Intracellular temperature varies as changes in cellular activities including enzyme reactions, [2] cell division, [3] gene expression, [4] and cell-selective treatment to the disease. [5] Studies have shown that cells could respond to regulate intracellular temperature, [6] for instance, mitochondrial heat generation of brown fat cells, heat shock protein production [7] to prevent the necrosis and apoptosis of certain cells, and heat emission at tumor metabolism or local infection according to medical science. [8] However, how would cellular temperature changes due to external thermal stimulation, and the variance between different species of cells, remain unknown. Thus, the measurement of real-time intracellular temperature under stimuli is of great importance for studying cellular processes and optimizing photothermal therapy. [9] This detection helps to explore and discover new phenomena and laws, meanwhile it is necessary to ensure the accuracy of detection. [10] Therefore, the real-time and accurate temperature probe in cells is still urgently needed. For that, research on intracellular thermometers has developed rapidly in the past decade, including nanomaterials based on luminescence are studied widely. [11] Besides a few reports of intrusive thermometers, noncontact luminescence thermometry is mainly used in vivo and in vitro, including infrared thermal detectors, small molecular compounds, fluorescent proteins, quantum dots, upconversion nanoparticles (UCNPs), etc. [12] Rare earth luminescent materials have been widely used because of their prominent advantages such as narrow emission band, good light stability, long luminescent lifetime, and decrease the interference of the autofluorescence from biological tissue. [13] After properly doping, rare earth luminescent nanomaterials have superior properties of temperature response with high resolution and sensitivity of optical signals, and their determination is relatively toilless. [14] Among them, Er 3+ doping nanomaterial is a very preeminent thermometer based on the change of the ratio of two emissions determined by Boltzmann distribution law, which is theoretically independent of the external factors. [15] It provides a chance to achieve the high accuracy of detection and imaging, and the obvious green visible light of Er 3+ is suitable for cellular measurement without tissue covered. However, there are significant disadvantages for this type of probe in biological measurement:Temperature as a typical parameter, which influences the status of living creatures, is essential to life activities and indicates the initial cellular activities. In recent years, the rapid development of nanotechnology provides a new tool for studying temperature variation at the micro-or nano-scales. In this study, an important phenomenon is observed at the cell level using luminescent probes to explore intracellular temperature changes, based on Yb-Er doping nanoparticles with special upconversion readout mode and intensity ratio signals (I 525 and I 545 ). Further optimiza...

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Oxidative stress (OS) is one of the main limiting factors affecting the length of lactation and milk quality in dairy cows. For high-producing dairy cows, the OS of mammary glands is a serious problem. Green tea polyphenols (GTP), found mainly in tea, are a combination of many phenols. GTP have a good effect on antioxidation, inflammation resistance, obesity, fat cell metabolism improvement, and lowering of blood lipid. Therefore, we studied the role of GTP on OS in dairy cows and further investigated whether GTP alleviates oxidative damage of bovine mammary epithelial cells (BMECs) induced by hydrogen peroxide (H2O2) and its underlying molecular mechanism. In this study, 500 μM of H2O2 for 12 h incubation was chosen as the condition of the OS model of BMECs. In addition, the present results found that treatment with GTP alleviated the oxidative damage induced by H2O2 [the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were significantly increased, and the contents of malondialdehyde (MDA), 8-isoprostaglandin (8-iso-PG), 8-oxo-deoxyguanosine (8-OHdG), and protein carbonyl (PC) and caspase-3 and caspase-9 activities were significantly reduced]. These effects are related to the activation of the erythrocyte-derived nuclear factor 2-like protein 2 (NFE2L2) signaling pathway and the inactivation of the caspase/Bcl-2 apoptotic pathway. When NFE2L2 short interfering RNA (siRNA) was used to downregulate the expression of NFE2L2 in cultured BMECs, NFE2L2-siRNA transfection abolished the protective effect of GTP on H2O2-induced intracellular reactive oxygen species (ROS) accumulation and apoptosis. In addition, the mitogen-activated protein kinase (MAPK) inhibition test further proved that GTP relieved H2O2-induced oxidative damage by activating the NFE2L2 signaling pathway, which was achieved by activating the extracellular-regulated kinase 1/2 (ERK1/2) signaling pathway. Overall, the results indicate that GTP has a beneficial effect on the redox balance of BMECs. In addition, GTP might be a latent antioxidant in vivo, which can be administered to ruminants during stressful periods such as the perinatal period.