scholarly journals New holozoans with cellular resolution from the early Ediacaran Weng'an Biota, Southwest China

2021 ◽  
pp. jgs2021-061
Author(s):  
Zongjun Yin ◽  
Weichen Sun ◽  
Joachim Reitner ◽  
Maoyan Zhu
Keyword(s):  
Southwest China ◽  
Three Dimensional ◽  
Testate Amoebae ◽  
Cambrian Explosion ◽  
Cellular Slime Mold ◽  
Circular Opening ◽  
Content Type ◽  
Biological Affinity ◽  
Cellular Slime ◽  
Phylogenetic Affinities

The embryo-like fossils from the early Ediacaran Weng'an Biota (Southwest China, 609 million years ago), widely interpreted as members of holozoans, potentially provide insights to understanding the early evolution of development of metazoans and the rise of the animal kingdom. However, the biodiversity of the embryo-like fossil assemblage is largely underestimated, and its more precise phylogenetic affinities within the holozoan tree are still under debate. Here we describe a new species of embryo-like fossil Ostiosphaera rara n. gen. n. sp. from the Ediacaran Weng'an Biota. These three-dimensional, phosphatized specimens exhibit a spherical morphology, an ornamented thick envelope with a circular opening and a membrane-bounded, multicellular inner body. In terms of biological characteristics, Ostiosphaera rara show similarities to a number of extant and fossil analogues including testate amoebae, unicellular green algae, cellular slime mold Fonticuida and co-occurring Weng'an embryo-like fossils. Although the phylogenetic affinity of Ostiosphaera rara is difficult to constrain very precisely based on the available evidence, it is reasonable to follow the holozoan interpretation for them, since that they share the same grade complexity with the co-occurring embryo-like fossils such as Megasphaera and Helicoforamina in terms of the combination of biological features. It is worth mentioning that the new holozoans resemble asexual reproductive gemmules of fossil and living demosponges in size, morphology, circular opening, and cellular anatomy. If the similarity between them reflects biological affinity rather than convergent evolution, this discovery would force us to rethink the evolutionary history of Precambrian sponges.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

scholarly journals A way of following individual cells in the migrating slugs ofDictyostelium discoideum

1998 ◽  
Vol 95 (16) ◽  
pp. 9355-9359 ◽  
Author(s):  
J. T. Bonner
Keyword(s):  
Dictyostelium Discoideum ◽  
Three Dimensional ◽  
Time Lapse ◽  
Mineral Oil ◽  
New Method ◽  
Environmental Cues ◽  
Cellular Slime Mold ◽  
High Point ◽  
Cellular Slime ◽  
The Individual

In the development of the cellular slime moldDictyostelium discoideumthere is a stage in which the aggregated amoebae form a migrating slug that moves forward in a polar fashion, showing sensitive orientation to environmental cues, as well as early signs of differentiation into anterior prestalk and posterior prespore cells. Heretofore it has been difficult to follow the movement of the individual cells within the slug, but a new method is described in which small, flat (one cell thick) slugs are produced in a glass-mineral oil interface where one can follow the movement of all the cells. Observations of time-lapse videos reveal the following facts about slug migration: (i) While the posterior cells move straight forward, the anterior cells swirl about rapidly in a chaotic fashion. (ii) Turning involves shifting the high point of these hyperactive cells. (iii) Both the anterior and the posterior cells move forward on their own power as the slug moves forward. (iv) There are no visible regular oscillations within the slug. (v) The number of prestalk and prespore cells is proportional for a range of sizes of these mini-slugs. All of these observations on thin slugs are consistent with what one finds in normal, three-dimensional slugs.

scholarly journals Characterization of the Roco Protein Family in Dictyostelium discoideum

2010 ◽  
Vol 9 (5) ◽  
pp. 751-761 ◽  
Author(s):  
Wouter N. van Egmond ◽  
Peter J. M. van Haastert
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Formation ◽  
Slime Mold ◽  
Stalk Cell ◽  
Cellular Slime Mold ◽  
Developmental Defects ◽  
Content Type ◽  
Ras Gtpases ◽  
Cellular Slime

ABSTRACT The Roco family consists of multidomain Ras-GTPases that include LRRK2, a protein mutated in familial Parkinson's disease. The genome of the cellular slime mold Dictyostelium discoideum encodes 11 Roco proteins. To study the functions of these proteins, we systematically knocked out the roco genes. Previously described functions for GbpC, Pats1, and QkgA (Roco1 to Roco3) were confirmed, while novel developmental defects were identified in roco4- and roco11-null cells. Cells lacking Roco11 form larger fruiting bodies than wild-type cells, while roco4-null cells show strong developmental defects during the transition from mound to fruiting body; prestalk cells produce reduced levels of cellulose, leading to unstable stalks that are unable to properly lift the spore head. Detailed phylogenetic analysis of four slime mold species reveals that QkgA and Roco11 evolved relatively late by duplication of an ancestor roco4 gene (later than ∼300 million years ago), contrary to the situation with other roco genes, which were already present before the split of the common ancestor of D. discoideum and Polysphondylium pallidum (before ∼600 million years ago). Together, our data show that the Dictyostelium Roco proteins serve a surprisingly diverse set of functions and highlight Roco4 as a key protein for proper stalk cell formation.

Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 90-92 ◽  
Author(s):  
Mark E. Linskey
Keyword(s):  
Gamma Knife ◽  
Stereotactic Radiotherapy ◽  
Three Dimensional ◽  
Late Recurrence ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Complication Rates ◽  
Content Type ◽  
Single Fraction ◽  
Fine Print

✓ By definition, the term “radiosurgery” refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed “stereotactic radiotherapy.” There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image—targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS “halo effect.” It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the expense of potential late recurrence. The answer to minimizing complications while maintaining maximum tumor control is improved conformality of radiosurgery dose planning and not resorting to homeopathic radiosurgery doses or hypofractionation radiotherapy schemes.

scholarly journals Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Emily G. Sweeney ◽  
Andrew Nishida ◽  
Alexandra Weston ◽  
Maria S. Bañuelos ◽  
Kristin Potter ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Three Dimensional ◽  
Structural Features ◽  
Agent Based Modeling ◽  
Emergent Properties ◽  
Cellular Interactions ◽  
Biofilm Growth ◽  
Content Type ◽  
Agent Based ◽  
H Pylori

ABSTRACTBacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms ofHelicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterizedH. pyloristrains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCEMost bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown thatHelicobacter pyloribacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and thatH. pylorimutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that localH. pyloribehavior of repulsion from high AI-2 could explain the overall architecture ofH. pyloribiofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.

A biomimetic 3D airflow sensor made of an array of two piezoelectric metal-core fibers

Sensor Review ◽  
2017 ◽  
Vol 37 (3) ◽  
pp. 312-321 ◽  
Author(s):  
Yixiang Bian ◽  
Can He ◽  
Kaixuan Sun ◽  
Longchao Dai ◽  
Hui Shen ◽  
...  
Keyword(s):  
Design Methodology ◽  
Spherical Surface ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Piezoceramic Cylinder ◽  
Metal Core ◽  
Content Type ◽  
3D Space ◽  
Highly Sensitive ◽  
Airflow Sensor

Purpose The purpose of this paper is to design and fabricate a three-dimensional (3D) bionic airflow sensing array made of two multi-electrode piezoelectric metal-core fibers (MPMFs), inspired by the structure of a cricket’s highly sensitive airflow receptor (consisting of two cerci). Design/methodology/approach A metal core was positioned at the center of an MPMF and surrounded by a hollow piezoceramic cylinder. Four thin metal films were spray-coated symmetrically on the surface of the fiber that could be used as two pairs of sensor electrodes. Findings In 3D space, four output signals of the two MPMFs arrays can form three “8”-shaped spheres. Similarly, the sensing signals for the same airflow are located on a spherical surface. Originality/value Two MPMF arrays are sufficient to detect the speed and direction of airflow in all three dimensions.

Comparison of the reluctance laminated and solid rotor synchronous machine operating at high temperatures

2019 ◽  
Vol 38 (4) ◽  
pp. 1111-1119 ◽  
Author(s):  
Marcin Lefik ◽  
Krzysztof Komeza ◽  
Ewa Napieralska-Juszczak ◽  
Daniel Roger ◽  
Piotr Andrzej Napieralski
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Three Dimensional ◽  
Synchronous Machine ◽  
Point Of View ◽  
Heat Sources ◽  
Model Calculations ◽  
Content Type ◽  
Thermal Phenomenon ◽  
Practical Implications

Purpose The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor. Design/methodology/approach To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used. Findings The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness. Research limitations/implications The main problem, despite the use of parallel calculations, is the long calculation time. Practical implications The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines. Originality/value The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

The generation of adaptive assembly from predicting change propagation

2015 ◽  
Vol 35 (3) ◽  
pp. 269-280 ◽  
Author(s):  
Hu Qiao ◽  
Rong Mo ◽  
Ying Xiang
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Original Method ◽  
Change Propagation ◽  
Assembly Model ◽  
Practical Application ◽  
Content Type ◽  
Design Structure ◽  
Aided Design ◽  
Practical Implications

Purpose – The purpose of this paper is to establish an adaptive assembly, to realize the adaptive changing of the models and to improve the flexibility and reliability of assembly change. For a three-dimensional (3D) computer-aided design (CAD) assembly in a changing process, there are two practical problems. One is delivering parameters’ information not smoothly. The other one is to easily destroy an assembly structure. Design/methodology/approach – The paper establishes associated parameters design structure matrix of related parts, and predicts possible propagation paths of the parameters. Based on the predicted path, structured storage is made for the affected parameters, tolerance range and the calculation relations. The study combines structured path information and all constrained assemblies to build the adaptive assembly, proposes an adaptive change algorithm for assembly changing and discusses the extendibility of the adaptive assembly. Findings – The approach would improve the flexibility and reliability of assembly change and be applied to different CAD platform. Practical implications – The examples illustrate the construction and adaptive behavior of the assembly and verify the feasibility and reasonability of the adaptive assembly in practical application. Originality/value – The adaptive assembly model proposed in the paper is an original method to assembly change. And compared with other methods, good results have been obtained.

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