Biology subjects

Changede, R.

Publications and source records attributed to Changede, R..

5 recordsLinked to original sources

bioRxiv2025

Efficacy of immunostimulant feed additive ShrimpGuard, for the preventive management of White Spot Syndrome Virus (WSSV) infection in shrimps

White spot syndrome virus (WSSV) is a virulent lethal viral pathogen affecting shrimp aquaculture worldwide. Current solutions for WSSV management can be divided into three categories; farm management, selective breeding or genetic engineering to get WSSV resistant varieties of shrimp, and developing vaccine or drug-like solutions specifically targeting WSSV. At present, farm management or good farming practice is the most reliable way of managing the problem, anti-WSSV vaccine, or anti-WSSV drugs that are reliable and scalable in the market are not available. We have developed a feed additive named "ShrimpGuard" using our SOLAQ (Solutions for Agriculture and Aquaculture) platform that specifically provides Shrimp protection against the WSSV infection. Here we report protection observed in both laboratory and farm demonstrations, in Penaeus vannamei. Collectively, these studies show that Shrimp-Guard does not cause any adverse effects on shrimp health and is able to provide significant protection to shrimp against WSSV infection. Briefly, the immune parameters of shrimp respond to ShrimpGuard treatment with increase observed in Total haemocyte count, and activity of prophenoloxidase. Further, survival rates of shrimp treated with ShrimpGuard after WSSV infection was between 80-100 % compared to 0% survival observed in untreated shrimp. The ShrimpGuards performance was tested in production farms and it was found that ShrimpGuard is safe for farm-based applications and the data obtained shows a positive impact on shrimp yield after ShrimpGuard treatment.

immunology↗

bioRxiv2024

Nano-clusters of ligand-activated integrins organize immobile, signalling active, nano-clusters of phosphorylated FAK required for mechanosignalling in focal adhesions

Transmembrane signalling receptors, such as integrins, organise as nanoclusters that are thought to provide several advantages including, increasing avidity, sensitivity (increasing the signal-to-noise ratio) and robustness (signalling above a threshold rather than activation by a single receptor) of the signal compared to signalling by single receptors. Compared to large micron-sized clusters, nanoclusters offer the advantage of rapid turnover for the disassembly of the signal. However, if nanoclusters function as signalling hubs remains poorly understood. Here, we employ fluorescence nanoscopy combined with photoactivation and photobleaching at sub-diffraction limited resolution of [~]100nm length scale within a focal adhesion to examine the dynamics of diverse focal adhesion proteins. We show that (i) subregions of focal adhesions are enriched in immobile population of integrin {beta}3 organised as nanoclusters, which (ii) in turn serve to organise nanoclusters of associated key adhesome proteins-vinculin, focal adhesion kinase (FAK) and paxillin, demonstrating that signalling proceeds by formation of nanoclusters rather than through individual proteins. (iii) Distinct focal adhesion protein nanoclusters exhibit distinct dynamics dependent on function. (iv) long-lived nanoclusters function as signalling hubs-wherein phosphorylated FAK and paxillin formed stable nanoclusters in close proximity to immobile integrin nanoclusters which are disassembled in response to inactivation signal by phosphatase PTPN12 (v) signalling takes place in response to an external signal such as force or geometric arrangement of the nanoclusters and when the signal is removed, these nanoclusters disassemble. Taken together, these results demonstrate that signalling downstream of transmembrane receptors is organised as hubs of signalling proteins (FAK, paxillin, vinculin) seeded by nanoclusters of the transmembrane receptor (integrin).

cell biology↗

bioRxiv2023

Intrinsic self-organization of integrin nanoclusters within focal adhesions is required for cellular mechanotransduction

Upon interaction with the extracellular matrix, the integrin receptors form nanoclusters as a first biochemical response to ligand binding. Here, we uncover a critical biodesign principle where these nanoclusters are spatially self-organized, facilitating effective mechanotransduction. Mouse Embryonic Fibroblasts (MEFs) with integrin {beta}3 nanoclusters organized themselves with an intercluster distance of [~]550 nm on uniformly coated fibronectin substrates, leading to larger focal adhesions. We determined that this spatial organization was driven by cell-intrinsic factors since there was no pre-existing pattern on the substrates. Altering this spatial organization using cyclo-RGD functionalized Titanium nanodiscs (of 100 nm, corroborating to the integrin nanocluster size) spaced at intervals of 300 nm (almost half), 600 nm (normal) or 1000 nm (almost double) resulted in abrogation in mechanotransduction, indicating that a new parameter i.e., an optimal intercluster distance is necessary for downstream function. Overexpression of -actinin, which induces a kink in the integrin tail, disrupted the establishment of the optimal intercluster distance, while simultaneous co-overexpression of talin head with -actinin rescued it, indicating a concentration-dependent competition, and that cytoplasmic activation of integrin by talin head is required for the optimal intercluster organization. Additionally, talin head-mediated recruitment of FHOD1 that facilitates local actin polymerization at nanoclusters, and actomyosin contractility were also crucial for establishing the optimal intercluster distance and a robust mechanotransduction response. These findings demonstrate that cell-intrinsic machinery plays a vital role in organizing integrin receptor nanoclusters within focal adhesions, encoding essential information for downstream mechanotransduction signalling.

cell biology↗

bioRxiv2018

Ligand Geometry Controls Adhesion formation via Integrin Clustering

Integrin-mediated cell matrix adhesions are key to sensing the geometry and rigidity of the extracellular environment to regulate vital cellular processes. In vivo, the extracellular matrix (ECM) is composed of a fibrous mesh. To understand the geometry that supports adhesion formation on fibrous substrates, we patterned 10 nm gold-palladium single lines or pairs of lines (total width within 100 nm), mimicking thin single ECM fibers or a minimal mesh geometry, respectively and functionalized it with integrin binding ligand Arg-Gly-Asp (RGD). Single lines showed reduced focal adhesion kinase (FAK) recruitment and did not support cell spreading or formation of focal adhesions, despite the presence of a high density of integrin-binding ligands. Using super resolution microscopy, we observed transient integrin clusters on single lines, whereas stable 110 nm integrin clusters formed on pairs of lines similar to those on continuous substrates. This indicated that two-dimensional ligand geometry is required for adhesion formation on rigid substrates. A mechanism to form modular 100nm integrin clusters bridging the minimal fiber mesh would require unliganded integrins. We observed that integrin mutants unable to bind ligand co-clustered with ligand-bound integrins when present in an active extended conformation. Thus, these results indicate that functional integrin clusters are required to form focal adhesions and unliganded integrins can co-cluster to bridge between thin matrix fibers and can form stable integrin adhesions on dense fibrous networks.

cell biology↗

bioRxiv2018

A novel localization based biosensor, SEDAR, visualizes spatio-temporal dynamics of activated Ras in endogenous Drosophila tissues

Chemokine signaling via growth factor receptor tyrosine kinases (RTKs) regulates development, differentiation, growth and disease implying that it is involved in a myriad of cellular processes. A single RTK, for example the Epidermal Growth Factor Receptor (EGFR), is used repeatedly for a multitude of developmental programs. Quantitative differences in magnitude and duration of RTK signaling can bring about different signaling outcomes. Understanding this complex RTK signals requires real time visualization of the signal. To visualize spatio-temporal signaling dynamics, a biosensor called SEnsitive Detection of Activated Ras (SEDAR) was developed. It is a localization-based sensor that binds to activated Ras directly downstream of the endogenous activated RTKs. This binding was reversible and SEDAR expression did not cause any detectable perturbation of the endogenous signal. Using SEDAR, endogenous guidance signaling was visualized during RTK mediated chemotaxis of border cells in Drosophila ovary. SEDAR localized to both the leading and rear end of the cluster but polarized at the leading edge of the cluster. Perturbation of RTKs that led to delays in forward migration of the cluster correlated with loss of SEDAR polarization in the cluster. Gliding or tumbling behavior of border cells was a directly related to the high or low magnitude of SEDAR polarization respectively, in the leading cell showing that signal polarization at the plasma membrane provided information for the migratory behavior. Further, SEDAR localization to the plasma membrane detected EGFR mediated signaling in five distinct developmental contexts. Hence SEDAR, a novel biosensor could be used as a valuable tool to study the dynamics of endogenous Ras activation in real time downstream of RTKs, in three-dimensional tissues, at an unprecedented spatial and temporal resolution.

developmental biology↗