Biology subjects

Carter, N.

Publications and source records attributed to Carter, N..

6 recordsLinked to original sources

bioRxiv2025

Accelerated biomass loss in western US forestlands due to shifting fire regime

Wildfires influence the distribution of biomass across the Earths surface and drive losses of carbon from the land surface to the atmosphere. Although the global budget between terrestrial and atmospheric carbon pools is comparatively well understood (Jones et al., 2024; MacCarthy et al., 2024), the growing size and severity of wildfires present an increasing challenge to regional carbon accounting. To quantify vegetation biomass across arid systems in the western US, we used remote sensing data to estimate the aboveground live biomass density (Mg ha-1) at 30-meter resolution across the states of Utah and Nevada annually from 2000 to 2022. Time series biomass maps showed accelerated loss of terrestrial carbon to the atmosphere as a result of increasing wildfire, with annual biomass burnt increasing at 0.105 {+/-} 0.024 Mt yr-1 (mean {+/-} standard deviation) after 2015. Recent shifts in the wildfire regime show a transition from predominantly early-season fires in low-biomass grasses and shrubs to late-season fires in higher-biomass forestlands. The proportion of total biomass loss attributed to wildfires in forestland areas increased from an average of 76% per year before 2015 to 94% in the years that followed. Furthermore, we found that recent droughts contributed to increased biomass loss in forestland areas, whereas biomass in non-forestland areas appeared unaffected by drought conditions. These findings underscore the escalating impact of climate change on fire regimes, highlighting the urgent need for adaptive land management strategies to mitigate carbon loss and preserve ecosystem resilience in the face of ongoing aridification.

ecology↗

bioRxiv2025

Investigating the relationship Between AMBRA1 and Cell Proliferation in Melanoma

The protein Activating molecule in Beclin1-regulated autophagy1 (AMBRA1), discovered in 2007, is crucial for autophagy and plays roles in nervous system development, cell survival, and proliferation. This study investigates AMBRA1s involvement in various cellular processes using a systems-based "omics" approach, focusing on melanoma. Transcriptomic analysis of the overexpression or the knock-down of AMBRA1 was shown to result in significant dysregulation of several transcripts. This appears to have identified several novel roles for AMBRA1 in a range of cellular pathways; some of these are hallmarks of cancer signaling including, MAPK, angiogenesis, tissue growth factor signaling, axon guidance and Wnt signaling. Yeast two-hybrid assays performed in this study identified novel binding partners that can provide evidence for new roles for AMBRA1 in different cellular processes. The work shows that AMBRA1 loss appears to upregulate metastatic genes/proteins supporting the role of AMBRA1 as a tumor suppressor gene in melanoma.

cancer biology↗

bioRxiv2025

ATPγS unbiases kinesin

Kinesin-1 microtubule motors are ATP-fuelled, twin-headed cargo transporters that step processively along microtubules, with a load-dependent directional bias. Here we show using single molecule optical trapping that 1 mM ATP{gamma}S, a slowly-hydrolysed analogue, substantially defeats the biasing mechanism, whereas 1 {micro}M ATP{gamma}S supports it. Our data argue that kinesin re-registers itself between steps into an Await-Isomerisation (AI) state that engenders both on-axis steps and off-axis missteps, and that missteps can be rescued. In the AI state, ATP or ATP{gamma}S is bound but neck-linker docking and nucleotide hydrolysis are inhibited. Load-dependent exit from the AI state establishes hydrolytic competence via catalytic site closure and coupled neck-linker docking, which guides the tethered head to its next on-axis site. By overpopulating the AI state, ATP{gamma}S reveals its pivotal role in the biasing mechanism, whose control logic maximises steered diffusion-to-capture of the leading kinesin-1 head under load, at the expense of futile nucleotide turnover.

biophysics↗

bioRxiv2022

Bio-inspired artificial printed bioelectronic cardio-3D-cellular constructs

Bioelectronics is a growing field where novel smart materials are required to interface biology with electronic components. Conductive hydrogels have recently emerged as a promising material for biosensing/actuating applications as they can provide a wet, nanostructured and electrically conductive environment, minimising the mismatch between biological and electronic systems. In this work, we propose a strategy to develop conductive bioinks compatible with the freeform reversible embedding of suspended hydrogels (FRESH) extrusion bioprinting method. These bioinks are based on decellularized extracellular matrix (dECM), extracted from three different tissues (small intestine submucosa, liver and bone) and were characterised. 3D structures were manufactured containing human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs), exhibiting cell viabilities >80%. Multi-walled carbon nanotubes (MWCNTs) were selected as an additional component of the bioinks. The addition of the MWCNTs enhanced the conductive features of the hydrogels and the morphology of the dECM fibres. Electrical stimulation (ES) through alternating currents was applied to hPSC-CMs encapsulated in 3D structures manufactured with the previous material and our results indicated two main findings: (1) in the absence of external ES, the conductive properties of the materials can improve the contractile behaviour of the hPSC-CMs and (2) this effect is significantly enhanced under the application of external ES. Genetic markers analysed showed a trend towards a more mature state of the cells evaluated by the TNNI3/TNNI1 ratio, with upregulated SERCA2 and RYR2 calcium handling proteins when compared to controls and downregulation of calcium channels involved in the generation of pacemaking currents (CACNA1H). These results demonstrate the potential of our strategy to manufacture conductive hydrogels in complex geometries for bioactuating purposes. However, further development of the 3D bioprinting techniques is required to achieve higher control over the nano- and microarchitectures of the structures to improve their biomimicry.

bioengineering↗

bioRxiv2020

Biodiversity Conservation Can Coexist with Increasing Human Footprint

The human footprint index is an extensively used tool for interpreting the accelerating pressure of humanity on Earth. Up to now, the process of creating the human footprint index has required significant data and modeling, and updated versions of the index often lag the present day by many years. Here we introduce a near-present, global-scale machine learning-based human footprint index (ml-HFI) which is capable of routine update using satellite imagery alone. We present the most up-to-date map of the human footprint index, and document changes in human pressure during the past 20 years (2000 to 2019). Moreover, we demonstrate its utility as a monitoring tool for the United Nations Sustainable Development Goal 15 (SDG15), "Life on Land", which aims to foster sustainable development while conserving biodiversity. We identify 43 countries that are making progress toward SDG15 while also experiencing increases in their ml-HFI. We examine a subset of these in the context of conservation policies that may or may not enable continued progress toward SDG15. This has immediate policy relevance, since the majority of countries globally are not on track to achieve Goal 15 by the declared deadline of 2030. Moving forward, the ml-HFI may be used for ongoing monitoring and evaluation support toward the twin goals of fostering a thriving society and global Earth system.

ecology↗

bioRxiv2019

Inferring wildlife poaching in Southeast Asia with multispecies dynamic site-occupancy models

Determining the space race between sympatric species is crucial to understand the effects of interspecific interactions on the extinction risk of species threatened by poachers, predators, pathogens, and invasive competitors. Dynamic two-species occupancy models provide a flexible framework to decompose complex species interaction patterns while accounting for imperfect detection. In particular, these models can describe poachers-wildlife interactions by considering the occupancy, the extinction and colonisation probabilities of wildlife conditional on the presence or absence of poachers and vice versa. We apply our model to a case study on wildlife poaching in the Eastern plains of Cambodia. We used co-occurrence data extracted from the database of the SMART partnership to study the distribution dynamics between poachers and six ungulate species regarded as main prey of tigers. We used 4 years of survey data reporting the locations of ranger patrols on the detection of snares with visual detections or presence signs of the ungulates. Our results showed that a substantial proportion of the sites occupied by ungulate species went extinct over the years of the study while the proportion of sites colonised by poachers increased. We also showed, for the first time, that spatio-temporal heterogeneity in the patrolling effort explains a great deal of the variation in the detection of poachers and ungulates. Our approach provides practitioners with a flexible and robust tool to assess conservation status of species and extinction risk of wildlife populations. It can assist managers in better evaluating, learning and adapting the patrolling strategies of rangers.

ecology↗