Gain-of-function mutational activation of human tRNA synthetase procytokine

Disease-causing mutations occur in genes for aminoacyl tRNA synthetases. That some mutations are dominant suggests a gain of function. Native tRNA synthetases, such as tyrosyl-tRNA synthetase (TyrRS) and tryptophanyl-tRNA synthetase, catalyze aminoacylation and are also procytokines that are activated by natural fragmentation. In principle, however, gain-of-function phenotypes could arise from mutational activation of synthetase procytokines. From crystal structure analysis, we hypothesized that a steric block of a critical Glu-Leu-Arg (ELR) motif in full-length TyrRS suppresses the cytokine activity of a natural fragment. To test this hypothesis, we attempted to uncover ELR in the procytokine by mutating a conserved tyrosine (Y341) that tethers ELR. Site-specific proteolytic cleavage and small-angle X-ray scattering established subtle opening of the structure by the mutation. Strikingly, four different assays demonstrated mutational activation of cytokine functions. The results prove the possibilities for constitutive gain-of-function mutations in tRNA synthetases.     

Physics beyond Standard Model: Working group 3 report

This is a summary of the beyond the Standard Model (including model building) working group of the WHEPP-X workshop held at Chennai from January 3 to 15, 2008. Participants: Neelima Agarwal, S K Agarwalla, C S Aulakh, A Belyaev, S S Biswal, B Bhattacharjee, G Bhattacharyya, L Calibbi, D Choudhury, E J Chun, D Das, A De Roeck, N G Deshpande, E Dudas, A Giri, D Grellshceid, R Godbole, S Goswami, M Guchait, M Hirsch, R Kaul, B Kodrani, M C Kumar, A Kundu, Y Mambrini, P Mathews, B Mellado, R Mohanta, S Mohanty, A Nyffeler, S Pakvasa, M K Parida, M Passera, C Petridou, S Poddar, P Poulose, A Rajaraman, G Rajasekaran, V Ravindran, Kumar Rao, D P Roy, Probir Roy, K A Saheb, V H Satheeshkumar, T Schwetz, A Tripathi, R Vaidya and S Vempati     

Statistical features of quantum evolution

It is shown that the integral of the uncertainty of energy with respect to time is independent of the particular Hamiltonian of the quantum system for an arbitrary pseudo-unitary (and hence $ \mathcal{P}\mathcal{T} $ \mathcal{P}\mathcal{T} -) quantum evolution. The result generalizes the time-energy uncertainty principle for pseudo-unitary quantum evolutions. Further, employing random matrix theory developed for pseudo-Hermitian systems, time correlation functions are studied in the framework of linear response theory. The results given here provide a quantum brachistochrone problem where the system will evolve in a thermodynamic environment with spectral complexity that can be modelled by random matrix theory.     

Characteristics of Sulfobacin A from a Soil Isolate Chryseobacterium gleum

A nonmotile, nonspore-forming, Gram-negative, aerobic, small rod-shaped bacterium, isolated from soil, was identified as Chryseobacterium gleum on the basis of 16S rRNA gene sequence analysis. It was observed to grow luxuriously at pH 9 and tolerate highly alkaline environment up to pH 12. Orange red color was a peculiar character of these cells which on purification obtained 60–80 mg/l and found to be sphingosine type of sulfonolipid “sulfobacin A” on the basis of infrared, nuclear magnetic resonance, and mass spectral data. Inhibition of sulfobacin A synthesis by incorporation of l-cycloserine in culture growth medium suggested presence of serine palmitoyl transferase which is one of the important enzymes involved in its biosynthesis. Sulfobacin A from C. gleum LMG P-22264 exhibited cytotoxicity against four cell lines tested. Maximum activity against human mammary adenocarcinoma cells was indicative of its potential as an anticancer agent.     

Effective chemical route for the synthesis of silver nanostructures in formamide

Poly(N-vinyl-2-pyrrolidone) (PVP) and gelatin protected silver nanostructures are prepared in formamide by simple chemical route. Both PVP and gelatin stabilized silver nanoparticles in formamide lead to the formation of nanostructures of various definite geometric shapes and sizes. The effect of anisotropy on the surface plasmon absorption band is analyzed by monitoring the UV-Visible absorption spectra of gelatin stabilized silver nanoparticles. The particles were characterized by UV-Visible absorption spectra and TEM.     

Comparison of different calibration approaches in the application of thermal desorption technique: A test on gaseous reduced sulfur compounds

In this study, the reliability of thermal desorbing technique was investigated using the gaseous standards of five reduced sulfur compounds (RSCs: hydrogen sulfide, methane thiol, dimethyl sulfide, carbon disulfide, and dimethyl disulfide). A series of calibration experiments for RSCs were performed using gas chromatography (GC) with pulsed flame photometric detector (PFPD) that is interfaced with a thermal desorber (TD) unit. These calibration data were evaluated by means of two contrasting concepts: fixed standard concentration method (FSC: variable volumetric injection of standard gases prepared at a given concentration) and fixed standard volume method (FSV: injection of multiple standards with varying concentrations at a given volume). When the results of both methods were compared, RSCs generally showed enhanced sensitivity with increasing concentration (FSC) and sample loading volume (FSV). This study highlights that TD-based calibration properties are practically undistinguishable between different sample transfer approaches (e.g., FSV and FSC). As a result, the calibration properties of RSCs derived by thermal desorption technique are greatly distinguished from those of direct injection into GC.     

Probing solute-solvent interaction in 1-ethyl-3-methylimidazolium-based room temperature ionic liquids: A time-resolved fluorescence anisotropy study

Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA?>?ESU?>?TCB?>?TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs.

A nodal domain theorem for integrable billiards in two dimensions

Eigenfunctions of integrable planar billiards are studied — in particular, the number of nodal domains, ν$\nu$ of the eigenfunctions with Dirichlet boundary conditions are considered. The billiards for which the time-independent Schrödinger equation (Helmholtz equation) is separable admit trivial expressions for the number of domains. Here, we discover that for all separable and non-separable integrable billiards, ν$\nu$ satisfies certain difference equations. This has been possible because the eigenfunctions can be classified in families labelled by the same value of mmodkn$mmodkn$, given a particular k$k$, for a set of quantum numbers, m,n$m,n$. Further, we observe that the patterns in a family are similar and the algebraic representation of the geometrical nodal patterns is found. Instances of this representation are explained in detail to understand the beauty of the patterns. This paper therefore presents a mathematical connection between integrable systems and difference equations.     

Modify SRS-induced crosstalk with variety of fiber in SCM–WDM transmission links

In this paper, the SRS-induced crosstalk has been evaluated in a SCM–WDM communication links at different modulation frequencies and transmission lengths for variety of fiber. Results show that SRS-induced crosstalk dominates at low frequency. As the dispersion and effective area of fiber (A_eff) decreases, initially the crosstalk remains high and then it decreases with increase in modulation frequency. The present work shows that out of five different types of fiber, standard single mode fiber (SMF) has minimum crosstalk (−78 to −38) dB, (−55 to −33) dB and (−46 to −34) dB at modulation frequencies, transmission lengths and optical powers. Dispersion compensation fiber (DCF) has maximum crosstalk (−60 to −12) dB, (−37 to −12) dB and (−27 to −12) dB at modulation frequencies and transmission lengths.