Biology subjects

Paul, G.

Publications and source records attributed to Paul, G..

10 recordsLinked to original sources

bioRxiv2026

Genomic hallmarks of parasexual reproduction in three hybrid groups of the human pathogen Cryptococcus neoformans

Hybridization is a major driver of fungal evolution, yet knowledge of the molecular mechanisms underpinning hybridization and its genomic impact remain limited. Here, we analyse 197 Cryptococcus neoformans genomic sequences, including 13 newly sequenced strains, identifying three genetically clustered and distinct hybrid groups (H1, H2 and H3) each with unique parental origins and ecological associations. Using phylogenomics, population structure analyses, and long-read genome assemblies, we identified hybrid genomes with chromosome-wide loss of heterozygosity (LOH), inheritance of large intact parental haplotype blocks and widespread aneuploidy within and across genomes. These patterns are also observed when progeny were generated with spo11{Delta} parents, indicating these features are a result of a meiotic-independent process such as parasex. This is further underscored by discovery of haploid and near-haploid recombinants in both spo11{Delta} mutant progeny and reanalysed wild-type hybrid progeny. We hypothesise these haploid and near-haploid recombinants are generated through ploidy reduction via independent chromosome assortment because of concerted chromosomal loss, which is a key feature of the parasexual cycle. Phenotypic assays demonstrated that several hybrid isolates have diverse growth and virulence patterns, underscoring functional consequences of genome plasticity. Together, our work suggests a non-meiotic reproductive process contributes to shape the genotypic and phenotypic diversity of Cryptococcus neoformans.

genomics↗

bioRxiv2026

Aging-associated endo-lysosomal dysfunction drives inflammaging and neurodegeneration through the STING-IFN-I axis

All animals age. However, aging is a heterogeneous process and individual organisms age differently. Moreover, within the same organism, cells or organs do not age at the same time or speed. For instance, although neurodegeneration is a key trait of aging, neurological symptoms normally manifest long after multiple indicators of aging in peripheral tissues. The genetic determinants of aging remain poorly understood. Mutations in leucine-rich repeat kinase 2 (LRRK2) are major genetic risk factors for Parkinsons disease (PD). By analyzing PD patients and mice with LRRK2 gain of function mutation (LRRK2GoF), we demonstrate that PD is an accelerated aging disease characterized by systemic low-grade STING-dependent inflammation (inflammaging) that first manifests in the periphery then disrupts the blood brain barrier and progresses to the brain resulting in neurodegeneration. Mechanistically, we demonstrate that a primary consequence of aging or Lrrk2GoF is endolysosomal decline. This results in the cytosolic build-up of extraneous self-DNA and subsequent shedding of DNA-containing extracellular vesicles thereby triggering the cGAS- STING pathway cell-intrinsically and intercellularly in distant host cells. This study unveils the cGAS-STING pathway and LRRK2GoF as key determinants and potential targets for preventive or therapeutic strategies against accelerated aging, inflammaging and neurodegeneration.

immunology↗

bioRxiv2025

Stage-specific regulation of the Plasmodium falciparum proteasome activity reveals adaptive rewiring in artemisinin resistance

The ubiquitin-proteasome system (UPS) is essential for Plasmodium falciparum to maintain protein homeostasis, adapt to proteotoxic stress, and regulate parasite growth and stage transitions. The proteolytic 20S proteasome core is the central component of the UPS, where unfolded protein substrates are degraded into oligopeptides. Mechanisms regulating malaria parasite proteasome activity are poorly understood and have not been thoroughly studied. This knowledge gap is especially critical in the context of artemisinin (ART) resistance, where parasite survival depends on an enhanced stress response, including a greater reliance on the UPS. Here, we profiled proteasome activity and abundance across the parasite intraerythrocytic developmental cycle (IDC) in both ART-sensitive (ART-S) Dd2 and ART-resistant (ART-R) Dd2K13R539T parasites. We uncovered striking stage-specific regulation: proteasome activity was abundant in the ring stage, decreased in trophozoites, and then peaked in schizonts. Furthermore, ART-R Dd2K13R539T parasites exhibited higher ring-stage proteasome activity than ART-S Dd2, despite reduced proteasome abundance, suggesting a unique adaptive rewiring of proteasome function. To study proteasome regulation in the parasite, we manipulated proteasome abundance in Dd2 and Dd2K13R539T by creating a conditional knockdown of PfUMP1, a conserved proteasome maturation factor. PfUMP1 depletion disrupted 20S assembly, decreased proteasome activity, and led to parasite death. These experiments uncovered two key features of proteasome regulation in P. falciparum: (1) the absence of canonical transcriptional regulation of proteasome genes in response to downregulation of proteasome activity, and (2) ART-R parasites exhibit a ring-stage specific increased sensitivity to proteasome downregulation. Together, our findings reveal a previously unrecognized layer of proteasome regulation in malaria parasites and how, as part of their survival adaptations to decreased hemoglobin uptake associated with ART resistance, these parasites alter proteasome function to survive. This work reinforces the therapeutic potential of the proteasome as a stage- and resistance-specific antimalarial target.

microbiology↗

bioRxiv2025

Gut Microbiota Shifts with Lifetime Duration of Oral Contraception Use

To investigate the effects of lifetime duration of oral contraceptive (OC) use, we reanalyzed publicly available 16S rRNA sequencing data from fecal samples of OC users and non-users collected at different timepoints in the menstrual cycle. We profiled the microbial composition of subjects and identified 32 significantly differentially abundant Amplicon Sequence Variants (padj<0.05) with increasing lifetime use duration including 16 ASVs belonging to class Clostidia that decreased with longer OC use. Some Clostridia species are known to recycle estrogen; lifetime duration of OC exposure could thus influence womens health through gut microbiome composition and hormone regulation.

microbiology↗

bioRxiv2025

LFA-1 Interaction with GBP-130 on Plasmodium falciparum-infected Red Blood Cells mediates NK Cell Activation and Parasite Control

Natural Killer (NK) cells contribute to early immunity against Plasmodium falciparum by recognizing and eliminating infected red blood cells (iRBCs), a process mediated in part by the integrin LFA-1. However, the cognate parasite ligand for LFA-1 has remained unknown. Here, we identify Glycophorin Binding Protein-130 (PfGBP-130) as a surface-expressed ligand on iRBCs that binds the I-domain of LFA-1 (LFA-1 I). Using an LFA-1 I-Fc fusion protein, we demonstrate stage-specific binding to iRBCs, and LC-MS/MS analysis of immunopreciptates of I-Fc bound to iRBC revealed PfGBP-130 as a high-confidence interactor. Recombinant PfGBP-130 binds NK and THP-1 cells in an LFA-1-dependent manner. Co-culture assays show that PfGBP-130 promotes NK cell activation, degranulation, and facilitates contact-dependent killing of iRBCs. Neutralizing antibodies against PfGBP-130 significantly impair these responses. Our findings establish PfGBP-130 as the LFA-1 ligand on iRBCs, providing new insight into NK cell-mediated immunity in malaria and identifying a potential target for host-directed interventions.

immunology↗

bioRxiv2025

Alternative splicing generates a Ribosomal Protein S24 isoform induced by neuroinflammation and neurodegeneration

Neuroinflammation, particularly that involving reactive microglia, the brains resident immune cells, is implicated in the pathogenesis of major neurodegenerative diseases. However, early markers of this process are in high demand. Multiple studies have reported changes in ribosomal protein (RP) expression during neurodegeneration, but the significance of these changes remains unclear. Ribosomes are evolutionarily conserved protein synthesizing machines, and although commonly viewed as invariant, accumulating evidence suggest functional ribosome specialization through variation in their protein composition. By analyzing cell type-specific translating mRNAs from mouse brains, we identify distinct RP expression patterns between neurons, astrocytes, and microglia, including neuron-specific RPs, Rpl13a and Rps10. We also observed complex expression relationships between RP paralogs and their canonical counterparts, suggesting regulated mechanisms for generating heterogeneous ribosomes. Analysis across brain regions revealed that Rplp0 and Rpl13a, commonly used normalization references, show heterogeneous expression, raising important methodological considerations for gene expression studies. Importantly, we show that Rps24, an essential ribosome component that undergoes alternative splicing to produce protein variants with different C-termini, exhibits striking cell type-specific isoform expression in brain. The Rps24c isoform is predominantly expressed in microglia and is increased by neuroinflammation caused by aging, neurodegeneration, or inflammatory chemicals. We verify increased expression of S24-PKE, the protein variant encoded by Rps24c, in brains with Alzheimers disease, Parkinsons disease, and Huntingtons disease, and relevant mouse models, using isoform-specific antibodies. These findings establish heterogeneous RP expression as a feature of brain cell types and identify Rps24c/S24-PKE as a novel marker for neuroinflammation and neurodegeneration.

neuroscience↗

bioRxiv2024

Mapping Grip Force to Muscular Activity Towards Understanding Upper Limb Musculoskeletal Intent using a Novel Grip Strength Model

This work aims to evaluate a grip strength model, developed using a piecewise linear function based on the Woods and Bigland-Ritchie EMG-force model, which correlates the relationship between measured grip force and muscular activity. The grip strength model is compared against the results derived from an upper limb musculoskeletal model. Experimental results demonstrate the models efficacy in estimating surface electromyography (sEMG) readings from force measurements, with a mean root mean square error (RMSE) of 0.2035 and a standard deviation of 0.1207 for muscle activation (dimension-less). Moreover, incorporating sEMG readings associated with grip force does not significantly affect the optimization of muscle activation in the upper arm, as evidenced by kinematic data analysis from dynamic tasks. This validation underscores the models potential to enhance musculoskeletal model-based motion analysis pipelines without distorting results. Consequently, this research emphasizes the prospect of integrating external models into existing human motion analysis frameworks, presenting promising implications for physical Human-Robot Interactions (pHRI).

physiology↗

bioRxiv2023

Neither alpha-synuclein-preformed fibrils derived from patients with GBA1 mutations nor the host murine genotype significantly influence seeding efficacy in the mouse olfactory bulb.

Parkinsons disease (PD) is a neurodegenerative disease characterized by progressive motor symptoms and alpha-synuclein (syn) aggregation in the nervous system. For unclear reasons, PD patients with certain GBA mutations (GBA-PD) have a more aggressive clinical progression. Two testable hypotheses that can potentially account for this phenomenon are that GBA1 mutations promote syn spread or drive the generation of highly pathogenic syn polymorphs (i.e., strains). We tested these hypotheses by treating homozygous GBA1 D409V knockin (KI) mice with human -syn-preformed fibrils (PFFs) and treating wild-type mice (WT) with several syn-PFF polymorphs amplified from brain autopsy samples collected from patients with idiopathic PD and GBA-PD patients with either homozygous or heterozygous GBA1 mutations. Robust phosphorylated-syn (PSER129) positive pathology was observed at the injection site (i.e., the olfactory bulb granular layer) and throughout the brain six months following PFF injection. The PFF seeding efficiency and degree of spread were similar regardless of the mouse genotype or PFF polymorphs. We found that PFFs amplified from the human brain, regardless of patient genotype, were generally more effective seeders than wholly synthetic PFFs (i.e., non-amplified); however, PFF concentration differed between these two studies, and this might also account for the observed differences. To investigate whether the molecular composition of pathology differed between different seeding conditions, we permed Biotinylation by Antibody Recognition on PSER129 (BAR-PSER129). We found that for BAR-PSER129, the endogenous PSER129 pool dominated identified interactions, and thus, very few potential interactions were explicitly identified for seeded pathology. However, we found Dctn2 interaction was shared across all PFF conditions, and Nckap1 and Ap3b2 were unique to PFFs amplified from GBA-PD brains of heterozygous mutation carriers. In conclusion, both the genotype and syn strain had little effect on overall seeding efficacy and global PSER129-interactions.

neuroscience↗

bioRxiv2020

CASSPER: A Semantic Segmentation based Particle Picking Algorithm for Single Particle Cryo-Electron Microscopy

Single-particle cryo-electron microscopy has emerged as the method of choice for structure determination of proteins and protein complexes. However, particle identification and selection which is a prerequisite for achieving high-resolution still poses a major bottleneck for automating the steps of structure determination. Here, we present a generalised deep learning tool, CASSPER, for the automated detection and isolation of protein particles in transmission microscope images. This deep learning tool uses Semantic Segmentation and a collection of visually prepared training samples to capture the differences in the transmission intensities of protein, ice, carbon and other impurities found in the micrograph. CASSPER is the first method to do pixel level classification and completely eliminates the need of manual particle picking. Integration of Contrast Limited Adaptive Histogram Equalization (CLAHE) in CASSPER enables high-fidelity particle detection even in micrographs with variable ice thickness and contrast. In addition, our generalized model for cross molecule picking works with high efficiency on unseen datasets and can potentially pick particles on-the-fly, thereby, enabling automation of data processing.

biophysics↗

bioRxiv2019

Environmental reservoirs of Mycobacterium bovis and Mycobacterium tuberculosis in the Ruaha region, Tanzania

This study was designed to investigate the prevalence of members of the Mycobacterium tuberculosis complex (MTBC) in the environment of pastoralists and villagers in the Iringa district, adjacent to the Ruaha National Park in Tanzania. Utilising specific qPCR assays, both Mycobacterium bovis and Mycobacterium tuberculosis were detected in cattle faeces, boma soil, water and household dust. M. bovis was also found in goat faeces and goat boma soil. This is the first report of faecal shedding of M. bovis in goats and the first molecular survey of faecal shedding in cattle. The prevalence of both bacterial species varied by village, area, season and sample type. Geographical and temporal correlations across sample types were suggestive of cross species transmission. This non-invasive test has previously been rigorously validated for screening other mammals; in this study it has successfully been applied to detect M. bovis and M. tuberculosis in livestock faeces and the environment.

microbiology↗