Biology subjects

Wright, A. J.

Publications and source records attributed to Wright, A. J..

9 recordsLinked to original sources

bioRxiv2026

Are you represented? Subjective vs objective skin color determination for healthcare and research purposes.

Despite questionable accuracy, subjective methods to categorize skin color are heavily relied upon in research and medicine. Objective skin color determination is expensive requiring specialized instrumentation and interpretation. We compare three subjective approaches, i) Fitzpatrick Skin Type Scale (FST), ii) Pantone SkinTone Guide (PST) and, iii) Monk Skin Tone Scale (MST), with objectively measured skin color from a spectrophotometer in 87 volunteers to understand the limitations of each method. In agreement with others, we show that the popular FST questionnaire correlates poorly with the objective approach. However, PST color swatches provide good correlation with spectrophotometer measurements. PST consists of 110+ swatches that are inexpensive and easy to use, however, similar to other reports, the volunteers found the number of swatches overwhelming and/or excessive. We found that the recently introduced MST is not representative of reality with only 3 of the 10 color groups representing our volunteers and published populations of volunteers. In future, we propose using 9 color swatches to split the spectrum of human skin color into 10 groupings (Nottingham Skin Categories - NSC) that are representative of the global population. This new approach would be easy to implement and inexpensive in research, healthcare and cosmetics settings, and maps directly to objective, quantitative, measures taken with a spectrophotometer. For the testing and development of new optical devices, NSC would provide increased comparability between studies and ensure studies are representative of local/global populations. In the clinic NSC would be useful for dermatology, photodynamic therapy and dosage assessment for topical medicine, for example.

scientific communication and education↗

bioRxiv2025

KATANIN promotes cell elongation and division to generate proper cell numbers in maize organs

Microtubule severing is essential for proper eukaryotic cell elongation and division. Here we show that the microtubule severing protein, KATANIN, is encoded by two genes in Zea mays (maize) called Discordia3a (Dcd3a) and Dcd3b. Loss of function allele combinations contribute to reduced microtubule severing and decreased cell elongation. The latter results in reduced cell number by slowing entry into mitosis. KATANIN is important for preprophase band (PPB) formation and positioning, and nuclear positioning in symmetric cell divisions. A combination of these defects contributes to generating mutant plants with small size and aberrant shape.

plant biology↗

bioRxiv2025

Hybrid Scaffolds Decouple Biochemical & Biophysical Regulation of Cell Phenotype

The extracellular matrix changes dramatically during the progression of diseases like cancer. These complex, tissue-specific changes are not adequately replicated by most current biomaterial disease models. Here we demonstrate, for the first time, a biomaterial system allowing combined, independent control over stiffness, composition and 3D collagen architecture. We demonstrate successful perfusion of defined hydrogel formulations into ice-templated collagen scaffolds, controlling the composition of these hybrid scaffolds at constant stiffness. The Youngs moduli of these hybrid scaffolds can also be tuned independently of composition via chemical crosslinking. Encapsulation of human dermal fibroblasts reveals that fibroblast morphology depends on hybrid scaffold composition and on viscoelasticity, highlighting the importance of a system that decouples biophysical from biochemical properties. Finally, we demonstrate application of this system to exert combined control over biochemical and biophysical drivers of cell growth and invasion, focussing on breast cancer as proof-of-concept. We show that collagen fibre patterning enhances breast cancer cell proliferation, also directing the invasion of patient-derived breast cancer cells. These hybrid scaffolds are therefore promising new tools for dissecting the diverse but complementary roles played by the extracellular matrix in regulating cell phenotype, in a range of healthcare applications.

bioengineering↗

bioRxiv2025

β1 Integrin-FAK-Piezo1 signalling axis drives in-situ stiffening mediated ECM remodelling and invasion of 3D breast epithelium

Stiffening of tissue is a hallmark of cancer progression, driving invasive phenotypes through complex interactions between cells and their extracellular matrix (ECM). However, the mechanisms linking mechanical cues to ECM remodelling and invasion remain incompletely understood. Here, using an in-situ stiffening model that allows for modulation of ECM stiffness around fully formed normal mammary acini embedded in their native ECM microenvironment, we identify critical steps in basement membrane (BM) and stromal ECM remodelling during invasion and discover the molecular mechanisms driving this process. We find that stiffening of the ECM around normal mammary acini results in rapid loss and degradation of laminin (LN) and upregulation of the fibronectin (FN) secretion around the acini. This priming phase is followed by the onset of invasion which requires localized upregulation of LN production and ECM remodelling. Mechanistically, ECM production and remodelling as well as invasion is mediated by {beta}1 integrin-FAK signalling, which activates mechanosensitive ion channels (MSCs). Further, we identify Piezo1 as the MSC downstream of {beta}1 integrin-FAK that drives BM disruption and stromal ECM remodelling. Taken together, our results identify the mechanisms by which stiffness can trigger invasive phenotypes from normal tissues.

cell biology↗

bioRxiv2024

The mitotic chromosome periphery: a fluid coat that mediates chromosome mechanics

Mitotic chromosomes are specialised packets of condensed genetic material with dynamic mechanical properties. Each chromosome is coated by a sheath of proteins and RNA, called the mitotic chromosome periphery (MCP). The MCP is widely considered as an essential chromosome compartment where its multiple functions bestow material properties important for successful cell division. However, the details of the micromechanical properties of mitotic chromosomes, and specifically if and how the MCP contributes to these features, remain poorly understood. In this study, we present the most comprehensive characterisation of single-chromosome mechanics to date spanning a broadband frequency range, using optical tweezers and a novel microrheology technique. We extend this analysis to the first direct measurements of MCP micromechanics by manipulating levels of Ki-67, the chief organiser of this compartment, and apply a rheological model to isolate its contribution to chromosome dynamics. We report that the MCP governs high-frequency self-reorganisation dynamics and acts as a structural constraint, providing force-damping properties that mitigate mitotic stress. This work significantly advances our understanding of chromosome micromechanics and how the MCP contributes to the fundamental properties of chromosomes.

biophysics↗

bioRxiv2022

OptoRheo: Simultaneous in situ micro-mechanical sensing and 3D imaging of live cell cultures

Biomechanical cues from the extracellular matrix (ECM) are essential for directing many cellular processes, from normal development and repair, to disease progression. To better understand cell-matrix interactions, we have developed a new instrument named OptoRheo that combines light sheet fluorescence microscopy with particle tracking microrheology. OptoRheo lets us image cells in 3D as they proliferate over several days while simultaneously sensing the mechanical properties of the surrounding extracellular and pericellular matrix at a sub-cellular length scale. OptoRheo can be used in two operational modalities (with and without an optical trap) to extend the dynamic range of microrheology measurements. We corroborated this by characterising the ECM surrounding live breast cancer cells in two distinct culture systems, cell clusters in 3D hydrogels and spheroids in suspension culture. This cutting-edge instrument will transform the exploration of drug transport through complex cell culture matrices and optimise the design of the next-generation of disease models.

bioengineering↗

bioRxiv2021

The OPAQUE1/DISCORIDA2 myosin XI is required for phragmoplast guidance during asymmetric cell division in maize

Formative asymmetric divisions produce cells with different fates and are critical for development. We show the myosin XI protein, OPAQUE1 (O1), is necessary for asymmetric divisions during maize stomatal development. We analyzed stomatal precursor cells prior to and during asymmetric division to determine why o1 mutants have abnormal division planes. Cell polarization and nuclear positioning occur normally in the o1 mutant, and the future site of division is correctly specified. The defect in o1 occurs during late cytokinesis, when the phragmoplast forms the nascent cell plate. Initial phragmoplast guidance in o1 is correct; however, as phragmoplast expansion continues o1 phragmoplasts become misguided. To understand how O1 contributes to phragmoplast guidance, we identified O1-interacting proteins. Maize kinesins related to the Arabidopsis thaliana division site markers PHRAGMOPLAST ORIENTING KINESINs (POKs), which are also required for correct phragmoplast guidance, physically interact with O1. We propose that different myosins are important at multiple steps of phragmoplast expansion, and the O1 actin motor and POK-like microtubule motors work together to ensure correct late-stage phragmoplast guidance.

plant biology↗

bioRxiv2020

Microrheology reveals microscale viscosity gradients in planktonic systems

Microbial activity in planktonic systems creates a dynamic and heterogeneous microscale seascape that harbours a diverse community of microorganisms and ecological interactions of global significance. In recent decades a great effort has been put into understanding this complex system, particularly focusing on the role of chemical patchiness, while overlooking a physical parameter that governs microbial life and is affected by biological activity: viscosity. Here we use microrheological techniques to measure viscosity at length scales relevant to microorganisms. Our results reveal the viscous nature and the spatial extent of the phycosphere, the microenvironment surrounding phytoplankton cells, and show heterogeneity in viscosity at the microscale. Such heterogeneity affects the distribution of chemicals and microorganisms, with pervasive and profound implications for the functioning of the planktonic ecosystem. One Sentence SummaryMicrorheology measurements unveil the existence of layers of increased viscosity surrounding phytoplankton cells and within aggregates.

ecology↗

bioRxiv2019

A universal scaling method for biodiversity-ecosystem functioning relationships

Global biodiversity is declining at rates faster than at any other point in human history. Experimental manipulations of biodiversity at small spatial scales have demonstrated that communities with fewer species consistently produce less biomass than higher diversity communities. However, understanding how the global extinction crisis is likely to impact global ecosystem functioning will require applying these local and largely experimental findings to natural systems at substantially larger spatial and temporal scales. Here we propose that we can use two simple macroecological patterns - the species area curve and the biomass-area curve - to upscale the species richness-biomass relationship. We demonstrate that at local spatial scales, each additional species will contribute more to biomass production with increasing area sampled because the species-area curve saturates and the biomass-area curve increases monotonically. We use species-area and biomass-area curves from a Minnesota grassland and a Panamanian tropical dry forest to examine the species richness - biomass relationship at three and ten sampling extents, respectively. In both datasets, the observed relationship between biodiversity and biomass production at every sampling extent was predicted from simple species-area and biomass-area relationships. These findings suggest that macroecological patterns like the species-area curve underpin the scaling of biodiversity-ecosystem functioning research and can be used to predict these relationships at the global scales where they are relevant for species loss.

ecology↗