AMBRA1 is able to induce mitophagy via LC3 binding, regardless of PARKIN and p62/SQSTM1

Damaged mitochondria are eliminated by mitophagy, a selective form of autophagy whose dysfunction associates with neurodegenerative diseases. PINK1, PARKIN and p62/SQTMS1 have been shown to regulate mitophagy, leaving hitherto ill-defined the contribution by key players in 'general' autophagy. In basal conditions, a pool of AMBRA1 - an upstream autophagy regulator and a PARKIN interactor - is present at the mitochondria, where its pro-autophagic activity is inhibited by Bcl-2. Here we show that, upon mitophagy induction, AMBRA1 binds the autophagosome adapter LC3 through a LIR (LC3 interacting region) motif, this interaction being crucial for regulating both canonical PARKIN-dependent and -independent mitochondrial clearance. Moreover, forcing AMBRA1 localization to the outer mitochondrial membrane unleashes a massive PARKIN- and p62-independent but LC3-dependent mitophagy. These results highlight a novel role for AMBRA1 as a powerful mitophagy regulator, through both canonical or noncanonical pathways

Martensitic transformations of Cu-Al-Ni single crystals in tension/compression

Cu-Al-Ni alloys, similarly as other Cu-base shape memory alloys, transform into more martensitic structures α1'(6R), β1'(18R) and γ1'(2H),, depending on the temperature, stress, load axis orientation, sense of loading and composition. The transformation stress-temperature conditions at which individual transitions take place are beneficially represented in so called non-equilibrium stress-temperature phase diagrams. On the basis of the σ-T diagrams, complex history dependent thermomechanical behaviors of SMA single crystals undergoing sequentially multiple solid state transitions can be easily understood and predicted. Since chemical composition of the alloy crystals affects mainly the equilibrium transformation temperatures, T0, and only slightly the slopes of the transformation lines in the σ-T diagrams, the diagrams mainly shift in the temperature range (over ~200K) with the compositional variations. The shape of the diagrams, however, may change significantly when the T0 shifts for individual transitions are different. Knowledge of the compositional dependence of σ-T diagrams would be beneficial for the development of shape memory alloys with specific required thermomechanical properties. The aim of the present work is experimental investigation of the martensitic transformations and construction of the σ-T diagram for Cu-Al-Ni alloy with lower Al content (T0>363K) and comparison with our previous results obtained on alloys with higher Al content (T0<263K)

Parameters of Martensite Transformation and Structural State in Rapidly Quenched Ti35Ni15Cu Shape Memory Alloys

Influence of the quenching rate on the martensite transformation parameters (transformation temperatures and hysteresis) of 50Ti35Ni15Cu shape memory ribbons obtained by meltspinning technique has been studied. Increase of quenching rate results in decrease of the B2←→B19 and B19←→B19' martensite transformations temperatures, broadening of direct and reverse transformation intervals, decrease of hysteresis. The B2-type ordering takes place during rapid solidification. Rapid solidification of 50Ti35Ni15Cu alloy results in fine β-phase grain size structure with relative large size scattering. Two types of martensite morphology, plate-like and triangular shapes, have been observed in ribbons

Effect of carbon and cold rolling on the latent heat upon ε → γ transformation in metastable Fe-Mn alloys

Metastable Fe-Mn alloys exhibit a non-thermoelastic martensitic transformation which is accompanied by a significant thermal effect (ca. 20 J/g). Among Fe-Mn alloys, the highest value of latent heat was registered in alloys with 17-18 wt. % Mn. In this work we investigate effects of carbon (up to 0.4 wt. %) and cold rolling (5-25% of thickness reduction) on the latent heat and the temperature hysteresis of the martensitic transformation. Changes in chemical and phase composition are analyzed based on the goal of enthalpy maximizing. The martensite ↔ austenite transitions are registered using differential scanning calorimetry and dilatometry. The phase composition is determined by means of X-ray diffraction. An effect of thermocycling is considered in connection with microstructural and enthalpy changes

A two-stage martensite transformation in a Cu-13.99 mass% Al-3.5 mass% Ni alloy

The reverse martensite transformation of an as-quenched Cu-Al-Ni shape memory alloy presents two separate stages which are studied by means of calorimetry. The first stage, corresponding to the lower temperatures, presents a thermal hysteresis of about 10 K, a continuous behavior of the energy dissipation and a very low acoustic emission. The second stage, at higher temperatures, presents a thermal hysteresis of about 40 K, a rather jerky character in the energy dissipation and a higher level of acoustic emission. The first stage progressively disappears and the transformation temperatures increase when the alloy is aged at 473 K for 573 K but the difference in temperatures between the two stages, of about 25 degrees, remains constant. An analysis by SEM of the microstructure during the transformation, in accordance with the above-mentioned features, shows that the beta prime //1- and gamma prime //1-phases coexist in the martensite. The occurrence of the beta prime //1 martensite is assisted by internal strain energy created during the direct transformation.status: publishe