The selenium (Se)-containing antioxidant selenoneine (2-selenyl-Nα,Nα,Nα-trimethyl-l-histidine) has recently been discovered to be the predominant form of organic Se in tuna blood. Although dietary intake of fish Se has been suggested to reduce methylmercury (MeHg) toxicity, the molecular mechanism of MeHg detoxification by Se has not yet been determined. Here, we report evidence that selenoneine accelerates the excretion and demethylation of MeHg, mediated by a selenoneine-specific transporter, organic cations/carnitine transporter-1 (OCTN1). Selenoneine was incorporated into human embryonic kidney HEK293 cells transiently overexpressing OCTN1 and zebrafish blood cells by OCTN1. The Km for selenoneine uptake was 13.0 μM in OCTN1-overexpressing HEK293 cells and 9.5 μM in zebrafish blood cells, indicating high affinity of OCTN1 for selenoneine in human and zebrafish cells. When such OCTN1-expressing cells and embryos were exposed to MeHg–cysteine (MeHgCys), MeHg accumulation was decreased and the excretion and demethylation of MeHg were enhanced by selenoneine. In addition, exosomal secretion vesicles were detected in the culture water of embryos that had been microinjected with MeHgCys, suggesting that these may be responsible for MeHg excretion and demethylation. In contrast, OCTN1-deficient embryos accumulated MeHg, and MeHg excretion and demethylation were decreased. Furthermore, Hg accumulation was decreased in OCTN1-overexpressing HEK293 cells, but not in mock vector-transfected cells, indicating that selenoneine and OCTN1 can regulate MeHg detoxification in human cells. Thus, the selenoneine-mediated OCTN1 system regulates secretory lysosomal vesicle formation and MeHg demethylation.Electronic supplementary materialThe online version of this article (doi:10.1007/s10126-013-9508-1) contains supplementary material, which is available to authorized users.

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A novel porous-core kagome lattice photonic crystal fiber (PCF) is designed and analyzed in this paper for terahertz (THz) wave guidance. Using finite element method (FEM), properties of the proposed kagome lattice PCF are simulated in details including the single-mode propagation, dispersion profile, fraction of power in the porous-core with different core porosity, effective material loss (EML) and confinement loss. Simulation results indicate that 82.5% of bulk material loss of Topas can be reduced by using core porosity of 70%. The calculated EML is as low as 0.035 cm -1 at operating frequency 1 THz. In addition, the proposed PCF also exhibits relatively low confinement loss and a much more flattened dispersion profile with single mode propagation.Index Terms-Effective material loss, kagome lattice PCF, terahertz wave guidance. 0733-8724 (c)

The graphical abstract reflects the content of the entire paper; catalyst complexes for upgrading biomass to ester-based biolubricants.