High-level expression of Trigonopsis variabilis D-amino acid oxidase in Escherichia coli using lactose as inducer

The use of lactose as inducer for the expression of Trigonopsis variabilis D-amino acid oxidase gene (daao) was investigated in Escherichia coli regulated by T7 or T5 promoter. The daao gene was prepared by reverse transcriptase-polymerase chain reaction and cloned into pET21b and pQE-30 to yield pET-DAAO and pQE-DAAO, respectively. The His(6)-tagged DAAO was expressed in E. coli and had a M-r value of approximately 39.3 kDa. In lactose-induced E. coli BL21 (DE3) (pET-DAAO), the expressed DAAO could comprise up to 15% of total soluble proteins and a productivity of 23.4 U ml(-1) was obtained

String Theory on Lorentzian AdS_3 in Minisuperspace

We investigate string theory on Lorentzian AdS_3 in the minisuperspace approximation. The minisuperspace model reduces to the worldline theory of a scalar particle in the Lorentzian AdS_3. The Hilbert space consists of normalizable wave functions, and we see that the unitarity of the theory (or the self-adjointness of the Hamiltonian) restricts the possible sets of wave functions. The restricted wave functions have the property of probability conservation (or current conservation) across the horizons. Two and three point functions are also computed. In the Euclidean model functional forms of these quantities are restricted by the SL(2,R) symmetry almost uniquely, however, in the Lorentzian model there are several ambiguities left. The ambiguities are fixed by the direct computation of overlaps of wave functions.Comment: 32 pages, no figures, minor changes, references adde

Oscillations During Inflation and the Cosmological Density Perturbations

Adiabatic (curvature) perturbations are produced during a period of cosmological inflation that is driven by a single scalar field, the inflaton. On particle physics grounds -- though -- it is natural to expect that this scalar field is coupled to other scalar degrees of freedom. This gives rise to oscillations between the perturbation of the inflaton field and the perturbations of the other scalar degrees of freedom, similar to the phenomenon of neutrino oscillations. Since the degree of the mixing is governed by the squared mass matrix of the scalar fields, the oscillations can occur even if the energy density of the extra scalar fields is much smaller than the energy density of the inflaton field. The probability of oscillation is resonantly amplified when perturbations cross the horizon and the perturbations in the inflaton field may disappear at horizon crossing giving rise to perturbations in scalar fields other than the inflaton. Adiabatic and isocurvature perturbations are inevitably correlated at the end of inflation and we provide a simple expression for the cross-correlation in terms of the slow-roll parameters.Comment: 23 pages, uses LaTeX, added few reference

Variational Mean Field approach to the Double Exchange Model

It has been recently shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a richer variety of first and second order transitions than previously anticipated, and that such transitions are consistent with the magnetic properties of manganites. Here we present a thorough discussion of the variational Mean Field approach that leads to the these results. We also show that the effect of the Berry phase turns out to be crucial to produce first order Paramagnetic-Ferromagnetic transitions near half filling with transition temperatures compatible with the experimental situation. The computation relies on two crucial facts: the use of a Mean Field ansatz that retains the complexity of a system of electrons with off-diagonal disorder, not fully taken into account by the Mean Field techniques, and the small but significant antiferromagnetic superexchange interaction between the localized spins.Comment: 13 pages, 11 postscript figures, revte

Iron valence in double-perovskite (Ba,Sr,Ca)2FeMoO6: Isovalent substitution effect

In the Fe-Mo based B-site ordered double-perovskite, A2FeMoO6.0, with iron in the mixed-valence II/III state, the valence value of Fe is not precisely fixed at 2.5 but may be fine-tuned by means of applying chemical pressure at the A-cation site. This is shown through a systematic 57Fe Mossbauer spectroscopy study using a series of A2FeMoO6.0 [A = (Ba,Sr) or (Sr,Ca)] samples with high degree of Fe/Mo order, the same stoichiometric oxygen content and also almost the same grain size. The isomer shift values and other hyperfine parameters obtained from the Mossbauer spectra confirm that Fe remains in the mixed-valence state within the whole range of A constituents. However, upon increasing the average cation size at the A site the precise valence of Fe is found to decrease such that within the A = (Ba,Sr) regime the valence of Fe is closer to II, while within the A = (Sr,Ca) regime it is closer to the actual mixed-valence II/III state. As the valence of Fe approaches II, the difference in charges between Fe and Mo increases, and parallel with this the degree of Fe/Mo order increases. Additionally, for the less-ordered samples an increased tendency of clustering of the anti-site Fe atoms is deduced from the Mossbauer data.Comment: 19 pages, 6 figures, submitted to Phys. Rev.

Global Fluctuation Spectra in Big Crunch/Big Bang String Vacua

We study Big Crunch/Big Bang cosmologies that correspond to exact world-sheet superconformal field theories of type II strings. The string theory spacetime contains a Big Crunch and a Big Bang cosmology, as well as additional ``whisker'' asymptotic and intermediate regions. Within the context of free string theory, we compute, unambiguously, the scalar fluctuation spectrum in all regions of spacetime. Generically, the Big Crunch fluctuation spectrum is altered while passing through the bounce singularity. The change in the spectrum is characterized by a function $\Delta$, which is momentum and time-dependent. We compute $\Delta$ explicitly and demonstrate that it arises from the whisker regions. The whiskers are also shown to lead to ``entanglement'' entropy in the Big Bang region. Finally, in the Milne orbifold limit of our superconformal vacua, we show that $\Delta\to 1$ and, hence, the fluctuation spectrum is unaltered by the Big Crunch/Big Bang singularity. We comment on, but do not attempt to resolve, subtleties related to gravitational backreaction and light winding modes when interactions are taken into account.Comment: 68 pages, 1 figure; typos correcte

Strings in the Extended BTZ Spacetime

We study string theory on the extended spacetime of the BTZ black hole, as described by an orbifold of the SL(2,R) WZW model. The full spacetime has an infinite number of disconnected boundary components, each corresponding to a dual CFT. We discuss the computation of bulk and boundary correlation functions for operators inserted on different components. String theory correlation functions are obtained by analytic continuation from an orbifold of the SL(2,C)/SU(2) coset model. This yields two-point functions for general operators, including those describing strings that wind around the horizon of the black hole.Comment: 35 pages, harvmac, 5 eps figures, uses epsf.tex. (v2): Extended discussion in section 3.1, typo corrections, references adde

Hypoxia-induced SETX links replication stress with the unfolded protein response

YesTumour hypoxia is associated with poor patient prognosis and therapy resistance. A unique transcriptional response is initiated by hypoxia which includes the rapid activation of numerous transcription factors in a background of reduced global transcription. Here, we show that the biological response to hypoxia includes the accumulation of R-loops and the induction of the RNA/DNA helicase SETX. In the absence of hypoxia-induced SETX, R-loop levels increase, DNA damage accumulates, and DNA replication rates decrease. Therefore, suggesting that, SETX plays a role in protecting cells from DNA damage induced during transcription in hypoxia. Importantly, we propose that the mechanism of SETX induction in hypoxia is reliant on the PERK/ATF4 arm of the unfolded protein response. These data not only highlight the unique cellular response to hypoxia, which includes both a replication stress-dependent DNA damage response and an unfolded protein response but uncover a novel link between these two distinct pathways.SR, KBL, PV and MH were supported by a CRUK grant C5255/A23755 (awarded to E.M.H.). N.N. was supported by an MRC studentship (MC_ST_U16007). I. P.F. was supported by CRUK Oxford Centre Prize DPhil Studentship C38302/A12981. N.G. was supported by a Royal Society University Research fellowship. W.-C.C. was funded by CRUK grant 23969 (awarded to F.M.B.). S.F.E.-K. was supported by a Wellcome Trust Investigator Award (103844) and a Lister Institute of Preventative Medicine Fellowship (137661). J.G. was supported by a Jean Shanks Foundation/ Pathological Society of Great Britain and Ireland Clinical PhD Fellowship (JSPS CPhD 2018 01)

Expanding the proteome of an RNA virus by phosphorylation of an intrinsically disordered viral protein

The human proteome contains myriad intrinsically disordered proteins. Within intrinsically disordered proteins, polyproline-II motifs are often located near sites of phosphorylation. Wehave used an unconventional experimental paradigm to discover that phosphorylation by protein kinase A (PKA) occurs in the intrinsically disordered domain of hepatitis C virus nonstructural protein 5A (NS5A) on Thr-2332 near one of its polyproline-II motifs. Phosphorylation shifts the conformational ensemble of the NS5A intrinsically disordered domain to a state that permits detection of the polyproline motif by using 15N-, 13C-based multidimensional NMR spectroscopy. PKA-dependent proline resonances were lost in the presence of the Src homology 3 domain of c-Src, consistent with formation of a complex. Changing Thr-2332 to alanine in hepatitisCvirus genotype 1b reduced the steady-state level of RNA by 10-fold; this change was lethal for genotype 2a. The lethal phenotype could be rescued by changing Thr-2332 to glutamic acid, a phosphomimetic substitution. Immunofluorescence and transmission electron microscopy showed that the inability to produce Thr(P)-2332-NS5A caused loss of integrity of the virus-induced membranous web/replication organelle. An even more extreme phenotype was observed in the presence of small molecule inhibitors of PKA. We conclude that the PKA-phosphorylated form of NS5A exhibits unique structure and function relative to the unphosphorylated protein. We suggest that post-translational modification of viral proteins containing intrinsic disorder may be a general mechanism to expand the viral proteome without a corresponding expansion of the genome

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186