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Noble gases in the Martian meteorite Northwest Africa 2737: A new chassignite signature
We report noble gas data for the second chassignite, Northwest Africa (NWA) 2737, which was recently found in the Moroccan desert. The cosmic ray exposure (CRE) age based on cosmogenic 3He, 21Ne, and 38Ar around 10-11 Ma is comparable to the CRE ages of Chassigny and the nakhlites and indicates ejection of meteorites belonging to these two families during a discrete event, or a suite of discrete events having occurred in a restricted interval of time. In contrast, U-Th/He and K/Ar ages <0.5 Ga are in the range of radiometric ages of shergottites, despite a Sm-Nd signature comparable tothat of Chassigny and the nakhlites (Misawa et al. 2005). Overall, the noble gas signature of NWA2737 resembles that of shergottites rather than that of Chassigny and the nakhlites: NWA 2737 doesnot contain, in detectable amount, the solar-like xenon found in Chassigny and thought to characterizethe Martian mantle nor apparently fission xenon from 244Pu, which is abundant in Chassigny andsome of the nakhlites. In contrast, NWA 2737 contains Martian atmospheric noble gases trapped inamounts comparable to those found in shergottite impact glasses. The loss of Martian mantle noblegases, together with the trapping of Martian atmospheric gases, could have occurred duringassimilation of Martian surface components, or more likely during shock metamorphism, which isrecorded in the petrology of this meteorite.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202
Intraarticular fentanyl compared with morphine for pain relief following arthroscopic knee surgery
Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins[S]
Exosomes are bioactive vesicles released from multivesicular bodies (MVB) by intact cells and participate in intercellular signaling. We investigated the presence of lipid-related proteins and bioactive lipids in RBL-2H3 exosomes. Besides a phospholipid scramblase and a fatty acid binding protein, the exosomes contained the whole set of phospholipases (A2, C, and D) together with interacting proteins such as aldolase A and Hsp 70. They also contained the phospholipase D (PLD) / phosphatidate phosphatase 1 (PAP1) pathway leading to the formation of diglycerides. RBL-2H3 exosomes also carried members of the three phospholipase A2 classes: the calcium-dependent cPLA2-IVA, the calcium-independent iPLA2-VIA, and the secreted sPLA2-IIA and V. Remarkably, almost all members of the Ras GTPase superfamily were present, and incubation of exosomes with GTPγS triggered activation of phospholipase A2 (PLA2)and PLD2. A large panel of free fatty acids, including arachidonic acid (AA) and derivatives such as prostaglandin E2 (PGE2) and 15-deoxy-Δ12,14-prostaglandinJ2 (15-d PGJ2), were detected. We observed that the exosomes were internalized by resting and activated RBL cells and that they accumulated in an endosomal compartment. Endosomal concentrations were in the micromolar range for prostaglandins; i.e., concentrations able to trigger prostaglandin-dependent biological responses. Therefore exosomes are carriers of GTP-activatable phospholipases and lipid mediators from cell to cell