Biology subjects

DAS, A.

Publications and source records attributed to DAS, A..

4 recordsLinked to original sources

bioRxiv2026

An Interpretable EEG Machine Learning Prototype for Alzheimers Disease Classification

Resting-state electroencephalography (EEG) can capture the slowing of neural oscillations associated with Alzheimers disease (AD), but many machine-learning studies remain difficult to inspect, reproduce, or test. This study developed an interpretable, subject-level AD versus healthy-control classifier from the dataset OpenNeuro ds004504 and deployed it as a public research prototype. Preprocessed eyes-closed EEG recordings from 36 people with AD and 29 healthy controls were analysed. Welch power spectral density estimates were used to generate absolute and relative bandpower summaries, theta/alpha and delta/alpha ratios, a slow/fast ratio, and signal-level descriptors. Five-fold stratified cross-validation compared two Random Forest configurations, EEG Logistic Regression, an age-only baseline, and an EEG-plus-age model. EEG Logistic Regression gave the strongest mean fold-wise performance: accuracy 0.846, balanced accuracy 0.848, F1 score 0.849, and ROC-AUC 0.948. Age alone was near chance, while adding age did not improve the EEG-only model. The feature pattern was consistent with AD-related EEG slowing, including higher slow-wave-related ratios and lower relative alpha power. The trained pipeline was deployed as a Gradio application on Hugging Face Spaces. The result is a reproducible research and educational prototype, not a clinical diagnostic device, and requires external validation before any clinical interpretation.

neuroscience↗

bioRxiv2026

Subcellular dynamics of leghemoglobin is modulated by its site-specific serine phosphorylation during symbiotic nitrogen fixation in Lotus japonicus

Symbiotic nitrogen fixation (SNF) relies on aerobic respiration, yet the key enzyme, nitrogenase, is extremely oxygen labile. Leghemoglobin (Lb) resolves this "oxygen paradox" by buffering and facilitating O2 transport. However, the dynamic regulation of Lb during nodule development remains poorly understood. Earlier results from our laboratory demonstrated that site-specific serine phosphorylation of Lb reduces its oxygen sequestration capacity. Here, we investigated the spatio-temporal regulation of Lb with the progress of rhizobial load during SNF. Fluorescence immunohistochemistry (FIHC) using anti-Lb antibody revealed that its localization gradually shifted from the plasma membrane to the cytoplasm of infected cells as nodules mature. Using phospho-peptide (Lb) specific antibodies, we found that serine phosphorylation triggers this translocation. Furthermore, FIHC in conjunction with immunoprecipitation followed by immunoblotting with phospho- and non-phospho-peptide specific antibodies demonstrated that the non-phosphorylated form is detectable as early as 9 dpi, whereas the phosphorylated forms were first detected at 11 dpi and progressively accumulated during nodule maturation. This spatio-temporal transition coincides with increasing rhizobial colonization and is accompanied by a decline in the non-phosphorylated pool. Therefore, the increased cytoplasmic pool of phosphorylated Lb, which exhibits reduced oxygen sequestration capacity, likely functions in promoting oxygen transport to sustain elevated rhizobial respiration. Together, these findings demonstrate that site-specific serine phosphorylation represents one of the key regulatory mechanisms linking Lb localization dynamics with progression of rhizobial infection, thereby contributing to the maintenance of oxygen homeostasis during SNF.

plant biology↗

bioRxiv2026

Distinct Regulation of Host Defences by CRISPR-Cas in Typhoidal and Non-Typhoidal Salmonella serovars

CRISPR-Cas systems are best known for their role in adaptive immunity, but emerging evidence suggests broader regulatory functions. Here, we show that the CRISPR-Cas system acts as a serovar-specific regulator of stress adaptation in Salmonella enterica, exerting opposing effects in host-restricted (S. Typhi) and broad-host-range (S. Typhimurium) serovars. In S. Typhi, CRISPR-Cas system deletion reduces acid and bile tolerance by impairing envelope integrity and repressing key stress-response regulators (envZ, cadB, phoPQ, lexA, ruvB, wecD), while increasing resistance to cationic antimicrobial peptides via pmr activation and reduced oxidative damage. Conversely, CRISPR-Cas system loss in S. Typhimurium enhances acid survival-partly through speF upregulation but increases sensitivity to antimicrobial peptides. Spacer-1 of S. Typhi CRISPR-I array as the main regulator of gene expression, and its reintroduction partially restored stress tolerance, supporting spacer-dependent control of physiological pathways. These findings establish the CRISPR-Cas system as a non-canonical, spacer-dependent regulator of stress response networks in S. enterica, revealing its contribution to the evolutionary divergence of survival strategies between S. Typhi and S. Typhimurium.

microbiology↗

bioRxiv2023

Evolution of tandem repeats in putative CSP to enhance its function: A recent and exclusive event in Plasmodium vivax in India

The molecular hitchhiking model proposes that linked non-coding regions also undergo fixation, while fixing a beneficial allele in a population. This concept can be applied to identify loci with functional and evolutionary significance. Putative circumsporozoite protein (CSP) in Plasmodium vivax (PvpuCSP) identified following the molecular hitchhiking model, holds evolutionary significance. We investigated the extent of genetic polymorphism in PvpuCSP and the role of natural selection which shapes the genetic composition and maintains the diversity in P. vivax isolates from India. Sequencing the putative CSP of P. vivax (PvpuCSP) in 71 isolates revealed a well-conserved N- and C-terminal, constituting around 80% of the gene. PCR amplification and sequencing validated extensive diversity in the repeat region, ranging from 1.8 to 2.2 kb towards the C-terminal, identifying 37 different alleles from 71 samples. The recent and exclusive accumulation of repeats in puCSP within P. vivax highlights its highly variable length polymorphism, making it a potential marker for estimating diversity and infection complexity. Episodic diversifying selection in the PvpuCSP repeat region, evidenced by statistically significant p-values and likelihood ratios, enhances amino acid diversity at various phylogenetic levels, facilitating adaptation for accommodating different substrates for degradation.

evolutionary biology↗