scholarly journals Switching environments, synchronous sex, and the evolution of mating types

2020 ◽  
Author(s):  
Ernesto Berríos-Caro ◽  
Tobias Galla ◽  
George W. A. Constable
Keyword(s):  
Lower Number ◽  
Integer Partitions ◽  
Mating Types ◽  
Biological Processes ◽  
Selective Sweeps ◽  
Kolmogorov Equations ◽  
Switching Regimes ◽  
Analytic Approximations ◽  
Model Dynamics ◽  
Slow Switching

While facultative sex is common in sexually reproducing species, for reasons of tractability most mathematical models assume that such sex is asynchronous in the population. In this paper, we develop a model of switching environments to instead capture the effect of an entire population transitioning synchronously between sexual and asexual modes of reproduction. We use this model to investigate the evolution of the number of self-incompatible mating types in finite populations, which empirically can range from two to thousands. When environmental switching is fast, we recover the results of earlier studies that implicitly assumed populations were engaged in asynchronous sexual reproduction. However when the environment switches slowly, we see deviations from previous asynchronous theory, including a lower number of mating types at equilibrium and bimodality in the stationary distribution of mating types. We provide analytic approximations for both the fast and slow switching regimes, as well as a numerical scheme based on the Kolmogorov equations for the system to quickly evaluate the model dynamics at intermediate parameters. Our approach exploits properties of integer partitions in number theory. We also demonstrate how additional biological processes such as selective sweeps can be accounted for in this switching environment framework, showing that beneficial mutations can further erode mating type diversity in synchronous facultatively sexual populations.

Fluorescent potentiometric dyes for membrane-potential imaging

1994 ◽  
Vol 52 ◽  
pp. 166-167
Author(s):  
Leslie M. Loew
Keyword(s):  
Membrane Potential ◽  
Single Cells ◽  
Quantitative Imaging ◽  
Optical Recording ◽  
Biological Processes ◽  
Major Focus ◽  
The Past ◽  
Excitable Systems ◽  
Major Application ◽  
The Impact

A major application of potentiometric dyes has been the multisite optical recording of electrical activity in excitable systems. After being championed by L.B. Cohen and his colleagues for the past 20 years, the impact of this technology is rapidly being felt and is spreading to an increasing number of neuroscience laboratories. A second class of experiments involves using dyes to image membrane potential distributions in single cells by digital imaging microscopy - a major focus of this lab. These studies usually do not require the temporal resolution of multisite optical recording, being primarily focussed on slow cell biological processes, and therefore can achieve much higher spatial resolution. We have developed 2 methods for quantitative imaging of membrane potential. One method uses dual wavelength imaging of membrane-staining dyes and the other uses quantitative 3D imaging of a fluorescent lipophilic cation; the dyes used in each case were synthesized for this purpose in this laboratory.

Apoptosis and development

2003 ◽  
Vol 39 ◽  
pp. 11-24 ◽  
Author(s):  
Justin V McCarthy
Keyword(s):  
Drosophila Melanogaster ◽  
Mammalian Cells ◽  
Cell Number ◽  
Model Organisms ◽  
Biological Processes ◽  
Nematode Caenorhabditis Elegans ◽  
Apoptotic Pathway ◽  
Genetic Pathways ◽  
Evolutionarily Conserved ◽  
Multicellular Organisms

Apoptosis is an evolutionarily conserved process used by multicellular organisms to developmentally regulate cell number or to eliminate cells that are potentially detrimental to the organism. The large diversity of regulators of apoptosis in mammalian cells and their numerous interactions complicate the analysis of their individual functions, particularly in development. The remarkable conservation of apoptotic mechanisms across species has allowed the genetic pathways of apoptosis determined in lower species, such as the nematode Caenorhabditis elegans and the fruitfly Drosophila melanogaster, to act as models for understanding the biology of apoptosis in mammalian cells. Though many components of the apoptotic pathway are conserved between species, the use of additional model organisms has revealed several important differences and supports the use of model organisms in deciphering complex biological processes such as apoptosis.

A Dynamic Systems Approach to Personality

2001 ◽  
Vol 6 (3) ◽  
pp. 172-176 ◽  
Author(s):  
Lawrence A. Pervin
Keyword(s):  
Dynamic Systems ◽  
Systems Approach ◽  
Biological Processes ◽  
Recent Advances ◽  
Dynamic View ◽  
The Future ◽  
History Of

David Magnusson has been the most articulate spokesperson for a holistic, systems approach to personality. This paper considers three concepts relevant to a dynamic systems approach to personality: dynamics, systems, and levels. Some of the history of a dynamic view is traced, leading to an emphasis on the need for stressing the interplay among goals. Concepts such as multidetermination, equipotentiality, and equifinality are shown to be important aspects of a systems approach. Finally, attention is drawn to the question of levels of description, analysis, and explanation in a theory of personality. The importance of the issue is emphasized in relation to recent advances in our understanding of biological processes. Integrating such advances into a theory of personality while avoiding the danger of reductionism is a challenge for the future.

Mechanisms of Signaling through Urokinase Receptor and the Cellular Response

1999 ◽  
Vol 82 (08) ◽  
pp. 305-311 ◽  
Author(s):  
Yuri Koshelnick ◽  
Monika Ehart ◽  
Hannes Stockinger ◽  
Bernd Binder
Keyword(s):  
Cell Surface ◽  
Proteolytic Activity ◽  
Tumor Invasion ◽  
Cellular Response ◽  
Transmembrane Protein ◽  
Urokinase Receptor ◽  
Biological Processes ◽  
In Vivo Models ◽  
Proteolytic Activation ◽  
Core Proteins

IntroductionThe urokinase-urokinase receptor (u-PA-u-PAR) system seems to play a crucial role in a number of biological processes, including local fibrinolysis, tumor invasion, angiogenesis, neointima and atherosclerotic plaque formation, inflammation, and matrix remodeling during wound healing and development.1-6 Binding of urokinase to its specific receptor provides cells with a localized proteolytic potential. It stimulates conversion of cell surface-bound plasminogen into active plasmin, which, in turn, is required for proteolytic degradation of basement membrane components, including fibronectin, collagen, laminin, and proteoglycan core proteins.7 Moreover, plasmin activates other matrix-degrading enzymes, such as matrix metalloproteinases.8 Overexpression of u-PA/u-PAR correlates with tumor invasion and metastasis formation,9-13 while reduction of cell-surface bound u-PA and inhibition of u-PAR expression leads to a significant decrease of invasive and metastatic activity.14 Specific antagonists that suppress binding of u-PA to u-PAR have been shown to inhibit cell-surface plasminogen activation, tumor growth, and angiogenesis both in vitro and in vivo models.15,16 Independently of its proteolytic activity, u-PA is implicated in many biological processes that seem to require u-PAR-mediated intracellular signal transduction, such as proliferation, chemotactic movement and adhesion, migration, and differentiation.17 Data obtained in the late 1980s indicated that u-PA not only provides cells with local proteolytic activity, but might also be capable of transducing signals to the cell.18-22 At that time, however, the u-PAR has just been isolated, cloned, and identified as a glycosylphosphatidylinositol (GPI)-linked protein and not a transmembrane protein. Signaling via the u-PAR was, therefore, regarded as being unlikely, and the effects of u-PA on cell proliferation18-22 were thought to be mediated by proteolytic activation of latent growth factors. The assumption of direct signaling via u-PAR was, in fact, considered controversial, until about 10 years later when a physical association between u-PAR and signaling proteins was found.23 From this report on, several proteins associated with u-PAR have been identified. Now, u-PAR seems to be part of a large “signalosome” associated and interacting with several proteins on both the outside and inside of the cell.

The Datalogical Drug Mule

2017 ◽  
Vol 3 (3) ◽  
pp. 9-29
Author(s):  
Juan Llamas-Rodriguez
Keyword(s):  
Information And Communication Technologies ◽  
Communication Technologies ◽  
Data Driven ◽  
Biological Processes ◽  
Cultural Narratives ◽  
Government Documents ◽  
Human Labor ◽  
Information And Communication ◽  
Data Capturing ◽  
Legal Structures

Borders and bodies are increasingly regulated by data-capturing mechanisms spread across the world through information and communication technologies. This article traces the features and implications of such a border-body datalogical entanglement through the figure of the drug mule. It analyzes government documents and recorded case studies to argue that this figure emerges from an assemblage of cultural narratives, legal structures, human labor, technical practices, and biological processes. The datalogical drug mule is already implicated in a struggle over what, and how, data is meaningful and actionable. Investigating this figure allows us to begin disentangling the data-driven mechanisms that constitute modern borders and bodies while at the same time accounting for analog continuities in contemporary practices of border security.

Electrical Capacitance Volume Tomography (ECVT) for industrial and medical applications-An Overview

2015 ◽  
Vol 11 (1) ◽  
pp. 2897-2908
Author(s):  
Mohammed S.Aljohani
Keyword(s):  
Imaging Technique ◽  
Three Dimensional ◽  
Biological Processes ◽  
Electrical Capacitance ◽  
Image Reconstruction Techniques ◽  
Phase Dynamics ◽  
Non Invasive ◽  
Electrical Capacitance Volume Tomography ◽  
And Performance ◽  
Optimization And Performance

Tomography is a non-invasive, non-intrusive imaging technique allowing the visualization of phase dynamics in industrial and biological processes. This article reviews progress in Electrical Capacitance Volume Tomography (ECVT). ECVT is a direct 3D visualizing technique, unlike three-dimensional imaging, which is based on stacking 2D images to obtain an interpolated 3D image. ECVT has recently matured for real time, non-invasive 3-D monitoring of processes involving materials with strong contrast in dielectric permittivity. In this article, ECVT sensor design, optimization and performance of various sensors seen in literature are summarized. Qualitative Analysis of ECVT image reconstruction techniques has also been presented.

Update regarding anemia in heart failure

Medic ro ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 8-13
Author(s):  
Roxana Marcela Sânpălean ◽  
Dorina Nastasia Petra
Keyword(s):  
Heart Failure ◽  
Iron Deficiency ◽  
Multidisciplinary Team ◽  
Significant Proportion ◽  
Life Quality ◽  
Lower Number ◽  
Nutritional Deficiencies ◽  
Cardiac Morbidity ◽  
Appropriate Treatment

Heart failure (HF) is a burden for the healthcare system. The incidence will increase significantly due to the aging of po­pu­la­tion, which is associated with multiple comorbidities. Ane­mia and iron deficiency are common in patients with HF, their etiology being often multifactorial. The screening for anemia and iron deficiency is recommended as soon as pos­si­ble. There are often no targeted investigations, therefore a significant proportion of cases are underdiagnosed. The ma­nagement of patients may focus on identifying and correcting the cause. Anemia can occur due to nutritional deficiencies, infla­m­mation, renal failure, bone marrow dysfunction, neuro­hor­mo­nal activity, treatment and hemodilution. The appropriate the­ra­py for the patients with anemia and HF will contribute to the improvement of life quality. The only recommended iron product is ferric carboxymalose administered by in­tra­venous infusion. Under the appropriate treatment, the pa­tients showed an increase in effort tolerance, with an im­prove­ment in symptomatology and a lower number of hos­pi­ta­li­za­tion days. The management of these cases is handled by a multidisciplinary team consisting of a general prac­ti­tio­ner, a cardiologist and other specialists if the patient has other comorbidities. The role of the general practitioner is essential, as he can perform proper screening, prevention and management, developed by a multidisciplinary team, in order to reduce the cardiac morbidity and mortality.  

Biomimetic Extracellular Vesicles Embedded with Black Phosphorus for Molecular Recognition-Guided Biomineralization

2018 ◽  
Author(s):  
Yingqian Wang ◽  
Xiaoxia Hu ◽  
Lingling Zhang ◽  
Chunli Zhu ◽  
Jie Wang ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Extracellular Vesicles ◽  
Inorganic Phosphate ◽  
Physiological Activity ◽  
Medical Engineering ◽  
Matrix Vesicles ◽  
Black Phosphorus ◽  
Photothermal Effect ◽  
Biological Processes ◽  
Extracellular Environment

Extracellular vesicles (EVs) are involved in the regulation of cell physiological activity and the reconstruction of extracellular environment. Matrix vesicles (MVs) are a type of EVs, and they participate in the regulation of cell mineralization. Herein, bioinspired MVs embedded with black phosphorus are functionalized with cell-specific aptamer (denoted as Apt-bioinspired MVs) for stimulating biomineralization. The aptamer can direct bioinspired MVs to targeted cells, and the increasing concentration of inorganic phosphate originated from the black phosphorus can facilitate cell biomineralization. The photothermal effect of the Apt-bioinspired MVs also positively affects mineralization. In addition, the Apt-bioinspired MVs display outstanding bone regeneration performance. Considering the excellent behavior of the Apt-bioinspired MVs for promoting biomineralization, our strategy provides a way of designing bionic tools for studying the mechanisms of biological processes and advancing the development of medical engineering.<br>

Quantum Mechanical Calculations Suggest That Lignin Polymerization Is Kinetically Controlled

2019 ◽  
Author(s):  
Terry Gani ◽  
Michael Orella ◽  
Eric Anderson ◽  
Michael Stone ◽  
Fikile Brushett ◽  
...  
Keyword(s):  
Plant Cell ◽  
First Principles ◽  
Plant Cell Wall ◽  
Biological Processes ◽  
Plant Cell Walls ◽  
Biomass Valorization ◽  
Effective Strategies ◽  
Radical Coupling ◽  
Kinetically Controlled ◽  
Atomistic Models

Lignin is an abundant biopolymer important for plant function while holding promise as a renewable source of valuable chemicals. Although the lignification process in plant cell walls has been long-studied, a comprehensive, mechanistic understanding on the molecular scale remains elusive. A better understanding of lignification will lead to improved atomistic models of the plant cell wall that could, in turn, inform effective strategies for biomass valorization. Here, using first-principles quantum chemical calculations, we show that a simple model of kinetically-controlled radical coupling broadly rationalizes qualitative experimental observations of lignin structure across a wide variety of biomass types, thus paving the way for predictive, first-principles models of lignification while highlighting the ability of computational chemistry to help illuminate complex biological processes.

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