Multiplexed Targeted Quantitative Proteomics Predicts Hepatic Glucuronidation Potential

Phase II metabolism is prominently governed by UDP-glucuronosyltransferases (UGTs) in humans. These enzymes regulate the bioactivity of many drugs and endogenous small molecules in many organs, including the liver, a major site of regulation by the glucuronidation pathway. This study determined the expression of hepatic UGTs by targeted proteomics in 48 liver samples and by measuring the glucuronidation activity using probe substrates. It demonstrates the sensitivity and accuracy of nano-ultra-performance liquid chromatography with tandem mass spectrometry to establish the complex expression profiles of 14 hepatic UGTs in a single analysis. UGT2B7 is the most abundant UGT in our collection of livers, expressed at 69 pmol/mg microsomal proteins, whereas UGT1A1, UGT1A4, UGT2B4, and UGT2B15 are similarly abundant, averaging 30–34 pmol/mg proteins. The average relative abundance of these five UGTs represents 81% of the measured hepatic UGTs. Our data further highlight the strong relationships in the expression of several UGTs. Most notably, UGT1A4 correlates with most measured UGTs, and the expression levels of UGT2B4/UGT2B7 displayed the strongest correlation. However, significant interindividual variability is observed for all UGTs, both at the level of enzyme concentrations and activity (coefficient of variation: 45%–184%). The reliability of targeted proteomics quantification is supported by the high correlation between UGT concentration and activity. Collectively, these findings expand our understanding of hepatic UGT profiles by establishing absolute hepatic concentrations of 14 UGTs and further suggest coregulated expression between most abundant hepatic UGTs. Data support the value of multiplexed targeted quantitative proteomics to accurately assess specific UGT concentrations in liver samples and hepatic glucuronidation potential

Probing electron-phonon interaction through two-photon interference in resonantly driven semiconductor quantum dots

We investigate the temperature dependence of photon coherence properties through two-photon interference (TPI) measurements from a single quantum dot (QD) under resonant excitation. We show that the loss of indistinguishability is related only to the electron-phonon coupling and is not affected by spectral diffusion. Through these measurements and a complementary microscopic theory, we identify two independent separate decoherence processes, both of which are associated with phonons. Below 10 K, we find that the relaxation of the vibrational lattice is the dominant contribution to the loss of TPI visibility. This process is non-Markovian in nature and corresponds to real phonon transitions resulting in a broad phonon sideband in the QD emission spectra. Above 10 K, virtual phonon transitions to higher lying excited states in the QD become the dominant dephasing mechanism, this leads to a broadening of the zero phonon line, and a corresponding rapid decay in the visibility. The microscopic theory we develop provides analytic expressions for the dephasing rates for both virtual phonon scattering and non-Markovian lattice relaxation

Large-scale flow driven by turbulently generated internal gravity waves

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Optical Probing of Rayleigh Wave Driven Magnetoacoustic Resonance

International audienceThe resonant interaction of electrically excited traveling surface acoustic waves and magnetization has hitherto been probed through the acoustic component. In this work we investigated it using time-resolved magneto-optical detection of magnetization dynamics. To that end, we develop an experimental scheme where laser pulses are used both to generate the acoustic wave frequency and to probe magnetization dynamics, thus ensuring perfect phase locking. The light-polarization dependence of the signal enables us to disentangle elasto-optical and magneto-optical contributions and to obtain the in-plane and out-of-plane components of the magnetization dynamics. Magnetization precession is proven to be driven solely by the acoustic wave. Its amplitude is shown to resonate at the same field at which we detect piezoelectrically the resonant attenuation of the acoustic wave, clearly evidencing the magnetoacoustic resonance with high sensitivity

Optical Probing of Wave Driven Magneto-acoustic Resonance

Publiée sous le titre Optical Probing of Rayleigh Wave Driven Magneto-acoustic ResonanceInternational audienceThe resonant interaction of electrically excited traveling surface acoustic waves and magnetization has hitherto been probed through the acoustic component. In this work we investigated it using time-resolved magneto-optical detection of magnetization dynamics. To that end, we develop an experimental scheme where laser pulses are used both to generate the acoustic wave frequency and to probe magnetization dynamics, thus ensuring perfect phase locking. The light-polarization dependence of the signal enables us to disentangle elasto-optical and magneto-optical contributions and to obtain the in-plane and out-of-plane components of the magnetization dynamics. Magnetization precession is proven to be driven solely by the acoustic wave. Its amplitude is shown to resonate at the same field at which we detect piezoelectrically the resonant attenuation of the acoustic wave, clearly evidencing the magnetoacoustic resonance with high sensitivity

Nitrogen vacancy center in cubic silicon carbide : a promising qubit in the 1.5μm spectral range for photonic quantum networks

We have investigated the optical properties of the (NV)− center in 3C-SiC to determine the photoluminscence zero phonon line (ZPL) associated with the 3E→3A2 intracenter transition. Combining electron paramagnetic resonance and photoluminescence spectroscopy, we show that the NV−center in 3C-SiC has a ZPL line at 1.468 μm in excellent agreement with theoretical predictions. The ZPL line can be observed up to T=100 K. The negatively charged NV center in 3C-SiC is the structural isomorphe of the NV center in diamond and has equally a spin S=1 ground state and a spin S=1 excited state, long spin lattice relaxation times and presents optically induced groudstate spin polarization. These properties make it already a strong competitor to the NV center in diamond, but as its optical domain is shifted in the near infrared at 1.5μm, the NV center in 3C-SiC is compatible with quantum photonic networks and silicon based microelectronics.Published versio

Evidence for near-infrared photoluminescence of nitrogen vacancy centers in 4 H -SiC

International audienceWe present evidence of near-infrared photoluminescence (PL) signature of nitrogen vacancy centers (NCVSi)− in silicon carbide (SiC). This center exhibits an S=1 ground state spin similar to the NV− center in diamond. We have performed photoluminescence excitation measurements at cryogenic temperature and demonstrated efficient photoexcitation of distinct photoluminescence from (NCVSi)− in 4H-SiC. Furthermore, by correlating the energies of measured zero phonon lines (ZPLs) with theoretical values derived from hybrid density functional theory each of the ZPLs has been associated to the respective occupation of hexagonal (h) and quasicubic (k) lattice sites in close analogy to neutral divacancy centers (VCVSi)0 in the same material. Finally, with the appropriate choice of excitation energy we demonstrated the selective excitation of (NCVSi)− PL with no contamination by (VCVSi)0 PL, thereby opening the way towards the optical detection of (NCVSi)− electron spin resonance