The study of tissue organization and morphogenesis requires quantitative analysis of 3D biological samples, a challenging task owing to limitations in imaging dense organs at single-cell resolution. Current 3D segmentation and quantification tools often struggle with the low resolution and signal-to-noise ratios typical of images taken in vivo or deep within tissues. To address this, we developed Object Stitching by Clustering of Adjacent Regions (OSCAR), a framework that combines machine learning with non-linear fitting and statistical algorithms specifically designed to quantify biological 3D stacks with high cellular density and low signal-to-background ratio based on nuclear staining. As proof of principle, the framework is applied to quantify the growth and organizational dynamics of the developing zebrafish vertebrate retina, showing that the cell numbers increase exponentially, while cell density increases and average nuclear volume decreases. Overall, its high accuracy, ease of use and reduced computational requirements establish OSCAR as a valuable tool for automated image analysis of densely packed tissues composed of cell subtypes that can be distinguished by specific labeling.

ABSTRACTImmune cells rapidly respond to tissue damage through dynamic properties of the cytoskeleton. How microtubules control immune cell functions during injury responses remains poorly understood. Within skin, tissue-resident macrophages known as Langerhans cells use dynamic dendrites to surveil the epidermis for damage and migrate through a densely packed epithelium to wounds. Here, we used Langerhans cells within the adult zebrafish epidermis as a model to investigate roles of microtubules in immune cell tissue surveillance, phagocytosis and directed migration. We describe microtubule organization within Langerhans cells and show that depolymerizing the microtubule cytoskeleton alters dendrite morphology, debris engulfment and migration efficiency. We found that the microtubule organizing center positions adjacent to engulfed debris and that its position correlates with navigational pathfinding during tissue-level migration. Stabilizing microtubules inhibits Langerhans cell motility during directed cell migration by impairing navigation around cellular obstacles. Collectively, our work demonstrates requirements for microtubules in the dynamic actions of tissue-resident macrophages during epithelial surveillance and wound repair.

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Ling Jin is first author on ‘ An acentrosomal aster with atypical microtubule polarity recruits cytokinesis signals to its center in Xenopus egg extracts’, published in JCS. Ling is a PhD student in the lab of Xianrui Cheng at the Department of Biological Sciences, University of Southern California, Los Angeles, USA, investigating the dynamics and transformations of living systems, with a particular interest in using striking models and unconventional perspectives to address broad biological questions and develop innovative methods with wide applicability.

The British Society for Cell Biology (BSCB), established in 1965, is a charitable organisation that 'aims to promote research and exchange of information relating to all branches of cell biology'. The Society hosts and supports meetings and conferences relevant to cell biology and plays a crucial role in raising awareness towards scientific policies in the UK and Ireland. Since its early days, the society has held strong ties with The Company of Biologists, a not-for-profit publisher that strives to inspire biology and support biologists. In this Essay, to commemorate the 100-year anniversary of The Company of Biologists, I discuss the evolution of the BSCB and highlight its relationship with the Company from when the Society was founded through to the present day.

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Ahsan Javed is first author on ‘ Piezo1 balances membrane and cortex tension to stabilize intercellular junctions and maintain the epithelial barrier’, published in JCS. Ahsan is a PhD Student in the lab of Sara Wickström at the University of Helsinki, Finland, investigating how Piezo1 protein helps skin cells sense tension at molecular scale and allows the efficient formation of cell–cell junctions essential for maintaining the skin barrier as we age.

ABSTRACTHuman exposure to arsenicals is associated with devastating diseases such as cancer and neurodegeneration. At the same time, arsenic-based drugs are used as therapeutic agents. The ability of arsenic to directly bind to proteins is correlated with its toxic and therapeutic effects, highlighting the importance of elucidating arsenic–protein interactions. In this study, we took a proteomic approach and identified 174 proteins that bind to arsenic in Saccharomyces cerevisiae. Proteins involved in nucleocytoplasmic transport were markedly enriched among the arsenic-binding proteins, and we demonstrate that arsenic binding to nuclear import factors results in their relocation from the nuclear envelope and subsequent aggregation in the cytosol. Similarly, nuclear pore proteins that make up the nuclear pore complex mislocalized and aggregated in arsenic-exposed cells. Consequently, arsenic was shown to inhibit nuclear protein import and export. We propose a model in which arsenic binding to nuclear transport factors leads to their mislocalization and aggregation, which disrupts nucleocytoplasmic transport and causes arsenic sensitivity.

Cell survival after irradiation depends on the cell cycle at the time of exposure. This has been thought to be due to cell cycle-dependent nuclear DNA damage repair mechanisms. Here, we show the relationships between the exposed dose, the cell cycle phase at the time of exposure and changes in mitochondrial DNA copy numbers (mtDNAcn) after irradiation. We used a fluorescent ubiquitylation-based cell cycle indicator (FUCCI), which allows visualization of the cell cycle, and confirmed cell cycle synchronization in human cervical HeLa cells. In synchronous HeLa-FUCCI cells, the mtDNAcn changed with the progression of the cell cycle. Also, G1 phase-synchronized cells showed a dose-dependent increase of mtDNAcn at 48 h after X-ray exposure, whereas G2 cells showed a dose-dependent increase at 24 h. In addition, S phase-synchronized cells showed a dose-dependent increase at 24 and 48 h after irradiation. These results showed the cell cycle- and dose-dependent effects on mtDNAcn after irradiation, which might shed light on the emerging role of mitochondrial genome and in cell survival.

Mechanosensitive ion channels are found across all classes of life, suggesting that cellular force sensing is an ancient sense. In mammals, mechanosensitive ion channels are expressed in many cells and tissues, and disrupting their function can impact an array of physiological processes. The identification and characterisation of mammalian mechanosensitive ion channels has been driven by in vitro patch-clamp electrophysiology studies. However, challenges arise when applying insights from these biophysical measurements across scales. Electrophysiology studies do not capture the complexity of force sensing in vivo, where the nature of mechanical loading, the mechanics of the local environment and the co-expression of accessory molecules can all influence mechanosensitive ion channel function. In addition, a nuanced perspective acknowledging the varying roles that ion channels can play in force-sensing pathways and the distinctions in activation profiles of mechanosensitive ion channels is required to better understand channel-mediated mechanotransduction. In this Opinion article, by synthesising our knowledge of these activation profiles gleaned from in vitro studies, we argue that only by considering mechanosensitive ion channel function within an appropriate cellular and mechanical context will we be able to better understand the roles of this fascinating class of molecule in mammalian cells in vivo.

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Ryosuke Seino is first author on ‘ Cell cycle- and dose-dependent effects on mitochondrial DNA copy number variation following irradiation’, published in JCS. Ryosuke is a Research Fellow in the lab of Hisanori Fukunaga at Department of Biomedical Science and Engineering, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan, working on quantitative exploration of biological responses to environmental stress through combined experimental and theoretical approaches.

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Liz Kurtz is first author on ‘ The scaffold protein CasL restrains membrane blebbing and promotes T cell migration’, published in JCS. Liz is a PhD student in the lab of Nathan Roy at SUNY Upstate Medical University, New York, USA. She is interested in understanding the dynamics of immune cell migration and what drives different migration patterns and decisions during disease states.