The combination of in vitro models of biological membranes based on solid-supported lipid bilayer... more The combination of in vitro models of biological membranes based on solid-supported lipid bilayers (SLBs) and of surface sensitive techniques, such as neutron reflectometry (NR), atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D), is well suited to provide quantitative information about molecular level interactions and lipid spatial distributions. In this work, cellular plasma membranes have been mimicked by designing complex SLB, containing phosphatidylinositol 4,5-bisphosphate (PtdIns4,5P2) lipids as well as incorporating synthetic lipo-peptides that simulate the cytoplasmic tails of transmembrane proteins. The QCM-D results revealed that the adsorption and fusion kinetics of PtdIns4,5P2 are highly dependent of Mg2+. Additionally, it was shown that increasing concentrations of PtdIns4,5P2 leads to the formation of SLBs with higher homogeneity. The presence of PtdIns4,5P2 clusters was visualized by AFM. NR provided important insights a...
pH and solvent sensitive fractal self-assembly of human amylin and fractal characteristics of its... more pH and solvent sensitive fractal self-assembly of human amylin and fractal characteristics of its aggregates are investigated using different microscopy, laser light scattering, and molecular docking techniques.
International Journal of Biological Macromolecules, 2019
In a type-II diabetes disease, amylin protein takes an incorrect structure that leads to the form... more In a type-II diabetes disease, amylin protein takes an incorrect structure that leads to the formation of the amyloid fibril. The conversion mechanism of amyloid fibril is not well understood. We have observed a repulsive interaction, in terms of second virial co-efficient (A), between protein molecules in their native state in the PBS buffer through laser light scattering technique. The A switches from repulsive (positive A) to attractive (negative A) interactions with elapsed time favoring the formation and growth of the fibril. We report aggregation and fibril growth kinetics of amylin protein in different environmental conditions. The measurement of shape factor (ρ) through light scattering experiment shows a transition from coil-like structure to rod-like growth. In addition to rod-like growth, sheet-like growth of fibril is also observed through analytical and high-resolution TEM imaging techniques. The nucleation leading to elongation of fibrils as well as stacking of individual fibril perpendicular to the fibril axis is held by hydrogen bonding observed through high-resolution TEM.
The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis... more The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis. Additionally, a spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr, as well as soluble tubulin, in the spindle region. This membranous “spindle env...
Character and rapidity of protein diffusion in intracellular fluids are key determinants of the d... more Character and rapidity of protein diffusion in intracellular fluids are key determinants of the dynamics and steady state of a plethora of biochemical reactions. So far, an anomalous diffusion in cytoplasmic fluids with viscoelastic and even glassy characteristics has been reported in a variety of organisms on several length scales and timescales. Here, we show that the contiguous fluid of former cytoplasm and nucleoplasm features an anisotropically varying diffusion of macromolecules during eukaryotic cell division. In metaphase, diffusion in the contiguous nucleocytoplasmic fluid appears less anomalous along the spindle axis as compared to perpendicular directions. As a consequence, the long-time diffusion of macromolecules preferentially points along the spindle axis, leading to prolonged residence of macromolecules in the spindle region. Based on our experimental data, we suggest that anisotropic diffusion facilitates the encounter and interaction of spindle-associated proteins,...
2011 International Conference on Nanoscience, Technology and Societal Implications, 2011
Curcumin is the principal curcuminoid of the popular Indian spice Curcuma longa (Turmeric), which... more Curcumin is the principal curcuminoid of the popular Indian spice Curcuma longa (Turmeric), which is a member of ginger family (Zingiberaceae). Inspite of showing extraordinary medicinal properties its commercialized formulation is still a challenge because of its poor solubility, bioavailability and rapid plasma clearance. In our work, different shapes of nanocurcumin are prepared in alcohol-water solutions using sonication assisted solvent worsening method. The nanocrcumin in the suspension have been characterized using Dynamic and Static Light Scattering (DLS and SLS) and Transmission Electron Microscopy methods. The DLS data revealed that the curcumin nanoparticles in the suspension had asymmetric shape with effective hydrodynamic radius in the range of 120- 160nm. With increase in water concentration in the solvent medium the shape of the nanocurcumin was seen to undergo a gradual transition from isotropic to anisotropic state which was supported by TEM study. The in vitro antimicrobial activity (Inhibition) of the nanocurcumin has been compared with that of the normal curcumin using Broth dilution and Kirby- Bauer methods against both Gram positive and Gram negative bacteria. The efficacy of nanocurcumin is marginally better than curcurmin per se. We observed that nanocurcumin had better dispersibility and enhanced bioavailability in hydrophilic environment as compared to normal curcumin.
ABSTRACT Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibi... more ABSTRACT Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anomalous current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition from space charge limited conduction to negative differential resistance on crossing a certain bias of 20 V. Here, the maximum current (Imax) found to be around 20lA and Imax was found to scale with applied pressure (P) following empirical relation Imax�P 1/4 indicating that these films can be used as pressure sensors
Pictorial depiction of solvation of elastin molecule in aqueous and ethanol solutions. Polymer ch... more Pictorial depiction of solvation of elastin molecule in aqueous and ethanol solutions. Polymer chain collapse in water and swelling in binary solvent.
The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis... more The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis. Additionally, a spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr, as well as soluble tubulin, in the spindle region. This membranous “spindle envelope” confined spindle assembly, and its mechanical disruption compromised faithful chromosome segregation. Thus, cytoplasmic compartmentalization persists during early mitosis to promote spindle assembly and function.
fluids are key determinants of the dynamics and steady state
of a plethora of biochemical reactio... more fluids are key determinants of the dynamics and steady state of a plethora of biochemical reactions [1, 2]. So far, an anomalous diffusion in cytoplasmic fluids with viscoelastic and even glassy characteristics has been reported in a variety of organisms on several length scales and timescales [3– 6]. Here, we show that the contiguous fluid of former cytoplasm and nucleoplasm features an anisotropically varying diffusion of macromolecules during eukaryotic cell division. In metaphase, diffusion in the contiguous nucleocytoplasmic fluid appears less anomalous along the spindle axis as compared to perpendicular directions. As a consequence, the long-time diffusion of macromolecules preferentially points along the spindle axis, leading to prolonged residence of macromolecules in the spindle region. Based on our experimental data, we suggest that anisotropic diffusion facilitates the encounter and interaction of spindle-associated proteins, e.g., during the formation of a dynamic spindle matrix
Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anoma... more Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anomalous current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition from space charge limited conduction to negative differential resistance on crossing a certain bias of 20 V. Here, the maximum current (Imax) found to be around 20 lA and Imax was found to scale with applied pressure (P) following empirical relation ImaxP1/4 indicating that these films can be used as pressure sensors
The combination of in vitro models of biological membranes based on solid-supported lipid bilayer... more The combination of in vitro models of biological membranes based on solid-supported lipid bilayers (SLBs) and of surface sensitive techniques, such as neutron reflectometry (NR), atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D), is well suited to provide quantitative information about molecular level interactions and lipid spatial distributions. In this work, cellular plasma membranes have been mimicked by designing complex SLB, containing phosphatidylinositol 4,5-bisphosphate (PtdIns4,5P2) lipids as well as incorporating synthetic lipo-peptides that simulate the cytoplasmic tails of transmembrane proteins. The QCM-D results revealed that the adsorption and fusion kinetics of PtdIns4,5P2 are highly dependent of Mg2+. Additionally, it was shown that increasing concentrations of PtdIns4,5P2 leads to the formation of SLBs with higher homogeneity. The presence of PtdIns4,5P2 clusters was visualized by AFM. NR provided important insights a...
pH and solvent sensitive fractal self-assembly of human amylin and fractal characteristics of its... more pH and solvent sensitive fractal self-assembly of human amylin and fractal characteristics of its aggregates are investigated using different microscopy, laser light scattering, and molecular docking techniques.
International Journal of Biological Macromolecules, 2019
In a type-II diabetes disease, amylin protein takes an incorrect structure that leads to the form... more In a type-II diabetes disease, amylin protein takes an incorrect structure that leads to the formation of the amyloid fibril. The conversion mechanism of amyloid fibril is not well understood. We have observed a repulsive interaction, in terms of second virial co-efficient (A), between protein molecules in their native state in the PBS buffer through laser light scattering technique. The A switches from repulsive (positive A) to attractive (negative A) interactions with elapsed time favoring the formation and growth of the fibril. We report aggregation and fibril growth kinetics of amylin protein in different environmental conditions. The measurement of shape factor (ρ) through light scattering experiment shows a transition from coil-like structure to rod-like growth. In addition to rod-like growth, sheet-like growth of fibril is also observed through analytical and high-resolution TEM imaging techniques. The nucleation leading to elongation of fibrils as well as stacking of individual fibril perpendicular to the fibril axis is held by hydrogen bonding observed through high-resolution TEM.
The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis... more The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis. Additionally, a spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr, as well as soluble tubulin, in the spindle region. This membranous “spindle env...
Character and rapidity of protein diffusion in intracellular fluids are key determinants of the d... more Character and rapidity of protein diffusion in intracellular fluids are key determinants of the dynamics and steady state of a plethora of biochemical reactions. So far, an anomalous diffusion in cytoplasmic fluids with viscoelastic and even glassy characteristics has been reported in a variety of organisms on several length scales and timescales. Here, we show that the contiguous fluid of former cytoplasm and nucleoplasm features an anisotropically varying diffusion of macromolecules during eukaryotic cell division. In metaphase, diffusion in the contiguous nucleocytoplasmic fluid appears less anomalous along the spindle axis as compared to perpendicular directions. As a consequence, the long-time diffusion of macromolecules preferentially points along the spindle axis, leading to prolonged residence of macromolecules in the spindle region. Based on our experimental data, we suggest that anisotropic diffusion facilitates the encounter and interaction of spindle-associated proteins,...
2011 International Conference on Nanoscience, Technology and Societal Implications, 2011
Curcumin is the principal curcuminoid of the popular Indian spice Curcuma longa (Turmeric), which... more Curcumin is the principal curcuminoid of the popular Indian spice Curcuma longa (Turmeric), which is a member of ginger family (Zingiberaceae). Inspite of showing extraordinary medicinal properties its commercialized formulation is still a challenge because of its poor solubility, bioavailability and rapid plasma clearance. In our work, different shapes of nanocurcumin are prepared in alcohol-water solutions using sonication assisted solvent worsening method. The nanocrcumin in the suspension have been characterized using Dynamic and Static Light Scattering (DLS and SLS) and Transmission Electron Microscopy methods. The DLS data revealed that the curcumin nanoparticles in the suspension had asymmetric shape with effective hydrodynamic radius in the range of 120- 160nm. With increase in water concentration in the solvent medium the shape of the nanocurcumin was seen to undergo a gradual transition from isotropic to anisotropic state which was supported by TEM study. The in vitro antimicrobial activity (Inhibition) of the nanocurcumin has been compared with that of the normal curcumin using Broth dilution and Kirby- Bauer methods against both Gram positive and Gram negative bacteria. The efficacy of nanocurcumin is marginally better than curcurmin per se. We observed that nanocurcumin had better dispersibility and enhanced bioavailability in hydrophilic environment as compared to normal curcumin.
ABSTRACT Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibi... more ABSTRACT Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anomalous current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition from space charge limited conduction to negative differential resistance on crossing a certain bias of 20 V. Here, the maximum current (Imax) found to be around 20lA and Imax was found to scale with applied pressure (P) following empirical relation Imax�P 1/4 indicating that these films can be used as pressure sensors
Pictorial depiction of solvation of elastin molecule in aqueous and ethanol solutions. Polymer ch... more Pictorial depiction of solvation of elastin molecule in aqueous and ethanol solutions. Polymer chain collapse in water and swelling in binary solvent.
The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis... more The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis. Additionally, a spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr, as well as soluble tubulin, in the spindle region. This membranous “spindle envelope” confined spindle assembly, and its mechanical disruption compromised faithful chromosome segregation. Thus, cytoplasmic compartmentalization persists during early mitosis to promote spindle assembly and function.
fluids are key determinants of the dynamics and steady state
of a plethora of biochemical reactio... more fluids are key determinants of the dynamics and steady state of a plethora of biochemical reactions [1, 2]. So far, an anomalous diffusion in cytoplasmic fluids with viscoelastic and even glassy characteristics has been reported in a variety of organisms on several length scales and timescales [3– 6]. Here, we show that the contiguous fluid of former cytoplasm and nucleoplasm features an anisotropically varying diffusion of macromolecules during eukaryotic cell division. In metaphase, diffusion in the contiguous nucleocytoplasmic fluid appears less anomalous along the spindle axis as compared to perpendicular directions. As a consequence, the long-time diffusion of macromolecules preferentially points along the spindle axis, leading to prolonged residence of macromolecules in the spindle region. Based on our experimental data, we suggest that anisotropic diffusion facilitates the encounter and interaction of spindle-associated proteins, e.g., during the formation of a dynamic spindle matrix
Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anoma... more Thin fluid films of discotic nanoclay particles dispersed in water were observed to exhibit anomalous current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition from space charge limited conduction to negative differential resistance on crossing a certain bias of 20 V. Here, the maximum current (Imax) found to be around 20 lA and Imax was found to scale with applied pressure (P) following empirical relation ImaxP1/4 indicating that these films can be used as pressure sensors
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Papers by Nisha Pawar
spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell
imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy
in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the
accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic
spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical
modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular
crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr,
as well as soluble tubulin, in the spindle region. This membranous “spindle envelope” confined spindle assembly, and
its mechanical disruption compromised faithful chromosome segregation. Thus, cytoplasmic compartmentalization persists
during early mitosis to promote spindle assembly and function.
of a plethora of biochemical reactions [1, 2]. So far, an anomalous
diffusion in cytoplasmic fluids with viscoelastic and
even glassy characteristics has been reported in a variety
of organisms on several length scales and timescales [3–
6]. Here, we show that the contiguous fluid of former cytoplasm
and nucleoplasm features an anisotropically varying
diffusion of macromolecules during eukaryotic cell division.
In metaphase, diffusion in the contiguous nucleocytoplasmic
fluid appears less anomalous along the spindle axis as
compared to perpendicular directions. As a consequence,
the long-time diffusion of macromolecules preferentially
points along the spindle axis, leading to prolonged residence
of macromolecules in the spindle region. Based on
our experimental data, we suggest that anisotropic diffusion
facilitates the encounter and interaction of spindle-associated
proteins, e.g., during the formation of a dynamic spindle
matrix
current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition
from space charge limited conduction to negative differential resistance on crossing a certain bias of
20 V. Here, the maximum current (Imax) found to be around 20 lA and Imax was found to scale with
applied pressure (P) following empirical relation ImaxP1/4 indicating that these films can be used as
pressure sensors
spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell
imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy
in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the
accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic
spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical
modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular
crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr,
as well as soluble tubulin, in the spindle region. This membranous “spindle envelope” confined spindle assembly, and
its mechanical disruption compromised faithful chromosome segregation. Thus, cytoplasmic compartmentalization persists
during early mitosis to promote spindle assembly and function.
of a plethora of biochemical reactions [1, 2]. So far, an anomalous
diffusion in cytoplasmic fluids with viscoelastic and
even glassy characteristics has been reported in a variety
of organisms on several length scales and timescales [3–
6]. Here, we show that the contiguous fluid of former cytoplasm
and nucleoplasm features an anisotropically varying
diffusion of macromolecules during eukaryotic cell division.
In metaphase, diffusion in the contiguous nucleocytoplasmic
fluid appears less anomalous along the spindle axis as
compared to perpendicular directions. As a consequence,
the long-time diffusion of macromolecules preferentially
points along the spindle axis, leading to prolonged residence
of macromolecules in the spindle region. Based on
our experimental data, we suggest that anisotropic diffusion
facilitates the encounter and interaction of spindle-associated
proteins, e.g., during the formation of a dynamic spindle
matrix
current-voltage (I-V) characteristics at room temperature. The I-V characteristics exhibit a transition
from space charge limited conduction to negative differential resistance on crossing a certain bias of
20 V. Here, the maximum current (Imax) found to be around 20 lA and Imax was found to scale with
applied pressure (P) following empirical relation ImaxP1/4 indicating that these films can be used as
pressure sensors