TY - JOUR A1 - Kim, Seonghoon A1 - Zhang, Bo A1 - Wang, Zhaorong A1 - Fischer, Julian A1 - Brodbeck, Sebastian A1 - Kamp, Martin A1 - Schneider, Christian A1 - Höfling, Sven A1 - Deng, Hui T1 - Coherent Polariton Laser JF - Physical Review X N2 - The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices. KW - polariton laser KW - condensed matter physics KW - photonics KW - quantum physics KW - coherent light Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166597 VL - 6 IS - 011026 ER - TY - JOUR A1 - Zhao, Bo A1 - Zhang, Keya A1 - Bhuripanyo, Karan A1 - Choi, Chan Hee J. A1 - Villhauer, Eric B. A1 - Li, Heng A1 - Zheng, Ning A1 - Kiyokawa, Hiroaki A1 - Schindelin, Hermann A1 - Yin, Jun T1 - Profiling the Cross Reactivity of Ubiquitin with the Nedd8 Activating Enzyme by Phage Display JF - PLoS ONE N2 - The C-terminal peptides of ubiquitin (UB) and UB-like proteins (UBLs) play a key role in their recognition by the specific activating enzymes (E1s) to launch their transfer through the respective enzymatic cascades thus modifying cellular proteins. UB and Nedd8, a UBL regulating the activity of cullin-RING UB ligases, only differ by one residue at their C-termini; yet each has its specific E1 for the activation reaction. It has been reported recently that UAE can cross react with Nedd8 to enable its passage through the UB transfer cascade for protein neddylation. To elucidate differences in UB recognition by UAE and NAE, we carried out phage selection of a UB library with randomized C-terminal sequences based on the catalytic formation of UB similar to NAE thioester conjugates. Our results confirmed the previous finding that residue 72 of UB plays a "gate-keeping" role in E1 selectivity. We also found that diverse sequences flanking residue 72 at the UB C-terminus can be accommodated by NAE for activation. Furthermore heptameric peptides derived from the C-terminal sequences of UB variants selected for NAE activation can function as mimics of Nedd8 to form thioester conjugates with NAE and the downstream E2 enzyme Ubc12 in the Nedd8 transfer cascade. Once the peptides are charged onto the cascade enzymes, the full-length Nedd8 protein is effectively blocked from passing through the cascade for the critical modification of cullin. We have thus identified a new class of inhibitors of protein neddylation based on the profiles of the UB C-terminal sequences recognized by NAE. KW - protein NEDD8 KW - E1 KW - system KW - conjugation KW - pathway KW - complex KW - ligases KW - purification KW - neddylation KW - expression Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128479 SN - 1932-6203 VL - 8 IS - e70312 ER - TY - JOUR A1 - Song, Ning-Ning A1 - Xiu, Jian-Bo A1 - Huang, Ying A1 - Chen, Jia-Yin A1 - Zhang, Lei A1 - Gutknecht, Lise A1 - Lesch, Klaus Peter A1 - Li, He A1 - Ding, Yu-Qiang T1 - Adult Raphe-Specific Deletion of Lmx1b Leads to Central Serotonin Deficiency JF - PLoS ONE N2 - The transcription factor Lmx1b is essential for the differentiation and survival of central serotonergic (5-HTergic) neurons during embryonic development. However, the role of Lmx1b in adult 5-HTergic neurons is unknown. We used an inducible Cre-LoxP system to selectively inactivate Lmx1b expression in the raphe nuclei of adult mice. Pet1-CreER(T2) mice were generated and crossed with Lmx1b(flox/flox) mice to obtain Pet1-CreER(T2); Lmx1b(flox/flox) mice (which termed as Lmx1b iCKO). After administration of tamoxifen, the level of 5-HT in the brain of Lmx1b iCKO mice was reduced to 60% of that in control mice, and the expression of tryptophan hydroxylase 2 (Tph2), serotonin transporter (Sert) and vesicular monoamine transporter 2 (Vmat2) was greatly down-regulated. On the other hand, the expression of dopamine and norepinephrine as well as aromatic L-amino acid decarboxylase (Aadc) and Pet1 was unchanged. Our results reveal that Lmx1b is required for the biosynthesis of 5-HT in adult mouse brain, and it may be involved in maintaining normal functions of central 5-HTergic neurons by regulating the expression of Tph2, Sert and Vmat2. KW - Molecular-genetics KW - Sonic hedgehog KW - Neurons KW - Mice KW - Brain KW - Expression KW - System KW - PET-1 KW - Transporter KW - Disorders Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133581 VL - 6 IS - 1 ER -