Symmetry and asymmetry in biological structures

Ocklenburg, Sebastian; Mundorf, Annakarina

doi:10.1073/pnas.2204881119

Cited by 27 publications

(16 citation statements)

References 10 publications

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“…Less information is required to describe bonding patterns that lead to higher symmetry, and thus such phenotypes have a higher probability of appearing upon random mutations [ 3 ]. One could imagine extending this preference for symmetry, modulated by processes such as symmetry breaking [ 71 ], to larger-scale developmental processes (see [ 72 , 73 ] for a discussion). In other cases, including the RNA secondary structures and branching morphologies (see ref [ 74 ]), different signatures of simplicity need to be employed to identify processes that can be described by shorter algorithms, which should be easier to find through random mutations.…”

Section: Discussionmentioning

confidence: 99%

Bias in the arrival of variation can dominate over natural selection in Richard Dawkins’s biomorphs

Martin,

Camargo,

Louis

2024

PLoS Comput Biol

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Biomorphs, Richard Dawkins’s iconic model of morphological evolution, are traditionally used to demonstrate the power of natural selection to generate biological order from random mutations. Here we show that biomorphs can also be used to illustrate how developmental bias shapes adaptive evolutionary outcomes. In particular, we find that biomorphs exhibit phenotype bias, a type of developmental bias where certain phenotypes can be many orders of magnitude more likely than others to appear through random mutations. Moreover, this bias exhibits a strong preference for simpler phenotypes with low descriptional complexity. Such bias towards simplicity is formalised by an information-theoretic principle that can be intuitively understood from a picture of evolution randomly searching in the space of algorithms. By using population genetics simulations, we demonstrate how moderately adaptive phenotypic variation that appears more frequently upon random mutations can fix at the expense of more highly adaptive biomorph phenotypes that are less frequent. This result, as well as many other patterns found in the structure of variation for the biomorphs, such as high mutational robustness and a positive correlation between phenotype evolvability and robustness, closely resemble findings in molecular genotype-phenotype maps. Many of these patterns can be explained with an analytic model based on constrained and unconstrained sections of the genome. We postulate that the phenotype bias towards simplicity and other patterns biomorphs share with molecular genotype-phenotype maps may hold more widely for developmental systems.

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Section: Discussionmentioning

confidence: 99%

Bias in the arrival of variation can dominate over natural selection in Richard Dawkins’s biomorphs

Martin,

Camargo,

Louis

2024

PLoS Comput Biol

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“…The false assumptions inevitably lead to the wrong unsolvable question. The collective labor of modern scientific society delivers evidence that space-time symmetry and relativity (STSR) are the fundamental properties of nature [17] and primary determinants of life [12,33]. The advances in quantum mechanics and group theory confirm the long-time-repining intuitive assumption, influencing the minds of the greatest scientists from Gailey to Dirac, that the principle of invariance (i.e., symmetry) is "analogous" to the relativity principle [34].…”

Section: Molecular Chiralitymentioning

confidence: 99%

Enigma of Pyramidal Neurons: Congruence to Molecular, Cellular, Physiological, Cognitive and Psychological Function

Dyakin¹

2023

Preprint

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In bilaterians organism, the signaling of pyramidal neurons (PyrNs) is linked to the relative (prevalent) molecular chirality and physiological, perceptual, cognitive, and psychological functions and dysfunctions, providing the coupling of the central nervous system downstream and upstream evolutionary and developmental processes. The most apparent and discriminating morphological specificity of PyrNs is the geometry of the cell body. However, the question "why/how PyrNs soma gains the shape of quasi-tetrahedral symmetry" has never been explicitly articulated. If the basic function of PyrNs is sensory space perception, supporting the orientation, and movement coordination, then the pyramidal shape of soma is the best evolutionary-selected geometry to perform sensory-motor coupling. In biology, the impact of chiral symmetry (handedness) is evident at all levels of biological organization, from the prevalent symmetry of biological molecules to the morphology and function of bilateral organisms. How the tetrahedral symmetry of biomolecules is linked to the morphology and functions of bilateral organisms remains a challenging question. Cell chirality represents an intermediate point connecting two poles of biochirality. In this holistic perspective, examining the PyrNs' morphology-circuitry-function link is crucial to understanding the complex interaction between genetic, epigenetic, and environmental factors in the evolution of the CNS. The predictive power of our hypothesis can be partially expressed by the statement that the most integral and reliable biomarker of the neurodegenerative (including aging) and mental (including all variants of psychiatric illness) disorders would be the detection of the hemispheric asymmetry of D-amino acids (D-AAs) level in pyramidal neurons (PyrNs).

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“…Hemispheric specialization is a crucial aspect of brain organization that supports human cognitive functions, including language and attention (Hartwigsen et al, 2021; Hervé et al, 2013; Ocklenburg & Mundorf, 2022; Toga & Thompson, 2003; Vallortigara & Rogers, 2020; Wan et al, 2022). Previous research has shown neuroanatomical differences between the left and right hemispheres at the macroscale (Amunts et al, 2003; Glasser et al, 2022; Goldberg et al, 2013; Kong et al, 2018; Kuo & Massoud, 2022; Sha et al, 2021; Williams et al, 2023).…”

Section: Mainmentioning

confidence: 99%

Microstructural asymmetry in the human cortex

Wan,

Saberi,

Paquola

et al. 2024

Preprint

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While macroscale brain asymmetry and its relevance for human cognitive function have been consistently shown, the underlying neurobiological signatures remain an open question. Here, we probe layer-specific microstructural asymmetry of the human cortex using intensity profiles from post-mortem cytoarchitecture. An anterior-posterior cortical pattern of left-right asymmetry was found, varying across cortical layers. A similar anterior-posterior pattern was observed using in vivo microstructural imaging, with in vivo asymmetry showing the strongest similarity with layer III. Microstructural asymmetry varied as a function of age and sex and was found to be heritable. Moreover, asymmetry in microstructure corresponded to asymmetry of intrinsic function, in particular in sensory areas. Last, probing the behavioral relevance, we found differential association of language and markers of mental health with asymmetry, illustrating a functional divergence between inferior-superior and anterior-posterior microstructural axes anchored in microstructural development. Our study highlights the layer-based patterning of microstructural asymmetry of the human cortex and its functional relevance.

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Symmetry and asymmetry in biological structures

Cited by 27 publications

References 10 publications

Bias in the arrival of variation can dominate over natural selection in Richard Dawkins’s biomorphs

Bias in the arrival of variation can dominate over natural selection in Richard Dawkins’s biomorphs

Enigma of Pyramidal Neurons: Congruence to Molecular, Cellular, Physiological, Cognitive and Psychological Function

Microstructural asymmetry in the human cortex

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