Biology subjects

Chhetri, P.

Publications and source records attributed to Chhetri, P..

3 recordsLinked to original sources

bioRxiv2026

Elevational variation in gut microbial community composition and predicted functional potential across three Himalayan redstart species

Environmental gradients and seasonal migration may influence host-associated microbial communities, yet their contributions to gut microbiome variation in montane birds remain poorly understood. We investigated gut microbial communities across 1,300 to 4,200 m in three Himalayan redstarts (Phoenicurus fuliginosus, P. leucocephalus, and P. frontalis) exhibiting contrasting seasonal movement strategies. Using 16S rRNA gene sequencing of 46 fecal samples, we characterized microbial diversity, community composition, distance decay relationships, co-occurrence networks, and predicted functional potential. Elevation was significantly associated with microbial community composition, explaining approximately 3% of variation, whereas host species showed no significant association after accounting for elevation. P. fuliginosus exhibited significant compositional differences among most sampled elevations, whereas P. leucocephalus showed significant positive distance decay relationships. Alpha diversity showed no consistent elevational trend, while core microbial taxa and co-occurrence networks varied among elevational groups. PICRUSt2 analyses identified 28 predicted KEGG Level 3 pathways differing significantly among elevations, including pathways associated with amino acid, lipid, glycan, carbohydrate, and bile acid metabolism. Together, these findings highlight elevation as a significant correlate of gut microbial community composition and predicted functional potential, with distinct patterns of microbial turnover among closely related Himalayan redstarts.

microbiology↗

bioRxiv2025

Integrated landscape genomics reveals biogeography and climate-driven local adaptation in high-altitudes

High-elevation environments harbor unique species adapted to altitudinal and environmental extremes. However, due to logistical challenges of sampling such species throughout their distribution across steep and varied terrains, studies often lack comprehensive evidence to understand patterns of population divergence, local adaptation, and how current adaptations may influence future vulnerability. In this study, we utilized Tibetan Partridge (Perdix hodgsoniae), a high-altitude endemic bird found between 2800-5000 meters across the arid western and humid northeastern regions of the Sino-Himalayan landscape. This regions complex topography-characterized by tall mountains, deep valleys, and contrasting climatic conditions provided opportunities for investigating population divergence, local adaptation, and climate-related vulnerability. We integrated population-scale whole-genome sequencing with ecological, climatic, landscape, and morphological data to examine current patterns of local adaptation and forecast future risks. Our findings show that both biogeographic barriers and climatic variation drive rapid population divergence in P. hodgsoniae, reflected in distinct morphological traits and population genetic structure. Western populations, inhabiting dry and fragmented landscapes, exhibit adaptations to temperature extremes with low genetic diversity, reduced habitat suitability, limited gene flow, and weak connectivity--factors that increase their vulnerability to future environmental changes. In contrast, northeastern populations, living in more humid regions, show genetic adaptations linked to precipitation, maintain high genetic diversity and habitat connectivity, and may serve as evolutionary refugia under future climate scenarios. This study underscores the value of integrating genomic, ecological, and landscape data to reveal mechanisms of divergence and adaptation, and to develop robust predictions for conservation planning under rapidly changing environmental conditions.

evolutionary biology↗

bioRxiv2025

Predicting Metabolic Dysfunction Associated Steatotic Liver Disease Risk Using Patient-Derived Induced Pluripotent Stem Cells

Background and AimsMetabolic Dysfunction Associated Steatotic Liver Disease (MASLD) is reversible at early stages, making early identification of high-risk individuals clinically valuable. Previously, we demonstrated that patient-derived induced pluripotent stem cells (iPSCs) harboring MASLD DNA risk variants exhibit greater oleate-induced intracellular lipid accumulation than those without these variants. This study aimed to develop an iPSC-based MASLD risk predictor using functional lipid accumulation assessments. MethodsWe quantified oleate-induced intracellular lipid accumulation in iPSCs derived from three cohorts of diverse ancestry: 1) CIRM cohort (20 biopsy-confirmed MASH cases, 2 biopsy-confirmed MASLD cases, 17 controls), 2) POST cohort (18 MASLD cases, 17 controls), and 3) UCSF cohort (4 biopsy-confirmed MASH cases, 8 controls). Lipid accumulation levels in the CIRM cohort were used to define an iPSC-based MASLD risk score, which was used to predict case/control status in the POST and UCSF cohorts. ResultsIn all three cohorts, lipid accumulation was higher in MASLD/MASH cases vs. controls (CIRM cases vs. controls 3.32 {+/-} 0.25 vs. 2.70 {+/-} 0.19 -fold change, p=0.06; POST cases vs. controls 3.63 {+/-} 0.33 vs. 2.70 {+/-} 0.31, p=0.05; and UCSF cases vs. controls 4.39{+/-}0.46 vs. 2.03{+/-}0.20, p=0.0002). The iPSC-based MASLD risk score achieved a sensitivity of 44% and specificity of 75% in the POST cohort and 75% and 100%, respectively, in the UCSF cohort. Differences in cohort disease severity and cardiometabolic profiles may explain performance variability. ConclusionWhile validation in larger cohorts is needed, these findings suggest that oleate-induced intracellular lipid accumulation in subject-derived iPSCs is predictive of MASH development. Additional cellular phenotypes and donor information should be explored to improve predictive accuracy to inform MASLD surveillance and prevention strategies.

cell biology↗