Biology subjects

Sardar, A.

Publications and source records attributed to Sardar, A..

3 recordsLinked to original sources

bioRxiv2025

CBL1/9-CIPK6 complex negatively regulates Respiratory burst oxidase homolog D in Arabidopsis thaliana

Plant innate immune response must be a well-balanced process with positive and negative regulations for the plants to survive. Calcium signalling is essential for pathogen-associated molecular pattern (PAMP)-driven Respiratory burst oxidase homolog D (RbohD)-mediated reactive oxygen species (ROS) burst. We show Calcium-sensors Calcineurin B like protein 1 (CBL1) and CBL9 and their interacting protein kinase CIPK6 negatively regulate RbohD activity and immune response in Arabidopsis thaliana. Arabidopsis mutant cbl1cbl9, like cipk6, exhibited enhanced resistance and ROS production when infected with the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). CBL1 and CBL9 enhanced kinase activity of CIPK6. Plasma membrane localization of CBL1 and CBL9 and CIPK6 kinase activity were associated with the ROS production and immune response. CBL1/9-CIPK6 module interacts with RbohD at the plasma membrane and phosphorylates its N-terminal cytoplasmic domain at a non-conserved (Ser33) and a conserve (Ser39) Serine residue. While Ser39 phosphorylation increased RbohD activity, Ser33 phosphorylation drastically reduced it and superseded the effect of Ser39 phosphorylation. Replacement of Ser33 with alanine or aspartic acid made RbohD a super-active or low-active enzyme, respectively. Our study reports a direct mechanism of negative regulation of ROS production and plant immune response by a Calcium-signalling module in Arabidopsis. Overall, this study provides a novel insight into how calcium signaling integrates with immune regulation to prevent excessive ROS accumulation, ensuring a balanced plant immune response. One Sentence SummaryInactivation of RbohD by CBL1/CBL9-CIPK6 complex negatively regulates the plant immunity against Pst DC3000 infection in Arabidopsis.

plant biology↗

bioRxiv2023

Development and Analytical Evaluation of a Point-of-Care Electrochemical Biosensor for Rapid and Accurate SARS-CoV-2 Detection

The COVID-19 pandemic has underscored the critical need for rapid and accurate screening and diagnostic methods for potential respiratory viruses. Existing COVID-19 diagnostic approaches face limitations either in terms of turnaround time or accuracy. In this study, we present an electrochemical biosensor that offers nearly instantaneous and precise SARS-CoV-2 detection, suitable for point-of-care and environmental monitoring applications. The biosensor employs a stapled hACE-2 N-terminal alpha helix peptide to functionalize an in-situ grown polypyrrole conductive polymer on a nitrocellulose membrane backbone through a chemical process. We assessed the biosensors analytical performance using heat-inactivated omicron and delta variants of the SARS-CoV-2 virus in artificial saliva (AS) and nasal swabs (NS) samples diluted in a strong ionic solution. Virus identification was achieved through electrochemical impedance spectroscopy (EIS) and frequency analyses. The assay demonstrated a limit of detection of 40 TCID50/mL, with 95% sensitivity and 100% specificity. Notably, the biosensor exhibited no cross-reactivity when tested against the influenza virus. The entire testing process using the biosensor takes less than a minute. In summary, our biosensor exhibits promising potential in the battle against pandemic respiratory viruses, offering a platform for the creation of rapid, compact, portable, and point-of-care devices capable of multiplexing various viruses. This groundbreaking development has the capacity to significantly bolster our readiness and response to future viral outbreaks.

bioengineering↗

bioRxiv2023

Hypothesis-free phenotype prediction within a genetics-first framework

Cohort-wide sequencing studies have revealed that the largest category of variants is those deemed rare, even for the subset located in coding regions (99% of known coding variants are seen in less than 1% of the population1-3). Our understanding of how rare genetic variants influence disease and organism-level phenotypes has achieved limited progress, partly explained by the intrinsic difficulty in statistically evaluating the biological significance of rare events. Here we show that discoveries can instead be made through a knowledge-based approach using protein domains and ontologies (function and phenotype) that considers all coding variants regardless of allele frequency. We describe an ab initio, genetics-first method making molecular knowledge-based interpretations for exome-wide non-synonymous variants for phenotypes at the organism and cellular level. By using this reverse approach, we identify plausible novel genetic causes for developmental disorders that have eluded other established methods and present novel molecular hypotheses for the causal genetics of 40 phenotypes generated from a direct-to-consumer genotype cohort. This system offers a chance to extract further discovery from genetic data after standard tools have been applied.

genomics↗