Biology subjects

Trivedi, D.

Publications and source records attributed to Trivedi, D..

8 recordsLinked to original sources

bioRxiv2025

Global Skeletal Muscle Metabolomics Reveals Mechanisms Behind Higher Response to Resistance Training in Older Adults

To understand the mechaisnm behind high respond (HighR) compared to low respond (LowR) to resistnace training (RT) and whey protein supplementation (20g/day), we analysied vastus laterails muscle biopsies from a total of 50 participants. Utilising the MRI muscle cross-sectional area (CSA) data, we defined responders as those who had hypertrophy exceeding the 1.7% method error. Quadriceps CSA in the lower responder (LowR) (n=25, mean age 69{+/-}5 years) and HighR (n=25, mean age 67{+/-}4 years) increased from 53.6 {+/-} 12.1 cm2 to 55.4 {+/-} 12.8 cm2 after 10 weeks of RET (3.3 {+/-} 1.7%, P < 0.001) and increased the absolute CSA in the higher responders (HighR) from 53.7 {+/-} 12.5 cm2 to 59.2 {+/-} 13.6 cm2 (10.3 {+/-} 2.0%, P < 0.001). Muscle biopsies were taken from the vastus lateralis before and after RT. We performed untargeted liquid chromatography-mass spectrometry metabolomics to investigate changes in muscle metabolic regulation. The partial least squares discriminant analysis (PLS-DA) yielded the best results using the polar extracts, achieving a 75% average correct classification rate for predicting HighR and LowR. There was no signifncat differences in metabolomic profile at the basline. Our findings revealed several metabolic pathways, including branched-chain amino acid catabolism, tryptophan metabolism (indole and kynurenine pathways), the TCA cycle, gut-derived metabolites, carnitine shuttle metabolism as prominent pathways disrupted in LowR. We provide new insights and has the potential to identify and enhance interventions targeting muscle metabolism, ultimately improving muscle mass and strength to reduce the risk of sarcopenia and frailty in older age.

systems biology↗

bioRxiv2024

Catabolism of extracellular glutathione supplies amino acids to support tumor growth

Restricting amino acids from tumors is an emerging therapeutic strategy with significant promise. While typically considered an intracellular antioxidant with tumor-promoting capabilities, glutathione (GSH) is a tripeptide of cysteine, glutamate, and glycine that can be catabolized, yielding amino acids. The extent to which GSH-derived amino acids are essential to cancers is unclear. Here, we find that GSH catabolism promotes tumor growth. We show that depletion of intracellular GSH does not perturb tumor growth, and extracellular GSH is highly abundant in the tumor microenvironment, highlighting the potential importance of GSH outside of tumors. We find supplementation with GSH can rescue cancer cell survival and growth in cystine-deficient conditions, and this rescue is dependent on the catabolic activity of {gamma}-glutamyltransferases (GGTs). Finally, pharmacologic targeting of GGTs activity prevents the breakdown of circulating GSH, lowers tumor cysteine levels, and slows tumor growth. Our findings indicate a non-canonical role for GSH in supporting tumors by acting as a reservoir of amino acids. Depriving tumors of extracellular GSH or inhibiting its breakdown is potentially a therapeutically tractable approach for patients with cancer. Further, these findings change our view of GSH and how amino acids, including cysteine, are supplied to cells.

cancer biology↗

bioRxiv2021

Transgenic resources for functional studies on the hsrω gene in Drosophila

The hsr{omega} gene of Drosophila melanogaster, an early discovered non-coding developmentally active and stress-inducible gene, has pleiotropic actions through its multiple nuclear and cytoplasmic non-coding transcripts. With a view to understand this diverse functions and mechanisms of actions of this gene, we generated a series of transgenic lines for over-expression or RNAi of different transcripts and CRISPR-Cas9 mediated deletion alleles. These are described here.

genetics↗

bioRxiv2020

Valorization of CO2 through lithoautotrophic production of sustainable chemicals in Cupriavidus necator

Coupling recent advancements in genetic engineering of diverse microbes and gas-driven fermentation provides a path towards sustainable commodity chemical production. Cupriavidus necator H16 is a suitable species for this task because it effectively utilizes H2 and CO2 and is genetically tractable. Here, we demonstrate the versatility of C. necator for chemical production by engineering it to produce three products from CO2 under lithotrophic conditions: sucrose, polyhydroxyalkanoates (PHAs), and lipochitooligosaccharides (LCOs). We engineered sucrose production in a co-culture system with heterotrophic growth 30 times that of WT C. necator. We engineered PHA production (20-60% DCW) and selectively altered product composition by combining different thioesterases and phaCs to produce copolymers directly from CO2. And, we engineered C. necator to convert CO2 into the LCO, a plant growth enhancer, with titers of [~]1.4 mg/L--equivalent to yields in its native source, Bradyrhizobium. We applied the LCOs to germinating seeds as well as corn plants and observed increases in a variety of growth parameters. Taken together, these results expand our understanding f how a gas-utilizing bacteria can promote sustainable production.

synthetic biology↗

bioRxiv2020

A genome engineering resource to uncover principles of cellular organization and tissue architecture by lipid signalling

Phosphoinositides (PI) are key regulators of cellular organization in eukaryotes and genes that tune PI signalling are implicated in human disease mechanisms. Biochemical analyses and studies in cultured cells have identified a large number of proteins that can mediate PI signalling. However, the role of such proteins in regulating cellular processes in vivo and development in metazoans remains to be understood. Here we describe a set of CRISPR based genome engineering tools that allow the manipulation of each of these proteins with spatial and temporal control during metazoan development. We demonstrate the use of these reagents to deplete a set of 103 proteins individually in the Drosophila eye and identify several new molecules that control eye development. Our work demonstrates the power of this resource in uncovering the molecular basis of tissue homeostasis during normal development and in human disease biology.

genetics↗

bioRxiv2019

Extended synaptotagmin regulates plasma membrane-endoplasmic reticulum contact site structure and lipid transfer function in vivo

Inter-organelle communication between closely apposed membranes is proposed at Membrane Contact Sites (MCS). However the regulation of MCS structure and their functional relevance in vivo remain debated. The extended synaptotagmins (Esyt) are evolutionarily conserved proteins proposed to function at MCS. However, loss of all three Esyts in yeast or mammals shows minimal phenotypes questioning the functional importance of Esyt. We report that in Drosophila photoreceptors, MCS number is regulated by PLC{beta} activity. Photoreceptors of a null allele of Drosophila extended synaptotagmin (dEsyt) show loss of ER-PM MCS. Loss of dEsyt results in mislocalization of RDGB, an MCS localized lipid transfer protein, required for photoreceptor structure and function, ultimately leading to retinal degeneration. dEsyt depletion enhanced the retinal degeneration, reduced light responses and slower rates of plasma membrane PIP2 resynthesis seen in rdgB mutants. Thus, dEsyt function and PLC{beta} signaling regulate ER-PM MCS structure and lipid transfer in Drosophila photoreceptors.

cell biology↗

bioRxiv2019

Synthetic gene circuits enable systems-level biosensor discovery at the host-microbe interface

The composition and function of the gut microbiota are strongly associated with human health, and dysbiosis is linked to an array of diseases, ranging from obesity and diabetes to infection and inflammation. Engineering synthetic circuits into gut bacteria to sense, record and respond to in vivo signals is a promising new approach for the diagnosis, treatment and prevention of disease. Here, we repurpose a synthetic bacterial memory circuit to rapidly screen for and discover new in vivo-responsive biosensors in commensal gut Escherichia coli. We develop a pipeline for rapid systems-level library construction and screening, using next-generation sequencing and computational analysis, which demonstrates remarkably robust identification of responsive biosensors from pooled libraries. By testing both genome-wide and curated libraries of potential biosensor triggers--each consisting of a promoter and ribosome binding site (RBS)--and using RBS variation to augment the range of trigger sensitivity, we identify and validate triggers that selectively activate our synthetic memory circuit during transit through the gut. We further identify biosensors with increased response in the inflamed gut through comparative screening of our libraries in healthy mice and those with intestinal inflammation. Our results demonstrate the power of systems-level screening for the identification of novel biosensors in the gut and provide a platform for disease-specific screening using synthetic circuits, capable of contributing to both the understanding and clinical management of intestinal illness. IMPORTANCEThe gut is a largely obscure and inaccessible environment. The use of live, engineered probiotics to detect and respond to disease signals in vivo represents a new frontier in the management of gut diseases. Engineered probiotics have also shown promise as a novel mechanism for drug delivery. However, the design and construction of effective strains that respond to the in vivo environment is hindered by our limited understanding of bacterial behavior in the gut. Our work expands the pool of potential biosensors for the healthy and diseased gut, providing insight into host-microbe interactions and enabling future development of increasingly complex synthetic circuits. This method also provides a framework for rapid prototyping of engineered systems and for application across bacterial strains and disease models.

synthetic biology↗

bioRxiv2018

FMRFa receptor stimulated Ca2+ signals alter the activity of flight modulating central dopaminergic neurons in Drosophila melanogaster

Neuropeptide signaling influences animal behavior by modulating neuronal activity and thus altering circuit dynamics. Insect flight is a key innate behavior that very likely requires robust neuromodulation. Cellular and molecular components that help modulate flight behavior are therefore of interest and require investigation. In a genetic RNAi screen for G-protein coupled receptors that regulate flight bout durations, we earlier identified several receptors, including the receptor for the neuropeptide FMRFa (FMRFaR). To further investigate modulation of insect flight by FMRFa we generated CRISPR-Cas9 mutants in the gene encoding the Drosophila FMRFaR. The mutants exhibit significant flight deficits with a focus in dopaminergic cells. Expression of a receptor specific RNAi in adult central dopaminergic neurons resulted in progressive loss of sustained flight. Further, genetic and cellular assays demonstrated that FMRFaR stimulates intracellular calcium signaling through the IP3R and helps maintain neuronal excitability in a subset of dopaminergic neurons for positive modulation of flight bout durations.\n\nAuthor summaryNeuropeptides play an important role in modulating neuronal properties such as excitability and synaptic strength and thereby influence innate behavioral outputs. In flying insects, neuromodulation of flight has been primarily attributed to monoamines. In this study, we have used the genetically amenable fruit fly, Drosophila melanogaster to identify a neuropeptide receptor that is required in adults to modulate flight behavior. We show from both knockdown and knockout studies that the neuropeptide receptor, FMRFaR, present on a few central dopaminergic neurons, modulates the duration of flight bouts. Overexpression of putative downstream molecules, the IP3R, an intracellular Ca2+-release channel, and CaMKII, a protein kinase, significantly rescue the flight deficits induced by knockdown of the FMRFaR. Our data support the idea that FMRFaR and CaMKII help maintain optimal membrane excitability of adult dopaminergic neurons required to sustain longer durations of flight bouts. We speculate that the ability to maintain longer flight bouts in natural conditions enhances the individuals capacity to search and reach food sources as well as find sites suitable for egg laying.

genetics↗