Synthesis of 1d,e; To a solution of 2-(9-phenanthrenyl)phenol or 2-(9anthracenyl)phenol (25 mmol) and 2,6-lutidine (4.6 g, 43 mmol) in toluene (50 mL) under an atmosphere of Ar was slowly added SnCl 4 (0.75 mL, 6.4 mmol). The solution was stirred at rt for 20 min. Paraformaldehyde was added (4.3 g, 140 mmol) and the reaction was stirred at 1 10C for 12 h. After cooling to rt, the reaction mixture was poured into water (300 mL), acidified to pH 1 with concentrated HCI, extracted with diethyl ether (500 mL), separated, the combined organic layers washed twice with sat. brine, and dried over Na 2 SO 4. The solvent was removed by rotary evaporation to yield a yellow oil. The crude product was purified by flash chromatography on silica gel eluting with hexanes:ethyl acetate (9:1) to yield a white solid.

When brassinosteroid (BR) levels are low, the GSK3-like kinase BIN2 phosphorylates and inactivates the BZR1 transcription factor to inhibit growth in plants. BR promotes growth by inducing dephosphorylation of BZR1, but the phosphatase that dephosphorylates BZR1 has remained unknown. Here we identified protein phosphatase 2A (PP2A) as BZR1-interacting proteins using tandem affinity purification. Genetic analyses demonstrated a positive role of PP2A in BR signalling and BZR1 dephosphorylation. Members of the B'regulatory subunits of PP2A directly interact with BZR1's putative PEST domain containing the site of the bzr1-1D mutation. Interaction with and dephosphorylation by PP2A are enhanced by the bzr1-1D mutation, reduced by two intragenic bzr1-1D suppressor mutations, and abolished by deletion of the PEST domain. This study reveals a crucial function of PP2A in dephosphorylating and activating BZR1 and completes the set of core components of the BR-signalling cascade from cell surface receptor kinase to gene regulation in the nucleus.

A 2D atomic-layer-thickness phototransistor based on a graphene-MoS2 bybrid device is constructed with a photoresponse much larger than that of individual graphene or MoS2 based phototransistors. Strong and selective light absorption in the MoS2 layer creates electric charges that are transferred to graphene layers derived by a build-in electrical field, where they recirculate many times due to the high carrier mobility of graphene. Gate tunable Fermi level in graphene layer allows the responsivity of this hybrid phototransistor to be continuously tuned from 0 to about 10(4) mA/W by the gate voltage. Furthermore, large scale, flexible, and transparent 2D phototransistors with high responsivity are constructed from the CVD-grown graphene and MoS2 flakes. The high responsivity, gate-tunable sensitivity, wavelength selectivity, and compatibility with current circuit technologies of this type device give it great potential for future application in integrated nano-optoelectronic systems.

Plant growth and development are coordinated by several groups of small-molecule hormones, including brassinosteroids (BRs) and gibberellins (GAs). Physiological and molecular studies have suggested the existence of crosstalk between BR and GA signaling. We report that BZR1, a key transcription factor activated by BR signaling, interacts in vitro and in vivo with REPRESSOR OF ga1-3 (RGA), a member of the DELLA family of transcriptional regulators that inhibits the GA signaling pathway in Arabidopsis thaliana. Genetic analyses of plants with mutations in the genes encoding RGA and BZR1 revealed that RGA suppressed root and hypocotyl elongation of the gain-of-function mutant bzr1-1D. Ectopic expression of proteins of the DELLA family reduced the abundance and transcriptional activity of BZR1. Reporter gene analyses further indicated that BZR1 and RGA antagonize each other's transcriptional activity. Our data indicated that BZR1 and RGA served as positive and negative regulators, respectively, of both the BR and the GA signaling pathways and establish DELLAs as mediators of signaling crosstalk between BRs and GAs in controlling cell elongation and regulation of plant growth.

No abstract