scholarly journals The Emergence of the Bilateral Symmetry in Animals: A Review and a New Hypothesis

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 261
Author(s):  
Søren Toxvaerd
Keyword(s):  
Rotational Symmetry ◽  
Bilateral Symmetry ◽  
Enzymatic Reactions ◽  
Undifferentiated Cell ◽  
Biological Cells ◽  
Biological Organism ◽  
New Hypothesis ◽  
Biological Organisms

Most biological organisms exhibit different kinds of symmetry; an Animal (Metazoa), which is our Darwinist ancestor, has bilateral symmetry, and many plants exhibit rotational symmetry. It raises some questions: I. How can the evolution from an undifferentiated cell without bilateral symmetry to a complex biological organism with symmetry, which is based on asymmetric DNA and enzymes, lead to the bilateral symmetry? II. Is this evolution to an organism with bilateral symmetry obtained by other factors than DNA and enzymatic reactions? The existing literature about the evolution of the bilateral symmetry has been reviewed, and a new hypothesis has been formulated based on these reviews. The hypothesis is that the morphogenesis of biosystems is connected with the metabolism and that the oscillating kinetics in the Glycolysis have played a role in the polarity of the biological cells and in the establishment of the bilateral symmetry in Animals.

scholarly journals Geometric morphometrics of nested symmetries: Hierarchical INTER- AND INTRA-INDIVIDUAL VARIATION IN BIOLOGICAL SHAPES

2018 ◽  
Author(s):  
Yoland Savriama ◽  
Sylvain Gerber
Keyword(s):  
Individual Variation ◽  
Biological Object ◽  
Sea Urchins ◽  
Rotational Symmetry ◽  
Large Body ◽  
Bilateral Symmetry ◽  
Morphological Integration ◽  
Full Symmetry ◽  
Masticatory Apparatus ◽  
Complex Organ

AbstractSymmetry is a pervasive feature of organismal shape and the focus of a large body of research in Biology. Here, we consider complex patterns of symmetry where a phenotype exhibits a hierarchically structured combination of symmetries. We extend the Procrustes ANOVA for the analysis of nested symmetries and the decomposition of the overall morphological variation into components of symmetry (among-individual variation) and asymmetry (directional and fluctuating asymmetry). We illustrate its use with the Aristotle’s lantern, the masticatory apparatus of ‘regular’ sea urchins, a complex organ displaying bilateral symmetry nested within five-fold rotational symmetry. Our results highlight the importance of characterising the full symmetry of a structure with nested symmetries. Higher order rotational symmetry appears strongly constrained and developmentally stable compared to lower level bilateral symmetry. This contrast between higher and lower levels of asymmetry is discussed in relation to the spatial pattern of the lantern morphogenesis. This extended framework is applicable to any biological object exhibiting nested symmetries, regardless of their type (e.g., bilateral, rotational, translational). Such cases are extremely widespread in animals and plants, from arthropod segmentation to angiosperm inflorescence and corolla shape. The method therefore widens the research scope on developmental instability, canalization, developmental modularity and morphological integration.

scholarly journals MSBOTS: a multiple small biological organism tracking system robust against non-ideal detection and segmentation conditions

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11750
Author(s):  
Xiaoying Wang ◽  
Eva Cheng ◽  
Ian S. Burnett
Keyword(s):  
Standard Deviation ◽  
State Of The Art ◽  
Tracking System ◽  
Pharmaceutical Research ◽  
Research Use ◽  
Public Research ◽  
Biological Organism ◽  
Movement Trajectories ◽  
Imaging Conditions ◽  
Biological Organisms

Accurately tracking a group of small biological organisms using algorithms to obtain their movement trajectories is essential to biomedical and pharmaceutical research. However, object mis-detection, segmentation errors and overlapped individual trajectories are particularly common issues that restrict the development of automatic multiple small organism tracking research. Extending on previous work, this paper presents an accurate and generalised Multiple Small Biological Organism Tracking System (MSBOTS), whose general feasibility is tested on three types of organisms. Evaluated on zebrafish, Artemia and Daphnia video datasets with a wide variety of imaging conditions, the proposed system exhibited decreased overall Multiple Object Tracking Precision (MOTP) errors of up to 77.59%. Moreover, MSBOTS obtained more reliable tracking trajectories with a decreased standard deviation of up to 47.68 pixels compared with the state-of-the-art idTracker system. This paper also presents a behaviour analysis module to study the locomotive characteristics of individual organisms from the obtained tracking trajectories. The developed MSBOTS with the locomotive analysis module and the tested video datasets are made freely available online for public research use.

scholarly journals From spiral cleavage to bilateral symmetry: The developmental cell lineage of the annelid brain

2018 ◽  
Author(s):  
Pavel Vopalensky ◽  
Maria Antonietta Tosches ◽  
Kaia Achim ◽  
Mette Handberg-Thorsager ◽  
Detlev Arendt
Keyword(s):  
Nervous System ◽  
Marine Invertebrates ◽  
Rotational Symmetry ◽  
Cell Lineage ◽  
Bilateral Symmetry ◽  
Cell Types ◽  
Spiral Cleavage ◽  
Larval Brain ◽  
Larval Stages ◽  
Extensive Cell

AbstractThe spiral cleavage pattern is characteristic for Spiralia (Lophotrochozoa), a large assembly of marine invertebrates. In most cases, spiral cleavage produces freely swimming, trochophora-type larvae with a simple nervous system that controls ciliary locomotion. These larvae acquire bilateral symmetry, as manifested for example in the larval brain. The transition from the rotational symmetry of spiral cleavage into the bilateral adult body has not yet been understood. Here, we present the developmental cell lineage of the brain of the annelid Platynereis dumerilii from the zygote until the mid-trochophore stage (~30 hpf), in combination with a gene expression atlas for several embryonic and larval stages. Comparison of multiple embryos reveals a highly stereotypical development and an invariant cell lineage of the differentiated cell types. In addition, we observe a fundamental subdivision of the larval brain into a highly proliferative dorsolateral region and an early differentiating ventromedial region that gives rise to the apical nervous system. The transition from rotational to bilateral symmetry progresses gradually from the lateral to the central regions. Strikingly, the spiral-to-bilateral transition does not involve extensive cell migration. Rather, corresponding cells in different spiral quadrants acquire highly divergent identities in line with their bilateral position.

scholarly journals Personal identity and the psychological continuity theory

2020 ◽  
Vol 63 (3) ◽  
pp. 87-104
Author(s):  
Mirjana Sokic
Keyword(s):  
Personal Identity ◽  
Critical Analysis ◽  
Essential Property ◽  
Sufficient Criterion ◽  
Psychological Continuity ◽  
Continuity Theory ◽  
Biological Organism ◽  
Biological Organisms

According to the psychological continuity theory - which is one of the most popular philosophical approaches to the problem of personal identity -some sort of psychological relation represents the necessary (although, perhaps not the sufficient) criterion of a person?s persistence through time. The main aim of this paper is to provide a detailed critical analysis of two well-known arguments against the psychological continuity theory, both of which heavily rely on the animalist view on personal identity; that is to say, on the view according to which the essential property of persons is that they are biological organisms. The first argument purports to refute the psychological continuity theory by appealing to the fact that all persons are numerically identical to fetuses and that it is utterly implausible to attribute psychological properties or capacities to fetuses. The second argument attempts to show that every person is numerically identical to the biological organism that remains after its death and which does not have any psychological properties and capabilities. Hopefully, the final result of the analysis in this paper will show that the two arguments do not represent a satisfactory alternative to the psychological continuity theory.

Exemplification and Characterization Moves in the Classroom Teaching of Geometry Concepts

1980 ◽  
Vol 11 (1) ◽  
pp. 10-21
Author(s):  
Randall I. Charle
Keyword(s):  
Preservice Teachers ◽  
Small Groups ◽  
Rotational Symmetry ◽  
Bilateral Symmetry ◽  
Concept Acquisition ◽  
Classroom Teaching ◽  
Second Grade ◽  
Second Grade Students ◽  
Trained Teachers

The purposes of this study were to determine whether teachers can be trained to use exemplification (E) and characterization (C) moves and whether the use of these moves facilitates concept acquisition. Each of 18 preservice teachers (9 trained, 9 control) taught two 20-minute lessons on geometry concepts to small groups of second-grade students. Significant differences favoring the trained teachers were found for the number of E and C moves. Mean student posttest scores for the trained teachers were significantly greater than scores for the control teachers. The number of nonexamples used for teaching bilateral symmetry and the number of examples used for teaching rotational symmetry accounted for a significant amount of the variance in posttest scores.

Comparison of Calculated and Recorded Electron Energy-Loss Spectra of Aluminium and Carbon

1990 ◽  
Vol 48 (2) ◽  
pp. 64-65
Author(s):  
L. Reimer ◽  
R. Oelgeklaus
Keyword(s):  
Fourier Transform ◽  
Energy Loss ◽  
Electron Energy ◽  
Rotational Symmetry ◽  
Mean Free Path ◽  
Single Scattering ◽  
Specimen Thickness ◽  
Two Dimensional ◽  
Image Position ◽  
Electron Energy Loss

Quantitative electron energy-loss spectroscopy (EELS) needs a correction for the limited collection aperture α and a deconvolution of recorded spectra for eliminating the influence of multiple inelastic scattering. Reversely, it is of interest to calculate the influence of multiple scattering on EELS. The distribution f(w,θ,z) of scattered electrons as a function of energy loss w, scattering angle θ and reduced specimen thickness z=t/Λ (Λ=total mean-free-path) can either be recorded by angular-resolved EELS or calculated by a convolution of a normalized single-scattering function ϕ(w,θ). For rotational symmetry in angle (amorphous or polycrystalline specimens) this can be realised by the following sequence of operations :(1)where the two-dimensional distribution in angle is reduced to a one-dimensional function by a projection P, T is a two-dimensional Fourier transform in angle θ and energy loss w and the exponent -1 indicates a deprojection and inverse Fourier transform, respectively.

A New Hypothesis About Schizophrenia

2002 ◽  
Author(s):  
H. W. Moises ◽  
T. Zoega ◽  
I. I. Gottesman
Keyword(s):  
New Hypothesis

An Electronic Study Form to Support Collaborating Agents in the Management of Clinical Knowledge

1999 ◽  
Vol 38 (03) ◽  
pp. 154-157
Author(s):  
W. Fierz ◽  
R. Grütter
Keyword(s):  
Procedural Knowledge ◽  
Health Care Provision ◽  
Markup Language ◽  
Artificial Agents ◽  
Care Provision ◽  
Clinical Knowledge ◽  
Extensible Markup ◽  
Implementation Level ◽  
Biological Organisms ◽  
Representation Of Knowledge

AbstractWhen dealing with biological organisms, one has to take into account some peculiarities which significantly affect the representation of knowledge about them. These are complemented by the limitations in the representation of propositional knowledge, i. e. the majority of clinical knowledge, by artificial agents. Thus, the opportunities to automate the management of clinical knowledge are widely restricted to closed contexts and to procedural knowledge. Therefore, in dynamic and complex real-world settings such as health care provision to HIV-infected patients human and artificial agents must collaborate in order to optimize the time/quality antinomy of services provided. If applied to the implementation level, the overall requirement ensues that the language used to model clinical contexts should be both human- and machine-interpretable. The eXtensible Markup Language (XML), which is used to develop an electronic study form, is evaluated against this requirement, and its contribution to collaboration of human and artificial agents in the management of clinical knowledge is analyzed.

On the origin of khutū

2008 ◽  
Vol 35 (2) ◽  
pp. 306-318 ◽  
Author(s):  
C. LAVERS ◽  
M. KNAPP
Keyword(s):  
Twentieth Century ◽  
Medieval Literature ◽  
Ice Age ◽  
New Hypothesis

Khutū was a material derived from an animal used by Medieval Asian peoples in the manufacture of knife handles and as an alexipharmic. Al-Bīrūnī (973–1048) made extensive enquiries into the origin of khutū but reached no definite conclusion. Literary scholars in the first half of the twentieth century identified the walrus and narwhal as probable sources, but in ignoring aspects of the literature on khutū’s appearance and provenance left a number of questions unanswered. We clarify and extend this research and identify further clues to the identity of khutū. We concur that walrus ivory was one source of khutū, suggest that the remains of “Ice Age” mammals may have influenced development of the medieval literature on khutū more than previous investigators realized, and offer a new hypothesis of khutū’s origin.

Sign in / Sign up

Export Citation Format

Share Document