Biology subjects

Pickering, M.

Publications and source records attributed to Pickering, M..

9 recordsLinked to original sources

bioRxiv2023

Size-Dependent Expression of the Fission Yeast Cdc13 Cyclin is Conferred by Translational Regulation

The major fission yeast cyclin, Cdc13, has been shown to increase in concentration in correlation with cell size, and has been proposed to thereby regulate cell size at division. However, the mechanism of its cell-size regulation has been unknown. Here, we show that Cdc13 is regulated post-transcriptionally. Its transcript is not expressed in a size-dependent manner, rather a size-dependent concentration of protein is expressed from a size-independent concentration of mRNA. Moreover, we show that the expression of Cdc13 is, in fact, size dependent, as opposed to simply size-correlated due to time-dependent expression. We identify a 20-amino-acid motif, which includes the APC D-box degron, as necessary and sufficient for size-dependent expression, which allowed us to construct a size-independent allele of cdc13. Using this allele, we show that size-dependent expression of Cdc13 is not required for size control in fission yeast cells.

cell biology↗

bioRxiv2022

ACSM1 and ACSM3 regulate prostate cancer fatty acid metabolism to promote tumour growth and constrain ferroptosis

Prostate tumours are highly reliant on lipids for energy, growth and survival. Activity of the androgen receptor (AR) is associated with reprogramming of lipid metabolic processes in prostate cancer, although the molecular underpinnings of this relationship remain to be fully elucidated. Here, we identified Acyl-CoA Synthetase Medium Chain Family Members 1 and 3 (ACSM1 and ACSM3) as AR-regulated mediators of prostate cancer metabolism and growth. ACSM1 and ACSM3 are upregulated in prostate tumours compared to non-malignant tissues and other cancer types. Both enzymes enhanced proliferation and protected PCa cells from death in vitro, while silencing ACSM3 led to reduced tumour growth in an orthotopic xenograft model. We show that ACSM1 and ACSM3 are major regulators of the PCa lipidome and enhance energy production via fatty acid oxidation. Metabolic dysregulation caused by loss of ACSM1/3 led to mitochondrial oxidative stress, lipid peroxidation and cell death by ferroptosis. Conversely, over-expression of ACSM1/3 enabled PCa cells to survive toxic doses of medium chain fatty acids and promoted resistance to ferroptosis-inducing drugs and AR antagonists. Collectively, these studies uncover a new link between AR and lipid metabolism and position ACSM1 and ACSM3 as key players in prostate cancer progression and therapy resistance.

cancer biology↗

bioRxiv2021

Similar neural networks respond to coherence during comprehension and production of discourse

When comprehending discourse, listeners engage default mode regions associated with integrative semantic processing to construct a situation model of its content. We investigated how similar networks are engaged when we produce, as well as comprehend, discourse. During fMRI, participants spoke about a series of specific topics and listened to discourse on other topics. We tested how activation was predicted by natural fluctuations in the global coherence of the discourse, i.e., the degree to which utterances conformed to the expected topic. The neural correlates of coherence were similar across speaking and listening, particularly in default mode regions. This network showed greater activation when less coherent speech was heard or produced, reflecting updating of mental representations when discourse did not conform to the expected topic. In contrast, regions that exert control over semantic activation showed task-specific effects, correlating negatively with coherence during listening but not during production. Participants who showed greater activation in left inferior prefrontal cortex also produced more coherent discourse, suggesting a specific role for this region in goal-directed regulation of speech content. Results suggest strong correspondence of discourse representations during speaking and listening. However, they indicate that the semantic control network plays different roles in comprehension and production.

neuroscience↗

bioRxiv2020

Characterisation of Geometric Variance in the Epithelial Nerve Net of the Ctenophore Pleurobrachia pileus

Neuroscience currently lacks a diverse repertoire of model organisms, resulting in an incomplete understanding of what principles of neural function generalise and what are species-specific. Ctenophores display many neurobiological and experimental features which make them a promising candidate to fill this gap. They possess a nerve net distributed across their outer body surface, just beneath the epithelial layer. There is a long-held assumption that nerve nets are simple and random while lacking distinct organisational principles. We want to challenge this assumption and determine how stereotyped the structure of this network really is. We validated an approach to estimate body surface area in Pleurobrachia pileus using custom Optical Projection Tomography and Light Sheet Morphometry imaging systems. We used an antibody against tyrosylated -tubulin to visualise the nerve net in situ. We used an automated segmentation approach to extract the morphological features of the nerve net. We characterised organisational rules of the epithelial nerve net in P. pileus in animals of different sizes and at different regions of the body. We found that specific morphological features within the nerve net are largely un-changed during growth. These properties must be essential to the functionality of the nervous system and therefore are maintained during a change in body size. We have also established the principles of organisation of the network and showed that some of the geometric properties are variable across different parts of the body. This suggests that there may be different functions occurring in regions with different structural characteristics. This is the most comprehensive structural description of a nerve net to date. This study also demonstrates the amenability of the ctenophore P. pileus for whole organism network analysis and shows their promise as a model organism for neuroscience, which may provide insights into the foundational principles of nervous systems.

neuroscience↗

bioRxiv2020

Colloblasts act as a biomechanical sensor for suitable prey in Pleurobrachia

Ctenophores are a group of largely-planktonic, gelatinous carnivores whose most common method of prey capture is nearly a phylum-defining trait. Tentaculate ctenophores release an unknown proteinaceous adhesive from specialised colloblast cells lining their tentacles following prey contact with the tentacles. There exist no extant studies of the mechanical properties of colloblast adhesive. We use live microscopy techniques to visualise adhesion events between Pleurobrachia pileus colloblasts and probes of different surface chemistries in response to probing with varying contact areas. We further define two mechanisms of adhesion termination upon probe retraction. Adapting a technique for measuring surface tension, we examine the adhesive strength of tentacles in the ctenophore Pleurobrachia bachei under varying pH and bonding time conditions, and demonstrate the destructive exhaustion of colloblast adhesive release. We find that colloblast-mediated adhesion is rapid, and that the bonding process is robust against shifts in ambient pH. However, we find that the Pleurobrachia colloblast adhesive system is among the weakest biological adhesive systems yet described. We place this surprising observation into a broader ecophysiological context by modeling prey capture for prey of a range of sizes. We find that limited use of colloblast adhesive with high surface area contact is suitable both for capturing appropriately sized prey and rejecting, by detachment, prey above a certain size threshold. This allows Pleurobrachia, lacking a mechanism to directly "see" potential prey they are interacting with, to invest in capturing only prey of an appropriate size, decreasing the risk of injury. Summary statementCtenophore colloblast adhesive is found to be strong, but few colloblasts are simultaneously active, producing a weakly-adhering system. A physical model demonstrates how such a system may filter unsuitable prey.

zoology↗

bioRxiv2020

The Incubot: A 3D Printer-Based Microscope for Long-Term Live Cell Imaging within a Tissue Culture Incubator

Commercial live cell imaging systems represent a large financial burden to research groups, while current open source incubator microscopy systems lack adaptability and are sometimes inadequate for complex imaging experimentation. We present here a low-cost microscope designed for inclusion within a conventional tissue culture incubator. The build is constructed using an entry level 3D printer as the basis for the motion control system, with Raspberry Pi imaging and software integration, allowing for reflected, oblique, and fluorescence imaging of live cell monolayers. The open source nature of the design is aimed to facilitate adaptation by both the community at large and by individual researchers/groups. The development of an adaptable and easy-to-use graphic user interface (GUI) allows for the scientist to be at the core of experimental design. Simple modifications of the base GUI code, or generation of an entirely purpose-built script, will allow microscopists to place their experimental design as the priority, as opposed to designing experiments to fit their current equipment. The build can be constructed for a cost of roughly C1000 and thus serves as a low-cost and adaptable addition to the open source microscopy community. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/121608v2_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@1aa58ceorg.highwire.dtl.DTLVardef@ac4678org.highwire.dtl.DTLVardef@467ae2org.highwire.dtl.DTLVardef@12da951_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2020

Characterising the Behaviour of the Ctenophore Pleurobrachia pileus in a Laboratory Aquaculture System

Neurobiological research focuses on a small number of model organisms, broadening the pool of animals used in research may lead to important insights into the evolution of nervous systems. The ctenophore is emerging as a promising model, but we are currently lacking an understanding into the relationship between behaviour and environment which is in part due to a lack of a standardised long-term laboratory husbandry system. We established a collection and husbandry system for wild caught Pleurobrachia pileus. We examined the behavioural profile of the animals over time in this controlled environment. We could reliably catch them on a seasonal basis, and we could keep the animals alive in our specialised aquarium system for months at a time. P. pileus spends most of the time in an inactive drifting state which is interspersed with periods of one of 5 active behaviours. The most common active behaviours are tentacle resetting and feeding. The longest duration behaviours include swimming up or down. Time of day does not appear to alter their behavioural profile. Gaining a better understanding of the behaviour of these animals has important implications for systems and evolutionary neuroscience.

neuroscience↗

bioRxiv2018

Fission Yeast Cells Grow Approximately Exponentially

How the rate of cell growth is influenced by cell size is a fundamental question of cell biology. The simple model that cell growth is proportional to cell size, based on the proposition that larger cells have proportionally greater synthetic capacity than smaller cells, leads to the predication that the rate of cell growth increases exponentially with cell size. However, other modes of cell growth, including bilinear growth, have been reported. The distinction between exponential and bilinear growth has been explored in particular detail in the fission yeast Schizosaccharomyces pombe. We have revisited the mode of fission yeast cell growth using high-resolution time-lapse microscopy and find, as previously reported, that these two growth models are difficult to distinguish both because of the similarity in shapes between exponential and bilinear curves over the two-fold change in length of a normal cell cycle and because of the substantial biological and experimental noise inherent to these experiments. Therefore, we contrived to have cells grow more than two fold, by holding them in G2 for up to eight hours. Over this extended growth period, in which cells grow up to 5.5-fold, the two growth models diverge to the point that we can confidently exclude bilinear growth as a general model for fission yeast growth. Although the growth we observe is clearly more complicated than predicted by simple exponential growth, we find that exponential growth is a robust approximation of fission yeast growth, both during an unperturbed cell cycle and during extended periods of growth.

cell biology↗

bioRxiv2018

The Flexiscope: a Low Cost, Flexible, Convertible, and Modular Microscope with Automated Scanning and Micromanipulation.

With technologies rapidly evolving, many research institutions are now opting to invest in costly, high-quality, specialised microscopes which are shared by many researchers. As a consequence, the user may not have the ability to adapt a microscope to their specific needs and limitations in experimental design are introduced. A flexible work-horse microscopy system is a valuable tool in any laboratory to meet the diverse needs of a research team and promote innovation in experimental design. We have developed the Flexiscope; a multi-functional, adaptable, efficient and high-performance microscopy/electrophysiology system for everyday applications in a neurobiology laboratory. The core optical components are relatively constant in the three configurations described here; an upright configuration, an inverted configuration and an upright/electrophysiology configuration. We have provided a comprehensive description of the Flexiscope. We show that this method is capable of oblique infrared illumination imaging, multi-channel fluorescent imaging, and automated 3D scanning of larger specimens. Image quality is conserved across the three configurations of the microscope, and conversion between configurations is possible quickly and easily, while the motion control system can be repurposed to allow sub-micron computer-controlled micromanipulation. The Flexiscope provides similar performance and usability to commercially available systems. However, as it can be easily reconfigured for multiple roles, it can remove the need to purchase multiple microscopes, giving significant cost savings. The modular re-configurable nature allows the user to customise the system to their specific needs and adapt/upgrade the system as challenges arise, without requiring specialised technical skills.

neuroscience↗