Biology subjects

Bell, N.

Publications and source records attributed to Bell, N..

5 recordsLinked to original sources

bioRxiv2025

Recovery of microbial ecophysiology and carbon accrual functions in peatlands under restoration

Peatlands are water-logged ecosystems that limit microbial decomposition making them effective carbon sinks. However, drainage or erosion removes these constraints on decomposition, switching them to carbon sources. Restoration aims to reverse these trends. Microbial ecophysiology influences carbon fluxes but how it responds to peatland degradation and restoration is poorly understood. Here we used metagenomics to study microbial functions and quantified growth rates using isotope labelling across seven sites in Britain, each with restored, degraded, and near-natural peatlands. We found that growth rates in restored treatments were comparable to the near-natural, but were significantly higher in degraded. This growth rate reduction in restored peatlands was dependent on the scale of degradation and the length of restoration, and was underpinned by a shift towards energetically less favourable metabolic pathways such as anaerobic respiration, fermentation, and carbon fixation. A peatland ecosystem health index estimated based on measurements of peat moisture, oxygen, pH, organic matter chemistry, and moss cover, explained a significant amount of variation in microbial ecophysiology across the gradient. We demonstrate that microbial ecophysiology changes with peatland ecosystem health in a predictable manner. This knowledge can inform restoration targets and monitoring of recovery to maximise the return of carbon accrual functions of peatlands.

microbiology↗

bioRxiv2023

Evaluation of In2Care mosquito stations for suppression of the Australian backyard mosquito, Aedes notoscriptus

Aedes notoscriptus (Skuse) is a container-inhabiting mosquito endemic to Australia that vectors arboviruses and is suspected to transmit Mycobacterium ulcerans, the cause of Buruli ulcer. We evaluated the effectiveness of the In2Care(R) station, which suppresses mosquito populations via the entomopathogenic fungus, Beauveria bassiana, and the insect growth regulator pyriproxyfen, the latter of which is autodisseminated among larval habitats by contaminated mosquitoes. A field trial was conducted using 110 In2Care(R) stations in a 50,000 m2 area and results were compared to four control areas that did not receive the treatment. Efficacy was evaluated by comparing egg counts and measuring larvicidal impact in surrounding breeding sites. Laboratory experiments validated the effect of B. bassiana on adult survival. Results of this field trial indicate that, six weeks after the In2Care(R) stations were deployed, treatment site ovitraps contained 43% fewer eggs than control site ovitraps, and 33% fewer eggs after ten weeks, suggesting that the In2Care(R) station was able to reduce the egg density of Ae. notoscriptus. Population reduction remained evident for up to three weeks after In2Care(R) stations were removed. Treatment site ovitraps had significantly fewer Ae. notoscriptus eclosing than control site ovitraps, confirming the pyriproxyfen autodissemination feature of the stations. An average reduction of 50% in adult eclosion was achieved. Exposure to B. bassiana resulted in four-times higher mortality among adult mosquitoes. Additionally, using fresh In2Care(R) nettings led to an 88% decrease in average survival compared to four-week-old nettings. The use of In2Care(R) stations has potential for suppressing Ae. notoscriptus egg density.

ecology↗

bioRxiv2023

Modulations of right hemisphere connectivity in young children relates to the perception of spoken words

The early school years shape a young brains capability to comprehend and contextualize words within milliseconds of exposure. Parsing word sounds (phonological interpretation) and word recognition (enabling semantic interpretation) are integral to this process. Yet little is known about the causal mechanisms of cortical activity during these early developmental stages. In this study, we aimed to explore these causal mechanisms via dynamic causal modelling of event-related potentials (ERPs) acquired from 30 typically developing children (ages 6 to 8 years) as they completed a spoken word-picture matching task. Source reconstruction of high-density electroencephalography (128 channels) was used to ascertain differences in whole-brain cortical activity during semantically "congruent" and "incongruent" conditions. Source activations analyzed during the N400 ERP window identified significant regions-of-interest (pFWE<.05) localized primarily in the right hemisphere when contrasting congruent and incongruent word-picture stimuli. Dynamic causal models (DCMs) were tested on source activations in the fusiform gyrus (rFusi), inferior parietal lobule (rIPL), inferior temporal gyrus (rITG) and superior frontal gyrus (rSFG). DCM results indicated that a fully connected bidirectional model with self-(inhibiting) connections over rFusi, rIPL and rSFG provided the highest model evidence, based on exceedance probabilities derived from Bayesian statistical inferences. Connectivity parameters of rITG and rSFG regions from the winning DCM were negatively correlated with behavioural measures of receptive vocabulary and phonological memory (pFDR<.05), such that lower scores on these assessments corresponded with increased connectivity between temporal pole and anterior frontal regions. The findings suggest that children with lower language processing skills required increased recruitment of right hemisphere frontal/temporal areas during task performance.

neuroscience↗

bioRxiv2019

A LAMP assay for the rapid and robust assessment of Wolbachia infection in Aedes aegypti under field and laboratory conditions

With Wolbachia-based arbovirus control programs being scaled and operationalised around the world, cost effective and reliable detection of Wolbachia in field samples and laboratory stocks is essential for quality control. Here we validate a modified loop-mediated isothermal amplification (LAMP) assay for routine scoring of Wolbachia in mosquitoes from laboratory cultures and the field, applicable to any setting. We show that this assay is a rapid and robust method for highly sensitive and specific detection of wAlbB Wolbachia infection within Aedes aegypti under a variety of conditions. We test the quantitative nature of the assay by evaluating pooled mixtures of Wolbachia-infected and uninfected mosquitoes and show that it is capable of estimating infection frequencies, potentially circumventing the need to perform large-scale individual analysis for wAlbB infection status in the course of field monitoring. These results indicate that LAMP assays are useful for routine screening particularly under field conditions away from laboratory facilities.\n\nImportanceReleases of mosquitoes infected with strains of Wolbachia bacteria are expanding around the world because this bacterium that lives inside cells provides an effective tool to suppress mosquito populations and the ability of mosquitoes to transmit viruses. The success of the release programs relies on rapid and effective means of detecting Wolbachia and scoring their frequencies in mosquitoes for quality control and for assessing the success of releases. Here we test a \"LAMP\" (Loop-mediated isothermal amplification) assay for robust detection of Wolbachia infections in laboratory and field mosquito populations. We show that the assay can detect the bacteria when present at a low density in samples, and with a high degree of reproducibility. The assay uses a simple protocol which requires minimal training. It can readily detect Wolbachia in mosquitoes obtained from traps that are routinely used in field surveys. The assay should be cost effective in a variety of settings.

genetics↗

bioRxiv2019

PEGylated surfaces for the study of DNA-protein interactions by atomic force microscopy

DNA-protein interactions are vital to cellular function, with key roles in the regulation of gene expression and genome maintenance. Atomic force microscopy (AFM) offers the ability to visualize DNA-protein interactions at nanometre resolution in near-physiological buffers, but it requires that the DNA be adhered to the surface of a solid substrate. This presents a problem when working at biologically relevant protein concentrations, where protein may be present at large excess in solution; much of the biophysically relevant information can therefore be occluded by non-specific protein binding to the underlying substrate. Here we explore the use of PLLx-b-PEGy block copolymers to achieve selective adsorption of DNA on a mica surface. Through varying both the number of lysine and ethylene glycol residues in the block copolymers, we show selective adsorption of DNA on mica that is functionalized with a PLL10-b-PEG113 / PLL1000-2000 mixture as viewed by AFM imaging in a solution containing high concentrations of streptavidin. We show that this selective adsorption extends to DNA-protein complexes, through the use of biotinylated DNA and streptavidin, and demonstrate that DNA-bound streptavidin can be unambiguously distinguished by in-liquid AFM in spite of an excess of unbound streptavidin in solution.

biophysics↗