Biology subjects

Kumari, S.

Publications and source records attributed to Kumari, S..

At least 73 records · Page 4Linked to original sources

bioRxiv2020

The Response of Bacterial Flagellar Motor to Stepwise Increase in NaCl Concentration

Many species of bacteria use flagella to navigate in its environment. The flagellum is a 7-10 m long helical filament with a rotary motor at its base embedded in the cell membrane and almost a dozen stator complexes. Proton motive force across the cell membrane powers the flagellar motors of E.coli and Salmonella. The motor stochastically switches between clockwise and counter-clockwise direction. A chemotaxis system causes the motor to change its direction, but the process is more complex as the switch is sensitive to load and proton motive force as well. NaCl is significant with regard to the flagellar motor as it affects the stator dynamics, proton motive force, and osmotaxis at higher concentration. Chemotaxis helps the bacteria for its growth and survival. E.colis natural habitat has high osmolarity and the organism uses use various mechanisms for osmoregulation. However, the role of flagellar motor to adapt to the changes in osmolarity, or osmotaxis, is not well studied. In this work, we dissipated the membrane potential of bacteria in pH 7 using step-wise increase in concentration of NaCl in motility buffer and studied the output of E.colis flagellar motor using tethered bead assay and swimming Salmonella enteritidis cells. We observed decrease in motor speed and switching rates with stepwise increase in NaCl concentration in the motility buffer. The mean speed of the motors decreased with NaCl concentration. The population of swimming cells tumbled more with increase in concentration of NaCl. At the single motor level, the motors biased to CCW rotation with decrease in membrane potential. In this study, we present our observations of the flagellar motor in high NaCl concentration, and explore how NaCl can be used to study various aspects of the bacterial flagellar motor. Statement of significanceSodium ion has been significant in the both the cellular energetics and the function of bacterial flagellar motor. Growing evidence show that the effect of sodium ions was not what hitherto thought it would be. It is involved in the sodium energetics, dissipate membrane potential, affect the flagellar stator dynamics of bacteria. Being an osmolyte, it influences the osmotaxis of bacteria. In this work, we studied the effect of NaCl on the response of the single bacterial flagellar motor of E.coli and swimming cells of Salmonella enteritidis. We observed that the effect of NaCl on the output of the flagellar motor was significant and it may affect the cells in various ways.

biophysics↗

bioRxiv2020

Lactobacillus rhamnosus attenuates bone loss and maintains bone health by skewing Treg-Th17 cell balance in Ovx mice

Osteoporosis is a systemic-skeletal disorder characterized by enhanced fragility of bones leading to increased rates of fractures and morbidity in large number of populations. Probiotics are known to be involved in management of various-inflammatory diseases including osteoporosis. But no study till date had delineated the immunomodulatory potential of Lactobacillus rhamnosus (LR) in bone-health. In the present study, we examine the effect of probiotic-LR on bone-health in osteoporotic (Ovx) mice model. We observed that administration of LR attenuated bone-loss in Ovx mice. Both the cortical and trabecular bone-content of LR treated group was significantly higher than Ovx-group. Remarkably, the percentage of osteoclastogenic-CD4+Ror{gamma}t+Th17 cells at distinct immunological sites such as BM, spleen, LN and PP were significantly reduced, whereas the percentage of anti-osteoclastogenic-CD4+Foxp3+Tregs and CD8+Foxp3+Tregs were significantly enhanced in LR-treated group thereby resulting in inhibition of bone-loss. The immunomodulatory-role of LR was further supported by serum-cytokine data with a significant reduction in proinflammatory-cytokines (IL-6, IL-17 and TNF-) along with enhancement in anti-inflammatory-cytokines (IL-10, IFN-{gamma}) in LR treated-group. Altogether, the present study for the first time establishes the osteoprotective role of LR on bone-health, thus highlighting the potential of LR in the treatment and management of various bone related diseases including osteoporosis.

immunology↗

bioRxiv2020

NBS1-CtIP-Mediated DNA End Resection Regulates cGAS Binding to Micronuclei

Cyclic GMP-AMP synthase (cGAS), an important component of immune signaling, is hyperactivated in cells defective for DNA damage response (DDR) signaling. However, a direct role for DDR factors in the regulation of cGAS functions is mostly unknown. Here, we provide novel evidence that Nijmegen breakage syndrome 1 (NBS1) protein, a well-studied DNA double-strand break (DSB) sensor, in coordination with ATM, a protein kinase, and CtBP-interacting protein (CtIP), a DNA end resection factor, functions as an upstream regulator of cGAS binding to micronuclei. Upon NBS1 binding to micronuclei via its fork-head-associated domain, it recruits ATM and CtIP via its N- and C-terminal domains, respectively. Subsequently, ATM stabilizes NBS1s interaction with micronuclei, and CtIP converts DSB ends into single-strand DNA ends, and these two key events preclude cGAS from binding to micronuclei. Notably, we show that purified cGAS cannot form a complex with DNA substrates that mimic resected DNA ends in vitro. Thus, NBS1 together with its binding partners modify the chromatin architecture of the micronuclei and that plays a critical role in cGASs binding to micronuclei.

immunology↗

bioRxiv2020

A testis-specific Heme Peroxidase HPX12 regulates male fertility in the mosquito Anopheles stephensi

In humans, dysregulation of the antioxidant defense system has a detrimental impact on male fertility and reproductive physiology. Establishing such a correlation in disease vectors may pave a new way to manipulate males reproductive physiology, but remains the least attended. Since long - term storage of healthy and viable sperm earmarks males reproductive competency, we tested whether the anti-oxidative system protein also influences male fertility in the mosquito An. stephensi. We showed that a testis-specific HPX12 is critical for maintaining the physiological homeostasis of male mosquitos reproductive organs. Disruption of this antioxidant enzyme by dsRNA silencing in the male mosquito severely impairs the reproductive potential of mated blood-fed female mosquitoes,resulting in a loss of 60% eggs. Our data demonstrate that increased ROS in the HPX12 mRNA depleted mosquitoes is an ultimate cause of sperm disabilities both qualitatively as well as quantitatively.

animal behavior and cognition↗

bioRxiv2020

Evaluation of Seed or Grain Storage Technologies from Indian Farming Societies Using A Hybrid and Multi-Attribute Approach

Soon after the introduction of green revolution, a parallel increment in percent food grain production and losses has been reported in India, which impedes the mission of achieving food security in India. In parts, among the major causes of these losses are the reluctance among farmers, especially of small holding, towards adoption of scientific storage methods/technologies and inability of the national agencies to meet the challenges imposed by the supply of surplus grains to them by the farmers. Although sets of traditional and improved grain storage technologies exist among Indian farming communities, a controversial account about their effectiveness and performance is available in the literature which negatively impacts the endeavour of bringing rapid developmental in the farming society. In a developing nation like India, a large section of farmers is often either unaware of the modern technologies or cannot logistically access them. They often rely on the traditional or semi-modern technologies without having a comprehensive account of the benefit and economic feasibility of the modern technologies. This impedes the vision of rapid development of the farmers and the process of infusing emerging technologies in the society. In order to develop an informative argument about the performance of the existing technologies, a nearly comprehensive study has been undertaken to compare the different traditional and improved grain storage structures used by Indian farmers. Both qualitative and quantitative parameters were compared individually and simultaneously to achieve their effect on performance individually and in unison. Another objective of the study was to test the applicability of hybrid and multi-attribute approach, based on Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for the performance evaluation and ranking of the attributes and structures. Finally, based on analysis and ideas borrowed out of literature a set of theoretical and conceptual guidelines to assist improvement in these structures was brought in. The study will help understand the status of grain storage technologies in the developing, resource-poor society and also increase the adoption and access of farmers to better post-harvest seed storage technologies.Competing Interest StatementThe authors have declared no competing interest.View Full Text

plant biology↗

bioRxiv2020

Salivary AsHPX12 influence pre-blood meal associated behavioral properties in the mosquito Anopheles stephensi

In the adult female mosquito, successful blood meal acquisition is accomplished by salivary glands, which releases a cocktail of proteins to counteract vertebrate host’s immune-homeostasis. However, the biological relevance of many salivary proteins remains unknown. Here, we characterize a salivary specific Heme peroxidase family member HPX12, originally identified from Plasmodium vivax infected salivary RNAseq data of the mosquito Anopheles stephensi. We demonstrate that dsRNA silencing mediated mRNA depletion of salivary AsHPX12 (80-90%), causes enhanced host attraction but reduced blood-meal acquisition abilities, by increasing probing propensity (31%), as well as probing time (100–200s, P<0.0001) as compared to control (35-90s) mosquitoes group. Altered expression of the salivary secretory and antennal proteins may account for an unusual fast release of salivary cocktail proteins, but the slowing acquisition of blood meal, possibly due to salivary homeostasis disruption of AsHPX12 silenced mosquitoes. A parallel transcriptional modulation in response to blood feeding and P. vivax infection, further establish a possible functional correlation of AsHPX12 role in salivary immune-physiology and Plasmodium sporozoites survival/transmission. We propose that salivary HPX12 may have a vital role in the management of ‘pre- and post’-blood meal associated physiological-homeostasis and parasite transmission.Figure 1: Schematic representation of mosquito’s blood meal acquisition and upshot on blood-feeding after silencing of salivary gland HPX-12. (A) After landing over host skin, mosquito mouthparts (proboscis) actively engaged to search, probe, and pierce the skin followed by a rapid release of the pre-synthesized salivary cocktail, which counteracts the host homeostasis, inflammation, and immune responses, during blood meal uptake. (B) Silencing of HPX-12 disrupts salivary gland homeostasis, enhancing mosquito attraction, possibly by up-regulating odorant-binding proteins genes-OBP-7,10 and OBP-20 expression in the Olfactory System. However, HPX-12 disruption may also cause significant effects on pre-blood meal associated probing abilities, which may be due to fast down-regulation of salivary cocktail proteins such as Anopheline, Apyrase, D7L proteins.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition↗

bioRxiv2020

Investigation of a night soil compost psychrotrophic bacterium Glutamicibacter arilaitensis LJH19 for its safety, efficient hydrolytic and plant growth-promoting potential

Night soil compost (NSC) has traditionally been a source of organic manure in north-western Himalaya. Lately, this traditional method is declining due to modernization, its unhygienic conditions and social apprehensions. Reduction in the age-old traditional practice has led to excessive usage of chemical fertilizers and shortage of water in the eco-sensitive region. Microbiological intervention was attempted to obtain bacterial consortia for accelerated degradation of human faeces in cold climate to improvise this traditional knowledge. Glutamicibacter arilaitensis LJH19, a psychrotrophic bacteria was identified as one such potential candidate for the proposed consortia. The bacterium was isolated from NSC of Lahaul valley and exhibited potential hydrolytic activities, the specific activities of amylase, cellulase and xylanase was observed as 186.76 U/mg, 21.85 U/mg and 11.31 U/mg respectively. Additionally, the strain possessed multiple plant growth-promoting (PGP) traits. The bacterium produced 166.11 {micro}g/ml indole acetic acid and 85.72 % siderophore units, and solubilized 44.76 {micro}g/ml phosphate. Whole genome sequence (3,602,821 bps) endorsed the cold adaptation, polysaccharide metabolism, PGP potential of the bacterium. Genome mining revealed biosynthetic gene clusters for type III polyketide synthase (PKS), terpene, and siderophore in agreement with its potential PGP traits. Comparative genomics within the genus revealed 217 unique genes specific to hydrolytic and PGP activity. Negative haemolysis and biofilm production and susceptibility towards all 12 tested antibiotics indicated the bacterium to be a safe bioinoculant. Genomic investigation supported the bacterium safety with absence of any virulence and antibiotic resistance genes. We propose the strain LJH19 to be a potentially safe bioinoculant candidate for efficient degradation of night soil owing to its survivability in cold and its efficient hydrolytic and PGP potential.

microbiology↗

bioRxiv2019

M-TRACK: a platform for live cell multiplex imaging reveals cell phenotypic transition dynamics inherently missing in snapshot data

Recent advances in single-cell techniques catalyze an emerging field of studying how cells convert from one phenotype to another, in a step-by-step process. Two grand technical challenges, however, impede further development of the field. Fixed cell-based approaches can provide genome-wide snapshots of cell status but have fundamental limits on revealing temporal information, and fluorescence-based live cell imaging approaches provide temporal information but are technically challenging for multiplex long-term imaging. We first developed a live-cell imaging platform that tracks cellular status change through combining endogenous fluorescent labeling that minimizes perturbation to cell physiology, and/or live cell imaging of high-dimensional cell morphological and texture features. With our platform and an A549 VIM-RFP EMT reporter line, live cell trajectories reveal parallel paths of epithelial-to-mesenchymal transition missing from snapshot data due to cell-cell heterogeneity. Our results emphasize the necessity of extracting dynamical information of phenotypic transitions from multiplex live cell imaging.

systems biology↗

bioRxiv2019

Regulatory T cell expansion by a highly CD25-dependent IL-2 mutein arrests ongoing autoimmunity

Interleukin-2 (IL-2) controls the homeostasis and function of regulatory T cells (Tregs) and defects in the IL-2 pathway contribute to multiple autoimmune diseases. Although recombinant IL-2 therapy has been efficacious in certain inflammatory conditions, the capacity for IL-2 to also activate inflammatory effector responses highlights the need for IL-2-based therapeutics with improved Treg-specificity. From a panel of rationally designed IL-2 variants, we identified IL-2 muteins with reduced potency and enhanced Treg-selectivity due to increased dependence on the IL-2-receptor component CD25. As an Fc-fused homodimer, the optimal Fc.IL-2 mutein induced selective Treg enrichment and reduced agonism of effector cells across a wide dose range. Furthermore, despite being a weaker agonist, overall Treg growth was greater and more sustained due to reduced receptor-mediated clearance of the Fc.IL-2 mutein compared to Fc-fused wild-type IL-2. Preferential Treg enrichment was also observed in the presence of activated pathogenic T cells in the autoimmune target organ, despite a loss of Treg-selectivity in an IL-2R-proximal response. These features allowed for extended resolution of spontaneous autoimmunity using infrequent dosing schedules. Thus, IL-2 muteins enable efficient, flexible, and targeted control of the autoimmune response. One Sentence SummaryA CD25-dependent IL-2 mutein selectively expands regulatory T cells and provides potent and targeted control of autoimmunity.

immunology↗

bioRxiv2019

Affinity-engineered human antibodies detect celiac disease gluten pMHC complexes and inhibit T-cell activation

Antibodies specific for antigenic peptides bound to major histocompatibility complex (MHC) molecules are valuable tools for studies of antigen presentation. Such T-cell receptor (TCR)-like antibodies may also have therapeutic potential in human disease due to their ability to target disease-associated antigens with high specificity. We previously generated celiac disease (CeD) relevant TCR-like antibodies that recognize the prevalent gluten epitope DQ2.5-glia-1a in complex with HLA-DQ2.5. Here, we report on second-generation high-affinity antibodies towards this epitope as well as a panel of novel TCR-like antibodies to another immunodominant gliadin epitope, DQ2.5-glia-2. The strategy for affinity engineering was based on Rosetta modeling combined with pIX phage display and is applicable to similar protein engineering efforts. We isolated picomolar affinity binders and validated them in Fab and IgG format. Flow cytometry experiments with CeD biopsy material confirm the unique disease specificity of these TCR-like antibodies and reinforce the notion that B cells and plasma cells have a dominant role in gluten antigen presentation in the inflamed CeD gut. Further, the lead candidate 3.C11 potently inhibited CD4+ T-cell activation and proliferation in vitro in an HLA and epitope specific manner, pointing to a potential for targeted disease interception without compromising systemic immunity. Significance StatementConsumption of gluten-containing food drives celiac disease in genetically predisposed individuals. The underlying disease mechanism is not fully understood, but it is strictly dependent on activation of pathogenic T cells. We have engineered high-affinity human antibodies recognizing the T-cell target HLA-DQ2.5 in complex with gluten epitopes and studied cell-specific antigen presentation in patients, which shows that plasma cells and not dendritic cells dominate the inflamed tissue. The only available treatment is lifelong adherence to a gluten-free diet, which is difficult and not effective in all cases. We show that at least one of our antibodies can specifically inhibit activation of pathogenic T-cells in vitro and therefore shows promise for therapy.

immunology↗

bioRxiv2019

An allosteric hot-spot in the tandem-SH2 domain of ZAP-70 regulates T-cell signaling

T-cell receptor (TCR) signaling is initiated by recruiting ZAP-70 to the cytosolic part of TCR. ZAP-70, a non-receptor tyrosine kinase, is composed of an N-terminal tandem SH2 (tSH2) domain connected to the C-terminal kinase domain. The ZAP-70 is recruited to the membrane through binding of tSH2 domain and the doubly-phosphorylated ITAM motifs of CD3 chains in the TCR complex. Our results show that the tSH2 domain undergoes a biphasic structural transition while binding to the doubly-phosphorylated ITAM-{zeta}1 peptide. The C-terminal SH2 domain binds first to the phosphotyrosine residue of ITAM peptide to form an encounter complex leading to subsequent binding of second phosphotyrosine residue to the N-SH2 domain. We decipher a network of non-covalent interactions that allosterically couple the two SH2 domains during binding to doubly-phosphorylated ITAMs. Mutation in the allosteric network residues, for example, W165C, uncouples the formation of encounter complex to the subsequent ITAM binding thus explaining the altered recruitment of ZAP-70 to the plasma membrane causing autoimmune arthritis in mice. The proposed mechanism of allosteric coupling is unique to ZAP-70, which is fundamentally different from Syk, a close homolog of ZAP-70 expressed in B-cells. SignificanceT-cell and B-cell signaling is initiated by the same family of non-receptor tyrosine kinases, ZAP-70 and Syk, respectively. ZAP-70 and Syk share homologous sequence and similar structural architecture, yet the two kinases differ in their mode of ligand recognition. ZAP-70 binds cooperatively to its ligand, whereas Syk binds uncooperatively. Spontaneous mutation (W165C) in the regulatory module of ZAP-70 impairs T-cell signaling causes autoimmune arthritis in SKG mice, the mechanism of which is unknown. We showed that ZAP-70 regulatory module undergoes a biphasic structural transition while binding to its ligand, which is fundamentally different from Syk. We presented a molecular mechanism of cooperativity in ZAP-70 regulatory module that explains altered ligand binding by ZAP-70 mutant found in SKG mice.

biochemistry↗

bioRxiv2019

Genetic changes of P. vivax tempers host tissue-specific responses in Anopheles stephensi

In our preceding study (Sharma et al., 2019; BioRxiv) we showed that in the gut lumen Plasmodium vivax follows a unique strategy of immuno-suppression by disabling gut flora proliferation. Here, we further demonstrate that post gut invasion, a shrewd molecular relationship with individual tissues such as midgut, hemocyte, salivary glands, and strategic changes in the genetic makeup of P. vivax favors its survival in the mosquito host. A transient suppression of metabolic machinery by early oocysts, and increased immunity against late oocysts suggested a unique mechanism of gut homeostasis restoration and Plasmodium population regulation. Though a hyper immune response of hemocyte was a key to remove free circulating sporozoites, but a strong suppression of salivary metabolic activities, may favor successful survival of invaded sporozoites. Finally, genetic alteration of P. vivax ensures evasion of mosquito responses. Conclusively, our system-wide RNAseq analysis provides first genetic evidences of direct mosquito-Plasmodium interaction and establishes a functional correlation.\n\nAuthor SummaryMalaria transmission dynamics is heavily influenced by mosquito -parasite interaction. When passing through tissue specific barriers, Plasmodium have to compromise by losing its own population, but genetic relation is unknown. To win the developmental race Plasmodium need to overcome two important immuno-physiological barriers. First one accounts an indirect 24-30hr long pre-invasive gut-microbe-parasite interaction in the gut lumen. And second one follows a direct post gut invasive 14-18 days interaction with midgut, hemocyte and salivary glands. During pre-invasive phase of interaction, we showed Plasmodium vivax follows immuno-suppression strategy by restricting microbial growth in the gut lumen. Here, we demonstrate that switch of parasite from one stage to another stage within mosquito vector is accompanied by genetic changes of parasite. Our data suggests genetic makeup change enables the parasite to manipulate the metabolism of mosquito tissues. This strategy not only clear off multifaceted mosquitos tissue specific immune responses, but also favors Plasmodium own survival and transmission. Comprehending this tissue specific interaction between host and parasite at molecular level could provide new tool to intervene the plasmodium life cycle within vector.

genomics↗

bioRxiv2019

Microbiome-Gut-Brain-Axis communication regulates metabolic switch in the mosquito Anopheles culicifacies

Periodic ingestion of a protein-rich blood meal by adult female mosquitoes causes a drastic metabolic change in their innate physiological status, which is referred to as metabolic switch. Although the down-regulation of olfactory factors is key to restrain host-attraction, how the gut metabolic switch modulates brain functions, and resilience physiological homeostasis remains unexplored. Here, we demonstrate that the protein-rich diet induces mitochondrial function and energy metabolism, possibly shifting the brains engagement to manage organismal homeostasis. A dynamic expression pattern of neuro-signaling and neuro-modulatory genes in both the brain and gut indicates an optimal brain-distant organ communication. Even after decapitation, significant modulation of the neuro-modulator receptor genes as well as quantitative estimation of neurotransmitters (NTs), together confer the guts ability to serve as a second brain. Finally, data on comparative metagenomic analysis and altered NTs dynamics of naive and aseptic mosquitoes provide the initial evidence that gut-endosymbionts are key modulators for the synthesis of major neuroactive molecules. Conclusively, our data establish a new conceptual understanding of microbiome-gut-brain-axis communication in mosquitoes. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=183 SRC="FIGDIR/small/774430v2_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@4fed8corg.highwire.dtl.DTLVardef@17494f3org.highwire.dtl.DTLVardef@df1cd7org.highwire.dtl.DTLVardef@1de7923_HPS_FORMAT_FIGEXP M_FIG Graphical abstract C_FIG HighlightsO_LIHighly proteinaceous blood meal uptake causes gut metabolic switch activity in mosquitoes. C_LIO_LIGuts calling shifts the brains administrative function from external communication to inter-organ management. C_LIO_LI Gut, as a Second brain plays a crucial role in the maintenance of physiological homeostasis. C_LIO_LIMetabolic switch and proliferation of symbiotic bacteria establish microbiome-gut-brain axis communication in mosquitoes. C_LI

animal behavior and cognition↗

bioRxiv2019

DOCK2 sets the threshold for entry into the virtual memory CD8+ T cell compartment by negatively regulating tonic TCR triggering

The control of cytoskeletal dynamics by Dedicator of cytokinesis 2 (DOCK2), a hematopoietic cell-specific actin effector protein, has been implicated in TCR signaling and T cell migration. Biallelic mutations in Dock2 have been identified in patients with a recessive form of combined immunodeficiency with defects in T, B and NK cell activation. Surprisingly, we show here that certain immune functions of CD8+ T cells are enhanced in the absence of DOCK2. Dock2-deficient mice have a pronounced expansion of their memory T cell compartment. Bone marrow chimera and adoptive transfer studies indicate that these memory T cells develop in a cell-intrinsic manner following thymic egress. Transcriptional profiling, TCR repertoire analyses and cell surface marker expression indicate that Dock2-deficient naive CD8+ T cells directly convert into virtual memory cells without clonal effector T cell expansion. This direct conversion to memory is associated with a selective increase in TCR sensitivity to selfpeptide MHC in vivo and an enhanced response to weak agonist peptides ex vivo. In contrast, the response to strong agonist peptides remains unaltered in Dock2-deficient T cells. Collectively, these findings suggest that the regulation of the actin dynamics by DOCK2 enhances the threshold for entry into the virtual memory compartment by negatively regulating tonic TCR triggering in response to weak agonists.

immunology↗

bioRxiv2018

Cytoskeletal tension actively sustains the T cell immunological synapse

When migratory T cells encounter antigen presenting cells (APCs), they arrest and form radially symmetric, stable intercellular junctions termed immunological synapses which facilitate exchange of crucial biochemical information and are critical for T cell immunity. While the cellular processes underlying synapse formation have been well-characterized, those that maintain the symmetry, and thereby the stability of the synapse remain unknown. Here we identify an antigen-triggered mechanism that actively promotes T cell synapse symmetry by generating cytoskeletal tension in the plane of the synapse through focal nucleation of actin via Wiskott -Aldrich syndrome Protein (WASP), and contraction of the resultant actin filaments by myosin II. Following T cell activation, WASP is degraded, leading to cytoskeletal rearrangement and tension decay, which result in synapse breaking. Thus, our study identifies and characterizes a mechanical program within otherwise highly motile T cells that sustains the symmetry and stability of the T cell-APC synaptic contact.

cell biology↗

bioRxiv2018

Non-histone human chromatin protein, PC4 is critical for genomic integrity and negatively regulates autophagy

Multifunctional human transcriptional positive co-activator 4 (PC4) is a bonafide non-histone component of the chromatin and plays a pivotal role in the process of chromatin compaction and functional genome organization. Knockdown of PC4 expression leads to a drastic open conformation of the chromatin and thereby altered nuclear architecture, defects in chromosome segregation and changed epigenetic landscape. Interestingly, these defects do not induce cellular death but result in enhanced cellular proliferation possibly through enhanced autophagic activity. PC4 depletion confers significant resistance to gamma irradiation. Exposure to gamma irradiation further induced autophagy in these cells. Inhibition of autophagy by small molecule inhibitors as well as by silencing of a critical autophagy gene drastically reduces the survivability PC4 knockdown cells. On the contrary, complementation with wild type PC4 could reverse this phenomenon, confirming the process of autophagy as the key mechanism for radiation resistance in absence of PC4. These data connect the unexplored role of chromatin architecture in regulating autophagy during a stress condition such as radiation.

molecular biology↗

bioRxiv2017

A synergistic transcriptional regulation of olfactory genes derives complex behavioral responses in the mosquito Anopheles culicifacies

Decoding the molecular basis of host seeking and blood feeding behavioral evolution/adaptation in the adult female mosquito may provide an opportunity to design new molecular strategy to disrupt human-mosquito interactions. However, despite the great progress in the field of mosquito olfaction and chemo-detection, little is known that how the sex-specific specialization of the olfactory system enables adult female mosquitoes to derive and manage complex blood feeding associated behavioral responses. A comprehensive RNAseq analysis of prior and post blood meal olfactory system of An. culicifacies mosquito revealed that a minor but unique change in the nature and regulation of key olfactory genes play a pivotal role in managing diverse behavioral responses. Age dependent transcriptional profiling demonstrated that adult female mosquitos chemosensory system gradually learned and matured to drive the host-seeking and blood feeding behavior at the age of 5-6 days. A zeitgeber time scale expression analysis of Odorant Binding Proteins (OBPs) unravels unique association with a late evening to midnight peak biting time. Blood meal-induced switching of unique sets of OBP genes and Odorant Receptors (ORs) expression coincides with the change in the innate physiological status of the mosquitoes. Blood meal follows up experiments provide enough evidence that how a synergistic and concurrent action of OBPs-ORs may drive prior and post blood meal complex behavioral events. Finally, tissue-specific gene expression analysis and molecular modelling predicted two uncharacterized novel sensory appendages proteins (SAP-1 & SAP2) unique to An. culicifacies mosquito and may play a central role in the host-seeking behavior.\n\nSignificanceEvolution and adaptation of blood feeding behavior not only favored the reproductive success of adult female mosquito but also make them an important disease vectors. Immediately after emergence, an environmental exposure may favor the broadly tuned olfactory system of mosquitoes to derive complex behavioral responses. But, how these olfactory derived genetic factors manage female specific pre and post blood meal associated complex behavioral responses are not well known. We unraveled synergistic actions of olfactory factors governs an innate to prime learning strategy to facilitate rapid blood meal acquisition and downstream behavioral activities. A species-specific transcriptional profiling and an in-silico analysis predict novel sensory appendages protein, as a unique target to design disorientation strategy against the mosquito Anopheles culicifacies.

animal behavior and cognition↗

bioRxiv2017

Sex Specific Molecular Responses Of Quick-To-Court In Indian Malarial Vector Anopheles culicifacies: Conflict Of Mating And/Or Blood Feeding?

Understanding the molecular basis of mosquito behavioral complexity is central to the design of novel molecular tool to fight against their vector borne diseases. Although, olfactory system play important role to guide and manage many behavioral co-ordinates including feeding, mating, breeding etc., but the sex specific regulation of olfactory responses remains unanswered. From our ongoing transcriptomic data annotation of blood fed adult female olfactory tissue of A. culicifacies mosquito, we identified a 383 bp long unique transcript encoding Drosophila homolog of Quick-To-Court protein, previously shown to regulate the courtship behavior in adult male Drosophila. A comprehensive in silico analysis predicts Ac-qtc is 1536 bp long single copy gene encoding 511 AA long protein, having high degree of conservation with other insect homolog. Age dependent increased expression of putative Ac-qtc in the naive mosquitoes correlates the maturation of olfactory system, necessary to meet sex specific conflicting demand of mating (mate finding) vs. host-seeking behavioral responses. Though, 16-18 hour of starvation did not altered Ac-qtc expression in both the sexes, however blood feeding significantly modulated its response in the adult female mosquitoes, confirming that it may not be involved in sugar feeding associated behavioural regulation. Finally, a behavioural-cum-molecular assay indicated that natural dysregulation of Ac-qtc in late evening may promotes key mating event of successful insemination process. We hypothesize that Ac-qtc may play unique role to meet and manage the sex specific conflicting demand of mosquito courtship behaviour and/or blood feeding behaviour in the adult female mosquitoes. A molecular mechanism elucidation may provide new knowledge to consider Ac-qtc as a key molecular target for mosquito borne disease management.

animal behavior and cognition↗