive area, we remain.
Self-Referential Encoding on Modules of Anticodon Pairs—Roots of the Biological Flow System Romeu Cardoso Guimarães Life (Basel). 2017 Jun; 7(2): 16. doi: 10.3390/life7020016
parole, parole, parole... Where's the beef? :) Complex functionally specified informational complexity.Dionisio
November 15, 2017
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We are not committed with the RNA World proposition and cannot offer a justified alternative. Some of the commonly accepted pre-biotic supports and guides for oligomerization reactions, e.g., from mineral surfaces such as clays [125], would be non-specific enough to accept diverse kinds of monomers. Any choice among the possibilities would have to rely upon robust experimentation.
Self-Referential Encoding on Modules of Anticodon Pairs—Roots of the Biological Flow System Romeu Cardoso Guimarães Life (Basel). 2017 Jun; 7(2): 16. doi: 10.3390/life7020016
parole, parole, parole... Where's the beef? :) Complex functionally specified informational complexity.Dionisio
November 15, 2017
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In view of the difficulties in taking sides with respect to the RNA World proposition and together with the possibility of the lack of hydropathy correlation with the dinucleotides being derived only from the poorness of the encoded amino acid set—just two, probably amidst other amino acids or other compounds polymerized together with them due to catalytic non-specificity—we prefer to say of an unknown constitution of the carriers.
Self-Referential Encoding on Modules of Anticodon Pairs—Roots of the Biological Flow System Romeu Cardoso Guimarães Life (Basel). 2017 Jun; 7(2): 16. doi: 10.3390/life7020016
parole, parole, parole... Where's the beef? :) Complex functionally specified informational complexity.Dionisio
November 15, 2017
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In face of the persisting doubts on the feasibility of a pure RNA world—in spite of the beauty in the RNA technology, our studies are plainly consistent with an early RNP world, late DNP. The nucleic acid and the protein component structures would have coevolved.
Self-Referential Encoding on Modules of Anticodon Pairs—Roots of the Biological Flow System Romeu Cardoso Guimarães Life (Basel). 2017 Jun; 7(2): 16. doi: 10.3390/life7020016
parole, parole, parole... Where's the beef? :) Complex functionally specified informational complexity.Dionisio
November 15, 2017
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I think there are two basic flaws of the paper. The first is more philosophic, the second more phylogenetic (incl. EVO-DEVO). [Zoltán Varga] The survey of causality is incomplete! [Zoltán Varga] These are insufficiently disentangled in the paper. [Zoltán Varga] [...] both the whole body and the infra-individual level structures act as biological entities reacting to the forces of their environment. Furthermore, both are built on the basis of genetic programs, which follow a linear order of activation. [author's response]
Demystification of animal symmetry: symmetry is a response to mechanical forces Gábor Holló Biol Direct. 2017; 12: 11. doi: 10.1186/s13062-017-0182-5
Did somebody say 'programs'? This paper seems to beg the question “where’s the beef?” It seems to draw pseudoscientific conclusions prematurely. Work in progress... stay tuned. They ain’t seen nothin’ yet. The most revealing discoveries are still ahead. Complex functionally specified informational complexity.Dionisio
November 13, 2017
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[...] there is very little concrete, let alone quantitative, argument here as how, specifically, physical factors produce symmetry. [Eugene Koonin] Regrettably, I do not have the impression that direct and [in]direct causes, and biological and physical factors are disentangled here in a satisfactory manner. [Eugene Koonin] [...] the paper lacks specific descriptions as to the precise extent physical factors determine symmetrical patterns in the animal body. However, please let me first underline that this hypothesis paper tries to give a general framework for thinking about symmetry, and not to offer exact explanations for individual cases for the specific animal taxa. [author's response] I am open to conducting further investigations; in this case, please, give more specific details on how to proceed. [author's response]
Demystification of animal symmetry: symmetry is a response to mechanical forces Gábor Holló Biol Direct. 2017; 12: 11. doi: 10.1186/s13062-017-0182-5
This paper seems to beg the question “where’s the beef?” It seems to draw pseudoscientific conclusions prematurely. Work in progress... stay tuned. They ain’t seen nothin’ yet. The most revealing discoveries are still ahead. Complex functionally specified informational complexity.Dionisio
November 13, 2017
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The exact mechanisms by which internal bilateral symmetry builds have been in part elucidated, although several aspects remain unclear. [...] the whole process of the formation of the symmetry plane, probably also including the factors which direct the interaction of the molecules mentioned, remains elusive. How the cells exactly sense the midline and how they stop there, however, remains a mystery [...] [...] a cellular community effect stemming from external physical forces may also play an important role in the process. [...] the answer to the bigger question of what the indirect causes of the two main symmetries are, is still missing. Bilateral symmetry is a major enigma in biology. Other potential ultimate factors which favour bilaterality remain to be discovered. Hopefully, our picture of animal symmetry will be further clarified when we will eventually be able to identify the ultimate causes behind the very origin of either radial or bilateral symmetry, long-sought answers to fundamental problems in evolutionary biology.
Demystification of animal symmetry: symmetry is a response to mechanical forces Gábor Holló Biol Direct. 2017; 12: 11. doi: 10.1186/s13062-017-0182-5
This paper seems to beg the question “where’s the beef?” It seems to draw pseudoscientific conclusions prematurely. Work in progress... stay tuned. They ain’t seen nothin’ yet. The most revealing discoveries are still ahead. Complex functionally specified informational complexity.Dionisio
November 13, 2017
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Symmetry is an eye-catching feature of animal body plans, yet its causes are not well enough understood. Symmetry is a frequent pattern in nature, often perceived as a source of beauty, and is also a salient property of animal body plans. The concept of the body plan can be defined as an ontogenetic pattern-organising algorithm, thanks to which the body develops in a specific order.
Demystification of animal symmetry: symmetry is a response to mechanical forces Gábor Holló Biol Direct. 2017; 12: 11. doi: 10.1186/s13062-017-0182-5
This paper seems to beg the question “where’s the beef?” It seems to draw pseudoscientific conclusions prematurely. They ain’t seen nothin’ yet. The most revealing discoveries are still ahead. Complex functionally specified informational complexity.Dionisio
November 12, 2017
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