RESUMO
The spin state of Fe can alter the key physical properties of silicate melts, affecting the early differentiation and the dynamic stability of the melts in the deep rocky planets. The low-spin state of Fe can increase the affinity of Fe for the melt over the solid phases and the electrical conductivity of melt at high pressures. However, the spin state of Fe has never been measured in dense silicate melts due to experimental challenges. We report detection of dominantly low-spin Fe in dynamically compressed olivine melt at 150 to 256 gigapascals and 3000 to 6000 kelvin using laser-driven shock wave compression combined with femtosecond x-ray diffraction and x-ray emission spectroscopy using an x-ray free electron laser. The observation of dominantly low-spin Fe supports gravitationally stable melt in the deep mantle and generation of a dynamo from the silicate melt portion of rocky planets.
RESUMO
Epithelial-mesenchymal-transition (EMT) is a key event for tumour cells to initiate metastasis leading to switching of E-cadherin to N-cadherin. Transglutaminase-2 (Tgase-2) expression is increased in TGF-ß1-induced EMT in A549 lung cancer cells or other lung cancer cells. The role and underlying mechanism of Tgase-2 in N-cadherin switching of TGF-ß1-induced EMT are not known. The involvement and mechanisms of Tgase-2 were investigated in A549 cells using chemical inhibitors, gene silencing and over-expression. TGF-ß1-induced EMT was suppressed by cystamine or gene silencing of Tgase-2. Suppression of Tgase-2 or the c-Jun-N-terminal kinase (JNK) inhibitor, SP600125, significantly reduced and over-expression of Tgase-2 increased the expression of N-cadherin. The relationship between Tgase-2 and JNK in the TGF-ß1-induced EMT of A549 cells was examined using Tgase-2 over-expressed A549 cells (A549(TG2)) and Tgase-2 silenced A549 cells (A549(shTG2)). JNK activation was significantly increased in A549(TG2) cells and decreased in A549(shTG2) cells. In contrast, PP2A expression was decreased in A549(TG2) and A549 cells and increased in A549(shTG2) cells. The involvement of Tgase-2 in N-cadherin expression was also confirmed in an in vivo lung cancer orthotopic model by injection of A549(WT) and A549(shTG2) cells into SCID mice. Tgase-2 expressing A549(WT) cells-injected mice group showed increased expressions of N-cadherin and JNK activation, but decreased expression of PP2A in lung cancer tissue comparing with the A549(shTG2) cells-injected group. These results suggested that Tgase-2 induces N-cadherin expression of TGF-ß1-induced EMT via JNK activation by PP2A down-regulation, and Tgase-2/PP2A/JNK might be a novel axis that affects N-cadherin switching in the EMT of A549 lung cancer cells.