Novel and sustainable carboxylation of terminal alkynes and CO2 to alkynyl carboxylic acids using triazolium ionic liquid-modified PMO-supported transition metal acetylacetonate as effective cooperative catalysts.

Efficient and sustainable chemical fixation of CO2 into value-added chemicals is one of the most promising objectives in environmental chemistry. In this work, transition metal acetylacetonate immobilized onto triazolium ionic liquid-modified periodic mesoporous organosilica PMO-IL-M(x) was successfully prepared and investigated as an effective and heterogeneous catalyst in the direct carboxylation of terminal alkynes and CO2 to the desired alkynyl carboxylic acids. It was found that the catalyst PMO-IL-Sn(0.3) exhibited extraordinary catalytic performance in terms of excellent activity, stability, productivity, and excellent yields under mild reaction conditions. Moreover, the catalyst PMO-IL-Sn(0.3) could be easily recovered and reused at least six times without considerable loss in catalytic activity. This work provides a sustainable and efficient synergistic strategy for the chemical fixation of carbon dioxide into valuable alkynyl carboxylic acids.

Carboxypeptidase E Regulates Activity-Dependent TrkB Neuronal Surface Insertion and Hippocampal Memory.

Activity-dependent insertion of the tropomyosin-related kinase B (TrkB) receptor into the plasma membrane can explain, in part, the preferential effect of brain-derived neurotrophic factor (BDNF) on active neurons and synapses; however, the underlying molecular mechanisms remain obscure. Here, we report a novel function for carboxypeptidase E (CPE) in controlling chemical long-term potentiation stimuli-induced TrkB surface delivery in hippocampal neurons. Total internal reflection fluorescence assays and line plot assays showed that CPE facilitates TrkB transport from dendritic shafts to the plasma membrane. The Box2 domain in the juxtamembrane region of TrkB and the C terminus of CPE are critical for the activity-dependent plasma membrane insertion of TrkB. Moreover, the transactivator of transcription TAT-CPE452-466, which could block the association between CPE and TrkB, significantly inhibited neuronal activity-enhanced BDNF signaling and dendritic spine morphologic plasticity in cultured hippocampal neurons. Microinfusion of TAT-CPE452-466 into the dorsal hippocampus of male C57BL/6 mice inhibited the endogenous interaction between TrkB and CPE and diminished fear-conditioning-induced TrkB phosphorylation, which might lead to an impairment in hippocampal memory acquisition and consolidation but not retrieval. These results suggest that CPE modulates activity-induced TrkB surface insertion and hippocampal-dependent memory and sheds light on our understanding of the role of CPE in TrkB-dependent synaptic plasticity and memory modulation.SIGNIFICANCE STATEMENT It is well known that BDNF acts preferentially on active neurons; however, the underlying molecular mechanism is not fully understood. In this study, we found that the cytoplasmic tail of CPE could interact with TrkB and facilitate the neuronal activity-dependent movement of TrkB vesicles to the plasma membrane. Blocking the association between CPE and TrkB decreased fear-conditioning-induced TrkB phosphorylation and led to hippocampal memory deficits. These findings provide novel insights into the role of CPE in TrkB intracellular trafficking as well as in mediating BDNF/TrkB function in synaptic plasticity and hippocampal memory.

[Effects of Solanum lycopersicum rootstock on biomass, amnio acid content and reactive oxygen species metabolism of grafted seedlings under salt stress]. / ç›èƒè¿«ä¸‹ç•ªèŒ„ç §æœ¨å¯¹å«æŽ¥è‹—ç”Ÿç‰©é‡ã€æ°¨åŸºé ¸å«é‡å’Œæ´»æ€§æ°§ä»£è°¢çš„å½±å“.

To explore the mechanism of Solanum lycopersicum rootstock function in enhancing salt tolerance of grafted seedlings, we examined the growth, Na+ accumulation, amino acid contents and active oxygen metabolism (ROS) in three grafted seedlings treated with and without 175 mmol·L-1 NaCl conditions. RS grafted seedlings were formed by split grafting using salt-sensitive variety 'Zhongza 9'(S) as scion and salt-tolerant variety 'OZ-006'(R) as rootstock, while the other two experiment materials were the scion self-grafted (SS) and rootstock self-grafted (RR) seedlings. The results showed that NaCl stress significantly increased the salt damage index and Na+ content, concomitantly with substantial decrease in growth rate and chlorophyll content of seedlings. More-over, there were significant differences among the grafting combinations, with an order of SS>RS>RR. NaCl stress significantly increased total amino acid content in the leaves and roots of the grafted seedlings. The amino acid contents were significantly higher than those in the control. There were 9 kinds of amino acid in RR and RS leaves, and 8 kinds in RR and RS roots, with the most significant change in proline. Only 2 and 4 kinds of amino acids in leaves and roots of SS were significantly higher than those in control, respectively. Amino acid contents among three grafted seedlings showed RR>RS>SS under NaCl stress. The contents of amino acid in RR and RS leaves increased by 32.8% and 16.6% compared with SS, and those in RR and RS roots increased by 53.1% and 32.5%, respectively. The changes of ROS were caused by NaCl stress, which enhanced the activities of antioxidant enzymes, the production rate of O2-· and MDA content in both leaves and roots. Among different grafted seedlings, RR had the most prominent increase of antioxidant enzymes activities in leaves and roots, followed by RS, and SS showed the smallest. The active oxygen levels among the three grafted seedlings were show as SS>RS>RR. In summary, rootstock alleviated salt damage of grafted seedlings by inhibiting Na+ transport upward, enhancing amino acid content and antioxidant enzyme activities. The salt tolerance ability showed remarkable difference among three different combinations of rootstock and scion, with a order of RR>RS>SS. Our results suggested that salt tolerance of S. lycopersicum grafted seedlings was mainly affected by the ability of rootstock salt tolerance, followed by scion, and also closely related to the regulation of both amino acid and active oxygen metabolism in seedlings.

Light affects salt stress-induced transcriptional memory of P5CS1 in Arabidopsis.

To cope with environmental stresses, plants often adopt a memory response upon primary stress exposure to facilitate a quicker and stronger reaction to recurring stresses. However, it remains unknown whether light is involved in the manifestation of stress memory. Proline accumulation is a striking metabolic adaptation of higher plants during various environmental stresses. Here we show that salinity-induced proline accumulation is memorable and HY5-dependent light signaling is required for such a memory response. Primary salt stress induced the expression of Δ1-pyrroline-5-carboxylate synthetase 1 (P5CS1), encoding a proline biosynthetic enzyme and proline accumulation, which were reduced to basal level during the recovery stage. Reoccurring salt stress-induced stronger P5CS1 expression and proline accumulation were dependent upon light exposure during the recovery stage. Further studies demonstrated that salt-induced transcriptional memory of P5CS1 is associated with the retention of increased H3K4me3 level at P5CS1 during the recovery stage. HY5 binds directly to light-responsive element, C/A-box, in the P5CS1 promoter. Deletion of the C/A-box or hy5 hyh mutations caused rapid reduction of H3K4me3 level at P5CS1 during the recovery stage, resulting in impairment of the stress memory response. These results unveil a previously unrecognized mechanism whereby light regulates salt-induced transcriptional memory via the function of HY5 in maintaining H3K4me3 level at the memory gene.

Biodegradation of Decabromodiphenyl Ether (BDE-209) by Crude Enzyme Extract from Pseudomonas aeruginosa.

The biodegradation effect and mechanism of decabromodiphenyl ether (BDE-209) by crude enzyme extract from Pseudomonas aeruginosa were investigated. The results demonstrated that crude enzyme extract exhibited obviously higher degradation efficiency and shorter biodegradation time than Pseudomonas aeruginosa itself. Under the optimum conditions of pH 9.0, 35 °C and protein content of 2000 mg/L, 92.77% of the initial BDE-209 (20 mg/L) was degraded after 5 h. A BDE-209 biodegradation pathway was proposed on the basis of the biodegradation products identified by GC-MS analysis. The biodegradation mechanism showed that crude enzyme extract degraded BDE-209 into lower brominated PBDEs and OH-PBDEs through debromination and hydroxylation of the aromatic rings.

[Influence of exogenous gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid contents in roots of melon seedling under hypoxia stress].

This paper investigated the influence of gamma-aminobutyric acid (GABA) on GABA metabolism and amino acid content under hypoxia stress by accurately controlling the level of dissolved oxygen in hydroponics, using the roots of melon 'Xiyu 1' seedlings as the test material. The results showed that compared with the control, the growth of roots was inhibited seriously under hypoxia stress. Meanwhile, the hypoxia-treated roots had significantly higher activities of glutamate decarboxylase (GAD), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST) as well as the contents of GABA, pyruvic acid, alanine (Ala) and aspartic acid (Asp). But the contents of glutamic acid (Glu) and alpha-keto glutaric acid in roots under hypoxia stress was obviously lower than those of the control. Exogenous treatment with GABA alleviated the inhibition effect of hypoxia stress on root growth, which was accompanied by an increase in the contents of endogenous GABA, Glu, alpha-keto glutaric acid and Asp. Furthermore, under hypoxia stress, the activities of GAD, GDH, GOGAT, GS, ALT, AST as well as the contents of pyruvic acid and Ala significantly decreased in roots treated with GABA. However, adding GABA and viny-gamma-aminobutyric acid (VGB) reduced the alleviation effect of GABA on melon seedlings under hypoxia stress. The results suggested that absorption of GABA by roots could alleviate the injury of hypoxia stress to melon seedlings. This meant that GABA treatment allows the normal physiological metabolism under hypoxia by inhibiting the GAD activity through feedback and maintaining higher Glu content as well as the bal- ance of carbon and nitrogen.

Simultaneous determination of 15 nitroimidazoles in cosmetics by HPLC coupled with electrospray ionization- tandem mass spectrometry.

A sensitive and reliable analytical method based on HPLC/MSIMS has been developed for the simultaneous determination of 15 nitroimidazoles in cosmetics. A diversity of cosmetic samples, including powder, lotion, shampoo, and cream were collected. The samples were ultrasonically extracted with aqueous methanol, and the extracts were then subjected to cleanup bySPE using an Oasis HLB cartridge followed by filtration with a 0.20 pm membrane filter. Afterwards, chromatographic separation was performed on an XSelect CSH C18 column (2.1 x 150 mm, 3.5 pm) maintained at 30°C within 15 min by a gradient of acetonitrile-0.1% aqueous formic acid solution at a flow rate of 0.25 mL/min. The mass spectrometric detection was carried, out using electrospray positive ionization under the multiple reaction monitoring mode. A good linearity was observed over the concentration range from 0.5 to 500 ng/mL. The intraday and interday precisions, which were investigated by determining all target compounds in cosmetics seven times/day and on 7 consecutive days, were below 5.00%. The mean recoveries at three spiked levels ranged from 80.42 to 100.83% with the RSDs from 0.45 to 9.02%. The LOQs were determined to be between 0.01 and 0.1 mg/kg. The method was sufficiently rapid, reliable, and sensitive for the determination of 15 nitroimidazoles in cosmetics.

[Effects of gamma-aminobutyric acid on the photosynthesis and chlorophyll fluorescence parameters of muskmelon seedlings under hypoxia stress].

By the method of hydroponic culture, this paper studied the effects of exogenous gamma-aminobutyric acid (GABA) on the photosynthetic pigment contents, photosynthesis, and chlorophyll fluorescence parameters of muskmelon seedlings under hypoxia stress. Hypoxia stress induced a significant decrease of photosynthetic pigment contents, resulting in the decrease of photosynthesis. Applying GABA could significantly increase the photosynthetic pigment contents, net photosynthetic rate (P(n)), stomatal conductance (G(s)), intercellular CO2 concentration (C(i)), carboxylation efficiency (CE), maximal photochemical efficiency of PS II (F(v)/F(m)), photochemical quenching (q(P)), apparent photosynthetic electron transfer rate (ETR), and quantum yield of PS II electron transport (phi(PS II)), and decrease the stomatal limitation value (L(s)), minimal fluorescence (F(o)), and non-photochemical quenching (NPQ) under both hypoxic and normal conditions. The alleviation effect of GABA on photosynthetic characteristics was more obvious under hypoxia stress. However, simultaneously applying GABA and VGB could significantly decrease the alleviation effect of GABA under hypoxia stress.