Biology subjects

Tyagi, V.

Publications and source records attributed to Tyagi, V..

6 recordsLinked to original sources

bioRxiv2025

Electrode position, size, and orientation determine efficacy of cervical epidural stimulation to recruit forelimb muscles in rats

Target engagement determines therapeutic efficacy. In spinal cord stimulation (SCS), efficacy depends on the attributes of the electrodes used to deliver stimulation, particularly their position, interelectrode distance, size, and current orientation. We tested the effects of these electrode parameters using cervical stimulation to elicit forelimb muscle responses in the rat. We implanted devices over the C6 dorsal root entry zone (DREZ) in eight rats and measured responses in six forelimb muscles. We used custom designed electrode arrays to systematically vary position, distance, and size with linear arrays, and current orientation with circular arrays. Stimulation consisted of biphasic and pseudomonophasic pulse shapes with bipolar or distant return, and a high-definition montage with four returns surrounding a central contact to increase local current density. Efficacy was calculated from the motor thresholds of recruitment curves, and parameters were compared using linear mixed models. For position, stimulation over the DREZ was most effective, reducing thresholds by 25.9% (p = 0.0002) relative to the midline; efficacy decreased as the electrode was positioned medial or lateral to the DREZ. For distance, placing the electrodes farther apart significantly improved efficacy (p = 0.0022). For size, large electrodes increased SCS efficacy, reducing thresholds by 21.5% (p = 0.0026) relative to small electrodes. After accounting for position and distance, current orientation did not affect SCS efficacy. Lastly, the high-definition montage decreased efficacy, increasing thresholds by 16.7% (p = 0.003) relative to monopolar stimulation with a distant return. In conclusion, electrode position, distance, and size had the greatest effect on SCS efficacy, with the optimal parameters combining large electrodes at the DREZ position with a distant return. These results have the potential to lower the current needed to engage cervical spinal circuitry and to inform the design of SCS systems to improve dexterity in people with neurological injury or disease.

neuroscience↗

bioRxiv2025

Development and validation of KASP markers for a novel powdery mildew resistance gene in wheat using BSR-Seq analysis

Wheat powdery mildew occurs as a devastating infection caused by the pathogenic fungi Blumeeria graminis f. sp. tritici (Bgt). The management of disease becomes much more effective when host resistance methods are employed. The WL711-2U/2B line served as the introgressed line to identify genes linked with powdery mildew resistance. This allowed us to look into the potential resistance components in response to powdery mildew infection. The resistance status of the line towards powdery mildew developed from a single dominant gene named PmAT. Bulked segregant RNA-Seq (BSR-Seq) together with previous QTL-Seq SNP markers helped identify strong candidate regions in chromosome arm 2B extending from 531114848 bp to 530235618 bp. The LOD score from this region reached 72.4 with a PVE% of 64.7, thus proving its main role in resistance. The physical position was subsequently locked up, which was different from the previously identified genes on the same chromosome arm in its position, suggesting that it is most likely a new Pm gene. The QTL interval contained five potential genes that we identified during this research. The five candidate genes directs the protein production, which performs functions linked to the pentatricopeptide repeat family as well as B-box-type zinc finger domain, P-loop-containing nucleoside triphosphate hydrolase, and plant peroxidase. HighlightThe identification of a new wheat powdery mildew resistance gene (PmAT) using a combination of BSR-Seq and QTL-Seq analysis, which located five candidate genes specifically on chromosome 2B.

genetics↗

bioRxiv2022

Single-particle tracking and machine-learning classification reveals heterogeneous Piezo1 diffusion

The mechanically-activated ion channel PIEZO1 is critical to numerous physiological processes, and is activated by diverse mechanical cues. The channel is gated by membrane tension and has been found to be mobile in the plasma membrane. We employed single particle tracking (SPT) of endogenous, tdTomato-tagged PIEZO1 using Total Internal Reflection Fluorescence Microscopy in live cells. Application of SPT unveiled a surprising heterogeneity of diffusing PIEZO1 subpopulations, which we labeled "mobile" and "immobile". We sorted these trajectories into the two aforementioned categories using trajectory spread. To evaluate the effects of the plasma membrane composition on PIEZO1 diffusion, we manipulated membrane composition by depleting or supplementing cholesterol, or by adding margaric acid to stiffen the membrane. To examine effects of channel activation on PIEZO1 mobility, we treated cells with Yoda1, a PIEZO1 agonist, and GsMTx-4, a channel inhibitor. We collected thousands of trajectories for each condition, and found that cholesterol removal and Yoda1 incubation increased the channels propensity for mobility. Conversely, we found that GsMTx-4 incubation and cholesterol supplementation resulted in a lower chance of mobile trajectories, whereas margaric acid incubation did not have a significant effect on PIEZO1 mobility. The "mobile" trajectories were analyzed further by fitting the time-averaged mean-squared displacement as a function of lag time to a power-law model, revealing mobile PIEZO1 puncta exhibit anomalous subdiffusion. These studies illuminate the fundamental properties governing PIEZO1 diffusion in the plasma membrane and set the stage to determine how cellular processes and interactions may influence channel activity and mobility. SIGNIFICANCEPIEZO1 is a mechanically-activated ion channel that regulates a number of physiological processes. Here we examine a fundamental biophysical property of PIEZO1 - its movement in the plasma membrane. We find that the mobility of PIEZO1 is surprisingly heterogeneous, with some PIEZO1 puncta showing high mobility and some displaying very limited mobility. Cholesterol depletion from the plasma membrane increases PIEZO1 mobility while cholesterol supplementation decreases mobility. Yoda1 treatment increases PIEZO1 mobility whereas GsMTx-4 treatment decreases channel mobility.

biophysics↗

bioRxiv2022

Single session of rTMS enhances brain metastability and intrinsic ignition

BackgroundEmerging evidence support the view that brain stimulation might improve essential tremor (ET) by altering brain networks and facilitating plasticity. Yet, we are still missing a mechanistic explanation of the whole brain dynamics underlying these plasticity defining changes. MethodIn this study, we explored the effect of low-frequency repetitive transcranial magnetic stimulation (rTMS) over left primary motor cortex (L-M1) on functional connectivity dynamics (FCD) in patients with ET. Resting-state fMRI (RsfMRI) was acquired before and after a single session of rTMS in 30 patients with ET and compared with RsfMRI of 20 age and gender matched healthy controls (HCs). We have measured the effect of brain stimulation using network topological re-organization through whole brain integration and segregation, brain stability and capacity of neural propagation through metastability and intrinsic ignition. ResultsPatients with ET had altered FCD measures compared to controls. After a single session rTMS, the brain connectivity measures approached normality and patients with ET revealed significantly higher integration, lower segregation with higher metastability and increased intrinsic ignition. ConclusionBrain metastability and intrinsic ignition measures could be valuable tools in appreciating mechanisms of brain stimulation in ET and other neurological diseases.

neuroscience↗

bioRxiv2020

Potential malaria vector Anopheles minimus (species A) still persisting in North East India

BackgroundVector borne infectious diseases affect two third of the worlds human population and cause mortality in millions each year. Malaria remains one of the major killers in the Indian sub-continent and transmitted uninterruptedly by many efficient vectors and their sibling species. In North East India (NE), Anopheles minimus has been recognized as an important vector which shares majority of malaria cases. This study primarily focuses on to recognize the presence and distribution of sibling species of An. minimus in certain endemic area of NE India. MethodsAnopheles species were collected and identified using available morphological keys. The genomic DNA was extracted from the mosquito specimen and used to perform species specific PCR (ss PCR) for molecular identification of major malaria vector An. minimus sibling species ResultMorphological identification suggested the presence of An. minimus sl in low density in the study area. The specimen of An. minimus subjected to ss PCR confirmed the prevalence of only one sibling species namely, An. minimus A in Sialmari and Chandubi. ConclusionThough in low density, but malaria vector An. minimus is still present in certain endemic areas of NE India. The ss PCR assay employed presently suggested that An. minimus sibling species A is prevailing in the region. Presently used ss PCR assay was simpler, faster, cheaper and more readily interpreted than earlier assays. This information could be useful in understanding of current prevalence and distribution of An. minimus sibling species complex in NE region of India.

ecology↗

bioRxiv2018

Characterization for Drought Tolerance and Physiological Efficiency in Novel Cytoplasmic Male Sterile Sources of Sunflower (Helianthus annuus L.)

AbstractSunflower is sensitive to drought and its hybrids have a limited cytoplasmic diversity. The wild cytoplasmic sources of sunflower are not well exploited to their potential for drought tolerance and hybrid development. In this respect, we carried out a Line x Tester based genetic study using 19 sunflower genotypes representing, 13 cytoplasmic male sterile (CMS) lines from wild and conventional sources, 2 maintainer lines, and 4 restorer lines. The CMS and maintainer lines were crossed with restorer lines to develop sixty one-way F1 hybrids. The parents and their hybrids were evaluated under two water regimes viz., normal irrigated and water stress. A total of twelve important plant descriptors were studied over a period of two years. The significant differences were observed between parents and hybrids in both water regimes. Hybrids were higher in average values for all the descriptors than parents. The role of female parent was more prominent in the expression of traits in hybrids as compared to male parents. The CMS sources varied significantly regarding seed yield per plant and other physiological traits. Proline content was three times higher in parents and their hybrids under water stress, and it was not correlated with any other descriptor. Accession CMS-PKU-2A was identified as the best general combiner for leaf area and specific leaf weight. Whereas, CMS-234A was the best general combiner for biological yield and photosynthetic efficiency under both the conditions. The cross combinations CMS-ARG-2A x RCR-8297, CMS-234A x P124R, and CMS-38A x P124R were found significant for biological yield, seed yield and oil content under both environments. Overall, this study provides useful information about the cytoplasmic effects on important sunflower traits and drought stress tolerance when used in the different combinations.

genetics↗