Geometrical isomers of bis(benzimidazol-2-ylethyl)sulfide)cobalt(II) diperchlorates: synthesis, structure, spectra and redox behavior of pink-[Co(bbes)2](ClO4)2 and blue-[Co(bbes)2](ClO4)2

1:1 and 1:2 cobalt complexes of bis(benzimidazol-2-ylmethyl)amine (bbma) bis(benzimidazol-2-ylmethyl)sulfide (bbms), bis(benzimidazol-2-ylethyl)sulfide (bbes) and diethylenetriamine (dien) were prepared and their spectral and redox behavior studied. Two geometrical isomers pink-[Co(bbes)₂]²⁺ and blue-[Co(bbes)₂]²⁺ were obtained when the complexes were prepared by using with bbes and they were separated manually and recrystallized. The octahedral structure of pink-[Co(bbes)₂]²⁺ was resolved by X-ray analysis. The electronic spectra show the presence of two geometrical isomers for Co(bbes)₂²⁺ in the solid state; for example, the spectral bands of pink-[Co(bbes)₂]²⁺ differs markedly with those of blue-[Co(bbes)₂]²⁺. This is consistent with the results obtained from magnetic measurements (5.10 BM for pink-Co(bbes)₂²⁺ and 4.72 BM for blue-[Co(bbes)₂]²⁺). Further, the behavior of the ligands (bbma, bbms, bbes) at different pH conditions was determined on the basis of ¹³C NMR studies. The redox potentials [Co(II)/Co(I)] of the complexes follow the trend [Co(bbma)₂]²⁺ < [Co(bbms)₂]²⁺ ≈ [Co(bbes)₂]²⁺ which demonstrates the stabilization of the Co(II) ion is more by both weak σ-donor and weak π-acceptor ligands rather than by σ-donor ligand.     

Mixotrophic metabolism in Burkholderia kururiensis subsp. thiooxydans subsp. nov., a facultative chemolithoautotrophic thiosulfate oxidizing bacterium isolated from rhizosphere soil and proposal for classification of the type strain of Burkholderia kururiensis as Burkholderia kururiensis subsp. kururiensis subsp. nov.

A thiosulfate-oxidizing facultative chemolithoautotrophic Burkholderia sp. strain ATSB13^T was previously isolated from rhizosphere soil of tobacco plant. Strain ATSB13^T was aerobic, Gram-staining-negative, rod shaped and motile by means of sub-terminal flagellum. Strain ATSB13^T exhibited mixotrophic growth in a medium containing thiosulfate plus acetate. A phylogenetic study based on 16S rRNA gene sequence analysis indicated that strain ATSB13^T was most closely related to Burkholderia kururiensis KP23^T (98.7%), Burkholderia tuberum STM678^T (96.5%) and Burkholderia phymatum STM815^T (96.4%). Chemotaxonomic data [G+C 64.0 mol%, major fatty acids, C_18:1 ω7c (28.22%), C_16:1 ω7c/15 iso 2OH (15.15%), and C_16:0 (14.91%) and Q-8 as predominant respiratory ubiquinone] supported the affiliation of the strain ATSB13^T within the genus Burkholderia. Though the strain ATSB13^T shared high 16S rRNA gene sequence similarity with the type strain of B. kururiensis but considerably distant from the latter in terms of several phenotypic and chemotaxonomic characteristics. DNA–DNA hybridization between strain ATSB13^T and B. kururiensis KP23^T was 100%, and hence, it is inferred that strain ATSB13^T is a member of B. kururiensis. On the basis of data obtained from this study, we propose that B. kururiensis be subdivided into B. kururiensis subsp. kururiensis subsp. nov. (type strain KP23^T = JCM 10599^T = DSM 13646^T) and B. kururiensis subsp. thiooxydans subsp. nov. (type strain ATSB13^T = KACC 12758^T).     

Screening and identification of random amplified polymorphic DNA (RAPD) markers linked to mungbean yellow mosaic virus (MYMV) resistance in mungbean (Vigna radiata (L.) Wilczek)

Bulk segregant analysis (BSA) and random amplified polymorphic DNA (RAPD) techniques were used to analyse the F2 individuals of susceptible VBN (Gg) 2 × resistant KMG 189 to screen and identify the molecular marker linked to mungbean yellow mosaic virus (MYMV) resistant gene in mungbean. Two DNA bulks namely resistant bulks and susceptible bulks were setup by pooling equal amount of DNA from five randomly selected plants of each disease response. A total of 72 random sequence decamer oligonucleotide primers were used for RAPD analysis. Primer OPBB 05 (5′-GGGCCGAACA-3′) generated OPBB 05 260 fragment in resistant parent and their bulks but not in the susceptible parent and their bulks. Co segregation analysis was performed in resistant and susceptible F2 individuals, it confirmed that OPBB 05 260 marker was tightly linked to mungbean yellow mosaic virus resistant gene in mungbean.     

Elucidating the Role of Disulfide Bond on Amyloid Formation and Fibril Reversibility of Somatostatin-14: RELEVANCE TO ITS STORAGE AND SECRETION*?

The storage of protein/peptide hormones within subcellular compartments and subsequent release are crucial for their native function, and hence these processes are intricately regulated in mammalian systems. Several peptide hormones were recently suggested to be stored as amyloids within endocrine secretory granules. This leads to an apparent paradox where storage requires formation of aggregates, and their function requires a supply of non-aggregated peptides on demand. The precise mechanism behind amyloid formation by these hormones and their subsequent release remain an open question. To address this, we examined aggregation and fibril reversibility of a cyclic peptide hormone somatostatin (SST)-14 using various techniques. After proving that SST gets stored as amyloid in vivo, we investigated the role of native structure in modulating its conformational dynamics and self-association by disrupting the disulfide bridge (Cys³–Cys¹⁴) in SST. Using two-dimensional NMR, we resolved the initial structure of somatostatin-14 leading to aggregation and further probed its conformational dynamics in silico. The perturbation in native structure (S-S cleavage) led to a significant increase in conformational flexibility and resulted in rapid amyloid formation. The fibrils formed by disulfide-reduced noncyclic SST possess greater resistance to denaturing conditions with decreased monomer releasing potency. MD simulations reveal marked differences in the intermolecular interactions in SST and noncyclic SST providing plausible explanation for differential aggregation and fibril reversibility observed experimentally in these structural variants. Our findings thus emphasize that subtle changes in the native structure of peptide hormone(s) could alter its conformational dynamics and amyloid formation, which might have significant implications on their reversible storage and secretion.     

Conditional ablation of the Notch2 receptor in the ocular lens

Notch signaling is essential for proper lens development, however the specific requirements of individual Notch receptors have not been investigated. Here we report the lens phenotypes of Notch2 conditionally mutant mice, which exhibited severe microphthalmia, reduced pupillary openings, disrupted fiber cell morphology, eventual loss of the anterior epithelium, fiber cell dysgenesis, denucleation defects, and cataracts. Notch2 mutants also had persistent lens stalks as early as E11.5, and aberrant DNA synthesis in the fiber cell compartment by E14.5. Gene expression analyses showed that upon loss of Notch2, there were elevated levels of the cell cycle regulators Cdkn1a (p21Cip1), Ccnd2 (CyclinD2), and Trp63 (p63) that negatively regulates Wnt signaling, plus down-regulation of Cdh1 (E-Cadherin). Removal of Notch2 also resulted in an increased proportion of fiber cells, as was found in Rbpj and Jag1 conditional mutant lenses. However, Notch2 is not required for AEL proliferation, suggesting that a different receptor regulates this process. We found that Notch2 normally blocks lens progenitor cell death. Overall, we conclude that Notch2-mediated signaling regulates lens morphogenesis, apoptosis, cell cycle withdrawal, and secondary fiber cell differentiation.     

Microwave-assisted preparation of bagasse and rice straw for the removal of emulsified oil from wastewater

The present study was carried out to examine modified bagasse and rice straw as absorbents for the removal of emulsified oil by a microwave-assisted technique. The raw adsorbents were chemically modified with sodium hydroxide and surfactant solution for better adsorption of oil. The surface modification was confirmed through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) analysis. Batch studies were performed to identify the influence of contact time, pH, dosage, speed, and temperature on the percentage of removal of emulsified oil from the wastewater. A maximum oil removal of 98.07% and 98.72% was achieved in microwave-assisted bagasse and rice straw at 313 K. The obtained data were compared with isotherm and kinetic models to understand the mechanism behind the adsorption. From the Langmuir isotherm model, a maximum adsorption capacity of 192.58 and 276.82 mg/g was observed for modified bagasse and rice straw. The oil-loaded raw and microwave-assisted adsorbents can act as a potential energy source for renewable energy.     

High IFN-gamma production of individual CD8 T lymphocytes is controlled by CD152 (CTLA-4)

CD8 T cell expansion and cytokine production is needed to generate an effective defense against viral invasion of the host. These features of CD8 T lymphocytes are regulated, especially during primary responses, by positive and negative costimulation. We show in this study that surface expression of CD152 is highly up-regulated on activated CD8 T lymphocytes during primary immune responses, suggesting a prominent regulatory role. Indeed, production of the proinflammatory cytokine IFN-gamma, but not TNF-alpha, by CD8 T cells was inhibited by CD152 engagement. The inhibition was regulated independent of proliferation and IL-2 production, but dependent on the quality of the TCR signaling. We show that signals induced by CD152 on activated CD8 T lymphocytes reduce the frequency of IFN-gamma(high)-expressing cells. Our data also show that in activated CD8 T cells, the CD152-mediated inhibition of cytokine production is more pronounced than inhibition of their proliferation.     

Attenuation of 1-(m-Chlorophenyl)-Biguanide Induced Hippocampus-Dependent Memory Impairment by a Standardised Extract of Bacopa monniera (BESEB CDRI-08)

Bacopa monniera is a well-known medhya-rasayana (memory enhancing and rejuvenating) plant in Indian traditional medical system of Ayurveda. The effect of a standardized extract of Bacopa monniera (BESEB CDRI-08) on serotonergic receptors and its influence on other neurotransmitters during hippocampal-dependent learning was evaluated in the present study. Wistar rat pups received a single dose of BESEB CDRI-08 during postnatal days 15–29 showed higher latency during hippocampal-dependent learning accompanied with enhanced 5HT_3A receptor expression, serotonin and acetylcholine levels in hippocampus. Furthermore, 5HT_3A receptor agonist 1-(m-chlorophenyl)-biguanide (mCPBG) impaired learning in the passive avoidance task followed by reduction of 5HT_3A receptor expression, 5HT and ACh levels. Administration of BESEB CDRI-08 along with mCPBG attenuated mCPBG induced behavioral, molecular and neurochemical alterations. Our results suggest that BESEB CDRI-08 possibly acts on serotonergic system, which in turn influences the cholinergic system through 5-HT₃ receptor to improve the hippocampal-dependent task.