Biology subjects

Arumugam, R.

Publications and source records attributed to Arumugam, R..

4 recordsLinked to original sources

bioRxiv2021

Metacommunity stability and persistence for predation turnoff in selective patches

Predation as an important trophic interaction of ecological communities controls the large-scale patterns of species distribution, population abundance and community structure. Numerous studies address that predation can mediate diversity and regulate the ecological community and food web stability through changes in the behaviour, morphology, development, and abundance of prey. Since predation has large effects on persistence and diversity, the local loss or removal of predation in a community can trigger a cascade of extinctions. In ecological theory, the effect of predation removal has been well studied in foodwebs, but it remains unclear in the case of a spatially distributed community connected by dispersal. In this study, the interaction between local and spatial processes is taken into account, we present how a predation turnoff in selective patches affects the stability and persistence of a metacommunity. Using a simple predator-prey metacommunity with a diffusive dispersal, we show the impact of predation on synchronized, asynchronized and source-sink dynamics. Our results reveal that predation turnoff in very few patches alters a perfectly synchronized oscillatory state into multicluster states consisting of various patterns. In a source-sink behaviour, predation turnoff in a source patch reduces the number of sink patches and changes the clusters. In general, predation turnoff in a finite number of patches increases the number of clusters through asynchronized (inhomogeneous) states, whereas predation turnoff in a larger number of patches can lead to the complete extinction of predators. Typically, there exists a critical number of patches below which the predation turnoff results in asynchronized states and above that predation turnoff leads to a synchronized state in prey population with complete extinction of predators. Further, our results identify the network configurations that exhibit a unique number of clusters. Moreover, prey density from the patches where predation is absent goes to a saturating state near the carrying capacity. Thus, this study stresses that predation turnoff in selective patches acts as a stabilizing mechanism that can promote metacommunity persistence.

ecology↗

bioRxiv2021

Dissecting the Cellular Landscape and Transcriptome Network in Viral Myocarditis by Single-Cell RNA Sequencing

Myocarditis induced with Coxsackievirus B3 (CVB3) is commonly employed to study viral pathogenesis in mice. Although infectious virus is cleared after the acute phase, affected animals chronically develop the features of dilated cardiomyopathy, which may involve the mediation of immune and non-immune cells. To dissect this complexity, we performed single-cell RNA sequencing on heart cells obtained from healthy and myocarditic mice, leading us to note that myocarditic mice had significantly higher proportions of myeloid cells, CD4 and CD8 T cells, and fibroblasts, whereas NK cells, ILCs and B cells were low. While the transcriptome profiles of myeloid cells revealed detection of monocytes and macrophages of M2 phenotype with pathways important in immune metabolism and inflammation, T cells consisted of Th17 cells, CTLs, and Treg cells with transcriptome signatures critical for cytotoxic functions. Although fibroblasts detected in myocarditic mice were phenotypically heterogeneous, their transcriptomes played roles in fibrosis and regulation of inflammation and immune responses. Additionally, analysis of intercellular communication networks revealed unique interactions and signaling pathways in the cardiac cellulome, whereas myeloid cells and T cells in myocarditic mice revealed uniquely upregulated transcription factors modulating cardiac remodeling functions. Taken together, our data suggest that M2 cells, T cells, and fibroblasts may cooperatively or independently participate in the pathogenesis of viral myocarditis.

immunology↗

bioRxiv2020

-SATA: A MATLAB based toolbox to estimate Current Density generated by Transcranial Direct Current Stimulation in an Individual Brain

BackgroundTranscranial Direct Current Stimulation (tDCS) is a technique where a weak current is passed through the electrodes placed on the scalp. The distribution of the electric current induced in the brain due to tDCS is provided by simulation toolbox like Realistic-volumetric-Approach-based-Simulator-for-Transcranial-electric-stimulation (ROAST). However, the procedure to estimate the total current density induced at the target and the intermediary region of the cortex is complex. The Systematic-Approach-for-tDCS-Analysis (SATA) was developed to overcome this problem. However, SATA is limited to standardized headspace only. Here we develop individual-SATA (-SATA) to extend it to individual head. MethodT1-weighted images of 15 subjects were taken from two Magnetic Resonance Imaging (MRI) scanners of different strengths. Across the subjects, the montages were simulated in ROAST. -SATA converts the ROAST output to Talairach space. The x, y and z coordinates of the anterior commissure (AC), posterior commissure (PC), and Mid-Sagittal (MS) points are necessary for the conversion. AC and PC are detected using the acpcdetect toolbox. We developed a method to determine the MS in the image and cross-verified its location manually using BrainSight(R). ResultDetermination of points with -SATA is fast and accurate. The -SATA provided estimates of the current-density induced across an individuals cortical lobes and gyri as tested on images from two different scanners. ConclusionResearchers can use -SATA for customizing tDCS-montages. With -SATA it is also easier to compute the inter-individual variation in current-density across the target and intermediary regions of the brain. The software is publicly available.

neuroscience↗

bioRxiv2018

A revisit to a low-cost method for the isolation of microsatellite markers: the case of the endangered Malayan tapir (Tapirus indicus)

There are many approaches to develop microsatellite markers. We revisited an easy and rapid Polymerase Chain Reaction (PCR)-cloning-sequencing method to design microsatellite markers for Tapirus indicus. Using six random amplified microsatellite (RAM) markers, this study had rapidly generated 45 unique genomic sequences containing microsatellites. After screening 15 terminal and seven intermediate microsatellite loci, we shortlisted five and seven which were amplified either by single- or multiplex PCR using the economical three-primer PCR method. Genotyping attempts were made with ten Tapirus indicus individuals using three of the terminal microsatellite loci and all seven intermediate loci. However, none of the terminal microsatellite loci were considered useful for population genotyping studies, while the seven intermediate loci showed good amplification but were monomorphic in the ten samples. Despite successful detection of amplified loci, we would like to highlight that, researchers who are interested in this alternative method for isolation of microsatellite loci to be cautious and be aware of the limitations and downfalls reported herein that could render these loci unsuitable for population genotyping.

genetics↗