scholarly journals Biophysical principles of choanoflagellate self-organization

2020 ◽  
Vol 117 (3) ◽  
pp. 1303-1311 ◽  
Author(s):  
Ben T. Larson ◽  
Teresa Ruiz-Herrero ◽  
Stacey Lee ◽  
Sanjay Kumar ◽  
L. Mahadevan ◽  
...  

Inspired by the patterns of multicellularity in choanoflagellates, the closest living relatives of animals, we quantify the biophysical processes underlying the morphogenesis of rosette colonies in the choanoflagellate Salpingoeca rosetta. We find that rosettes reproducibly transition from an early stage of 2-dimensional (2D) growth to a later stage of 3D growth, despite the underlying variability of the cell lineages. Our perturbative experiments demonstrate the fundamental importance of a basally secreted extracellular matrix (ECM) for rosette morphogenesis and show that the interaction of the ECM with cells in the colony physically constrains the packing of proliferating cells and, thus, controls colony shape. Simulations of a biophysically inspired model that accounts for the size and shape of the individual cells, the fraction of ECM, and its stiffness relative to that of the cells suffices to explain our observations and yields a morphospace consistent with observations across a range of multicellular choanoflagellate colonies. Overall, our biophysical perspective on rosette development complements previous genetic perspectives and, thus, helps illuminate the interplay between cell biology and physics in regulating morphogenesis.

2019 ◽  
Author(s):  
Ben T. Larson ◽  
Teresa Ruiz-Herrero ◽  
Stacey Lee ◽  
Sanjay Kumar ◽  
L. Mahadevan ◽  
...  

AbstractInspired by the patterns of multicellularity in choanoflagellates, the closest living relatives of animals, we quantify the biophysical processes underlying the morphogenesis of rosette colonies in the choanoflagellateSalpingoeca rosetta. We find that rosettes reproducibly transition from an early stage of 2D growth to a later stage of 3D growth, despite the underlying stochasticity of the cell lineages. We postulate that the extracellular matrix (ECM) exerts a physical constraint on the packing of proliferating cells, thereby sculpting rosette morphogenesis. Our perturbative experiments coupled with biophysical simulations demonstrates the fundamental importance of a basally-secreted ECM for rosette morphogenesis. In addition, this yields a morphospace for the shapes of these multicellular colonies, consistent with observations of a range of choanoflagellates. Overall, our biophysical perspective on rosette development complements previous genetic perspectives and thus helps illuminate the interplay between cell biology and physics in regulating morphogenesis.Significance statementComparisons among animals and their closest living relatives, the choanoflagellates, have begun to shed light on the origin of animal multicellularity and development. Here we complement previous genetic perspectives on this process by focusing on the biophysical principles underlying colony morphology and morphogenesis. Our study reveals the crucial role of the extracellular matrix in shaping the colonies and leads to a phase diagram that delineates the range of morphologies as a function of the biophysical mechanisms at play.


Author(s):  
Jinbao Zhang ◽  
Jaeyoung Lee

Abstract This study has two main objectives: (i) to analyse the effect of travel characteristics on the spreading of disease, and (ii) to determine the effect of COVID-19 on travel behaviour at the individual level. First, the study analyses the effect of passenger volume and the proportions of different modes of travel on the spread of COVID-19 in the early stage. The developed spatial autoregressive model shows that total passenger volume and proportions of air and railway passenger volumes are positively associated with the cumulative confirmed cases. Second, a questionnaire is analysed to determine changes in travel behaviour after COVID-19. The results indicate that the number of total trips considerably decreased. Public transport usage decreased by 20.5%, while private car usage increased by 6.4%. Then the factors affecting the changes in travel behaviour are analysed by logit models. The findings reveal significant factors, including gender, occupation and travel restriction. It is expected that the findings from this study would be helpful for management and control of traffic during a pandemic.


2020 ◽  
Vol 11 (1) ◽  
pp. 241
Author(s):  
Juliane Kuhl ◽  
Andreas Ding ◽  
Ngoc Tuan Ngo ◽  
Andres Braschkat ◽  
Jens Fiehler ◽  
...  

Personalized medical devices adapted to the anatomy of the individual promise greater treatment success for patients, thus increasing the individual value of the product. In order to cater to individual adaptations, however, medical device companies need to be able to handle a wide range of internal processes and components. These are here referred to collectively as the personalization workload. Consequently, support is required in order to evaluate how best to target product personalization. Since the approaches presented in the literature are not able to sufficiently meet this demand, this paper introduces a new method that can be used to define an appropriate variety level for a product family taking into account standardized, variant, and personalized attributes. The new method enables the identification and evaluation of personalizable attributes within an existing product family. The method is based on established steps and tools from the field of variant-oriented product design, and is applied using a flow diverter—an implant for the treatment of aneurysm diseases—as an example product. The personalization relevance and adaptation workload for the product characteristics that constitute the differentiating product properties were analyzed and compared in order to determine a tradeoff between customer value and personalization workload. This will consequently help companies to employ targeted, deliberate personalization when designing their product families by enabling them to factor variety-induced complexity and customer value into their thinking at an early stage, thus allowing them to critically evaluate a personalization project.


1982 ◽  
Vol 3 (4) ◽  
pp. 231-235 ◽  
Author(s):  
Ruth Engel

In this paper I hope to explain the reasons for developing a method to provide the individual with tools to cope with failure at an early stage of his life; additionally, the general principles of that method will be formulated. Obviously, the basic objective is ultimately aimed at conditioning the child's thinking towards development of different attitudes in relation to failure situations. Success of the method, in the long run, depends upon the repetition of similar techniques, at least during the first years of the child's schooling. Thus we tend to believe that if we ‘instil’ in the child the proposed way of relating, he will then be able to cope not only with failure in the future but also with pressures exerted by unskilled teachers in school, who may use failure as a threat. As an additional alternative there is proposed a general model of treating children who have not been trained at an earlier stage to deal with failure within the school framework.


Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3041
Author(s):  
Ren Jie Tuieng ◽  
Sarah H. Cartmell ◽  
Cliona C. Kirwan ◽  
Michael J. Sherratt

Exposure to sub-lethal doses of ionising and non-ionising electromagnetic radiation can impact human health and well-being as a consequence of, for example, the side effects of radiotherapy (therapeutic X-ray exposure) and accelerated skin ageing (chronic exposure to ultraviolet radiation: UVR). Whilst attention has focused primarily on the interaction of electromagnetic radiation with cells and cellular components, radiation-induced damage to long-lived extracellular matrix (ECM) proteins has the potential to profoundly affect tissue structure, composition and function. This review focuses on the current understanding of the biological effects of ionising and non-ionising radiation on the ECM of breast stroma and skin dermis, respectively. Although there is some experimental evidence for radiation-induced damage to ECM proteins, compared with the well-characterised impact of radiation exposure on cell biology, the structural, functional, and ultimately clinical consequences of ECM irradiation remain poorly defined.


2020 ◽  
Vol 14 (4) ◽  
pp. 719-728
Author(s):  
T. A. Klimova ◽  

Introduction. The paper addresses the issue of support of the students involved in a fully online retraining program, which imposes special requirements on the development of the self-education ability. The study aims to establish the conditions for organizing the support of self-education in a digital educational environment. Materials and methods. The study relies on the methodology proposed by G.N. Prozumentova for reconstructing the innovative experience to analyze the reflexive text materials of the Logbook of students of the retraining program; to identify the points of stress, misunderstanding, breaks, and transitions during training; and make an analytical generalization. Results of the study. Categories of difficulties encountered by students of the program in their self-educational activity were identified, and the conditions necessary to support self-education were established. These are points of self-determination, professional trials, points of reflection, and individual educational route. Conclusion. In the context of restrictive measures during the pandemic and the transition to the online educational process, self-skills related to self-education, i.e., self-organization, independence, and self-determination, become essential. These competences are an indispensable part of the work of a tutor. However, before the tutor can support someone, they need to build these self skills themselves. The established conditions in the retraining programs will facilitate this process. At the same time, additional studies are required to reveal in more detail the individual progress of a person under these conditions for building a model for supporting the development of self-education ability, and to determine the methods for tutors to provide the support of this progress. Keywords. Self-education, self-determination, individual educational route, professional retraining, tutor, digital environment, self skills.


Author(s):  
S. A. Yudin

The paper considers various approaches to studying the self-organization of students’ educational activity, the assumption about the interrelation of self-organization of educational activity and time perspective of the individual is made. The importance of self-organization of educational activity in the modern education system of higher education institutions comes to light. Stages of formation of self-organization and possible difficulties which a person can face are sorted out. Results of basic research of the time perspective and self-organization of university students are stated. The interrelation between commitment and alloted time is defined, as well as regularity, emotional coloring of time, structure of time and feeling of time. The received results specify the possible directions of the organization of forms of psychological support of university students having problems with self-organization of time in the educational process.


2021 ◽  
Vol 11 ◽  
Author(s):  
Ruoyue Tan ◽  
Guanghui Zhang ◽  
Ruochen Liu ◽  
Jianbing Hou ◽  
Zhen Dong ◽  
...  

Stomach adenocarcinoma (STAD) is a leading cause of cancer deaths, and the outcome of the patients remains dismal for the lack of effective biomarkers of early detection. Recent studies have elucidated the landscape of genomic alterations of gastric cancer and reveal some biomarkers of advanced-stage gastric cancer, however, information about early-stage biomarkers is limited. Here, we adopt Weighted Gene Co-expression Network Analysis (WGCNA) to screen potential biomarkers for early-stage STAD using RNA-Seq and clinical data from TCGA database. We find six gene clusters (or modules) are significantly correlated with the stage-I STADs. Among these, five hub genes, i.e., MS4A1, THBS2, VCAN, PDGFRB, and KCNA3 are identified and significantly de-regulated in the stage-I STADs compared with the normal stomach gland tissues, which suggests they can serve as potential early diagnostic biomarkers. Moreover, we show that high expression of VCAN and PDGFRB is associated with poor prognosis of STAD. VCAN encodes a large chondroitin sulfate proteoglycan that is the main component of the extracellular matrix, and PDGFRB encodes a cell surface tyrosine kinase receptor for members of the platelet-derived growth factor (PDGF) family. Consistently, Gene Ontology (GO) analysis of differentially expressed genes in the STADs indicates terms associated with extracellular matrix and receptor ligand activity are significantly enriched. Protein-protein network interaction analysis (PPI) and Gene Set Enrichment Analysis (GSEA) further support the core role of VCAN and PDGFRB in the tumorigenesis. Collectively, our study identifies the potential biomarkers for early detection and prognosis of STAD.


Sign in / Sign up

Export Citation Format

Share Document