Biology subjects

Philpott, J.

Publications and source records attributed to Philpott, J..

7 recordsLinked to original sources

bioRxiv2026

Essential function of femaleless in female gametogenesis controls gene drive spread in Anopheles gambiae

Insecticide resistance in mosquito vectors and antimalarial drug resistance in parasites threaten progress towards malaria elimination, prompting the development of alternative control strategies such as CRISPR-Cas9 gene drives. The sex determination gene femaleless (fle, AGAP013051), which is required for female development in Anopheles gambiae, is a promising target for population-suppression approaches aimed at disrupting female-specific genes that affect fertility or viability. However, its functions beyond sex determination remain unknown. Here, we engineered homing gene drives targeting fle and employed germline promoters with distinct temporal expression profiles, early-acting , zero population growth (zpg, AGAP006241) and late-acting sporulation defective 11 (spo11, AGAP010898), to modulate Cas9 activity. The zpg-driven system achieved up to 98% transmission through males but caused complete sterility in hemizygous females due to early biallelic disruption of fle during germline development. Delaying cas9 expression with the spo11 promoter partially restored female fertility, although female transmission remained close to Mendelian levels (59%). These results reveal an essential role for fle in female gametogenesis in addition to its established function in sex determination. Population modelling predicts that releasing zpg-drive males at 16.9% of the wild-type male population could reduce female abundance by 95% within 36 generations. Collectively, our findings reveal a previously unrecognised reproductive function of fle that limits gene-drive spread and provide important insights for the design of vector-control strategies targeting genes with essential germline functions.

synthetic biology↗

bioRxiv2026

Competitive multiplication rate variation of Plasmodium falciparum isolates is determined by differences in intrinsic potential

Malaria parasite virulence will be impacted by naturally occurring variation in multiplication rates. Clinical isolates of Plasmodium falciparum exhibit a range of multiplication rates under exponential growth conditions in culture, but it needs to be discovered if relative multiplication rates under competitive conditions are principally defined by this underlying multiplication rate potential. Relative multiplication rates of P. falciparum lines were investigated in 14-day competition assays against a standard competitor clone HB3, with other long-term laboratory-adapted clones showing similar or higher mean per-48-hour rates ranging from 0.98 to 1.51 relative to HB3. In contrast, thirteen Ghanaian clinical isolates cultured for close to two months prior to assay had lower rates, ranging from 0.46 to 0.76 relative to HB3. Analysing the single-genotype clinical isolates and laboratory-adapted clones, there was a highly significant correlation between the competitive rates and previously determined exponential rates (Spearmans rho = 0.95, P = 0.0003), which accounted for most of the observed variance (Pearsons r2 = 0.77, P = 0.004). Testing the effect of alternative nutritional supplementation with human serum or Albumax showed a majority of parasites had consistent competitive rates under either condition, indicating that intrinsic differences determine most variation among parasites.

microbiology↗

bioRxiv2025

FlowAgent: A Modular Agent-Based System for Automated Workflow Management and Data Interpretation

Reproducibility, automation, and flexibility remain persistent challenges in bioinformatics, where complex workflows require integration of diverse computational tools, rigorous quality control, and dynamic adaptability to evolving datasets. Existing workflow managers often trade off usability for flexibility, limiting accessibility for non-specialists and enforcing rigid execution pipelines. We present FlowAgent, an adaptive agent-based framework that embeds computational heuristics and intelligent decision-making into workflow management. Unlike static pipeline managers, FlowAgent leverages agentic systems for context-aware automation, enhancing error detection, correction, and real-time optimisation while minimising manual intervention. By integrating bioinformatics tools with adaptive control, FlowAgent ensures robust quality control and enables workflow execution through an intuitive natural language interface. This approach democratises advanced computational methods for biologists while allowing bioinformaticians to focus on high-level analysis. FlowAgent redefines workflow automation, making bioinformatics pipelines more intelligent, efficient, and accessible, ultimately accelerating scientific discovery across diverse omics data modalities. Availability and implementationFlowAgent is available with GLPv3 license at https://github.com/EnteloBio/flowagent

genomics↗

bioRxiv2024

Intrinsic multiplication rate variation of Plasmodium falciparum (in clinical isolates prior to elimination in Malaysia

Replication rates and virulence of pathogens are hypothesised to evolve in response to varying intensity of transmission and competition among genotypes. Under exponential growth conditions in culture, clinical isolates of the malaria parasite Plasmodium falciparum have variable intrinsic multiplication rates, but comparisons of samples from different areas are needed. To analyse parasites from an area of low endemicity, Malaysian clinical isolates cryopreserved prior to malaria elimination were studied. The mean and range of P. falciparum multiplication rates in Malaysian isolates was no less than that seen among isolates from more highly endemic populations in Africa, which does not support a hypothesis of adaptation to prevailing levels of infection endemicity. Moreover, the distribution of multiplication rates was similar between isolates with single parasite genotypes and those containing multiple genotypes, which does not support a hypothesis of facultative adjustment to competing parasites. Based on clinical isolates, the findings indicate that parasites may not evolve lower multiplication rates under conditions of reduced transmission, and that the virulence potential is likely to be undiminished in pre-elimination settings. This encourages efforts to eliminate endemic infection completely, as has been achieved at the national level in Malaysia.

microbiology↗

bioRxiv2024

Higher multiplication rates of Plasmodium falciparum in isolates from hospital cases compared with community infections

BackgroundParasite multiplication rates vary among Plasmodium falciparum isolates from patients with malaria, suggesting differences in virulence potential, although direct comparisons between hospital-based clinical cases and community infections are needed. MethodsCryopreserved blood samples from malaria cases presenting to a district hospital in The Gambia and infections detected in local communities were introduced to continuous culture under the same conditions. Thirty-four isolates (23 hospital-based and 11 community-based) were successfully established and then tested under exponential growth conditions over six days to derive estimated P. falciparum multiplication rates per cycle based on a 48-hour typical cycle length. ResultsA range of parasite multiplication rates in culture was seen across isolates, from 1.5-fold to 5.0-fold per cycle. Multiplication rates were significantly higher in the hospital-based isolates than the community-based isolates. There was a significantly positive correlation between parasitaemia in peripheral blood and multiplication rates in culture. There was no significant difference in multiplication rates between isolates with single or multiple parasite genotypes. ConclusionsThese findings are consistent with a hypothesis that intrinsic natural variation in parasite multiplication rate may affect levels of parasitaemia achieved during infection, and that this affects likelihood of hospital presentation. Results do not support a hypothesis that parasites modify their multiplication rates in response to competing parasites with different genotypes. SummaryRelevant to understanding parasite virulence, this study finds higher Plasmodium falciparum multiplication rates in cultured isolates from malaria cases presenting to hospital than in isolates from local community infections, and positive correlation with parasitaemia in peripheral blood of individuals.

microbiology↗

bioRxiv2021

Assessment of Plasmodium falciparum infection and fitness of genetically modified Anopheles gambiae aimed at mosquito population replacement

Genetically modified (GM) mosquitoes expressing anti-plasmodial effectors propagating through wild mosquito populations by means of gene drive is a promising tool to support current malaria control strategies. The process of generating GM mosquitoes involves genetic transformation of mosquitoes from a laboratory colony and, often, interbreeding with other GM lines to cross in auxiliary traits. These mosquito colonies and GM lines thus often have different genetic backgrounds and GM lines are invariably highly inbred, which in conjunction with their independent rearing in the laboratory may translate to differences in their susceptibility to malaria parasite infection and life history traits. Here, we show that laboratory Anopheles gambiae colonies and GM lines expressing Cas9 and Cre recombinase vary greatly in their susceptibility to Plasmodium falciparum NF54 infection. Therefore, the choice of mosquitoes to be used as a reference when conducting infection or life history trait assays requires careful consideration. To address these issues, we established an experimental pipeline involving genetic crosses and genotyping of mosquitoes reared in shared containers throughout their lifecycle. We used this protocol to examine whether GM lines expressing the antimicrobial peptide (AMP) Scorpine in the mosquito midgut interfere with parasite infection and mosquito survival. We demonstrate that Scorpine expression in the Peritrophin 1 (Aper1) genomic locus reduces both P. falciparum sporozoite prevalence and mosquito lifespan; both these phenotypes are likely to be associated with the disturbance of the midgut microbiota homeostasis. These data lead us to conclude that the Aper1-Sco GM line could be used in proof-of-concept experiments aimed at mosquito population replacement, although the impact of its reduced fitness on the spread of the transgene through wild populations requires further investigation.

microbiology↗

bioRxiv2018

Dual cryo-radiofrequency ablation enhances lesion depth in beating human left ventricular preparations

Thermally-mediated ablation has utilized various energy sources, including cryothermal, radiofrequency (RF), microwave, laser, and high-frequency ultrasound with the goal of creating lesions to terminate focal sources or block reentrant wavefronts. RF- and cryo-ablation (CR) cause cell death through different mechanisms, and leave behind tissue with altered thermal-electric properties. We aimed to assess the effect of sequential RF and CR combinations on lesion size. Left ventricular (LV) wedge preparations (n=17) were dissected from ten donated human hearts and four epicardial ablation protocols were compared: 1) RF-RF (n=7); 2) CR-CR (n=7); 3) RF-CR (n=7); and 4) CR-RF (n=7). Preparations were continuously paced and perfused with oxygenated Tyrode solution. Ablated tissue was perfused for 3 hours, sectioned, and stained with 2,3,5-triphenyltetrazolium chloride to delineate necrosis. The effect of initial thermal-electric tissue properties on lesion depth during RF application was determined using a finite element method (FEM). CR-RF generated the deepest lesion (p<0.05) compared to protocols 1-3, while lesion width and area were similar among protocols. No energy combination produced a transmural lesion (n=0 of 28) in LV preparations. FEM showed that electrical conductivity plays a more significant role in lesion creation compared to thermal conductivity. A 33% increase in the initial thermal and electrical tissue conductivity generated a 21% deeper lesion. We conclude that sequential application of CR followed by RF created the deepest lesion in beating human LV preparations. This increase in lesion depth may translate into improved therapeutic outcomes for arrhythmias with intramural origins.

bioengineering↗