Nitrate modulates stem cell dynamics in Arabidopsis shoot meristems through cytokinins

The shoot apical meristem (SAM) is responsible for the generation of all the aerial parts of plants. Given its critical role, dynamical changes in SAM activity should play a central role in the adaptation of plant architecture to the environment. Using quantitative microscopy, grafting experiments, and genetic perturbations, we connect the plant environment to the SAM by describing the molecular mechanism by which cytokinins signal the level of nutrient availability to the SAM. We show that a systemic signal of cytokinin precursors mediates the adaptation of SAM size and organogenesis rate to the availability of mineral nutrients by modulating the expression of WUSCHEL, a key regulator of stem cell homeostasis. In time-lapse experiments, we further show that this mechanism allows meristems to adapt to rapid changes in nitrate concentration, and thereby modulate their rate of organ production to the availability of mineral nutrients within a few days. Our work sheds light on the role of the stem cell regulatory network by showing that it not only maintains meristem homeostasis but also allows plants to adapt to rapid changes in the environment

Fluctuations of the transcription factor ATML1 generate the pattern of giant cells in the Arabidopsis\textit{Arabidopsis} sepal

Multicellular development produces patterns of specialized cell types. Yet, it is often unclear how individual cells within a field of identical cells initiate the patterning process. Using live imaging, quantitative image analyses and modeling, we show that during $\textit{Arabidopsis thaliana}$ sepal development, fluctuations in the concentration of the transcription factor ATML1 pattern a field of identical epidermal cells to differentiate into giant cells interspersed between smaller cells. We find that ATML1 is expressed in all epidermal cells. However, its level fluctuates in each of these cells. If ATML1 levels surpass a threshold during the G2 phase of the cell cycle, the cell will likely enter a state of endoreduplication and become giant. Otherwise, the cell divides. Our results demonstrate a fluctuation-driven patterning mechanism for how cell fate decisions can be initiated through a random yet tightly regulated process.This work was supported by NSF IOS Plant, Fungal, and Microbial Developmental Mechanisms grants IOS-1256733 and IOS-1553030 (AKHR). This work was further supported by the Gatsby Charitable Foundation (GAT3272/GLC to JL and GAT3395/PR4 to HJ) and the Swedish Research Council (VR2013:4632 to HJ). JT and PFJ acknowledge postdoctoral fellowships provided by the Herchel Smith Foundation. This work made use of the Cornell Center for Materials Research Shared Facilities, which are supported through the NSF MRSEC program (DMR-1120296)

Designing with information and empathy: Delivering human information to designers

This paper detailed research by McGinley into information and empathy resources to support people-centred design. It was published in a special edition of The Design Journal, an INT1-rated journal in the European Reference Index for the Humanities. The paper reported on the concept of information and empathy combinations and detailed a case study in which the author undertook the role of lead researcher. The reported case study was the design of safer drinks vessels for the UK pub industry, a project commissioned by the Home Office and managed by the Design Council. The case study reported on the process undertaken to explore glass-related assaults. Human information resources (i.e. mixed-media outputs, including reports, video and interactive software) were created to communicate the range of perspectives and insights obtained through design ethnography methods. The research was used by a design consultancy commissioned to re-design the pint glass, leading to a new concept that was developed and trialled in UK bars. McGinley and Caroline Till also wrote an accompanying publication that consolidated findings based on four months of research into alcohol-related violence. Design Out Crime: Using Design to Reduce Injuries from Alcohol-Related Violence in Pubs and Clubs (2010) was published by the Design Council and launched alongside resulting designs by the Home Secretary at the Design Council. The project received national media coverage and featured extensively in the national press (e.g. BBC News, Guardian, Metro, Daily Mail, Creative Review) Further to this work, McGinley was invited to become a ‘design ambassador’ for the Design Council’s ‘Keeping Connected’ Design Challenge (2011), which engaged high-school students with older communities. McGinley was also invited to present his work at Central Saint Martins Service Design Summer School (2012)

Tunable diffusive lateral inhibition in chemical cells

The Belousov-Zhabotinsky (BZ) reaction has become the prototype of nonlinear chemical dynamics. Microfluidic techniques provide a convenient method for emulsifying BZ solutions into monodispersed drops with diameters of tens to hundreds of microns, providing a unique system in which reaction-diffusion theory can be quantitatively tested. In this work, we investigate monolayers of microfluidically generated BZ drops confined in close-packed two-dimensional (2D) arrays through experiments and finite element simulations. We describe the transition from oscillatory to stationary chemical states with increasing coupling strength, controlled by independently varying the reaction chemistry within a drop and diffusive flux between drops. For stationary drops, we studied how the ratio of stationary oxidized to stationary reduced drops varies with coupling strength. In addition, using simulation, we quantified the chemical heterogeneity sufficient to induce mixed stationary and oscillatory patterns

Training moral sensitivity through video games: A review of suitable game mechanisms

The goal of this study is to support game designers in the selection and implementation of game mechanisms to promote players’ moral sensitivity. A lack of moral sensitivity may lead people to behave unethically, without awareness for their actions’ moral implications. In this study, we conduct a theory-based evaluation of 20 distinct game mechanisms in view of their potential to promote moral sensitivity. Moral sensitivity is thereby operationalized in terms of three learning outcomes: Empathic concern for relevant groups, alertness to values/principles, and awareness for one’s vulnerability to biases. This study suggests that moral sensitivity is best promoted through a careful combination of game mechanisms, addressing all three learning outcomes