scholarly journals Auxin regulates endosperm cellularization in Arabidopsis

2017 ◽  
Author(s):  
Duarte D. Figueiredo ◽  
Rita A. Batista ◽  
Claudia Kohler
Keyword(s):  
Endosperm Development ◽  
Auxin Biosynthesis ◽  
Causal Role ◽  
Auxin Activity ◽  
Event Triggering

AbstractThe endosperm is an ephemeral tissue that nourishes the developing embryo, similar to the placenta in mammals. In most angiosperms endosperm development starts as a syncytium, where nuclear divisions are not followed by cytokinesis. The timing of endosperm cellularization largely varies between species and the event triggering this transition remains unknown. Here we show that increased auxin biosynthesis in the endosperm prevents its cellularization, leading to seed arrest. Auxin-overproducing seeds phenocopy paternal-excess triploid seeds derived from hybridizations of diploid maternal plants with tetraploid fathers. Concurrently, auxin-related genes are strongly overexpressed in triploid seeds, correlating with increased auxin activity. Reducing auxin biosynthesis and signaling reestablishes endosperm cellularization in triploid seeds and restores their viability, highlighting a causal role of increased auxin in preventing endosperm cellularization. We propose that auxin determines the time of endosperm cellularization and thereby uncovered a central role of auxin in establishing hybridization barriers in plants.

Do Writing Directions Influence How People Map Space onto Time?

2018 ◽  
Vol 77 (4) ◽  
pp. 173-184
Author(s):  
Wenxing Yang ◽  
Ying Sun
Keyword(s):  
Mental Representations ◽  
Space Time ◽  
Horizontal Axis ◽  
Causal Role ◽  
Writing Systems ◽  
Temporal Cognition ◽  
Japanese Speakers ◽  
Psychological Experiments ◽  
Vertical Up

Abstract. The causal role of a unidirectional orthography in shaping speakers’ mental representations of time seems to be well established by many psychological experiments. However, the question of whether bidirectional writing systems in some languages can also produce such an impact on temporal cognition remains unresolved. To address this issue, the present study focused on Japanese and Taiwanese, both of which have a similar mix of texts written horizontally from left to right (HLR) and vertically from top to bottom (VTB). Two experiments were performed which recruited Japanese and Taiwanese speakers as participants. Experiment 1 used an explicit temporal arrangement design, and Experiment 2 measured implicit space-time associations in participants along the horizontal (left/right) and the vertical (up/down) axis. Converging evidence gathered from the two experiments demonstrate that neither Japanese speakers nor Taiwanese speakers aligned their vertical representations of time with the VTB writing orientation. Along the horizontal axis, only Japanese speakers encoded elapsing time into a left-to-right linear layout, which was commensurate with the HLR writing direction. Therefore, two distinct writing orientations of a language could not bring about two coexisting mental time lines. Possible theoretical implications underlying the findings are discussed.

Introduction

2018 ◽  
Author(s):  
Christopher Evan Franklin
Keyword(s):  
Moral Responsibility ◽  
Free Will ◽  
Human Agency ◽  
Causal Role ◽  
Central Question ◽  
Agent Causation ◽  
The Right

This chapter lays out the book’s central question: Assuming agency reductionism—that is, the thesis that the causal role of the agent in all agential activities is reducible to the causal role of states and events involving the agent—is it possible to construct a defensible model of libertarianism? It is explained that most think the answer is negative and this is because they think libertarians must embrace some form of agent-causation in order to address the problems of luck and enhanced control. The thesis of the book is that these philosophers are mistaken: it is possible to construct a libertarian model of free will and moral responsibility within an agency reductionist framework that silences that central objections to libertarianism by simply taking the best compatibilist model of freedom and adding indeterminism in the right junctures of human agency. A brief summary of the chapters to follow is given.

Causal role of oxidative stress in unfolded protein response development in the hyperthyroid state

2015 ◽  
Vol 89 ◽  
pp. 401-408 ◽  
Author(s):  
Luis A. Videla ◽  
Virginia Fernández ◽  
Pamela Cornejo ◽  
Romina Vargas ◽  
Juan Carrasco ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Unfolded Protein Response ◽  
Causal Role ◽  
Unfolded Protein ◽  
Hyperthyroid State ◽  
Protein Response
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