Biology subjects

Bhattacharya, A.

Publications and source records attributed to Bhattacharya, A..

6 recordsLinked to original sources

bioRxiv2018

Plasticity of the electrical connectome of C. elegans

The patterns of electrical synapses of an animal nervous system (\"electrical connectome\"), as well as the functional properties and plasticity of electrical synapses, are defined by the neuron type-specific complement of electrical synapse constituents. We systematically examine here properties of the electrical connectome of the nematode C. elegans through a genome- and nervous system-wide analysis of the expression pattern of the central components of invertebrate electrical synapses, the innexins, revealing highly complex combinatorial patterns of innexin expression throughout the nervous system. We find that the complex expression patterns of 12 out of 14 neuronally expressed innexins change in a strikingly neuron type-specific manner throughout most of the nervous system, if animals encounter harsh environmental conditions and enter the dauer arrest stage. We systematically describe the plasticity of locomotory patterns of dauer stage animals and, by analyzing several individual electrical synapses, we demonstrate that dauer stage-specific electrical synapse remodeling is responsible for specific aspects of the altered locomotory patterns as well as altered chemosensory behavior of dauer stage animals. We describe an intersectional gene regulatory mechanism, involving terminal selector and FoxO transcription factors that are responsible for inducing innexin expression changes in a neuron type- and environment-specific manner. Taken together, our studies illustrate the remarkably dynamic nature of electrical synapses on a nervous system-wide level and describe regulatory strategies for how these alterations are achieved.

neuroscience↗

bioRxiv2018

Discrimination Exposure and DNA Methylation of Stress-Related Genes in Latina Mothers

Latina mothers, who have the highest fertility rate among all ethnic groups in the US, are often exposed to discrimination. The biological impacts of this discrimination are unknown. This study is the first to explore the relationship between discrimination and DNA methylation of stress regulatory genes in Latinas. Our sample was Latina women (n = 147) with a mean age of 27.6 years who were assessed at 24-32 weeks gestation (T1) and 4-6 weeks postpartum (T2) and reside in the U.S. Blood was collected at T1, and the Everyday Discrimination Scale (EDS) was administered at T1 and T2. DNA Methylation at candidate gene regions was determined by bisulphite pyrosequencing. Associations between EDS and DNA methylation were assessed via zero-inflated Poisson models, adjusting for covariates and multiple-test comparisons. Discrimination was negatively associated with methylation at CpG sites within the glucocorticoid receptor (NR3C1) and brain-derived neurotrophic factor (BDNF) genes that were consistent over time. In addition, discrimination was negatively associated with methylation of a CpG in the glucocorticoid binding protein (FKBP5) at T1 but not at T2. This study underscores the complex biological pathways between discrimination and epigenetic modification in Latina women that warrant further investigation to better understand the genetic and psychopathological impact of discrimination on Latino mothers and their families.

genomics↗

bioRxiv2018

3D micro-environment regulates NF-κβ dependent adhesion to induce monocyte differentiation

Differentiation of monocytes entails their relocation from blood to the tissue, hence accompanied by an altered physicochemical micro-environment. While the mechanism by which the biochemical make-up of the micro-environment induces differentiation is known, the fluid-like to gel-like transition in the physical micro-environment is not well understood. Monocytes maintain non-adherent state to prevent differentiation. We establish that irrespective of the chemical makeup, a 3D gel-like micro-environment induces a positive-feedback loop of adhesion-MAPK-NF-{kappa}{beta} activation to facilitate differentiation. In 2D fluid-like micro-environment, adhesion alone is capable of inducing differentiation via the same positive-feedback signalling. Chemical inducer treatment in fluid-like micro-environment, increases the propensity of monocyte adhesion via a brief pulse of p-MAPK. The adhesion subsequently elicit differentiation, establishing that adhesion is both necessary and sufficient to induce differentiation in 2D/3D micro-environment. Our findings challenge the notion that adhesion is a result of monocyte differentiation. Rather its the adhesion which triggers the differentiation of monocytes. MAPK, and NF-{kappa}{beta} being key molecules of multiple signaling pathways, we hypothesize that biochemically inert 3D gel-like micro-environment would also influence other cellular functions.\n\nSummary statementThis article brings out a new insight into the novel mechanisms of monocyte differentiation solely driven by physical micro-environment and adhesion.

cell biology↗

bioRxiv2017

Cross talk between photo-pigments and graphene electron cloud - Designing a biodiode

We report emergence of a new electrical material by growing photosynthetic biofilm on a Dirac material, graphene. The material showed new conducting as well as semiconducting properties. Frequency dependent capacitive spectra further indicated presence of electrical isosbestic points(at 0.8 and 9MHz), implying two state dieletric transitions at critical frequencies. A notable reult was a Schottky diode like behavior in the IV curve. Voltage dependent conductance with conductance peaks near the Schottky diode threshold was observed. We obtained facilitated growth of photosynthetic biofilm in presence of graphene. Lastly higher bacterial metabolism was seen in graphene incorporated biofilm. For this zero band gap Dirac material this can only be interpreted as coupling of the electron transport chain of the bacterial biofilm and the graphene electron cloud.

biophysics↗

bioRxiv2017

Cooling Induced by Uphill Energy Transport in Plant Photosystems

The uphill energy transfer in photosystems implies input energy at higher wavelength leading to energy output at lower wavelength. Briefly, energy is uphill transported from photosystem I (PSI) to photosystem II (PSII), the latter having a lower wavelength emission. This uphill energy transport involves absorption of thermal energy from the surroundings. While such cooling effects have been reported in laser systems we report for the first time a white light driven cooling in thylakoid suspension. The cooling of the surrounding medium by appropriate illumination was illustrated using thermal measurements. Again cooling is inhibited by agents like 3-(3,4-Dichlorophenyl)-1,1-dimethylurea,that block the linear electron flow between the photocenters, implying a dependence of the cooling on interplay between such centers. Furthermore, it is possible to modulate the cooling pattern by addition of external agents like nanopaticles, some favoring further cooling (e.g., Ag nanoparticle) and some like Au or chlorophyll nanoparticles, showing insignificant or even reverse trends. Interestingly, the cooling is invariably associated with the 77K spectra of the thylakoid suspension. With reference to the dark control, an agent causing cooling always increases PSII to PSI ratio and vice versa i.e.,the uphill energy transport. Importantly, the cooling effect, apart from its import role in plant physiology can be exploited artificially for energy saving in post-harvest or food preservation.

bioengineering↗

bioRxiv2017

Nitric oxide sensing by chlorophyll a

Nitric oxide (NO) acts as a signalling molecule that has direct and indirect regulatory roles in various functional processes in biology, though in plant kingdom its role is relatively unexplored. One reason for this is the fact that sensing of NO is always challenging. There are very few probes that can classify the different NO species. The present paper proposes a simple but straightforward way for sensing different NO species using chlorophyll, the source of inspiration being hemoglobin that serves as a NO sink in most mamalian system. The proposed method is able to classify NO from DETA-NONOate or (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1,2-diolate, nitrite, nitrate and S-nitrosothiol or SNO. This discrimination is carried out by chlorophyll a (chl a) at nano molar (nM) order of sensitivity and at 293K to 310K. Molecular docking reveals the differential binding behaviour of NO and SNO with chlorophyll, the predicted binding affinity matching with the experimental observation. Additional expreiments with diverse range of cyanobacteria reveals that apart from spectroscopic approach the proposed sensing module can be used in microscopic inspection of NO speices. Binding of NO is sensitive to tempertaure and static magnetic field. This provides additional support to the involvement of the porphyrin ring structure to the NO sensing process. This also broadens the scope of the sensing methods as hinted in the text.

bioengineering↗