Effective charge measurements reveal selective and preferential accumulation of anions, but not cations, at the protein surface in dilute salt solutions

Specific-ion effects are ubiquitous in nature; however, their underlying mechanisms remain elusive. Although Hofmeister-ion effects on proteins are observed at higher (>0.3M) salt concentrations, in dilute (<0.1M) salt solutions nonspecific electrostatic screening is considered to be dominant. Here, using effective charge (Q*) measurements of hen-egg white lysozyme (HEWL) as a direct and differential measure of ion-association, we experimentally show that anions selectively and preferentially accumulate at the protein surface even at low (<100 mM) salt concentrations. At a given ion normality (50 mN), the HEWL Q* was dependent on anion, but not cation (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, GdnH⁺, and Ca²⁺), identity. The Q* decreased in the order F⁻ > Cl⁻ > Br⁻ > NO₃⁻ ∼ I⁻ > SCN⁻ > ClO₄⁻ ≫ SO₄²⁻, demonstrating progressively greater binding of the monovalent anions to HEWL and also show that the SO₄²⁻ anion, despite being strongly hydrated, interacts directly with the HEWL surface. Under our experimental conditions, we observe a remarkable asymmetry between anions and cations in their interactions with the HEWL surface.     

Nitric oxide synthase regulation and diversity: Implications in Parkinson’s disease

Nitric oxide (NO) is a janus faced chemical messenger, which, in the recent years, has been the focus of neurobiologists for its involvement in neurodegenerative disorders in particular, Parkinson's disease (PD). Nitric oxide synthase, the key enzyme involved in NO production exists in three known isoforms. The neuronal and inducible isoforms have been implicated in the pathogenesis of PD. These enzymes are subject to complex expressional and functional regulation involving mRNA diversity, phosphorylation and protein interaction. In the recent years, mRNA diversity and polymorphisms have been identified in the NOS isoforms. Some of these genetic variations have been associated with PD, indicating an etiological role for the NOS genes. This review mainly focuses on the NOS genes - their differential regulation and genetic heterogeneity, highlighting their significance in the pathobiology of PD.     

Torulaspora indica a novel yeast species isolated from coal mine soils

Four yeast strains (APSS 805, APSS 806, APSS 815 and AP-18) belonging to a novel Torulaspora species were isolated from coal mine soils of Singareni in Andhra Pradesh state, India. Another strain (PBA-22) was isolated from agricultural field soil from Gujarat state, India. The vegetative cells of all these strains were round, haploid and produced asci by conjugation between independent cells or mother cell and bud, with rough ascospores, suggesting their possible relation to ascomycetous yeast genus Torulaspora. Phylogenetic analysis of the D1/D2 domain of the large subunit (LSU) rRNA gene and Internal Transcribed Spacer (ITS) regions revealed that, among the five strains, three viz. APSS 805, APSS 806 and APSS 815 have identical sequences. The other two strains (AP-18 and PBA-22) differed from the other three strains in less than 1% nucleotide substitutions in the combined D1/D2 domain and ITS sequences, indicating that all of them (five strains) may belong to the same species. These five strains were closely related to Torulaspora globosa, but showed more than 3–7% sequence divergence from T. globosa and all other species in the genus Torulaspora in the combined sequence analysis of D1/D2 domain and ITS region of rRNA gene. In addition, these strains also showed distinct microsatellite finger-printing pattern from related species and differed in several physiological responses suggesting that these strains belong to a novel species of Torulaspora. We propose to name these strains as Torulaspora indica sp. nov., and designate APSS 805^T = MTCC 9772 ^T = CBS 12408 ^T as the type strain of this novel species. The Mycobank number of the novel species is MB 563738.     

Preoperative fine needle aspiration cytologic diagnosis of spindle cell myoepithelioma of the parotid gland: a case report

BACKGROUND: There are only rare case reports of preoperative fine needle aspiration cytologic (FNAC) diagnosis of myoepithelioma of the salivary gland. Myoepitheliomas with pure spindle cell morphology may simulate a variety of benign or malignant spindle cell soft tissue tumors. CASE: A 54-year-old woman presented with a history of progressively increasing swelling in the right parotid region. The clinical diagnosis was parotid malignancy. Routine FNAC yielded highly particulate material. The smears were cellular, with tissue fragments, clusters of spindle cells and numerous small globules and strands of bright magenta material. High cellular yield and pure spindle cell population with an accentuated chromatin pattern in Papanicolaou-stained smears simulated a low-grade spindle cell soft tissue sarcoma. A vague resemblance to a schwannoma was also noted. However, based on the characteristic findings of the May-Grünwald-Giemsa (MGG)-stained smears, a preoperative diagnosis of myoepithelioma was made and confirmed by subsequent histopathologic examination and immunohistochemistry. CONCLUSION: Cytologically, spindle cell myoepithelioma of the salivary gland may simulate low-grade spindle cell soft tissue sarcoma or schwannoma. However, optimal sampling of the lesion and logical interpretation of the MGG-stained smears, in the appropriate clinical situation, allow a confident preoperative diagnosis of these tumors.     

Stability of Lysozyme in Aqueous Extremolyte Solutions during Heat Shock and Accelerated Thermal Conditions

The purpose of this study was to investigate the stability of lysozyme in aqueous solutions in the presence of various extremolytes (betaine, hydroxyectoine, trehalose, ectoine, and firoin) under different stress conditions. The stability of lysozyme was determined by Nile red Fluorescence Spectroscopy and a bioactivity assay. During heat shock (10 min at 70°C), betaine, trehalose, ectoin and firoin protected lysozyme against inactivation while hydroxyectoine, did not have a significant effect. During accelerated thermal conditions (4 weeks at 55°C), firoin also acted as a stabilizer. In contrast, betaine, hydroxyectoine, trehalose and ectoine destabilized lysozyme under this condition. These findings surprisingly indicate that some extremolytes can stabilize a protein under certain stress conditions but destabilize the same protein under other stress conditions. Therefore it is suggested that for the screening extremolytes to be used for protein stabilization, an appropriate storage conditions should also be taken into account.     

Field spectroradiometry for discrimination of wetland components: a case study of a tropical inland wetland in India

Remote sensing has emerged as an effective tool for mapping, monitoring and assessment of wetland ecosystems. Spectral resolution of hyperspectral imagery allows collection of extensive information on dynamics of wetland components. Development of comprehensive spectral libraries using field spectroradiometry is imperative to tap the potential of hyperspectral imagery. In this study, an attempt has been made (i) to test the efficacy of field spectroradiometry data and processing techniques for identification and discrimination of wetland components, and (ii) to develop an approach for creating an extensive library for wetland components. Canopy level spectra of 13 macrophyte species representing different life-forms and water column reflectance spectra were collected seasonally at 16 sites in Bhindawas wetland of India for the years 2014 and 2015. Field spectra were processed using spectroscopic techniques including smoothing, derivative analysis and continuum removal. Results show derivative transforms to be efficient in identification and discrimination of wetland components. Magnitude and position of red-edge peak successfully discriminated different macrophytes with maximum and minimum value for Nymphoides indica and Hydrilla verticillata respectively. Continuum removal further strengthens the attributes of spectral data for species discrimination. Algorithms developed based on derivative transforms of water column spectra allow for continuous monitoring of bio-optical parameters and trophic status of the wetland. As a result of this research, sample-sets of field spectra providing a sound base for mapping and monitoring of wetland components were compiled, leading to the development of the first spectral library for an inland freshwater wetland in the Indian subcontinent. This research output in conjunction with advanced analytical tools and algorithms shall be utilized for wetland assessment in future studies.     

Ultrasonic storage modulus as a novel parameter for analyzing protein-protein interactions in high protein concentration solutions: correlation with static and dynamic light scattering measurements

The purpose of this work was to establish ultrasonic storage modulus (G') as a novel parameter for characterizing protein-protein interactions (PPI) in high concentration protein solutions. Using an indigenously developed ultrasonic shear rheometer, G' for 20-120 mg/ml solutions of a monoclonal antibody (IgG(2)), between pH 3.0 and 9.0 at 4 mM ionic strength, was measured at frequency of 10 MHz. Our understanding of ultrasonic rheology indicated decrease in repulsive and increase in attractive PPI with increasing solution pH. To confirm this behavior, dynamic (DLS) and static (SLS) light scattering measurements were conducted in dilute solutions. Due to technical limitations, light scattering measurements could not be conducted in concentrated solutions. Mutual-diffusion coefficient, measured by DLS, increased with IgG(2) concentration at pH 4.0 and this trend reversed as pH was increased to 9.0. Second virial coefficient, measured by SLS, decreased with increasing pH. These observations were consistent with the nature of PPI understood from G' measurements. Ultrasonic rheology, DLS, and SLS measurements were also conducted under conditions of increased ionic strength. The consistency between rheology and light scattering analysis under various solution conditions established the utility of ultrasonic G' measurements as a novel tool for analyzing PPI in high protein concentration systems.