Biophysical mechanisms of single-cell interactions with microtopographical cues

Biophysical cues encoded in the extracellular matrix (ECM) are increasingly being explored to control cell behavior in tissue engineering applications. Recently, we showed that cell adhesion to microtopographical structures (“micropegs”) can suppress proliferation in a manner that may be blunted by inhibiting cellular contractility, suggesting that this effect is related to altered cell-scaffold mechanotransduction. We now directly investigate this possibility at the microscale through a combination of live-cell imaging, single-cell mechanics methods, and analysis of gene expression. Using time-lapse imaging, we show that when cells break adhesive contacts with micropegs, they form F-actin-filled tethers that extend and then rupture at a maximum, critical length that is greater than trailing-edge tethers observed on topographically flat substrates. This critical tether length depends on myosin activation, with inhibition of Rho-associated kinase abolishing topography-dependent differences in tether length. Using cellular de-adhesion and atomic force microscopy indentation measurements, we show that the micropegs enhance cell-scaffold adhesive interactions without changing whole-cell elasticity. Moreover, micropeg adhesion increases expression of specific mechanotransductive genes, including RhoA GTPase and myosin heavy chain II, and, in myoblasts, the functional marker connexin 43. Together, our data support a model in which microtopographical cues alter the local mechanical microenvironment of cells by modulating adhesion and adhesion-dependent mechanotransductive signaling

Venice:A poem in Latin by James Crichton with an English version by Robert Crawford and eight photogravures by Norman McBeath

A poem in Latin by James Crichton with an English version in verse by Robert Crawford and eight photogravures by Norman McBeat

Holy Rood:a translation of the Old English poem 'The Dream of the Rood'

A verse translation of the Old English poem 'The Dream of the Rood' with an introduction by Robert Crawford and seven photographs by Norman McBeat

Light box

Poems and photographs commissioned to mark the 2015 UNESCO International Year of Ligh

Loch Computer

Poems by Meg Bateman (in Gaelic with English translation), Robert Crawford (in English), Jen Hadfield (in English), Peter Mackay(in Gaelic with English translation), with photographs by Norman McBeath and Leena Nammar

Sources of Object-Specific Effects in Representational Momentum

In this study we explore the sources of object-specific effects in representational momentum (RM). “Object-specific effects” refers to the elicitation of different patterns of RM by different objects. We examined whether object-specific effects could be produced by an object\u27s conceptual context, visual features, or their interaction. The conceptual context was composed of the object\u27s label with, in some cases, a description of the object, plus experimental trials requiring the participant to identify the object. In addition, we examined whether the contribution of visual features to object-specific effects came from one particular visual feature previously linked to RM (pointedness), or from the object\u27s overall appearance. Our results show that generally, the stimulus\u27 overall appearance must be consistent with its conceptual context for related conceptual knowledge to produce object-specific RM effects. These experiments therefore provide evidence that knowledge particular to an object, or its category, unconsciously affects mental transformations