Biology subjects

Venkatesh, K.

Publications and source records attributed to Venkatesh, K..

4 recordsLinked to original sources

bioRxiv2025

Histone acetylation alters nuclear morphology and architecture of human mesenchymal stem cells in rigidity dependent manner

Nuclear morphology which is closely linked to various cell functions and disease states, is known to be modulated by mechanical stimuli and chromatin modifications. However, the combined effects of substrate rigidity and chromatin modifications remain largely unexplored. In this study, we investigated the interplay between substrate rigidity and histone acetylation, mediated by the histone deacetylase inhibitor (HDACi) valproic acid (VA), in modulating nuclear morphology in human mesenchymal stem cells (hMSCs) cultured on substrates with varying rigidities. We found that VA-induced chromatin decondensation diminished the effects of soft substrates on nuclear morphological parameters, a change not observed on stiff substrates. Furthermore, we showed that the reduction in nuclear stiffness with VA treatment on both substrates was independent of lamin expression, highlighting chromatin decondensation as a key determinant of the observed change in nuclear stiffness. In addition, we demonstrated that soft substrates induced significant nuclear wrinkling, which was alleviated by HDACi treatment, while no such effect of VA was observed on stiff substrates. Together, our findings suggest that chromatin remodeling via HDACi can override substrate-dependent nuclear mechanotransduction on soft substrates, offering new insights into the epigenetic regulation of nuclear mechanics with potential implications for pathologies associated with nuclear morphology.

cell biology↗

bioRxiv2023

Characterization and Expression Analysis of Nitrate Reductase 6-1ABD Gene in Hexaploid Bread Wheat Under Different Nitrogen Regime

Nitrate reductase (NR) is the key rate-limiting enzyme of the nitrogen (N) assimilation process in plants, which has not been characterized in bread wheat under nitrogen stress, especially with respect to their homeologues. Total 9 NRs were identified and classified into 3 groups, which showed a close relationship with different wheat ancestors. The occurrence of N-responsive cis-acting regulatory elements like MYB, MYC, G-Box and GATA-motif confirmed their N-responsiveness. Expression of all the three groups of NR under N-stress revealed NR 6-1ABD group to be the most N-responsive, which was characterized further in detail. The study was carried out in two genotypes contrasting for their N-responsiveness (HD 2967: Highly responsive to applied N, and Choti Lerma: Less responsive to applied N) selected on the basis of field evaluation. Homeologous differences within a genotype were found much more than the genotypic differences of a specific homeologue coding sequence. Among the three homeologues, though NR 6-1D homeologue was found most responsive to N-stress, the contribution was maximum for this homeologue followed by NR 6-1A and least by NR 6-1B. We found that the expression of homeologues was linked to the presence of N-responsive cis- elements. All the homeologues of NR 6-1 in Choti Lerma were found less responsive to N-stress, in comparison to HD 2967, which might also be linked to N-use efficiency. Homeologous expression of NR 6-1ABD revealed negligible contribution of B-homeologue to N-stress. Homeologous differences of NR 6-1ABD was found much more than the genotypic differences. Hence, our study on wheat NR will be helpful in manipulating the specific homeologue of the NR gene in the future.

plant biology↗

bioRxiv2023

Unraveling the Interplay of Different Traits and Parameters Related to Nitrogen Use Efficiency in Wheat: Insights for Grain Yield Influence

Enhancing Nitrogen Use Efficiency (NUE) in wheat to optimize grain yield is a significant challenge. To address this challenge, a comprehensive study was conducted to investigate various morphological, biochemical, molecular parameters, and agronomic traits related to NUE. By examining various traits under both optimum-N (ON) and stressed-N (SN) conditions, the study explores the interrelationships among these traits, providing novel insights not previously reported. A set of 278 diverse wheat genotypes were assessed, encompassing eight NUE-related traits: Grain Yield, Biomass, Grain nitrogen, N at head, N at harvest, N-uptake, Nitrogen Uptake Efficiency, Nitrogen Utilization Efficiency, and NUE under both ON and SN conditions in the field. The findings demonstrated a significant positive correlation between grain yield and all NUE-related traits, highlighting their significance in comprehending the biological NUE of wheat plants. Notably, the study identified N-uptake and N-uptake related traits as key factors influencing the impact of soil nitrogen status on yield and associated parameters. These traits hold particular importance for selecting wheat genotypes with optimal yield and NUE in wheat cultivation. To complement the field data, representative genotypes were further subjected to a hydroponics experiment under absolute nitrogen control. This experiment provided insights into the effects of nitrogen stress on morphological parameters and the performance of eight essential nitrogen and carbon metabolizing enzymes. Correlation analysis highlighted the substantial influence of four key N-metabolizing enzymes, namely Nitrate Reductase, Glutamine Synthetase, Glutamate Oxo-Glutarate Amino Transferase, and Glutamate Dehydrogenase, on grain yield. Additionally, this study underscored the direct and indirect associations between seedling parameters and field traits, emphasizing the significance of shoot and root length parameters in nitrogen acquisition under nitrogen stress. In conclusion, these findings offer valuable insights into the intricate network of traits and parameters that influence wheat grain yield under varying nitrogen regimes. This knowledge can aid in the selection of wheat genotypes with enhanced NUE and grain yield, particularly in scenarios of reduced nitrogen application. Key PointsO_LIA comprehensive study in field and hydroponics conditions revealed differential responses of various morphological, biochemical, molecular parameters, and agronomic traits to different nitrogen levels. C_LIO_LIN-uptake related traits in field condition and chlorophyll content and morphological parameters in hydroponics condition were found as essential factors contributing to variations under both optimum and stressed N conditions. C_LIO_LIAmong the parameters observed in the seedling stage, SL and RL, along with the enzymes NR, GS, GOGAT, and GDH, demonstrated their influence on GY. C_LI

plant biology↗

bioRxiv2021

Cargo crowding, stationary clusters and dynamical reservoirs in axonal transport

Molecular motors drive the directed transport of presynaptic vesicles along the narrow axons of nerve cells. Stationary clusters of such vesicles are a prominent feature of axonal transport, but little is known about their physiological and functional relevance. Here, we develop a simulation model describing key features of axonal cargo transport with a view to addressing this question, benchmarking the model against our experiments in the touch neurons of C. elegans. Our simulations provide for multiple microtubule tracks and varied cargo motion states while also incorporating cargo-cargo interactions. Our model also incorporates obstacles to vesicle transport in the form of microtubule ends, stalled vesicles, and stationary mitochondria. We devise computational methodologies to simulate both axonal bleaching and axotomy, showing that our results reproduce the properties of both moving as well as stationary cargo in vivo. Increasing vesicle numbers leads to larger and more long-lived stationary clusters of vesicular cargo. Vesicle clusters are dynamically stable, explaining why they are ubiquitously seen. Modulating the rates of cargo motion-state switching allows cluster lifetimes and flux to be tuned both in simulations and experiments. We demonstrate, both in simulations and in an experimental system, that suppressing reversals leads to larger stationary vesicle clusters being formed while also reducing flux. Our simulation results support the view that the physiological significance of clusters is located in their role as dynamic reservoirs of cargo vesicles, capable of being released or sequestered on demand.

biophysics↗