Effects of distortions in ion-host systems on optical spectra, crystal-field and spin-Hamiltonian parameters of Cr ions doped pyrochlores YTiO and YSnO: exchange charge model and superposition model calculations.

Comparative modelling of the crystal-field parameters (CFPs), CF energy levels, and effective spin-Hamiltonian parameters (SHPs), , the -factors and zero-field splitting parameter (ZFSP), , of the ground state A of the Cr dopant ions in YTiO and YSnO is carried out. The CFPs are calculated using XRD structural data by employing two semi-empirical models: the exchange charge model (ECM) and superposition model (SPM). This two-fold approach ensures increased reliability of CFP modelling and thus of the final results.

Interplay of Ferritin Accumulation and Ferroportin Loss in Ageing Brain: Implication for Protein Aggregation in Down Syndrome Dementia, Alzheimer's, and Parkinson's Diseases.

Iron accumulates in the ageing brain and in brains with neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Down syndrome (DS) dementia. However, the mechanisms of iron deposition and regional selectivity in the brain are ill-understood. The identification of several proteins that are involved in iron homeostasis, transport, and regulation suggests avenues to explore their function in neurodegenerative diseases.

Evidence of fungal decay in petrified legume wood from the Neogene of the Bengal Basin, India.

Silicified fossil legume woods of Cynometroxylon Chowdhury & Ghosh collected from the Neogene (late Miocene) sediments of the Bengal Basin, eastern India, exhibit fungal decay seldom found in the fossil record. The wood possesses numerous perforate areas on the surface that seem to be the result of extensive fungal activity. In transverse section, the decayed areas (pockets) appear irregular to ellipsoidal in outline; in longitudinal section these areas of disrupted tissue are somewhat spindle-shaped.

Site-Specific Fluorescence Dynamics To Probe Polar Arrest by Fob1 in Replication Fork Barrier Sequences.

Fob1 protein plays an important role in aging and maintains genomic stability by avoiding clashes between the replication and transcription machinery. It facilitates polar arrest by binding to replication fork barrier (RFB) sites, present within the nontranscribed spacer region of the ribosomal DNA. Here, we investigate the mechanism of unidirectional arrest by creating multiple prosthetic forks within the RFB, with fluorescent adenine analogue 2-aminopurine incorporated site-specifically in both the "permissible" and "nonpermissible" directions.

Functional insights into the mode of DNA and ligand binding of the TetR family regulator TylP from .

Tetracycline repressors (TetRs) modulate multidrug efflux pathways in several pathogenic bacteria. In , they additionally regulate secondary metabolic pathways like antibiotic production. For instance, in the antibiotic producer a layered network of TetRs regulates the levels of the commercially important antibiotic tylosin, with TylP occupying the top of this cascading network.

Mode of DNA binding with γ-butyrolactone receptor protein CprB from Streptomyces coelicolor revealed by site-specific fluorescence dynamics.

Background: The γ-butyrolactone (GBL) binding transcription factors in Streptomyces species are known for their involvement in quorum sensing where they control the expression of various genes initiating secondary metabolic pathways. The structurally characterized member of this family CprB from Streptomyces coelicolor had earlier been demonstrated to bind a multitude of sequences containing a specific binding signature. Though structural breakthrough has been obtained for its complex with a consensus DNA sequence there is, however a dearth of information regarding the overall and site specific dynamics of protein-DNA interaction.

Fluorescence quenching studies of γ-butyrolactone binding protein (CprB) from Streptomyces coelicolor A3(2).

Quorum sensing is a cell density dependent phenomenon that utilizes small molecule inducers like γ-butyrolactones (GBLs) and their receptor proteins for adaptation to the environment. The cognate GBLs that bind to several of this GBL receptor family of proteins remain elusive. Here, using CprB protein from Streptomyces coelicolor A3(2) as a model system, we devise a method suited for ligand screening that would be applicable to the entire family of GBL receptors.

Structural basis of the substrate specificity of cytidine deaminase superfamily Guanine deaminase.

Guanine deaminases (GDs) are important enzymes involved in purine metabolism as well as nucleotide anabolism pathways that exhibit a high degree of fidelity. Here, the structural basis of the substrate specificity of GDs was investigated by determining a series of X-ray structures of NE0047 (GD from Nitrosomonas europaea) with nucleobase analogues and nucleosides. The structures demonstrated that the interactions in the GD active site are tailor-made to accommodate only guanine and any substitutions in the purine ring or introduction of a pyrimidine ring results in rearrangement of the bases in a catalytically unfavorable orientation, away from the proton shuttling residue E143.