No abstract

Brassicales contain a myrosinase enzyme that hydrolyzes glucosinolates to form toxic isothiocyanates (ITC), as a defense against bacteria, fungi, insects and herbivores including man. Low levels of ITC trigger a host defense system in mammals that protects them against chronic diseases. Because humans typically cook their brassica vegetables, destroying myrosinase, there is a great interest in determining how human microbiota can hydrolyze glucosinolates and release them, to provide the health benefits of ITC. ITC are highly reactive electrophiles, binding reversibly to thiols, but accumulating and causing damage when free thiols are not available. We found that addition of excess thiols released protein-thiol-bound ITC, but that the microbiome supports only poor hydrolysis unless exposed to dietary glucosinolates for a period of days. These findings explain why 3–5 servings a week of brassica vegetables may provide health effects, even if they are cooked.

Preharvest calcium application has been shown to increase broccoli microgreen yield and extend shelf life. In this study, we investigated the effect of calcium application on its metabolome using ultra-high-performance liquid chromatography with mass spectrometry. The data collected were analyzed using principal component analysis and orthogonal projection to latent structural discriminate analysis. Chemical composition comparison shows that glucosinolates, a very important group of phytochemicals, are the major compounds enhanced by preharvest treatment with 10 mM calcium chloride (CaCl2). Aliphatic glucosinolates (glucoerucin, glucoiberin, glucoiberverin, glucoraphanin, pentyl glucosinolate, and hexyl glucosinolate) and indolic glucosinolates (glucobrassicin, neoglucobrassicin, and 4-hydroxyglucobrassicin) were increased significantly in the CaCl2 treated microgreens using metabolomic approaches. Targeted glucosinolate analysis using the ISO 9167-1 method was further employed to confirm the findings. Results indicate that glucosinolates can be considered as a class of compounds that are responsible for the difference between two groups and a higher glucosinolate level was found in CaCl2 treated groups at each time point after harvest in comparison with the control group.

Crystal facet engineering of semiconductors has been proven to be an effective strategy to increase photocatalytic performances. However, the mechanism involved in the photocatalysis is not yet known. Herein, we report our success in that photocatalytic performances of the Cl(-) ion capped CoO octahedrons with exposed {111} facets were activated by a treatment using AgNO3 and NH3·H2O solutions. The clean CoO {111} facets were found to be highly reactivity faces. On the basis of the polar structure of the exposed {111} surfaces, a charge separation model between polar {111} surfaces is proposed. There is an internal electric field between polar {111} surfaces due to the spontaneous polarization. The internal electric field provides a driving force for charge separation. The reduction and oxidation reactions selectively take place on the positive and negative polar {111} surfaces. The charge separation model provides a clear insight into charge transfer in the semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts, solar cells, photoelectrodes, and other photoelectronic devices.

No abstract

Extracellular K(+) concentration ([K(+)]) is closely regulated by the concerted regulatory responses of kidney and muscle. In this study, we aimed to define the responses activated when dietary K(+) was moderately reduced from a control diet (1.0% K(+)) to a 0.33% K(+) diet for 15 days. Although body weight and baseline plasma [K(+)] (4.0 mM) were not reduced in the 0.33% K(+) group, regulatory responses to conserve plasma [K(+)] were evident in both muscle and kidney. Insulin-stimulated clearance of K(+) from the plasma was estimated in vivo in conscious rats with the use of tail venous and arterial cannulas. During infusion of insulin.(50 mU.kg(-1).min(-1)), plasma [K(+)] level fell to 3.2 +/- 0.1 mM in the 1.0% K(+) diet group and to only 3.47 +/- 0.07 mM in the 0.33% K(+) diet group (P < 0.01) with no reduction in urinary K(+) excretion, which is evidence of insulin resistance to cellular K(+) uptake. Insulin-stimulated cellular K(+) uptake was quantitated by measuring the K(+) infusion rate necessary to clamp plasma K(+) at baseline (in micromol.kg(-1).min(-1)) during 5 mU of insulin.kg(-1).min(-1) infusion: 9.7 +/- 1.5 in 1% K(+) diet was blunted to 5.2 +/- 1.7 in the 0.33% K(+) diet group (P < 0.001). Muscle [K(+)] and Na(+)-K(+)-ATPase activity and abundance were unchanged during the 0.33% K(+) diet. Renal excretion, which was measured overnight in metabolic cages, was reduced by 80%, from 117.6 +/- 10.5 micromol/h/animal (1% K(+) diet) to 24.2 +/- 1.7 micromol/h/animal (0.33% K(+) diet) (P < 0.001). There was no significant change in total abundance of key renal K(+) transporters, but 50% increases in both renal PTK cSrc abundance and ROMK phosphorylation in the 0.33% K(+) vs. 1% K(+) diet group, previously established to be associated with internalization of ROMK. These results indicate that plasma [K(+)] can be maintained during modest K(+) restriction due to a decrease in insulin-stimulated cellular K(+) uptake as well as renal K(+) conservation mediated by inactivation of ROMK, both without a detectable change in plasma [K(+)]. The error signals inciting and maintaining these responses remain to be identified.

No abstract

Highly sensitive and selective detection of trace nitrogen dioxide (NO2) in a complex outdoor air environment is an urgent need to guarantee human health and a beautiful environment. The effective combination of heterostructure and light irradiation is an important strategy to achieve high-performances gas sensors. However, the effect of light irradiation on gas-sensitive properties of heterostructure materials is not yet clear, and it is urgent to clarify the relationship between light irradiation and heterostructure for gas-sensing materials. Herein, a 530 nm-light-assisted Au–MoS2 gas sensor with a low detection limit as well as robust antihumidity interference ability is developed through introducing the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (NPs). Under 530 nm light illumination, a Au–MoS2 gas sensor can achieve limit detection of NO2 as low as 10 ppb without operating temperature along with robust antihumidity ability. The optical simulation and experimental results show that the modification of MoS2 by Au NPs (diameter: 30 nm) combined with the matching light-assisted (530 nm) gas detection mode can make MoS2 fully absorb visible light and effectively improve the extinction cross section by taking full advantage of the LSPR effect, which is the primary reason for the enhanced performances of a MoS2-based gas sensor. This work provides theoretical and experimental guidance for gas sensors to effectively enhance the ability of gas detection by means of the light-assisted mode at room temperature, which opens up a unique approach to design high-performance gas sensors for trace-level gas detection.