Biology subjects

Gautam, S.

Publications and source records attributed to Gautam, S..

30 records · Page 2Linked to original sources

bioRxiv2023

ClearX9™: an efficient alternative to fetal bovine serum for growing animal cells in vitro

Fetal Bovine Serum (FBS) is a nutrient-rich fluid that contains nutritional and macromolecular factors essential for cell growth. Every year millions of pregnant cows are slaughtered in search of FBS leading to huge environmental consequences. Here we report ClearX9 - an affordable, sustainable, ethical, and effective replacement for FBS. ClearX9 cell culture medium was used to grow HeLa (cervical cancer cells), HEK293T (embryonic kidney transformed cells) and Nthy Ori-3-1 (primary thyroid follicular transformed epithelial cells) and showed encouraging growth patterns and good cellular health. Compared with the FBS-enriched cell culture medium, ClearX9 scored positive on all the parameters suggesting ClearX9 as a credible alternative to FBS. In future, more work is required to establish the efficacy of ClearX9 in toxicology testing, bio-manufacturing, regenerative medicine, and vaccine research. HIGHLIGHTSO_LIClearX9 provides good nutritional support for the growth of animal cells C_LIO_LIClearX9 cell growth performance is comparable to the serum-enriched medium C_LIO_LIClearX9 maintains a healthy morphological profile of cells during division C_LIO_LIClearX9 generates a stress-free environment within cells C_LIO_LIClearX9 does not require animal slaughter and reduces carbon footprint C_LIO_LIClearX9 has applications in biotechnology and cell cultivated meat industry C_LI

cell biology↗

bioRxiv2022

Evaluation of the safety, immunogenicity and efficacy of a new live-attenuated lumpy skin disease vaccine in India

Lumpy skin disease (LSD) was reported for the first time in India in 2019 and since then, it has become endemic. Since a homologous (LSD-virus based) vaccine was not available in the country, goatpox virus (GPV)-based heterologous vaccine was authorized for mass immunization against LSD in cattle. This study describes the evaluation of safety, immunogenicity and efficacy of a new live-attenuated LSD vaccine developed using an Indian field strain (LSDV/India/2019/Ranchi). The virus was attenuated by continuous passage (P=50) in Vero cells. The vaccine (50th LSDV passage in Vero cells, named as Lumpi-ProVacInd) did not induce any local or systemic reaction upon its experimental inoculation in calves (n=10). At day 30 post-vaccination (pv), the vaccinated animals were shown to develop antibody- and cell-mediated immune response and exhibited complete protection upon virulent LSDV challenge. We observed a minimum Neethling response (0.018% animals; 5 out of 26940 animals) of the vaccine in field trials among 26940 animals. There was no significant reduction in the milk yield in lactating animals (n=10108), besides there was no abortion or any other reproductive disorder in the pregnant animals (n=2889). Sero-conversion was observed in 85.18% animals in the field by day 30 pv.

microbiology↗

bioRxiv2022

The Drosophila Dopamine 2-like receptor D2R (Dop2R) is required in the Blood Brain Barrier for male courtship

The blood brain barrier (BBB) has the essential function to protect the brain from potentially hazardous molecules while also enabling controlled selective uptake. How these processes and signaling inside BBB cells control neuronal function is an intense area of interest. Signaling in the adult Drosophila BBB is required for normal male courtship behavior and relies on male-specific molecules in the BBB. Here we show that the dopamine receptor D2R is expressed in the BBB and is required in mature males for normal mating behavior. Conditional adult male knockdown of D2R in BBB cells causes courtship defects. The courtship defects observed in genetic D2R mutants can be rescued by expression of normal D2R specifically in the BBB of adult males. Drosophila BBB cells are glial cells. Our findings thus identify a specific glial function for the DR2 receptor and dopamine signaling in the regulation of a complex behavior.

animal behavior and cognition↗

bioRxiv2022

A dual role for CRTH2 in acute lung injury

Acute respiratory distress syndrome (ARDS) is a life-threatening clinical condition defined by rapid-onset respiratory failure following acute lung injury (ALI). The high mortality rate and rising incidence of ARDS due to COVID-19 make it an important research priority. Here we sought to investigate the role of chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) in ARDS. CRTH2 is a G protein-coupled receptor best studied in the context of type 2 immunity, but it also exerts effects on neutrophilic inflammation. To evaluate its role in mouse models of ARDS, we first examined its expression pattern on murine neutrophils. We found it is expressed on neutrophils, but only after extravasation into the lung. Next, we showed that CRTH2 expression on extravasated lung neutrophils promotes cell survival, as genetic deletion of CRTH2 and pharmacologic inhibition of CRTH2 using fevipiprant both led to increased apoptosis in vitro. We then evaluated the role of CRTH2 in vivo using a murine model of LPS-induced ALI. In line with the pro-inflammatory effects of CRTH2 in vitro, we observed improvement of lung injury in CRTH2-deficient mice in terms of vascular leak, weight loss and survival after LPS administration. However, neutrophilic inflammation was elevated, not suppressed in the CRTH2 KO. This finding indicated a second mechanism offsetting the pro-survival effect of CRTH2 on neutrophils. Bulk RNAseq of lung tissue indicated impairments in type 2 immune signaling in the CRTH2 KO, and qPCR and ELISA confirmed downregulation of IL-4, which is known to suppress neutrophilic inflammation. Thus, CRTH2 may play a dual role in ALI, directly promoting neutrophil cell survival, but indirectly suppressing neutrophil effector function via IL-4.

immunology↗

bioRxiv2022

The AAA+ chaperone VCP disaggregates Tau fibrils and generates aggregate seeds

Amyloid-like aggregates of the microtubule-associated protein Tau are associated with several neurodegenerative disorders including Alzheimers disease. The existence of cellular machinery for the removal of such aggregates has remained unclear, as specialized disaggregase chaperones are thought to be absent in mammalian cells. Here we show in cell culture and in neurons that the AAA+ chaperone VCP is recruited to ubiquitylated Tau fibrils, resulting in their efficient disaggregation. Aggregate clearance depends on the functional cooperation of VCP with Hsp70 and the ubiquitin-proteasome machinery. Inhibition of VCP activity stabilizes large Tau aggregates, and is accompanied by a reduction in the amount of Tau species competent of prion- like aggregate seeding in recipient cells. Thus, disaggregation by VCP generates seeding-active Tau as byproduct. These findings identify VCP as a core component of the machinery for the removal of neurodegenerative disease aggregates and suggest that its activity can be associated with enhanced aggregate spreading in tauopathies.

cell biology↗

bioRxiv2021

Substrate dependent homeostatic control of c-di-AMP synthase (MsDisA) and hydrolase (MsPDE) from Mycobacterium smegmatis

Cyclic-di-nucleotide based secondary messengers regulate various physiological processes including the stress responses in bacteria. In the past decade, cyclic diadenosine monophosphate (c-di-AMP) has emerged as a crucial second messenger, implicated in fatty acid metabolism, antibiotic resistance, biofilm formation, virulence, DNA repair, ion homeostasis, sporulation etc. The level of c-di-AMP is maintained in the cell by the action of two opposing enzymes, namely diadenylate cyclase (DAC) and phosphodiesterase (PDE). In mycobacteria, this molecule is essential for its regulatory role in bacterial physiology and host-pathogen interactions. However, such modulation of c-di-AMP remains to be explored in Mycobacterium smegmatis. Here, we systematically characterised the c-di-AMP synthase (MsDisA) and a hydrolase (MsPDE) from M. smegmatis at different pH and osmolytic conditions in vitro. Our biochemical assays show that the MsDisA activity is enhanced during the alkaline stress and c-di-AMP is readily produced without any intermediates. At pH 9.4, the MsDisA promoter activity in vivo increases significantly, strengthening this observation. However, under physiological conditions, the activity of MsDisA was moderate with the formation of intermediates. To get further insights into the structural characteristics, we determined the cryo-EM structure of the MsDisA, revealing some interesting features. Biochemical analysis of individual domains shows that the N-terminal minimal region alone can form a functional octamer. Altogether, our results reveal the biochemical and structural regulation of mycobacterial c-di-AMP in response to various environmental stress.

biophysics↗

bioRxiv2021

IL-10 receptor blockade delivered simultaneous with BCG vaccination sustains long term protection against Mycobacterium tuberculosis infection in mice

Mycobacterium bovis bacillus Calmette-Guerin (BCG) immunization still remains the best vaccination strategy available to control the development of active tuberculosis (TB). Protection afforded by BCG vaccination gradually wanes over time and while booster strategies have promise, they remain under development. An alternative approach is to improve BCG efficacy through host-directed therapy. Building upon prior knowledge that blockade of interleukin-10 receptor 1 (IL-10R1) during early Mycobacterium tuberculosis (M.tb) infection improves and extends control of M.tb infection in mice, we employed a combined anti-IL-10R1/BCG vaccine strategy. A subcutaneous, single vaccination of BCG/IL10-R1 increased the numbers of CD4+ and CD8+ central memory T cells, and reduced TH1 and TH17 cytokine levels in the lung for up to 7 weeks post vaccination. Subsequent M.tb challenge in mice showed both an early (4 week) and sustained long-term (47 week) control of infection, which was associated with increased survival. In contrast, protection of BCG/saline vaccinated mice waned 8 weeks post M.tb infection. Our findings demonstrate that a single and simultaneous vaccination with BCG/IL10-R1 sustains long-term protection, identifying a promising approach to enhance and extend the current BCG mediated protection against TB.

immunology↗

bioRxiv2021

Extracellular Delivery of Functional Mitochondria Reverses the Dysfunction of CD4+ T Cells in Aging

Mitochondrial dysfunction alters cellular metabolism, increases tissue oxidative stress, and may be principal to the dysregulated signaling and function of CD4+ T lymphocytes in the elderly. In this proof of principle study, we investigated whether the transfer of functional mitochondria into CD4+ T cells that were isolated from old mice (aged CD4+ T cells), could abrogate aging-associated mitochondrial dysfunction, and improve the aged CD4+ T cell functionality. Our results show that the delivery of exogenous mitochondria to aged non-activated CD4+ T cells led to significant mitochondrial proteome alterations highlighted by improved aerobic metabolism and decreased cellular mitoROS. Additionally, mito-transferred aged CD4+ T cells showed improvements in activation-induced TCR-signaling kinetics displaying markers of activation (CD25), increased IL-2 production, enhanced proliferation ex vivo. Importantly, immune deficient mouse models (RAG-KO) showed that adoptive transfer of mito-transferred naive aged CD4+ T cells, protected recipient mice from influenza A and Mycobacterium tuberculosis infections. These findings support mitochondria as targets of therapeutic intervention in aging.

immunology↗

bioRxiv2020

An Abundant New Saponin-Polybromophenol Antibiotic (CU1) from Cassia fistula Bark Against Multi-Drug Resistant Bacteria Targeting RNA Polymerase

Spread of multidrug-resistant infections is a threat to human race and need for new drug development is great. Bark ethanol extract of Cassia fistula inhibited MDR bacteria isolated from Ganga River water, human and animal. On TLC, a gray colour major band ran fast (CU1; 6.6% of bark and ~30% of crude extract) which quickly purified on HPLC C18 column at 3 min. Chemical assays suggested a triterpene linked to polyphenol known as saponin. CHN Elements analysis (35.9% C; 5.5% H) did not identified nitrogen suggesting a polyphenol or glycoside. VU-Vis spectra gave high peak at below 200nm with a secondary peak at 275nm with minor hinge at 578nm indicating a fused ring with bromo-polyphenol. CU1 Mass (897 Daltons) with fragments of 515, 325, 269, 180 daltons and six halogen substitutions reflected by 82 molecular mass of DBr deviate six larger fragments. FT-IR suggested broad band at 3500-3000 cm-1 for -OH where as two strong peaks at 1552cm-1 for aromatic C=C and 1408cm-1 for phenol. Proton-NMR confirmed polymeric phenol at {delta} 4.86-4.91 ppm and tetratet at {delta}3.57-3.618 ppm with phenolic bromo-substituents. Carbon-NMR identified a strong peak at {delta}=23.7ppm for many C-Br and at 165ppm for a polybenzoid compound. CU1 inhibited the RNA Polymerase of E. coli (IC50=23g/ml) and M. tuberculosis (IC50=34g/ml) but not DNA polymerase. Gel shift assays demonstrated that CU1 drug interacted with enzyme and inhibited its binding to open promoter complex. Thus, CU1 phyto-chemical is an alternative safer and low cost drug against MDR-TB as well as other MDR pathogens.

microbiology↗

bioRxiv2020

The Hsc70 Disaggregation Machinery RemovesMonomer Units Directly from α-Synuclein FibrilEnds

Molecular chaperones contribute to the maintenance of cellular protein homeostasis through a wide range of mechanisms, including the assistance of de novo protein folding, the rescue of misfolded proteins, and the prevention of amyloid formation. Chaperones of the Hsp70 family have a striking capability of disaggregating otherwise irreversible aggregate structures such as amyloid fibrils that accumulate during the development of neurodegenerative diseases. However, the mechanisms of this key emerging functionality remain largely unknown. Here, we bring together microfluidic measurements with kinetic analysis and show that that the Hsp70 protein heat chock complement Hsc70 together with its two co-chaperones DnaJB1 and the nucleotide exchange factor Apg2 is able to completely reverse the aggregation process of alpha-synuclein, associated with Parkinsons disease, back to its soluble monomeric state. Moreover, we show that this reaction proceeds with first order kinetics in a process where monomer units are taken off directly from the fibril ends. Our results demonstrate that all components of the chaperone triad are essential for fibril disaggregation. Lastly, we quantify the interactions between the three chaperones as well as between the chaperones and the fibrils in solution, yielding both binding stoichiometries and dissociation constants. Crucially, we find that the stoichiometry of Hsc70 binding to fibrils suggests Hsc70 clustering at the fibril ends. Taken together, our results show that the mechanism of action of the Hsc70-DnaJB1-Apg2 chaperone system in disaggregating -synuclein fibrils involves the removal of monomer units without any intermediate fragmentation steps. These findings are fundamental to our understanding of the suppression of amyloid proliferation early in life and the natural clearance mechanisms of fibrillar deposits in Parkinsons disease, and inform on the possibilities and limitations of this strategy in the development of therapeutics against synucleinopathies and related neurodegenerative diseases.

biophysics↗

bioRxiv2020

Lethality of SARS-CoV-2 infection in K18 human angiotensin converting enzyme 2 transgenic mice

ABSTRACTVaccine and antiviral development against SARS-CoV-2 infection or COVID-19 disease currently lacks a validated small animal model. Here, we show that transgenic mice expressing human angiotensin converting enzyme 2 (hACE2) by the human cytokeratin 18 promoter (K18 hACE2) represent a susceptible rodent model. K18 hACE2-transgenic mice succumbed to SARS-CoV-2 infection by day 6, with virus detected in lung airway epithelium and brain. K18 ACE2-transgenic mice produced a modest TH1/2/17 cytokine storm in the lung and spleen that peaked by day 2, and an extended chemokine storm that was detected in both lungs and brain. This chemokine storm was also detected in the brain at day 4. K18 hACE2-transgenic mice are, therefore, highly susceptible to SARS-CoV-2 infection and represent a suitable animal model for the study of viral pathogenesis, and for identification and characterization of vaccines (prophylactic) and antivirals (therapeutics) for SARS-CoV-2 infection and associated severe COVID-19 disease.

microbiology↗

bioRxiv2019

Determination of Cas9/dCas9 associated toxicity in microbes

The CRISPR-Cas9 system has been used extensively in eukaryotic and prokaryotic systems for various applications. In case of the latter, a couple of previous studies had shown Cas9 protein expression associated toxicity. We studied the same in five microbes, viz Escherichia coli, Salmonella typhimurium, Mycobacterium smegmatis, Xanthomonas campestris and Deinococcus radiodurans. Transformation efficiency of plasmids carrying genes coding for Cas9 or dCas9 was used to gauge toxicity associated with Cas9 protein expression. Results showed differential levels of Cas9 toxicity among the bacteria and lower transformation efficiency for cas9/dcas9 bearing plasmids compared to controls in general. This indicated lethal effect of Cas9/dCas9 expression. While E. coli and S. typhimurium seemed to tolerate Cas9/dCas9 fairly well, in GC rich microbes, M. smegmatis, X. campestris and D. radiodurans, Cas9/dCas9 associated toxicity was acute.

microbiology↗