Biology subjects

Bird, J.

Publications and source records attributed to Bird, J..

5 recordsLinked to original sources

bioRxiv2025

Guanylate-Binding Proteins Promote Host Defense Against Leishmania major by Balancing iNOS/Arg-1 in Myeloid Cells

Cutaneous leishmaniasis (CL) is a debilitating neglected tropical disease characterized by lesions that can range from self-healing to permanent disfigurations. A predominant Th1 response, which stimulates IFN-{gamma} production, is crucial for parasite control during self-healing CL. While IFN-{gamma} primarily activates macrophages to produce nitric oxide via inducible nitric oxide synthase (iNOS) leading to parasite control, IFN-{gamma} also activates other downstream pathways involved in cell autonomous immunity. One such pathway is the activation of guanylate binding proteins (GBPs), a class of interferon inducible GTPases. However, the role of GBPs during CL has been minimally explored. Utilizing RNA-Seq we found that Leishmania major infection leads to the upregulation of several GBPs in C57Bl/6 mice. In vitro studies using GBPChr3 knockout (KO), and C57Bl/6 control mice reveal that bone marrow-derived macrophages (BMDMs) from KO mice exhibit higher parasite burdens following IFN-{gamma} treatment, independent of GBP localization to the parasite. Single-cell RNA-Seq identifies macrophages as the primary expressers of GBPs during L. major infection in vivo. In vivo, GBPChr3 KO mice display increased disease severity and parasite load. GBPChr3 KO macrophages and monocytes show elevated ARG-1 and reduced iNOS expression, indicating a shift toward a parasite-permissive environment that supports parasite growth. These findings highlight a critical role for GBPs in immune-mediated control of CL.

immunology↗

bioRxiv2021

Uncertainty in population estimates: a meta-analysis for petrels

O_LIPopulation estimates are commonly generated and used in conservation science. All estimates carry inherent uncertainty, but little attention has been given to when and how this uncertainty limits their use. This requires an understanding of the specific purposes for which population estimates are intended, an assessment of the level of uncertainty each purpose can tolerate, and information on current uncertainty. C_LIO_LIWe conducted a review and meta-analysis for a widespread group of seabirds, the petrels, to better understand how and why population estimates are being used. Globally petrels are highly threatened, and aspects of their ecology make them difficult to survey, introducing high levels of uncertainty into population estimates. C_LIO_LIWe found that by far the most common intended use of population estimates was to inform status and trend assessments, while less common uses were trialling methods to improve estimates, and assessing threat impacts and conservation outcomes. C_LIO_LIThe mean coefficient of variation for published estimates was 0.17 (SD = 0.14), with no evidence that uncertainty has been reduced through time. As a consequence of this high uncertainty, when we simulated declines equivalent to thresholds commonly used to trigger management, only 5% of studies could detect significant differences between population estimates collected 10 years apart for populations declining at a rate of 30% over three generations. C_LIO_LIReporting of uncertainty was variable with no dispersion statistics reported with 38% of population estimates and most not reporting key underlying parameters: nest numbers/density and nest occupancy. We also found no correlation between population estimates and either island size, body size or species threat status--potential predictors of uncertainty. C_LIO_LISynthesis and applications--Key recommendations for managers are to be mindful of uncertainty in past population estimates if aiming to collect contemporary estimates for comparison, to report uncertainty clearly for new estimates, and to give careful consideration to whether a proposed estimate is likely to achieve the requisite level of certainty for the investment in its generation to be warranted. We recommend a practitioner-based Value of Information assessment to confirm where there is value in reducing uncertainty. C_LI

ecology↗

bioRxiv2021

Detecting seabird responses to invasive species eradication

Maximising survey efficiency can help reduce the trade-off between spending limited conservation resources on evaluating performance of past interventions and directing those resources towards future interventions. Seabird responses to island eradications are often poorly evaluated owing to financial, logistical and methodological challenges associated with remote field work and species ecology. We surveyed an assemblage of threatened seabirds following the worlds largest island eradication of multiple invasive species, testing multiple survey designs and outputs. We compared the outcomes of two important choices made during survey design: 1) whether to use unbiased or targeted surveys; and 2) implementing design-based or model-based analyses. An unbiased whole-island stratified randomised survey design performed well in terms of confidence in the final population estimates for widespread species, but poorly for localised recolonising species. For widespread species, model-based analyses resulted in slightly lower population estimates with narrower confidence intervals than traditional design-based approaches but failed to capture the realised niches of recolonising species, resulting in population estimates three orders of magnitude higher than current best estimates. We conclude that a multi-method approach to survey design best captures the size and distribution of recovering populations when the study system is ecologically diverse--importantly our results suggest there is no single strategy for efficient surveys of diverse seabird communities following large island invasive species eradications.

ecology↗

bioRxiv2021

Differing ecological responses of seabirds to invasive species eradication

The impact of invasive species at seabird breeding islands causes a breakdown of important ecological functions such as prey consumption and nutrient transfer, and elevates extinction risk in impacted taxa. Eradicating invasive species from islands can result in substantial short-term recovery of seabird populations and consequently the prevalence of eradication programs as conservation tools is increasing. However, as the scale and complexity of eradications has increased, quantitative data on rates of recovery, especially from larger islands, remain limited. Furthermore, the mechanisms that govern recovery are poorly understood, limiting our ability to forecast outcomes and therefore prioritise effectively. Here, using the worlds largest multi-species vertebrate eradication from Macquarie Island as a case study, we show how responses to invasive species and their eradication differ. Species with broad realised niches whose breeding phenology minimizes time on land and corresponds with summer resource abundance remained extant alongside invasive species while more habitat-specific species present in winter were extirpated. Following eradication, immigration and flexibility to colonise under-utilised optimal habitat appears to be boosting population growth in recolonising species, whereas established populations appear to be tethered to refugial habitats by the influence of philopatry, and their recovery is slower as a result. Unpicking these differential responses and the mechanisms behind them provides valuable information to help predict responses in other systems as future eradications are planned.

ecology↗

bioRxiv2017

Bipolar filaments of human nonmuscle myosin 2-A and 2-B have distinct motile and mechanical properties

Nonmuscle myosin 2 (NM-2) powers cell motility and tissue morphogenesis by assembling into bipolar filaments that interact with actin. Although the enzymatic properties of purified NM-2 motor fragments have been determined, the emergent properties of filament ensembles are unknown. Using single myosin filament in vitro motility assays, we report fundamental differences in filaments formed of different NM-2 motors. Filaments consisting of NM2-B moved processively along actin, while under identical conditions, NM2-A filaments did not. By more closely mimicking the physiological milieu, either by increasing solution viscosity or by copolymerization with NM2-B, NM2-A containing filaments moved processively. Our data demonstrate that both the kinetic and mechanical properties of these two myosins, in addition to the stochiometry of NM-2 subunits, can tune filament mechanical output. We propose altering NM-2 filament composition is a general cellular strategy for tailoring force production of filaments to specific functions such as maintaining tension or remodeling actin.

biophysics↗