Controlled polymerization of isoprene promoted by a type of hemilabile XPN3 (X = O, S) ligand supported cobalt(ii) complexes: the role of a hemilabile donor on the level of control

2017 ◽  
Vol 8 (11) ◽  
pp. 1805-1814 ◽  
Author(s):  
Huafeng Chen ◽  
Weijing Pan ◽  
Kuo-Wei Huang ◽  
Xuequan Zhang ◽  
Dirong Gong
Keyword(s):  
Controlled Polymerization ◽  
Cobalt Dichloride

Cobalt dichloride complexes (Co1–Co9) carrying a novel type of hemilabile donor PN3 (L1–L3) or XPN3 (L4–L6, X = O; L7–L9, X = S) are reported as precursors for controlled polymerization of isoprene.

scholarly journals Actin Filament Polymerization Regulates Gliding Motility by Apicomplexan Parasites

2003 ◽  
Vol 14 (2) ◽  
pp. 396-406 ◽  
Author(s):  
D.M. Wetzel ◽  
S. Håkansson ◽  
K. Hu ◽  
D. Roos ◽  
L.D. Sibley
Keyword(s):  
Plasma Membrane ◽  
Actin Filaments ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Gliding Motility ◽  
Cell Entry ◽  
Controlled Polymerization ◽  
Apicomplexan Parasites ◽  
Rate Limiting

Host cell entry by Toxoplasma gondii depends critically on actin filaments in the parasite, yet paradoxically, its actin is almost exclusively monomeric. In contrast to the absence of stable filaments in conventional samples, rapid-freeze electron microscopy revealed that actin filaments were formed beneath the plasma membrane of gliding parasites. To investigate the role of actin filaments in motility, we treated parasites with the filament-stabilizing drug jasplakinolide (JAS) and monitored the distribution of actin in live and fixed cells using yellow fluorescent protein (YFP)-actin. JAS treatment caused YFP-actin to redistribute to the apical and posterior ends, where filaments formed a spiral pattern subtending the plasma membrane. Although previous studies have suggested that JAS induces rigor, videomicroscopy demonstrated that JAS treatment increased the rate of parasite gliding by approximately threefold, indicating that filaments are rate limiting for motility. However, JAS also frequently reversed the normal direction of motility, disrupting forward migration and cell entry. Consistent with this alteration, subcortical filaments in JAS-treated parasites occurred in tangled plaques as opposed to the straight, roughly parallel orientation observed in control cells. These studies reveal that precisely controlled polymerization of actin filaments imparts the correct timing, duration, and directionality of gliding motility in the Apicomplexa.

scholarly journals Differential growth and shape formation in plant organs

2018 ◽  
Vol 115 (49) ◽  
pp. 12359-12364 ◽  
Author(s):  
Changjin Huang ◽  
Zilu Wang ◽  
David Quinn ◽  
Subra Suresh ◽  
K. Jimmy Hsia
Keyword(s):  
Flexible Electronics ◽  
Differential Growth ◽  
Controlled Polymerization ◽  
Plant Organs ◽  
Quantitative Measurements ◽  
Shape Formation ◽  
Growth Controls ◽  
3D Shapes ◽  
Scientific Framework

Morphogenesis is a phenomenon by which a wide variety of functional organs are formed in biological systems. In plants, morphogenesis is primarily driven by differential growth of tissues. Much effort has been devoted to identifying the role of genetic and biomolecular pathways in regulating cell division and cell expansion and in influencing shape formation in plant organs. However, general principles dictating how differential growth controls the formation of complex 3D shapes in plant leaves and flower petals remain largely unknown. Through quantitative measurements on live plant organs and detailed finite-element simulations, we show how the morphology of a growing leaf is determined by both the maximum value and the spatial distribution of growth strain. With this understanding, we develop a broad scientific framework for a morphological phase diagram that is capable of rationalizing four configurations commonly found in plant organs: twisting, helical twisting, saddle bending, and edge waving. We demonstrate the robustness of these findings and analyses by recourse to synthetic reproduction of all four configurations using controlled polymerization of a hydrogel. Our study points to potential approaches to innovative geometrical design and actuation in such applications as building architecture, soft robotics and flexible electronics.

Microtubules influence compaction in preimplantation mouse embryos

Development ◽  
1984 ◽  
Vol 84 (1) ◽  
pp. 217-232
Author(s):  
Bernard Maro ◽  
Susan J. Pickering
Keyword(s):  
Significant Extent ◽  
Surface Binding ◽  
Controlled Polymerization ◽  
Cell Stage ◽  
Surface Polarization ◽  
Preimplantation Mouse Embryos ◽  
Contrast Microscopy ◽  
Preimplantation Mouse ◽  
Cell Organization

The role of microtubules during compaction of the 8-cell-stage mouse embryo was investigated using the drugs Taxol (which leads to a non-controlled polymerization of tubulin) and Nocodazole (which causes depolymerization of microtubules). Taxol inhibits compaction in most non-compacted embryos and reverses it in already compacted embryos. These effects were observed on both cell flattening (as judged by phase-contrast microscopy) and on cell surface polarization (as judged by scanning electron microscopy and the surface binding of fluorescent concanavalin A). In contrast Nocodazole does not inhibit cell flattening, but rather accelerates its completion. Nocodazole influences the detailed organization of the surface pole and appears to reduce the incidence of surface polarization but does not reverse polarity once established to a significant extent. We conclude that microtubules exercise a constraining role during compaction, influencing cell shape, cell organization and the time at which compaction takes place.

scholarly journals The Role of Polymer Structure in Formation of Various Nano- and Microstructural Materials: 30 Years of Research in the Laboratory of Nano- and Microstructural Materials at the Centre of Polymer and Carbon Materials PAS

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2892
Author(s):  
Natalia Oleszko-Torbus ◽  
Barbara Mendrek ◽  
Agnieszka Kowalczuk ◽  
Wojciech Wałach ◽  
Barbara Trzebicka ◽  
...  
Keyword(s):  
Carbon Materials ◽  
Biologically Active ◽  
Linear Polymers ◽  
Controlled Polymerization ◽  
Physiochemical Properties ◽  
Wide Range ◽  
Methacrylate Monomers ◽  
Academy Of Sciences ◽  
Active Substances

The review summarizes the research carried out in the Laboratory of Nano- and Microstructural Materials at the Centre of Polymer and Carbon Materials, Polish Academy of Sciences (CMPW PAS). Studies carried out for many years under the guidance of Professor Andrzej Dworak led to the development and exploration of the mechanisms of oxirane and cyclic imine polymerization and controlled radical polymerization of methacrylate monomers. Based on that knowledge, within the last three decades, macromolecules with the desired composition, molar mass and topology were obtained and investigated. The ability to control the structure of the synthesized polymers turned out to be important, as it provided a way to tailor the physiochemical properties of the materials to their specific uses. Many linear polymers and copolymers as well as macromolecules with branched, star, dendritic and hyperbranched architectures were synthesized. Thanks to the applied controlled polymerization techniques, it was possible to obtain hydrophilic, hydrophobic, amphiphilic and stimulus-sensitive polymers. These tailor-made polymers with controlled properties were used for the construction of various types of materials, primarily on the micro- and nanoscales, with a wide range of possible applications, mainly in biomedicine. The diverse topology of polymers, and thus their properties, made it possible to obtain various types of polymeric nanostructures and use them as nanocarriers by encapsulation of biologically active substances. Additionally, polymer layers were obtained with features useful in medicine, particularly regenerative medicine and tissue engineering.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

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