Earthquake-enhanced dissolved carbon cycles in ultra-deep ocean sediments.

Hadal trenches are unique geological and ecological systems located along subduction zones. Earthquake-triggered turbidites act as efficient transport pathways of organic carbon (OC), yet remineralization and transformation of OC in these systems are not comprehensively understood. Here we measure concentrations and stable- and radiocarbon isotope signatures of dissolved organic and inorganic carbon (DOC, DIC) in the subsurface sediment interstitial water along the Japan Trench axis collected during the IODP Expedition 386.

Megathrust earthquake drives drastic organic carbon supply to the hadal trench.

The giant 2011 Tohoku-oki earthquake has been inferred to remobilise fine-grained, young surface sediment enriched in organic matter from the slope into the >7 km deep Japan Trench. Yet, this hypothesis and assessment of its significance for the carbon cycle has been hindered by limited data density and resolution in the hadal zone. Here we combine new high-resolution bathymetry data with sub-bottom profiler images and sediment cores taken during 2012-2016 in order to map for the first time the spatial extent of the earthquake-triggered event deposit along the hadal Japan Trench.

Microglia derived from the axotomized adult rat facial nucleus uptake glutamate and metabolize it to glutamine in vitro.

Microglia in the axotomized adult rat facial nucleus (axoFN) have been shown to highly express a glutamate transporter (GLT-1). The microglia appear to serve as glutamate (Glu) scavengers in the axoFN. However, there is no evidence that the microglia actually have the ability to uptake Glu and convert it to Gln.

A simple convenient synthesis of L-[4-13C]glutamine.

L-[4-(13)C]Glutamine was synthesized from sodium [2-(13)C]acetate in 12 steps and 18% overall yield. A Wittig reaction of (R)-benzyl 4-formyl-2,2-dimethyloxazolidine-3-carboxylate and ethyl 2-(triphenylphosphoranylidene)[2-(13)C]acetate prepared from D-serine and sodium [2-(13)C]acetate, respectively, gave (4S)-4-(2-ethoxycarbonyl[2-(13)C]vinyl)-2,2-dimethyloxazolidine-3-carboxylic acid α,β-isopropylidene group, oxidation of the resulting hydroxyl group to a carboxyl group and transamidation of the ester moiety gave L-N-Cbz-[4-(13)C]glutamine (Cbz = benzyloxycarbonyl). Finally, removal of the Cbz group gave L-[4-(13)C]glutamine.

Up-regulation of glutamine synthesis in microglia activated with endotoxin.

We previously verified that newborn rat brain-derived microglia have the ability to uptake (14)C-glutamate (Glu) through glutamate transporter-1. A given amount of Glu incorporated into microglia was suspected to be metabolized to glutamine (Gln). However, the ability of microglia to do this had not been demonstrated.