Biology subjects

Arani, A.

Publications and source records attributed to Arani, A..

4 recordsLinked to original sources

bioRxiv2026

Slower-than-exponential viral decay is prevalent and can reshape virus-microbe dynamics

Viral population dynamics are shaped by production and loss. For viruses of microbes, high standing levels of viral abundances are interpreted as evidence of high rates of viral-induced cellular loss and viral production, followed by rapid extracellular viral decay. Here we reassess assumptions of rapid extracellular decay in 17 curated datasets, finding that biphasic decay either fits better or is statistically indistinguishable from exponential decay in approximately half the datasets. In addition to intrinsic heterogeneity in decay rates, biphasic decay at population scales can arise generically through aggregation mechanisms, where single virions decay and viral aggregates are protected. Integrating aggregation-induced biphasic decay into a virus-host model reveals that accounting for aggregation can recapitulate joint observations of high virion abundances and low infection prevalence, without assuming significant levels of uniformly inefficient infection. Together, our results suggest that durable extracellular virion persistence is environmentally relevant in shaping virus-microbe population dynamics.

ecology↗

bioRxiv2026

Comparing Harmonization Approaches for Protocol-Related Variability in Multisite Diffusion MRI Data

Diffusion MRI (dMRI) enables assessment of white matter microstructural abnormalities in Alzheimers disease (AD), and multisite datasets enable more robust modeling of non-biological variation that can confound analyses. The Alzheimers Disease Neuroimaging Initiative (ADNI) includes over 10 dMRI protocols, necessitating robust methods to model protocol-related variability when pooling data. Here, we compared three harmonization approaches: (1) mixed-effects models, (2) ComBat-GAM, and (3) eHarmonize, a reference-based lifespan method. We assessed their ability to reduce protocol-related variability in diffusion tensor imaging fractional anisotropy (FA) and mean diffusivity (MD) while preserving associations with cognitive impairment (CI), and amyloid-beta (A{beta}) and tau PET burden in 1,086 ADNI3/4 participants. All approaches yielded more closely aligned FA/MD distributions across protocols. Associations with clinical indicators of CI were highly consistent across approaches, whereas PET associations were less widespread and more variable. Overall, multiple strategies effectively modeled protocol-related variability while preserving AD-related associations.

neuroscience↗

bioRxiv2025

DTI versus NODDI White Matter Microstructural Biomarkers of Alzheimer's Disease

Diffusion MRI (dMRI) is a powerful tool to assess white matter (WM) microstructural abnormalities in Alzheimers disease (AD). The fourth phase of the Alzheimers Disease Neuroimaging Initiative (ADNI) now includes multiple multishell dMRI protocols, enabling both traditional and advanced dMRI model analyses. There is a need to evaluate whether multishell data offer deeper insights into WM pathology in AD than more widely available single-shell data by overcoming single-shell model limitations. Here, we fit single-shell DTI and multishell NODDI to dMRI data from 533 ADNI3/4 participants to assess their sensitivity to key clinical indicators of AD such as cognitive impairment, amyloid-beta and tau PET burden. Overall, we found that NODDI offered no major advantages in detecting cognitive impairment and tau pathology, but NODDI was marginally more sensitive to amyloid pathology.

neuroscience↗

bioRxiv2024

Episomal virus maintenance enables bacterial population recovery from infection and virus-bacterial coexistence

Hypersaline environments harbor the highest concentrations of virus-like particles (VLPs) reported for aquatic ecosystems. The substantial densities of both microbial populations and VLPs challenge traditional explanations of top-down control exerted by viruses. At close to saturation salinities, prokaryotic populations are dominated by Archaea and the bacterial clade Salinibacter. In this work we examine the episomal maintenance of a virus within a Salinibacter ruber host. We found that infected cultures of Sal. ruber M1 developed a population-level resistance and underwent systematic and reproducible recovery post infection that was counter-intuitively dependent on the multiplicity of infection (MOI), where higher MOI led to better host outcomes. Furthermore, we developed a nonlinear population dynamics model that successfully reproduced the qualitative features of the recovery. This suggests that the maintenance of the virus episomally, often referred to as pseudolysogeny, and lysis inhibition allow for host-virus co-existence under high MOI infections. Our results emphasize the ecological importance of exploring a spectrum of viral infection strategies beyond the conventional binary of lysis or lysogeny.

microbiology↗