Biology subjects

Rawat, K.

Publications and source records attributed to Rawat, K..

8 recordsLinked to original sources

bioRxiv2025

Copy number variations in mitochondrial DNA has a potent role in parasitic immunity against Haemonchus contortus-A novel report

Mitochondria is a cellular organelle responsible for a variety of function, apart from energy production through oxidative phosphorylation, TCA cycle, apoptosis, plays a major role in iron and calcium metabolism and immune functions against pathogens (bacterial, viral or parasitic). Unlike nucleus, mitochondria exist in multiple copies, with many copies of mitochondrial DNA. A metabolically active cell possess about 103 and 104 copies of the mitochondrial genome. Lowered mtDNA copy number leads to disorders or disease, in a similar way as mutation in mtDNA causes a wide range of disease or disorders. In this current article, we estimated mtDNA copy number through QPCR analysis of cytochrome B gene and revealed that healthy individuals have better mtDNA copy number compared to that of the infected ones under natural challenge in sheep model against the parasite Haemonchus contortus infection. We diagnosed the infected animals for H. contortus primarily with symptoms, followed by Faecal egg count and final confirmation through molecular diagnosis. We had characterized the cytochrome B gene from abomasum(stomach) of sheep, which is the site of predilection of this parasite. In our lab, earlier we have documented certain immune response nuclear genes to have antiparasitic role. We had reported the mutations in cytochrome B leading to debility and disease in sheep. Quantitative expression profile for cytochrome B is an indication of the copy number of mitochondrial genes and we observed significantly better expression profile of cytochrome B in healthy sheep in comparison to infected one. Thus, mitochondrial copy number is directly associated with antiparasitic immunity, first time reported.

genomics↗

bioRxiv2025

Peers over the past: Prior predation-risk experience does not dictate antipredator responses of individuals in groups

Animals with predation-risk experiences can use the information to modulate their antipredator responses and survive future risk conditions (behavioural carryover). However, different contexts, such as sociality, may alter the risks and associated responses for an individual. A group can provide benefits to an individual, such as dilution of risk, confusion effect, and improved vigilance, potentially modifying carryover payoffs. Therefore, we tested the impact of sociality on the behavioural carryover of predation-risk experience. We used Aedes aegypti as a model system, where we had already established carryover, showing that predation-risk experience dictates future behaviour in a solitary setting. In contrast to solitary settings, we predicted that the behavioural carryover would not manifest in a group setting due to differences in trade-offs. We compared the behaviour of experienced and naive individuals in group settings in the presence and absence of an immediate threat. Our findings revealed that the past predation-risk experience did not influence the behaviour of individuals in a group setting. Instead, the immediate threat environment affected experienced and naive individuals similarly. These results suggest that the experience from predation past is more relevant when prey are solitary than when they are in a group due to the additional group advantages.

ecology↗

bioRxiv2024

Don't Leave the Past Behind: How Larval Experience Shapes Pupal Antipredator Response in Aedes aegypti

Animals use predation encounters or risk experiences to influence their future antipredator responses. Such carryover effects of predation can benefit them by enhancing their antipredator behaviour and thereby decreasing their risk of mortality through predation. Despite these fitness benefits, behavioural carryovers of predation past may not be a common phenomenon in complex life cycles. Complex life cycles pose a unique evolutionary and physiological challenge to behavioural carryovers since every life stage is distinct in morphology, physiology, and function. Each life stage of a complex life cycle is expected to evolve its independent response based on the real-time threat level and manage the trade-offs accordingly. Along with the evolutionary challenge, physiological barriers can hamper behavioural carryovers, especially in holometabolous insects, where we observe extensive tissue remodelling and developmental compartmentalisation. We investigated behavioural carryover in the holometabolous mosquito model system, Aedes aegypti. We asked whether predation risk during a life stage carries over to the subsequent stage, influencing its behaviour, or if the next life stage responds according to its threat environment. Aedes aegypti has four major stages- egg, larva, pupa, and adult. We examined the effect of predation-risk experience across larval and pupal stages. Larval and pupal stages differ in morphology, physiology and function. They share the same habitat and, therefore, similar threats. We manipulated the threat of predation experienced by larvae and investigated its influence on pupal behaviour. We found behavioural carryover in the pupal stage for the first time and discovered exciting interactions between past experiences and the current threat environment. Our study underscores the crucial role of predation pressure in shaping the evolution of complex life cycles, emphasising the significance of early experiences with predators in influencing behavioural traits across distinct life stages.

ecology↗

bioRxiv2023

Role of IL-6 and IL10 immune response genes against nematode Haemonchus contortus in ovis aries- a novel report

Haemonchus contortus is one of the most deadly parasites affecting sheep industry causing heavy economic loss. In our earlier study, we have reported RIGI, an earlier established antiviral molecule and CD14 (an earlier established antibacterial molecule) to have potential role in antiparasitic immunity for the first time. In this current study, we aim to clone and sequence the IL-6 and IL10 genes in sheep (Ovis aries) and utilized bioinformatics methods to analyze and compare the functional and structural domains of peptides produced from IL6 and IL10. Furthermore, the study explored these domains in three-dimensional structures. The findings of this study provide molecular characterization of IL-6 and IL10 in sheep, which is essential for advancing our understanding of functional immune responses in this animal. We report IL6 and IL10 to have potential antiparasitic role against H. contortus for first time. The production of these molecules opens up possibilities for its potential use as recombinant proteins to manipulate the immune response. Evaluating its value in vaccine research and gaining a broader understanding of its role in immune responses becomes feasible with the availability of IL-6 and IL10. Moreover, the differential mRNA expression levels of IL-6, IL10 between healthy and diseased sheep indicate its crucial role in maintaining homeostasis and mounting immune responses. IL10 acts as receptor for H. contortus. The identification of this immune-responsive gene also offers new avenues for investigating long-term resistance to H. contortus infection in sheep.

genomics↗

bioRxiv2023

Coordinated Chemokine Expression Defines Macrophage Subsets Across Tissues

Tissue-resident macrophages in the lung comprising alveolar and interstitial macrophages (IMs) display a high degree of heterogeneity. In general, macrophage heterogeneity is thought to arise from various forms of activation that are heavily confounded by the recruitment of monocytes to the tissue-resident macrophage pool. To better understand the functional heterogeneity of IMs in the lung, we profiled the transcription of resident CD206hi and CD206lo IMs under steady-state and inflammatory conditions, excluding recruited macrophages. Rather than observing conventional in vitro M1 and M2 activation states, we identified seven chemokine-expressing IM subsets: IMck1 (Ccl2, Ccl7, Ccl12, and some Cxcl14), IMck2-4 (Ccl3, Ccl4, Ccl5, Cxcl1, Cxcl2, and Cxcl3), IMck5 (Ccl8), IMck6 (Ccl6 and Ccl9), IMck7 (Cxcl9 and Cxcl10), IMck8 (Cxcl13), and IMck9 (Ccl24), which were found in steady-state or induced by acute inflammation. Beyond the mouse lung, similar coordinated chemokine signatures were observed in macrophages and monocytes from other tissues and across species. Although all IMs expressed Pf4 (CXCL4), mainly CD206hi IMs were selectively depleted in Pf4CreR26EYFP-DTR mice. Loss of CD206hi IMs resulted in significantly reduced inflammatory cell influx in allergen- and infection-driven models, as well as significantly diminished tertiary lymphoid formation and subsequent accumulation of GL7+ germinal center B cells. Overall, our study highlights a division of labor among interstitial macrophages, reflected by the coordinated production of chemokines to control inflammatory cell influx and organize tertiary lymphoid tissue architecture. One Sentence SummaryThe study highlights a division of labor among interstitial macrophages, reflected by the coordinated production of chemokines to control inflammatory cell influx and organize tertiary lymphoid tissue architecture.

immunology↗

bioRxiv2021

Ovine CD14- an immune response gene has a role against gastrointesinal nematode Haemonchus contortus -a novel report

CD14 (also known as monocyte differentiation antigen) is an important immune response gene known to be primarily responsible for innate immunity against bacterial pathogen and as pattern recognition receptor (PRR) binds with LPS (endotoxin), lipoproteins, lipotechoic acid of bacteria.So far very limited work has been conducted in parasitic immunology. In the current study, we reported the role of CD14 in parasitic immunology in livestock species (sheep) for the first time. Ovine CD14 is characterized as a horse-shoe shaped as a bent solenoid with a hydrophobic amino-terminal pocket for CD14 along with domains. High mutation frequency was observed, out of total 41 mutations identified, 23 mutations were observed to be thermodynamically unstable and 11 mutations were deleterious in nature, causing major functional alteration of important domains of CD14, an indicative for variations in individual susceptibility for sheeps against Haemonchus contortus infestations. In silico studies with molecular docking reveals a role of immune response against Haemonchus contortus in sheep, which is later confirmed with experimental evidence through differential mRNA expression analysis for sheep, which revealed better expression of CD14 in Haemonchus contortus infected sheep compared to that of healthy sheep. We confirmed the above findings with supportive evidences with haematological and biochemical analyses. Phylogenetic analysis was conducted to assess the evolutionary relationship with respect to human and observed that sheep may well be used as model organism due better genetic closeness compared to that of mouse.

genomics↗

bioRxiv2020

A critical role for B cells in cancer immune surveillance

It is commonly believed that B cells play no role in cancer immune surveillance. However, this conclusion is based on studies using only a single B cell-deficient mouse strain, muMT mice, which does not show increased tumorigenesis compared with wild-type (WT) mice. In this study, we demonstrate a critical role for B cells in anti-tumor immunity and identify the cellular mechanisms that make muMT mice a special case. First, we replicate previous findings using a melanoma model in muMT mice. Then, we show that in muMT mice, B-cell deficiency is compensated for by a significant increase in another potent anti-tumor cell type, Type-1 interferon (IFN I)-producing plasmacytoid DCs (pDCs), resulting in normative anti-tumor responses. Depleting pDCs in muMT mice resulted in a significant increase in tumor size and burden. Conversely, adoptive transfer of antibodies from naive WT serum into pDC-depleted muMT mice significantly decreased the tumor load to WT levels. Additionally, a B cell antibody repertoire-deficient mouse strain, IghelMD4 mice, showed a 3-fold increase in tumors relative to WT mice. Overall, these findings indicate the need for a diverse antibody repertoire for early neoplastic cell recognition and the critical role B cells play in anti-cancer immunity.

cancer biology↗

bioRxiv2018

Dual role for fungal-specific outer kinetochore proteins during cell cycle and development in Magnaporthe oryzae

The outer kinetochore DASH/DAM complex ensures proper spindle structure and chromosome segregation. While DASH complex protein requirement diverges among different yeasts, its role in filamentous fungi has not been investigated so far. We studied the dynamics and role of middle (Mis12) and outer (Dam1 and Ask1) kinetochore proteins in the filamentous fungal pathogen, Magnaporthe oryzae, which undergoes multiple cell cycle linked developmental transitions. Both Dam1 and Ask1, unlike Mis12, were recruited to the nucleus specifically during mitosis. While Dam1 was not required for viability, loss of its function (dam1{Delta} mutant) delayed mitotic progression, resulting in impaired conidial and hyphal development in Magnaporthe. Intriguingly, both Dam1 and Ask1 also localised to the hyphal tips, in the form of punctae oscillating back and forth from the growing ends, suggesting that Magnaporthe DASH complex proteins may play a non-canonical role in polarised growth during interphase, in addition to their function in nuclear segregation during mitosis. Impaired appressorial (infection structure) development and function in the dam1{Delta} mutant suggest that fungus-specific Dam1 complex proteins could be an attractive target for a novel anti-fungal strategy.\n\nSummary StatementDASH complex proteins are differentially recruited to the nucleus during cell division and are intriguingly involved in polarised growth during development and differentiation in the rice blast fungus.

cell biology↗