Selenite Targets eIF4E-Binding Protein-1 to Inhibit Translation Initiation and Induce the Assembly of Non-Canonical Stress Granules

Stress granules (SGs) are large cytoplasmic ribonucleoprotein complexes that are assembled when cells are exposed to stress. SGs promote the survival of stressed cells by contributing to the reprogramming of protein expression as well as by blocking pro-apoptotic signaling cascades. These cytoprotective effects implicated SGs in the resistance of cancer cells to radiation and chemotherapy. We have found that sodium selenite, a selenium compound with chemotherapeutic potential, is a potent inducer of SG assembly. Selenite-induced SGs differ from canonical mammalian SGs in their morphology, composition and mechanism of assembly. Their assembly is induced primarily by eIF4E-binding protein1 (4EBP1)-mediated inhibition of translation initiation, which is reinforced by concurrent phosphorylation of eIF2α. Selenite-induced SGs lack several classical SG components, including proteins that contribute to pro-survival functions of canonical SGs. Our results reveal a new mechanism of mammalian SG assembly and provide insights into how selenite cytotoxicity may be exploited as an anti-neoplastic therapy

Localized transverse bursts in inclined layer convection

We investigate a novel bursting state in inclined layer thermal convection in which convection rolls exhibit intermittent, localized, transverse bursts. With increasing temperature difference, the bursts increase in duration and number while exhibiting a characteristic wavenumber, magnitude, and size. We propose a mechanism which describes the duration of the observed bursting intervals and compare our results to bursting processes in other systems.Comment: 4 pages, 8 figure

Multi-Orbital Molecular Compound (TTM-TTP)I_3: Effective Model and Fragment Decomposition

The electronic structure of the molecular compound (TTM-TTP)I_3, which exhibits a peculiar intra-molecular charge ordering, has been studied using multi-configuration ab initio calculations. First we derive an effective Hubbard-type model based on the molecular orbitals (MOs) of TTM-TTP; we set up a two-orbital Hamiltonian for the two MOs near the Fermi energy and determine its full parameters: the transfer integrals, the Coulomb and exchange interactions. The tight-binding band structure obtained from these transfer integrals is consistent with the result of the direct band calculation based on density functional theory. Then, by decomposing the frontier MOs into two parts, i.e., fragments, we find that the stacked TTM-TTP molecules can be described by a two-leg ladder model, while the inter-fragment Coulomb energies are scaled to the inverse of their distances. This result indicates that the fragment picture that we proposed earlier [M.-L. Bonnet et al.: J. Chem. Phys. 132 (2010) 214705] successfully describes the low-energy properties of this compound.Comment: 5 pages, 4 figures, published versio

Speech Communication

Contains reports on four research projects.U. S. Air Force (Air Force Cambridge Research Center, Air Research and Development Command) under Contract AF19(604)-6102National Science Foundatio

Pauli-limited superconductivity and antiferromagnetism in the heavy-fermion compound CeCo(In1-xZnx)5

We report on the anisotropic properties of Pauli-limited superconductivity (SC) and antiferromagnetism (AFM) in the solid solutions CeCo(In_{1-x}Zn_x)_5 (x<=0.07). In CeCo(In_{1-x}Zn_x)_5, the SC transition temperature T_c is continuously reduced from 2.3 K (x=0) to ~1.4 K (x=0.07) by doping Zn, and then the AFM order with the transition temperature of T_N~2.2 K develops for x larger than ~0.05. The present thermal, transport and magnetic measurements under magnetic field B reveal that the substitution of Zn for In yields little change of low-temperature upper critical field \mu_0H_{c2} for both the tetragonal a and c axes, while it monotonically reduces the SC transition temperature T_c. In particular, the magnitudes of \mu_0H_{c2} at the nominal Zn concentration of x = 0.05 (measured Zn amount of ~0.019) are 11.8 T for B||a and 4.8 T for B||c, which are as large as those of pure compound though T_c is reduced to 80% of that for x=0. We consider that this feature originates from a combination of both an enhanced AFM correlation and a reduced SC condensation energy in these alloys. It is also clarified that the AFM order differently responds to the magnetic field, depending on the field directions. For B||c, the clear anomaly due to the AFM transition is observed up to the AFM critical field of ~5 T in the thermodynamic quantities, whereas it is rapidly damped with increasing B for B||a. We discuss this anisotropic response on the basis of a rich variety of the AFM modulations involved in the Ce115 compounds.Comment: 10 pages, 7 figure

First measurement of coherent ϕ\phi-meson photoproduction from helium-4 near threshold

The differential cross sections and decay angular distributions for coherent $\phi$-meson photoproduction from helium-4 have been measured for the first time at forward angles with linearly polarized photons in the energy range $E_{\gamma} = \text{1.685-2.385 GeV}$. Thanks to the target with spin-parity $J^{P} = 0^{+}$, unnatural-parity exchanges are prohibited, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the dominance ($> 94\%$) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section ($\theta = 0^\circ$) for the $\gamma p \rightarrow \phi p$ reaction near the threshold, the energy dependence of the forward cross section ($\theta = 0^\circ$) for the $\gamma {^{4}\text{He}} \rightarrow \phi {^{4}\text{He}}$ reaction was analyzed. The comparison to $\gamma p \rightarrow \phi p$ data suggests that enhancement of the forward cross section arising from natural-parity exchanges, and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in the $\gamma p \rightarrow \phi p$ reaction near the threshold.Comment: 6 pages, 4 figure