Effect Of Administration Of Luteinizing-Hormone (Lh) And Deprivation Of Lh On The Proteins Of Smooth Endoplasmic-Reticulum Of Immature And Adult-Rat Leydig-Cells

Analysis of proteins of smooth endoplasmic reticulum (SER) of Leydig cells from immature and admit rats by two-dimensional polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of several new proteins in the adult rats. Administration of human chorionic gonadotropin to immature rats for ten days also resulted in a significant increase as well as the appearance of several new proteins. The general pattern of SDS-PAGE analysis of the SER proteins of Leydig cells resembled that of the adult rat. SDS-PAGE analysis of the SER proteins of Leydig cells from adult rats following deprivation of endogenous luteinizing hormone by administration of antiserum to ovine luteinizing hormone resulted in a pattern which to certain extent resembled that of an immature I at. Western Blot analysis of luteinizing hormone antiserum treated rat Leydig cell proteins revealed a decrease in the 17-alpha-hydroxylase compared to the control. These results provide biochemical evidence for the suggestion that one of the main functions of luteinizing hormone is the control of biogenesis and/or turnover SER of Leydig cells in the rat.

A model for the interaction of trifluoroethanol with peptides and proteins

The structural stabilizing property of 2,2,2-trifluoroethanol (TFE) in peptides has been widely demonstrated, More recently, TFE has been shown to enhance secondary structure content in globular proteins, and to influence quaternary interactions in protein multimers. The molecular mechanisms by which TFE exerts its Influence on peptide and protein structures remain poorly understood. The present analysis integrates the known physical properties of TFE with a variety of experimental observations on the interaction of TFE with peptides and proteins and on the properties of fluorocarbons. Two features of TFE, namely the hydrophobicity of the trifluoromethyl group and the hydrogen bonding character (strong donor and poor acceptor), emerge as the most important factors for rationalising the observed effects of TFE. A model is proposed for TFE interaction with peptides which involves an initial replacement of the hydration shell by fluoroalcohol molecules, a process driven by apolar interactions and favourable entropy of dehydration. Subsequent bifurcated hydrogen-bond formation with peptide carbonyl groups, which leave intramolecular interactions unaffected, promotes secondary structure formation.

The effect of pH on the unfolding pathway and stability of ribosome-inactivating protein abrin-II

The effect of pH on the unfolding pathway acid the stability of the toxic protein abrin-II have been studied by increasing denaturant concentrations of guanidine hydrochloride and by monitoring the change in 8,1-anilino naphthalene sulfonic acid (ANS) fluorescence upon binding to the hydrophobic sites of the protein. Intrinsic protein fluorescence, far and near UV-circular dichroism (CD) spectroscopy and ANS binding studies reveal that the unfolding of abrin-II occurs through two intermediates at pH 7.2 and one intermediate at pH 4.5. At pH 7.2, the two subunits A and B of abrin-II unfold sequentially. The native protein is more stable at pH 4.5 than at pH 7.2. However, the stability of the abrin-II A-subunit is not affected by a change in pH. These observations may assist in an understanding of the physiologically relevant transmembrane translocation of the toxin.

Characterization of an Evolutionarily Conserved Metallophosphoesterase That Is Expressed in the Fetal Brain and Associated with the WAGR Syndrome

Among the human diseases that result from chromosomal aberrations, a de novo deletion in chromosome 11p13 is clinically associated with a syndrome characterized by Wilms' tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR). Not all genes in the deleted region have been characterized biochemically or functionally. We have recently identified the first Class III cyclic nucleotide phosphodiesterase, Rv0805, from Mycobacterium tuberculosis, which biochemically and structurally belongs to the superfamily of metallophosphoesterases. We performed a large scale bioinformatic analysis to identify orthologs of the Rv0805 protein and identified many eukaryotic genes that included the human 239FB gene present in the region deleted in the WAGR syndrome. We report here the first detailed biochemical characterization of the rat 239FB protein and show that it possesses metallophosphodiesterase activity. Extensive mutational analysis identified residues that are involved in metal interaction at the binuclear metal center. Generation of a rat 239FB protein with a mutation corresponding to a single nucleotide polymorphism seen in human 239FB led to complete inactivation of the protein. A close ortholog of 239FB is found in adult tissues, and biochemical characterization of the 239AB protein demonstrated significant hydrolytic activity against 2',3'-cAMP, thus representing the first evidence for a Class III cyclic nucleotide phosphodiesterase in mammals. Highly conserved orthologs of the 239FB protein are found in Caenorhabditis elegans and Drosophila and, coupled with available evidence suggesting that 239FB is a tumor suppressor, indicate the important role this protein must play in diverse cellular events.

Highly efficient C-8 oxidation of substituted xanthines with substitution at the 1-, 3-, and 7- positions using biocatalysts

A bacterial consortium consisting of strains belongings to the genus Klebsiella and Rhodococcus quantitatively converts 1-, 3- and 7-substituted xanthines to their respective 8-oxo compounds.

Influence of lanthanum doping on the dielectric, ferroelectric and relaxor behaviour of barium bismuth titanate ceramics

Barium lanthanum bismuth titanate (Ba1−(3/2)xLaxBi4Ti4O15, x = 0–0.4) ceramics were fabricated using the powders synthesized via the solid-state reaction route. X-ray powder diffraction analysis confirmed the above compositions to be monophasic and belonged to the m = 4 member of the Aurivillius family of oxides. The effect of the partial presence of La3+ on Ba2+ sites on the microstructure, dielectric and relaxor behaviour of BaBi4Ti4O15 (BBT) ceramics was investigated. For the compositions pertaining to x ≤ 0.1, the dielectric constant at both room temperature and in the vicinity of the temperature of the dielectric maximum (Tm) of the parent phase (BBT) increased significantly with an increase in x while Tm remained almost constant. Tm shifted towards lower temperatures accompanied by a decrease in the magnitude of the dielectric maximum (εm) with an increase in the lanthanum content (0.1 < x ≤ 0.4). The dielectric relaxation was modelled using the Vogel–Fulcher relation and a decrease in the activation energy for frequency dispersion with increasing x was observed. The frequency dispersion of Tm was found to decrease with an increase in lanthanum doping, and for compositions corresponding to x ≥ 0.3, Tm was frequency independent. Well-developed P(polarization)–E(electric field) hysteresis loops were observed at 150 °C for all the samples and the remanent polarization (2Pr) was improved from 6.3 µC cm−2 for pure BBT to 13.4 µC cm−2 for Ba0.7La0.2Bi4Ti4O15 ceramics. Dc conductivities and associated activation energies were evaluated using impedance spectroscopy.

Effects of the filling process on the evolution of the mushy zone and macrosegregation in alloy casting

A numerical model of the entire casting process starting from the mould filling stage to complete solidification is presented. The model takes into consideration any phase change taking place during the filling process. A volume of fluid method is used for tracking the metal–air interface during filling and an enthalpy based macro-scale solidification model is used for the phase change process. The model is demonstrated for the case of filling and solidification of Pb–15 wt%Sn alloy in a side-cooled two-dimensional rectangular cavity, and the resulting evolution of a mushy region and macrosegregation are studied. The effects of process parameters related to filling, namely degree of melt superheat and filling velocity on macrosegregation in the cavity, are also investigated. Results show significant differences in the progress of the mushy zone and macrosegregation pattern between this analysis and conventional analysis without the filling effect.

The hemispheric asymmetry of solar activity during the last century and the solar dynamo

We believe the Babcock-Leighton process of poloidal field generation to be the main source of irregularity in the solar cycle. The random nature of this process may make the poloidal field in one hemisphere stronger than that in the other hemisphere at the end of a cycle. We expect this to induce an asymmetry in the next sunspot cycle. We look for evidence of this in the observational data and then model it theoretically with our dynamo code. Since actual polar field measurements exist only from the 1970s, we use the polar faculae number data recorded by Sheeley (1991, 2008) as a proxy of the polar field and estimate the hemispheric asymmetry of the polar field in different solar minima during the major part of the twentieth century. This asymmetry is found to have a reasonable correlation with the asymmetry of the next cycle. We then run our dynamo code by feeding information about this asymmetry at the successive minima and compare the results with observational data. We find that the theoretically computed asymmetries of different cycles compare favorably with the observational data, with the correlation coefficient being 0.73. Due to the coupling between the two hemispheres, any hemispheric asymmetry tends to get attenuated with time. The hemispheric asymmetry of a cycle either from observational data or from theoretical calculations statistically tends to be less than the asymmetry in the polar field (as inferred from the faculae data) in the preceding minimum. This reduction factor turns out to be 0.43 and 0.51 respectively in observational data and theoretical simulations.

A comparative study of the energetics, structures, and mechanisms of the HCN H HNC and LiCN <-> LiNC isomerizations

The potential energy surfaces of the HCN<->HNC and LiCN<->LiNC isomerization processes were determined by ab initio theory using fully optimized triple-zeta double polarization types of basis sets. Both the MP2 corrections and the QCISD level of calculations were performed to correct for the electron correlation. Results show that electron correlation has a considerable influence on the energetics and structures. Analysis of the intramolecular bond rearrangement processes reveals that, in both cases, H (or Li+) migrates in an almost elliptic path in the plane of the molecule. In HCN<->HNC, the migrating hydrogen interacts with the in-plane pi,pi* orbitals of CN, leading to a decrease in the C-N bond order. In LiCN<->LiNC, Li+ does not interact with the corresponding pi,pi* orbitals of CN.

Structure and Rheology of Cationic Molecular Hydrogels of Quinuclidine Grafted Bile Salts. Influence of the Ionic Strength and Counter-Ion type

Quinuclidine grafted cationic bile salts are forming salted hydrogels. An extensive investigation of the effect of the electrolyte and counterions on the gelation has been envisaged. The special interest of the quinuclidine grafted bile salt is due to its broader experimental range of gelation to study the effect of electrolyte. Rheological features of the hydrogels are typical of enthalpic networks exhibiting a scaling law of the elastic shear modulus with the concentration (scaling exponent 2.2) modeling cellular solids in which the bending modulus is the dominant parameter. The addition of monovalent salt (NaCl) favors the formation of gels in a first range (0.00117 g cm-3 (0.02 M) < TNaCl < 0.04675 g cm-3 (0.8 M)). At larger salt concentrations, the gels become more heterogeneous with nodal zones in the micron scale. Small-angle neutron scattering experiments have been used to characterize the rigid fibers ( ≈ 68 Å) and the nodal zones. Stress sweep and creeprecovery measurements are used to relate the lack of linear viscoelastic domain to a mechanism of disentanglement of the fibers from their associations into fagots. The electrostatic interactions can be screened by addition of salt to induce a progressive evolution toward flocculation. SEM, UV absorbance, and SAXS study of the Bragg peak at large Q-values complete the investigation.

Oestrogenic regulation and differential expression of WNT4 in the bonnet monkey and rodent epididymis

A role for oestrogen in regulating fluid reabsorption in the monkey epididymis was recently demonstrated. Here, these Studies are extended to identify potential oestrogen-regulated proteins in the cauda region of monkey epididymis treated with vehicle and oestrogen receptor antagonist (ICI 182780). Two-dimensional electrophoretic analysis was used to identify the proteins. The results indicated down-regulation of WNT4 in the ICI-182780-treated monkey cauda. In addition. the Wnt4f mRNA concentration was also reduced in the caput regions of ICI-182780-treated rats and oestrogen receptor knockout mice. WNT4 is a key regulator of gonadal differentiation in humans and mice and plays a pivotal role in early mouse embryogenesis. The results of the present Study establish the presence of WNT4 in the monkey epididymis and its regulation by oestrogen, and Suggest a role for WNT4 in maintaining epididymal homeostasis.

Similarities in the Genomic Sequence and Coat Protein-Structure of Plant Viruses

The genomic sequences of several RNA plant viruses including cucumber mosaic virus, brome mosaic virus, alfalfa mosaic virus and tobacco mosaic virus have become available recently. The former two viruses are icosahedral while the latter two are bullet and rod shaped, respectively in particle morphology. The non-structural 3a proteins of cucumber mosaic virus and brome mosaic virus have an amino acid sequence homology of 35% and hence are evolutionarily related. In contrast, the coat proteins exhibit little homology, although the circular dichroism spectrum of these viruses are similar. The non-coding regions of the genome also exhibit variable but extensive homology. Comparison of the brome mosaic virus and alfalfa mosaic virus sequences reveals that they are probably related although with a much larger evolutionary distance. The polypeptide folds of the coat protein of three biologically distinct isometric plant viruses, tomato bushy stunt virus, southern bean mosaic virus and satellite tobacco necrosis virus have been shown to display a striking resemblance. All of them consist of a topologically similar 8-standard β-barrel. The implications of these studies to the understanding of the evolution of plant viruses will be discussed.

Effect of chlorine on the adsorption of oxygen on Cu and Ag surfaces

Based on XPS and UVPS studies, it is shown that oxygen is preferentially adsorbed molecularly in the singlet state on Cu and Ag surfaces containing presorbed chlorine. Adsorption of chlorine on Cu and Ag surfaces containing presorbed atomic oxygen causes a disappearance of the oxygen. Extended Hückel calculations predict the observed behaviour.

Effect of electroslag refining on the fracture toughness and fatigue crack propagation rates in heat treated AISI 4340 steel

The AISI 4340 steel has been electroslag refined and the improvement in mechanical properties has been assessed. Electroslag refining (ESR) has improved tensile ductility, plane strain fracture toughness, Charpy fracture energy, and has decreased fatigue crack growth rates. The KIC values for the ESR steel are nearly twice those estimated in the unrefined steel and higher than those obtained in the vacuum arc remelted steel. Fatigue crack growth rates in region I and in region III are found to be decreased considerably in the ESR steel, while they are unaffected in region II. Measurements on heat treated samples have shown that the ESR steel has a better response to heat treatment. Both the suggested heat treatments namely austenitizing at 1140–1470 K as well as the conventional heat treatment of austenitizing at 1140 K have been followed. The improvement in the mechanical properties of ESR steel has been explained on the basis of removal of nonmetallic inclusions and reduction in sulfur content in the steel.

The effect of composition, electron irradiation and quenching on ionic conductivity in a new solid polymer electrolyte: (PEG) (x) NH4I

We have prepared, characterized and investigated a new PEG-2000 based solid polymer electrolyte (PEG) x NH4I. Ionic conductivity measurements have been made as a function of salt concentration as well as temperature in the range 265–330 K. Selected compositions of the electrolyte were exposed to a beam of 8 MeV electrons to an accumulated dose of 10 kGy to study the effect on ionic conductivity. The electrolyte samples were also quenched at liquid nitrogen temperature and conductivity measurements were made. The ionic conductivity at room temperature exhibits a characteristic double peak for the composition x = 20 and 70. Both electron beam irradiation and quenching at low temperature have resulted in an increase in conductivity by 1–2 orders of magnitude. The enhancement of conductivity upon irradiation and quenching is interpreted as due to an increase in amorphous region and decrease in crystallinity of the electrolyte. DSC and proton NMR measurements also support this conclusion.