Éditeur(s) : HAL CCSD Landes Bioscience
Résumé : International audience
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
Autophagy

hal-00735751
https://hal.archives-ouvertes.fr/hal-00735751
PUBMED : 22966490

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This article summarizes the geodynamic evolution of the Variscan to Mesozoic Tethyan subduction history, based on a review of geochronological data from Eastern Anatolia and the Lesser Caucasus, and new isotopic ages for the Georgian crystalline basements. The geological history of the basements of Georgia (Transcaucasus) and NE Turkey (eastern Pontides) appears to be similar and provides evidence for a continuously active continental margin above a north-dipping subduction since at least the Lower Jurassic. New La-ICPMS U-Pb ages from the Georgian basement provide further evidence for the derivation of the Transcaucasus and its western continuation (the eastern Pontides) from Gondwana. A migmatized granodiorite provides preserved magmatic zircon cores with an age of 474 ± 3 Ma, while the age of migmatization is constrained by its 343 ± 2 Ma metamorphic rims. Metamorphism is synchronous with widespread I-type granites that were emplaced at 335 ± 8 Ma in the neighbouring Dzirula massif, and in the eastern Pontides. These U-Pb ages are in close agreement with recently obtained Ar/Ar ages from biotites and muscovites from metamorphic schists and U-Pb ages ranging from 340 to 330 Ma in the Georgian basement. The narrow range of ages suggests that the Variscan LP-HT metamorphic event in the eastern Pontides and Georgia was of short duration and likely related to mantle-derived intrusives. Furthermore, we suggest that (1) rifting of the Pontides-Transcaucasus block (PTB) from Gondwana at 450–350 Ma could have been driven by roll-back of the south-dipping Rheic slab, (2) that the main metamorphic and coeval magmatic events are related to the accretion of the PTB to the Eurasian margin at c. 350 Ma, while the source of magmatism is ascribed to slab detachment of the south-dipping slab at 340 Ma and that (3) three subduction zones may have been contemporaneously active in the Tethyan domain during the Jurassic: (i) the Lesser Caucasus South Armenian Block (SAB) shares a similar Gondwana affinity, but bears younger ages for its MP-MT metamorphic evolution and calc-alkaline magmatism bracketed from 160 to 123 Ma; (ii) north-dipping subduction below the PTB from c. 210 Ma to 150 Ma; (iii) northward intra-oceanic subduction bracketed from 180 to 90 Ma between the SAB and the PTB.
ISSN: 0264-3707

hal-01347761
https://hal.archives-ouvertes.fr/hal-01347761
DOI : 10.1016/j.jog.2016.03.003

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The continental South Armenian Block – part of the Anatolide–Tauride South Armenian microplate – of Gondwana origin rifted from the African margin after the Triassic and collided with the Eurasian margin after the Late Cretaceous. During the Late Cretaceous, two northward dipping subduction zones were simultaneously active in the northern Neo-Tethys between the South Armenian Block in the south and the Eurasian margin in the north: oceanic subduction took place below the continental Eurasian margin and intra-oceanic subduction resulted in ophiolite obduction onto the South Armenian Block in the Late Cretaceous.The paleolatitude position of the South Armenian Block before its collision with Eurasia within paleogeographic reconstructions is poorly determined and limited to one study. This earlier study places the South Armenian Block at the African margin in the Early Jurassic. To reconstruct the paleolatitude history of the South Armenian Block, we sampled Upper Devonian–Permian and Cretaceous sedimentary rocks in Armenia. The sampled Paleozoic rocks have likely been remagnetized. Results from two out of three sites sampled in Upper Cretaceous strata pass fold tests and probably all three carry a primary paleomagnetic signal. The sampled sedimentary rocks were potentially affected by inclination shallowing. Therefore, two sites that consist of a large number of samples (> 100) were corrected for inclination shallowing using the elongation/inclination method.These are the first paleomagnetic data that quantify the South Armenian Block's position in the Tethys ocean between post-Triassic rifting from the African margin and post-Cretaceous collision with Eurasia. A locality sampled in Lower Campanian Eurasian margin sedimentary rocks and corrected for inclination shallowing, confirms that the corresponding paleolatitude falls on the Eurasian paleolatitude curve. The north–south distance between the South Armenian Block and the Eurasian margin just after Coniacian–Santonian ophiolite obduction was at most 1000 km.
ISSN: 0040-1951

hal-01365871
https://hal.archives-ouvertes.fr/hal-01365871
DOI : 10.1016/j.tecto.2015.01.012