Biology subjects

Kanwar, S.

Publications and source records attributed to Kanwar, S..

5 recordsLinked to original sources

bioRxiv2026

V-SWITCH: A single-vector OFF-to-ON fluorescent reporter of live RNA virus infections

Fluorescent reporters of viral infection are powerful tools for studying viral pathogenesis and host-pathogen interactions. Here, we present V-SWITCH, a highly modular, single-vector, cell-based OFF-to-ON fluorescent reporter that enables robust detection of viral infection in living cells. V-SWITCH is based on a split mNeonGreen (mNG) system employing a release-and-capture mechanism. In the "OFF" state, the mNG3A(1-10) fragment is anchored to the endoplasmic reticulum via a Sec61 transmembrane domain, while the mNG(11) fragment, fused to BFP, is constitutively expressed in the nucleus. Upon infection, the viral protease cleaves a protease cleavage site (PCS) adjacent to the mNG3A(1-10) fragment, liberating it for translocation into the nucleus. There, it complements mNG(11) to reconstitute fluorescence. The constitutive BFP serves as both an expression control and a nuclear segmentation marker for image analysis. Each module in this dual-cassette design is flanked by unique restriction sites allowing rapid swapping of virus-specific PCS, split fluorophores, membrane anchors, and promoters. We demonstrate the versatility of the V-SWITCH reporter for several viruses (Dengue virus, Zika virus, West Nile virus and Human Coronavirus OC43) in several cell lines (A549, BJ-5 fibroblasts, HEK293T and HeLa). Reporter activation enables clear discrimination of infected and uninfected cells by flow cytometry and reveals time-dependent and heterogeneous infection dynamics by live-cell imaging at single-cell resolution. Importantly, we demonstrate the potential of V-SWITCH to support both rapid functional screening for host factor dependencies, as well as high-throughput compound screening to enable antiviral discovery and comparative evaluation of therapeutic strategies across multiple viruses and cell types.

microbiology↗

bioRxiv2025

Global distribution of isoprenoid quinones across Bacteria

Isoprenoid quinones represent a class of redox lipids involved in many critical cellular functions, including ATP synthesis through electron transport chains. They thus occupy a pivotal role in the bioenergetics of all three domains of life. The diversity of quinone types observed across microbial taxa has long supported their use as chemotaxonomic markers in microbial systematics. More recently, variations in quinone repertoires have been linked to metabolic adaptations and a novel quinone was discovered. Despite a revived interest in the role of quinones, a unified perspective on the distribution of quinones in Bacteria is currently lacking. In this study, quinone biosynthetic pathways were systematically annotated in 26,264 high quality genomes of bacterial species, and specific information on quinones produced by over 6,000 bacterial species was extracted by text mining the abstracts of thousands of articles. The results were mapped onto a phylogenetic tree, providing the most comprehensive overview of quinone distribution in Bacteria to date. This enabled us to highlight the surprisingly dynamic evolutionary history of the two menaquinone-producing pathways. Moreover, the identification and experimental validation of a deeply branching ubiquinone pathway in Desulfobacterota represents the first occurrence of such a pathway outside the Pseudomonadota and provides insights into the nature of the ancestral UQ pathway. The updated compendium of bacterial quinones is a valuable resource to facilitate the prediction of quinone structural features from genomic data, to establish correlations between quinone structures and cellular traits, and to explore the evolution of quinone repertoires in connection with the diversification of microbial metabolisms.

microbiology↗

bioRxiv2025

Integrating phylodynamics and historical records reveals decades-old introductions of PRRSV into Costa Rica via international swine trade

BackgroundIn August 1995, necropsies on post-weaning piglets from the CA-CART farm in the province of Cartago, Costa Rica, revealed respiratory lesions, pleuritis, peritonitis, and arthritis. Skin lesions were also observed, progressing to scabs. A subsequent outbreak in 1996 prompted antibiotic administration. Mortality analysis from 1990 to 1995 showed no significant seasonal patterns, but yearly variations were noted. Piglets born in Costa Rica from imported gilts had a higher average mortality rate (10.65%) than the 8.11% mortality rate for piglets born from non-imported gilts and sows or imported sows (p = 0.002). MethodsIn March 1996, serum samples were sent for potential PRRS virus (PRRSV) diagnosis, and 10 PRRSV-2 ORF5 sequences collected during a prospective study from 2019-2021 were obtained from various locations in the country. In this article, we seek to investigate the evolutionary and spatio-temporal dynamics of PRRSV-2 in Costa Rica in the context of international swine movements using the phylodynamic framework integrated with the BEAST package. Results and DiscussionThe phylodynamic modeling estimated at least two independent PRRSV-2 introductions into the country. The earliest introduction occurred around 1978 (95% highest posterior density interval: 1959.01-1997.54) and led to the viruses circulating in the farm 1CRC with an origin from Japan, possibly via US swine exports. A second cluster, 4CRC, subsequently emerged within Costa Rica from the earlier 1CRC lineage (1990.24; 95% HPD interval = 1976.15-2010.30). Another viral introduction from the US occurred around 1991 (95% highest posterior density interval: 1974.34-2011.35) and established the 3CRC cluster. Though the viral introduction was traced back to the US, the limited genomic surveillance of PRRSV leaves room for considering alternative origins. ConclusionOur findings provide a high-resolution model of how international swine trade drives the introduction and evolution of a major livestock pathogen, highlighting the critical need for integrating genomic surveillance into biosecurity protocols.

microbiology↗

bioRxiv2024

Behavioral Interactions in Two Ant Species in The Southeast United States and Evidence for a Native Supercolony

Ants vary extensively in their colony structure, ranging from occupying single nests to tremendous supercolonies that occupy territories spanning large areas. Fewer than 1% of ants are known to produce supercolonies, yet they are disproportionately overrepresented in highly invasive ants. A broader understanding of supercolonial ants in their native range, therefore, may provide key insights into the factors that allow some ants to become invasive. Here, we show the results of behavioral assays of two native species of ants, Dorymyrmex bureni and D. smithi (Hymenoptera: Formicidae: Dolichoderinae) across geographically separated sites in southeastern Georgia, USA. We show that D. smithi has extremely low incidence of aggression in ants from sites up to 35 km apart, indicating that this may be a supercolonial species. In contrast, we show that D. bureni exhibits high levels of aggression between nest sites. Dorymyrmex smithi is also a temporary social parasite of D. bureni and these two species form mixed nests with no apparent interspecific aggression between workers, but we show that both species interact aggressively in assays within and between sites when the workers are derived from pure species nests. These findings represent an important addition to our knowledge of supercolonial species, and they also lay the groundwork for further studies of the parasitic relationship between these species.

animal behavior and cognition↗

bioRxiv2019

Wheat inositol pyrophosphate kinase (TaVIH2-3B) interacts with Fasciclin-like arabinogalactan (FLA6) protein and alters the plant cell-wall composition

BackgroundInositol pyrophosphates (PP-InsPs) are high-energy cellular molecules involved in different signalling and regulatory responses. Two distinct classes of inositol phosphate kinases responsible for the synthesis of PP-InsPs have been identified in Arabidopsis i.e. ITPKinase (inositol 1,3,4 trisphosphate 5/6 kinase) and PP-IP5Kinase (diphosphoinositol pentakisphosphate kinases). Plant PP-IP5Ks are capable of synthesizing InsP8 and were shown to control pathogenic defence and phosphate response signals. However, other roles offered by plant PP-IP5Ks, especially towards abiotic stress, remain poorly understood. ResultsHere, we characterized two Triticum aestivum L. (hexaploid wheat) PPIP5K homologs, TaVIH1 and TaVIH2, for their physiological functions. We demonstrated that wheat VIH proteins could utilize InsP7 as the substrate to produce InsP8, a process that requires the functional VIH-kinase domains. At the transcriptional level, both TaVIH1 and TaVIH2 are expressed in different wheat tissues, including developing grains, but show selective response to abiotic stresses during drought-mimic experiments. Overexpression of TaVIH2-3B homolog in Arabidopsis conferred tolerance to drought stress and rescued the sensitivity of Atvih2 mutants. RNAseq analysis of TaVIH2-3B transgenic lines of Arabidopsis showed a genome-wide reprogramming with remarkable effects on cell-wall biosynthesis genes with enhanced the accumulation of polysaccharides (arabinogalactan, cellulose and arabinoxylan). ConclusionsOverall, this work identifies a novel function of VIH proteins, implying their roles in modulating cell-wall homeostasis genes and providing water-deficit stress tolerance. This work suggests that the plant VIH enzymes could be linked to drought tolerance and also opens up investigations to address the roles of plant VIH derived products in generating drought resistant plants.

plant biology↗