Biology subjects

Lawrence, J.

Publications and source records attributed to Lawrence, J..

10 recordsLinked to original sources

bioRxiv2026

LANTHANUM (LaCl3) ADDITION DIVERSIFIES ORGANIC ACID PRODUCTION AND SIGNIFICANTLY ENHANCES METHANE PRODUCTION IN A METHANOGENIC CONSORTIUM

Trace elements, such as iron, nickel, and cobalt are known to regulate methanogenic activity in anaerobic digestors used for waste valorisation, but the potential role of rare earth elements remains poorly understood. This study investigated the effects of lanthanum (La) supplementation on biogas production, methane generation, volatile fatty acid (VFA) formation, and carbohydrate utilisation in anaerobic digestion (AD). Biomethane potential (BMP) assays conducted under mesophilic conditions (37C) using methanogenic sludge granules, and glucose as substrate, were supplemented with 0.1, 1, 10, and 100 mg/L lanthanum chloride (LaCl3). Biogas production and composition was monitored over a 96-h incubation, while sacrificial, batch bioreactors were used to evaluate temporal VFA and carbohydrate profiles. La supplementation significantly enhanced biogas and methane production in a concentration-dependent manner. The highest cumulative biogas yield (478.9 mL, corresponding to 179.5 mL biogas/g COD) and methane production (285.7 mL, corresponding to 107.1 mL CH4/g COD) were observed with 100 mg/L LaCl3, corresponding to increases of 88.7% and 186%, respectively, compared with La-free controls. CO2 production also increased with La concentration, whereas hydrogen production remained comparatively low. Acetic and butyric acids represented the dominant fermentation products (80-88% of total VFAs), but profiles of accumulated VFA in the bioreactors diversified with La addition, including showing caproate production, indicating changed biodegradation dynamics in the methanogenic microbiome. These findings demonstrate that lanthanum can stimulate anaerobic digestion performance and methane generation, highlighting the potential as a novel trace element additive to enhance biogas production. Research is now required to elucidate the underlying microbial and biochemical mechanisms, and establish optimal dosing strategies for large-scale applications.

microbiology↗

bioRxiv2025

Pseudomonas aeruginosa phenazines dictate site-specific competitive interactions with Klebsiella pneumoniae

Pseudomonas aeruginosa and Klebsiella pneumoniae are Gram-negative opportunistic pathogens that frequently colonize the human body and are major causes of infection. These bacteria are often co-isolated in polymicrobial urinary tract and lung infections, the latter of which is associated with increased disease severity and worse clinical outcomes. Despite their overlapping niches and clinical relevance, little is known about how these two pathogens interact and how those interactions influence human health. Given the growing recognition that microbial interactions are key drivers of disease, we investigated how P. aeruginosa and K. pneumoniae influence one another. We discovered an antagonistic interaction in which P. aeruginosa restricts the growth of K. pneumoniae. This inhibition is driven by phenazine production in P. aeruginosa, specifically the secondary metabolites pyocyanin and pyorubin, which are both necessary and sufficient to suppress K. pneumoniae growth. Using a diverse set of clinical isolates, we found that this antagonism is strain dependent. Both the susceptibility of K. pneumoniae to phenazines and the ability of P. aeruginosa to restrict K. pneumoniae growth varies between strains. Moreover, the necessity of phenazine production is specific to the site of infection. Together, these findings demonstrate that strain background and environmental context are critical determinants of pathogen interactions. Our work underscores the importance of considering these variables when investigating how microbial interactions influence infection and disease outcomes.

microbiology↗

bioRxiv2025

NETSseq Reveals Inflammatory and Aging Mechanisms in Distinct Cell Types Driving Cerebellar Decline in Ataxia Telangiectasia

The cellular and molecular changes driving the neurological abnormalities associated with ataxia - telangiectasia (A-T) are not well understood. Here, we applied our proprietary Nuclear Enriched Transcript Sort sequencing (NETSseq) platform to investigate changes in cell type composition and gene expression in human cerebellar post-mortem tissue from A-T and control donors. Compared to single-nuclei technologies, NETSseq provided a more robust detection of genes with low abundance, a higher cell type specific expression pattern, and significantly lower levels of cross-contamination. We found dysregulation in neurotransmitter signaling in granule neurons, potentially underlying the impaired motor coordination in A-T. Astrocytes and microglia have evidence of accelerated aging, with astrocytes being characterized by neurotoxic signatures, while microglia showed activation of DNA damage response pathways. These findings highlight the importance of NETSseq as a resource for investigating mechanisms and biological processes associated with disease, providing high-sensitivity, cell-specific insights to advance targeted therapies for neurodegenerative diseases.

neuroscience↗

bioRxiv2024

dsRNAmax: a Multi-Target Chimeric dsRNA Designer for Safe And Effective Crop Protection

Crop protection is undergoing significant evolution, transitioning toward sustainable approaches that minimise impacts on the environment and human health. Exogenous application of double-stranded RNA (dsRNA) that silences pest or pathogen genes via RNAi (RNA interference) has promise as a safe and effective next generation crop protection platform without the need for genetic modification. However, exogenous dsRNA application at scale presents challenges. Specifically, a single dsRNA sequence needs to balance targeting the standing variation in a target pest or pathogen group against the potential for adverse impacts in a vast array of non-target and beneficial organisms at the application site and broader environment. To address these competing demands, we present dsRNAmax (https://github.com/sfletc/dsRNAmax), a software package that employs k-mer based assembly of chimeric dsRNA sequences to target multiple related RNA sequences, to broaden the target spectrum. The package ensures designed dsRNAs have no defined contiguous sequence homology with any off-target sequences, which can range from single transcriptomes through to metagenome sequence data and beyond. The efficacy of this package is demonstrated by a dsRNAmax-designed dsRNA that inhibits multiple root-knot nematode species but not a non-target nematode species, despite its susceptibility to environmental RNAi and high homology of the target gene. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/628581v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@c776c5org.highwire.dtl.DTLVardef@1468e45org.highwire.dtl.DTLVardef@1268b08org.highwire.dtl.DTLVardef@171ee19_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2024

Protein degradation by small tag artificial bacterial E3 ligase

Targeting of proteins for degradation in a reversible manner is a powerful approach to decipher gene function and mimic drug effects, with great potential for drug target discovery and validation. A generalized approach is to tag a protein of interest and then use this tag to recruit an endogenously or exogenously expressed E3 ligase for its polyubiquitination and subsequent degradation via 26S proteasome. However, the often bulky size of the tag and the great variability of substrate-dependent degradation efficiency of mammalian E3 ligases pose great challenges in practice. Here we show that small tags (10-15 amino acids) can be used to efficiently tag endogenous proteins for degradation when coupled with an exogenously expressed artificial bacterial E3 ligase (ABEL) consisting of a tag-interacting moiety and the catalytic domain of the bacterial E3 ligase IpaH9.8. We name this versatile and efficient platform degradation by small tag ABEL (DESTABEL). Furthermore, we show that an ABEL containing a nanobody against human -synuclein mediates efficient degradation in primary neurons as well as in the adult mouse brain. Taken together, our data show that tag-dependent and independent ABELs are powerful yet flexible tools for studies of protein function and drug target validation.

molecular biology↗

bioRxiv2024

Radiation dermatitis in the hairless mouse model mimics human radiation dermatitis

Over half of all people diagnosed with cancer receive radiation therapy. Moderate to severe radiation dermatitis occurs in most human radiation patients, causing pain, aesthetic distress, and a negative impact on tumor control. No effective prevention or treatment for radiation dermatitis exists. The lack of well-characterized, clinically relevant animal models of human radiation dermatitis contributes to the absence of strategies to mitigate radiation dermatitis. Here, we establish and characterize a hairless SKH-1 mouse model of human radiation dermatitis by correlating temporal stages of clinical and pathological skin injury. We demonstrate that a single ionizing radiation treatment of 30 Gy using 6 MeV electrons induces severe clinical grade 3 peak toxicity at 12 days, defined by marked erythema, desquamation and partial ulceration, with resolution occurring by 25 days. Histopathology reveals that radiation-induced skin injury features temporally unique inflammatory changes. Upregulation of epidermal and dermal TGF-{beta}1 and COX-2 protein expression occurs at peak dermatitis, with sustained epidermal TGF-{beta}1 expression beyond resolution. Specific histopathological variables that remain substantially high at peak toxicity and early clinical resolution, including epidermal thickening, hyperkeratosis and dermal fibroplasia/fibrosis, serve as specific measurable parameters for in vivo interventional preclinical studies that seek to mitigate radiation-induced skin injury.

pathology↗

bioRxiv2023

Novel lytic and lysogenic cyanophages predicted to infect Microcoleus associated with anatoxin-producing benthic mats

Proliferations of toxic benthic cyanobacteria are increasingly being reported around the world. Of particular concern are Microcoleus-dominated mats associated with anatoxin production that have resulted in dog fatalities. Although the impact of cyanophages has been demonstrated in planktonic systems, their role in the population dynamics of benthic cyanobacteria has received little attention. Here we use metagenomics to explore phage presence in benthic mats from the Wolastoq|Saint John River (WR; New Brunswick, Canada) and Eel River (ER; California, US). Our survey recovered multiple viral-like sequences associated with different putative bacterial hosts, including two cyanophage genomes with apparently different replication strategies. A lysogenic cyanophage (predicted as a prophage) was found integrated in the genomes of Microcoleus sp. 3 recovered from five ER mat samples. This Microcoleus phage is related to previously described Phormidium phage counterparts. Also, we recovered lytic cyanophages from WR and ER mats dominated by anatoxin-producing Microcoleus, which was predicted as the putative host. Despite the geographical distance between WR and ER, the lytic Microcoleus phage genomes recovered from each river have similar sizes (circa 239 Kbp) and share similar gene content with high sequence identity. Phylogenetic analysis suggests that these lytic Microcoleus phages are distant from any other cyanophage previously described. Our results constitute the first report of cyanophages predicted to infect and therefore influence the population dynamics of mat-forming Microcoleus spp. associated with anatoxin production.

microbiology↗

bioRxiv2021

Cytometric Analysis of Diverse Glaucophyte Species Reveals Distinctive Signals Useful for Fluorescence-Based Detection and Sorting

Glaucophytes, red algae and viridiplants (green algae and land plants) are formally united in the supergroup Archaeplastida. Although diverse molecular and genomic evidence suggest the common origin of the three Archaeplastida lineages, the lack of a robust glaucophyte knowledgebase has limited comprehensive evaluations of competing hypotheses. Glaucophytes are rare and apparently confined to freshwater habitats. However, the distribution and diversity of these algae have not been thoroughly explored owing to challenges with detecting and isolating novel specimens. Here we examined the cytometric signatures of representative species of the genera Cyanophora, Cyanoptyche, Glaucocystis and Gloeochaete for a distinctive signal that would aid identification. Most glaucophytes analyzed presented a relatively high red fluorescence signal due to the presence of the blue phycobiliproteins C-phycocyanin and allophycocyanin. Cell-size differences and the concurrent presence of the red phycobiliprotein phycoerythrin in other algal lineages, such as red algae and cryptophytes, allowed us to distinguish glaucophytes from other photosynthetic cells containing blue phycobiliproteins. Our results indicate that the peculiar autofluorescence signal of glaucophytes will facilitate further identification and isolation on novel specimens of this scarce but important algal group.

plant biology↗

bioRxiv2019

Somatodendritic HCN channels in hippocampal OLM cells revealed by a convergence of computational models and experiments

Determining details of spatially extended neurons is a challenge that needs to be overcome. The oriens-lacunosum/moleculare (OLM) interneuron has been implicated as a critical controller of hippocampal memory making it essential to understand how its biophysical properties contribute to function. We previously used computational models to show that OLM cells exhibit theta spiking resonance frequencies that depend on their dendrites having hyperpolarization-activated cation channels (h-channels). However, whether OLM cells have dendritic h-channels is unknown. We performed a set of whole-cell recordings of OLM cells from mouse hippocampus and constructed multi-compartment models using morphological and electrophysiological parameters extracted from the same cell. The models matched experiments only when dendritic h-channels were present. Immunohistochemical localization of the HCN2 subunit confirmed dendritic expression. These models can be used to obtain insight into hippocampal function. Our work shows that a tight integration of model and experiment tackles the challenge of characterizing spatially extended neurons.

neuroscience↗

bioRxiv2019

Increased Replication Rates of Dissimilatory Nitrogen-Reducing Bacteria Leads to Decreased Anammox Reactor Performance

BackgroundAnaerobic ammonium oxidation (anammox) is a biological process employed to remove reactive nitrogen from wastewater. While a substantial body of literature describes the performance of anammox bioreactors under various operational conditions and perturbations, few studies have resolved the metabolic roles of their core microbial community members. ResultsHere, we used metagenomics to study the microbial community of a laboratory-scale anammox bioreactor from inoculation, through a performance destabilization event, to robust steady-state performance. Metabolic analyses revealed that nutrient acquisition from the environment is selected for in the anammox community. Dissimilatory nitrate reduction to ammonium (DNRA) was the primary nitrogen removal pathway that competed with anammox. Increased replication of bacteria capable of DNRA led to the out-competition of annamox bacteria, and the loss of the bioreactors nitrogen removal capacity. These bacteria were highly associated with the anammox bacterium and considered part of the core microbial community. ConclusionsOur findings highlight the importance of metabolic interdependencies related to nitrogen- and carbon-cycling within anammox bioreactors and the potentially detrimental effects of bacteria that are otherwise considered core microbial community members.

microbiology↗