Biology subjects

Johnstone, C.

Publications and source records attributed to Johnstone, C..

3 recordsLinked to original sources

bioRxiv2025

Epithelial-mesenchymal cell state heterogeneity predetermines differential phospho-signaling responses to epidermal growth factor stimulation

Understanding why isogenic cancer cells respond differently to equivalent oncogenic stimuli is vital for optimizing anticancer therapies. Emerging evidence suggests that pre-existing differences in cell state may modulate signaling responses to new stimuli, but the interplay of specific cell states and signals remains unclear. We investigated whether epithelial-mesenchymal (E/M) state, a major axis of cancer cell heterogeneity, influences signaling responses to epidermal growth factor (EGF), a critical oncogenic stimulus in non-small cell lung cancer (NSCLC). We imaged >64,000 A549 NSCLC cells labeled for DNA, F-actin and alternate signaling markers (p-AKT-S473, p-AKT-T308, p-ERK or p-S6) after acute stimulation. Quantitative single-cell morphological and spatial profiling defined a stimulus-invariant E/M state landscape over which EGF signaling responses were compared. This revealed state-dependent differences in signal-activation magnitudes, dynamics and subcellular routing. AKT responses exhibited phosphosite- and compartment-specific dynamics across states, with epithelial cells showing strong, transient membrane-localized S473 and higher internalized T308, whereas mesenchymal cells displayed weaker but sustained nuclear and ruffle-localized S473. Regression-based computational multiplexing concurrently inferred all signaling responses per cell, mapping state-dependent divergence in multi-molecular signaling trajectories. E/M state thus pre-determines distinctive spatiotemporal profiles of EGF-induced signaling, with implications for signaling functions and anti-signaling therapy responses across E/M state-diverse tumors.

cancer biology↗

bioRxiv2023

High resolution longitudinal molecular and morphological tracking of planktonic threats to salmon aquaculture.

Marine-phase salmonid aquaculture is a major component of the coastal economies of Northern Europe, North America and Chile and is under threat from numerous challenges to gill health, many of which originate from the phyto- and zooplankton. Associated losses are growing as a proportion of production year on year. A first step towards mitigating losses is to characterize the biological drivers of poor gill health. Numerous planktonic species have been implicated, including toxic and siliceous microalgae, hydrozoans and scyphozoans; however, rigorous longitudinal surveys of planktonic diversity and gill health have been lacking. In the current study, we present and assess an exhaustive identification approach combining both morphological and molecular methods (environmental DNA metabarcoding) approaches in combination with robust statistical models to identify the planktonic drivers of complex gill disease (CGD) and fish mortality. We undertook longitudinal molecular and microscopic evaluation at two marine aquaculture facilities on the west coast of Scotland using daily data collected during the 2021 growing season (March-October). Examining these two different sites, one sheltered and one exposed to the open sea, we identified new, important, and unexpected planktonic drivers (e.g. doliolids and appendicularians) of CGD and mortality and confirmed the significance of some established threats (e.g. hydrozoans and diatoms). We also explored delayed or lagged effects of planktonic abundances on gill health and undertook a comparison of environmental DNA metabarcoding and microscopy in their ability to identify and quantify planktonic species. Our data highlight the diversity of planktonic threats to salmonid aquaculture as well as the importance of using both molecular and morphological approaches to detect those. Despite our study relying on two farm sites only, our results evidence the role of the different planktonic players on salmon gill disease; there is now an urgent need to expand systematic longitudinal molecular and morphological approach across multiple sites and over multiple years. The resultant catalogue of main biological drivers will enable early warning systems, new treatments and, ultimately, a sustainable platform for future salmonid aquaculture in the marine environment.

zoology↗

bioRxiv2020

Survey of Australian STEMM Early Career Researchers: job insecurity and questionable research practices are major structural concerns

We sought to understand the pressures on Early Career Researchers (ECR) in the Science, Technology, Engineering, Mathematics, & Medicine (STEMM) disciplines, collecting data from 658 ECRs working in Australia. Respondents indicated a "love of science", but most also indicated an intention to leave their position. Decisions were primarily motivated by job insecurity (52%), while grievances included poor supervision (60%), bullying or harassment (34%), inequitable hiring practices (39%) and poor support for families (9.6%). A concerning rate of "questionable research practices" by colleagues (34.1% to 41.1%) was reported to have impacted ECR career advancement. Our study links recent reports that characterise the health of the research industry, providing direct insight from ECRs on job insecurity, workplace culture challenges, and the logical rise of questionable research practices. Internationally, nationally and institutionally the research community needs to improve job security (care for our people) and the quality of research data (our product).

scientific communication and education↗