scholarly journals An ABA-GA bistable switch can account for natural variation in the variability of Arabidopsis seed germination time

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Katie Abley ◽  
Pau Formosa-Jordan ◽  
Hugo Tavares ◽  
Emily YT Chan ◽  
Mana Afsharinafar ◽  
...  
Keyword(s):  
Seed Germination ◽  
Phenotypic Variability ◽  
Time Variability ◽  
Bistable Switch ◽  
Germination Time ◽  
Arabidopsis Seed ◽  
Aba Sensitivity ◽  
Recombinant Inbred Population ◽  
Underlying Mechanisms

Genetically identical plants growing in the same conditions can display heterogeneous phenotypes. Here we use Arabidopsis seed germination time as a model system to examine phenotypic variability and its underlying mechanisms. We show extensive variation in seed germination time variability between Arabidopsis accessions and use a multiparent recombinant inbred population to identify two genetic loci involved in this trait. Both loci include genes implicated in modulating abscisic acid (ABA) sensitivity. Mutually antagonistic regulation between ABA, which represses germination, and gibberellic acid (GA), which promotes germination, underlies the decision to germinate and can act as a bistable switch. A simple stochastic model of the ABA-GA network shows that modulating ABA sensitivity can generate the range of germination time distributions we observe experimentally. We validate the model by testing its predictions on the effects of exogenous hormone addition. Our work provides a foundation for understanding the mechanism and functional role of phenotypic variability in germination time.

scholarly journals An ABA-GA bistable switch can account for natural variation in the variability of Arabidopsis seed germination time

2020 ◽  
Author(s):  
Katie Abley ◽  
Pau Formosa-Jordan ◽  
Hugo Tavares ◽  
Emily Chan ◽  
Ottoline Leyser ◽  
...  
Keyword(s):  
Seed Germination ◽  
Phenotypic Variability ◽  
Time Variability ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Bistable Switch ◽  
Germination Time ◽  
Arabidopsis Seed ◽  
Recombinant Inbred Population ◽  
Exogenous Addition

AbstractGenetically identical plants growing in the same conditions can display heterogeneous phenotypes. Whether this phenotypic variability is functional and the mechanisms behind it are unclear. Here we use Arabidopsis seed germination time as a model system to examine phenotypic variability. We show extensive variation in seed germination time variability between Arabidopsis accessions, and use a multi-parent recombinant inbred population to identify two loci involved in this trait. Both loci include genes implicated in ABA signalling that could contribute to seed germination variability. Modelling reveals that the GA/ABA bistable switch underlying germination can amplify variability and account for the effects of these two loci on germination distributions. The model predicts the effects of modulating ABA and GA levels, which we validate genetically and by exogenous addition of hormones. We confirm that germination variability could act as a bet hedging strategy, by allowing a fraction of seeds to survive lethal stress.

scholarly journals Circadian Proteins Cry and Rev-erb Deepen Cellular Quiescence by Down-regulating Cyclin D and Cdk4,6

2021 ◽  
Author(s):  
Xia Wang ◽  
Bi Liu ◽  
Qiong Pan ◽  
Jungeun Sarah Kwon ◽  
Matthew A. Miller ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cyclin D ◽  
Bistable Switch ◽  
Quiescent Cells ◽  
Tissue Repair And Regeneration ◽  
Serum Stimulation ◽  
Cellular Quiescence ◽  
Underlying Mechanisms ◽  
Network Switch

The proper balance and transition between cellular quiescence and proliferation are critical to tissue homeostasis, and their deregulations are commonly found in many human diseases, including cancer and aging. Recent studies showed that the reentry of quiescent cells to the cell cycle is subjected to circadian regulation. However, the underlying mechanisms are largely unknown. Here, we report that two circadian proteins, Cryptochrome (Cry) and Rev-erb, deepen cellular quiescence in rat embryonic fibroblasts, resulting in stronger serum stimulation required for cells to exit quiescence and reenter the cell cycle. This finding was opposite from what we expected from the literature. By modeling a library of possible regulatory topologies linking Cry and Rev-erb to a bistable Rb-E2f gene network switch that controls the quiescence-to-proliferation transition and by experimentally testing model predictions, we found Cry and Rev-erb converge to downregulate Cyclin D/Cdk4,6 activity, leading to an ultrasensitive increase of the serum threshold to activate the Rb-E2f bistable switch. Our findings suggest a mechanistic role of circadian proteins in modulating the depth of cellular quiescence, which may have implications in the varying potentials of tissue repair and regeneration at different times of the day.

scholarly journals Hydrogen Gas Improves Seed Germination in Cucumber by Regulating Sugar and Starch Metabolisms

Horticulturae ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 456
Author(s):  
Panpan Huang ◽  
Changxia Li ◽  
Huwei Liu ◽  
Zongxi Zhao ◽  
Weibiao Liao
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Soluble Sugar ◽  
Hydrogen Gas ◽  
Cucumis Sativus L ◽  
Dependent Relationship ◽  
Development Processes ◽  
Underlying Mechanisms ◽  
Dose Dependent

Hydrogen gas (H2), an important gaseous regulator, is involved in various plant growth and development processes. However, there have been few studies on the role of H2 in seed germination. In this study, the role and underlying mechanisms of H2 in enhancing seed germination were investigated in cucumber (Cucumis sativus L.). The results revealed that the germination rate, germ length, germination index, and vitality index of cucumber exhibited a dose-dependent relationship with the increase in concentrations of hydrogen-rich water (HRW, a H2 donor; 0, 1, 10, 25, 50, 75, and 100%), attaining the maximum values with 75% HRW treatment. Treatment with 75% HRW resulted in higher contents of soluble sugar, soluble protein, and starch than the control. Additionally, the activity of α-amylase, β-amylase, and total amylase was significantly improved by 75% HRW treatment compared to the control, reaching the maximum values at 36 h. Moreover, the expression levels of starch-related genes AMY and BMY and sugar-related genes SS4 and SS3 were significantly upregulated by 75% HRW treatment during germination, particularly at 36 h. These results suggest that H2 might promote cucumber seed germination by increasing sugar and starch metabolisms.

scholarly journals Role of a Heterotrimeric G Protein in Regulation of Arabidopsis Seed Germination

2002 ◽  
Vol 129 (2) ◽  
pp. 897-907 ◽  
Author(s):  
Hemayet Ullah ◽  
Jin-Gui Chen ◽  
Shucai Wang ◽  
Alan M. Jones
Keyword(s):  
Seed Germination ◽  
G Protein ◽  
Heterotrimeric G Protein ◽  
Arabidopsis Seed

Response Interference as a Mechanism Underlying Implicit Measures

2008 ◽  
Vol 24 (4) ◽  
pp. 218-225 ◽  
Author(s):  
Bertram Gawronski ◽  
Roland Deutsch ◽  
Etienne P. LeBel ◽  
Kurt R. Peters
Keyword(s):  
Task Performance ◽  
Psychological Research ◽  
Implicit Measures ◽  
Mediation Model ◽  
Response Interference ◽  
Relevant Evidence ◽  
Moderated Mediation Model ◽  
Stimulus Features ◽  
Underlying Mechanisms

Over the last decade, implicit measures of mental associations (e.g., Implicit Association Test, sequential priming) have become increasingly popular in many areas of psychological research. Even though successful applications provide preliminary support for the validity of these measures, their underlying mechanisms are still controversial. The present article addresses the role of a particular mechanism that is hypothesized to mediate the influence of activated associations on task performance in many implicit measures: response interference (RI). Based on a review of relevant evidence, we argue that RI effects in implicit measures depend on participants’ attention to association-relevant stimulus features, which in turn can influence the reliability and the construct validity of these measures. Drawing on a moderated-mediation model (MMM) of task performance in RI paradigms, we provide several suggestions on how to address these problems in research using implicit measures.

The More You Say, the Less They Hear

2015 ◽  
Vol 27 (4) ◽  
pp. 159-169 ◽  
Author(s):  
Elsbeth D. Asbeek Brusse ◽  
Marieke L. Fransen ◽  
Edith G. Smit
Keyword(s):  
Hearing Protection ◽  
Entertainment Education ◽  
Mediating Role ◽  
Attitude Measures ◽  
Underlying Mechanisms

Abstract. This study examined the effects of disclosure messages in entertainment-education (E-E) on attitudes toward hearing protection and attitude toward the source. In addition, the (mediating) role of the underlying mechanisms (i.e., transportation, identification, and counterarguing) was studied. In an experiment (N = 336), three different disclosure messages were compared with a no-disclosure condition. The results show that more explicit disclosure messages negatively affect transportation and identification and stimulate the generation of counterarguments. In addition, the more explicit disclosure messages affect both attitude measures via two of these processes (i.e., transportation and counterarguing). Less explicit disclosure messages do not have this effect. Implications of the findings are discussed.

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