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1.
Langmuir ; 40(28): 14291-14302, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38950193

RESUMO

The key to enhancing water electrolysis efficiency lies in selecting highly efficient catalysts. Currently, high-entropy alloys (HEAs) are utilized in electrocatalysis applications owing to their diverse elemental composition, disordered elemental distribution, and the high solubility of each element, endowing them with excellent catalytic performance. The experiments were conducted using isoatomic FeNiCrMo HEA as a precursor, with a high-activity three-dimensional nanoporous structure rapidly synthesized via electrochemical one-step dealloying in a choline chloride-thiourea (ChCl-TU) deep eutectic solvent (DES). The results indicate that the dealloyed Fe20Co20Ni20Cr20Mo20 HEA mainly consists of two phases: face-centered cubic and σ phases. The imbalance in the distribution of elements in these two phases leads to quite different corrosion speeds with the FCC phase being preferentially corroded. Furthermore, synergistic electron coupling between surface atoms in the three-dimensional nanoporous structure strengthens the behavior of the oxygen evolution reaction (OER). At a current density of 40 mA cm-2, the overpotential after dealloying decreased to 370 mV, demonstrating excellent stability. The technique demonstrated in this work provides a novel approach to improve the catalytic activity of OER.

2.
Phys Chem Chem Phys ; 26(17): 12928-12938, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38456623

RESUMO

Copper has been shown to be an important substrate for the growth of borophenes. Copper-boron binary clusters are ideal platforms to study the interactions between copper and boron, which may provide insight about the underlying growth mechanisms of borophene on copper substrates. Here we report a joint photoelectron spectroscopy and theoretical study on two copper-doped boron clusters, CuB7- and CuB8-. Well resolved photoelectron spectra are obtained for the two clusters at different wavelengths and are used to understand the structures and bonding properties of the two CuBn- clusters. We find that CuB8- is a highly stable borozene complex, which possesses a half-sandwich structure with a Cu+ species interacting with the doubly aromatic η8-B82- borozene. The CuB7- cluster is found to consist of a terminal copper atom bonded to a double-chain B7 motif, but it has a low-lying isomer composed of a half-sandwich structure with a Cu+ species interacting with an open-shell η7-B72- borozene. Both ionic and covalent interactions are found to be possible in the binary Cu-B clusters, resulting in different structures.

3.
Phys Chem Chem Phys ; 26(6): 5356-5367, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38269413

RESUMO

Boron has been found to be able to form multiple bonds with lead. To probe Pb-B bonding, here we report an investigation of three Pb-doped boron clusters, PbB2-, PbB3O-, and PbB4O2-, which are produced by a laser ablation cluster source and characterized by photoelectron spectroscopy and ab initio calculations. The most stable structures of PbB2-, PbB3O-, and PbB4O2- are found to follow the formula, [PbB2(BO)n]- (n = 0-2), with zero, one, and two boronyl ligands coordinated to a triangular and aromatic PbB2 core, respectively. The PbB2- cluster contains a BB double bond and two Pb-B single bonds. The coordination of BO is observed to weaken Pb-B bonding but strengthen the BB bond in [PbB2(BO)n]- (n = 1, 2). The anionic [PbB2(BO)2]- and its corresponding neutral closed-shell [PbB2(BO)2] contain a BB triple bond. A low-lying Y-shaped isomer is also observed for PbB4O2-, consisting of a central sp2 hybridized B atom bonded to two boronyl ligands and a PbB unit.

4.
J Phys Chem A ; 128(18): 3564-3570, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38676655

RESUMO

Spontaneous symmetry-breaking is common in chemical and physical systems. Here, we show that by adding an electron to the C7v PbB8 cluster, which consists of a planar B8 disk with the Pb atom situated along the C7 axis, the Pb atom spontaneously moves to the off-axis position in the PbB8- anion. Photoelectron spectroscopy of PbB8- reveals a broad ground-state transition and a large energy gap, suggesting a highly stable closed-shell PbB8 borozene complex and a significant geometry change upon electron detachment. Quantum chemistry calculations indicate that the lowest unoccupied molecular orbital of the C7v PbB8 cluster is a degenerate π orbital mainly consisting of the Pb 6px and 6py atomic orbitals. Occupation of one of the 6p orbitals spontaneously break the C7v symmetry in the anion due to the Jahn-Teller effect. The large amplitude of the position change of Pb in PbB8- relative to PbB8 is surprising owing to bonding interactions between the Pb 6p orbital with the π orbital of the B8 borozene.

5.
Int J Neuropsychopharmacol ; 26(10): 680-691, 2023 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-37603290

RESUMO

BACKGROUND: Although depression has been a serious neuropsychiatric disorder worldwide, current antidepressants used in clinical practice have various weaknesses, including delayed onset and low rates of efficacy. Recently, the development of new antidepressants from natural herbal medicine has become one of the important research hotspots. Cucurbitacin B is a natural compound widely distributed in the Cucurbitaceae and Cruciferae families and has many pharmacological activities. The present study aimed to investigate whether cucurbitacin B possess antidepressant-like effects in mice. METHODS: The antidepressant-like effects of cucurbitacin B on mice behaviors were explored using the forced swim test, tail suspension test, open field test, sucrose preference test, and a chronic unpredictable mild stress model of depression together. Then, western blotting and immunofluorescence were used to examine the effects of cucurbitacin B on the brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling cascade and neurogenesis in the hippocampus of mice. Furthermore, BDNF-short hairpin RNA, K252a, and p-chlorophenylalanine methyl ester were adopted together to determine the antidepressant mechanism of cucurbitacin B. RESULTS: It was found that administration of cucurbitacin B indeed produced notable antidepressant-like effects in mice, which were accompanied with significant promotion in both the hippocampal BDNF-TrkB pathway and neurogenesis. The antidepressant mechanism of cucurbitacin B involves the hippocampal BDNF-TrkB system but not the serotonin system. CONCLUSIONS: Cucurbitacin B has the potential to be a novel antidepressant candidate.


Assuntos
Antidepressivos , Fator Neurotrófico Derivado do Encéfalo , Depressão , Animais , Humanos , Camundongos , Antidepressivos/farmacologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Depressão/tratamento farmacológico , Depressão/metabolismo , Modelos Animais de Doenças , Hipocampo , Estresse Psicológico/tratamento farmacológico , Estresse Psicológico/metabolismo
6.
Mol Psychiatry ; 2022 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-36434056

RESUMO

Elucidating the molecular mechanism underlying the hyperactivity of the hypothalamic-pituitary-adrenal axis during chronic stress is critical for understanding depression and treating depression. The secretion of corticotropin-releasing hormone (CRH) from neurons in the paraventricular nucleus (PVN) of the hypothalamus is controlled by salt-inducible kinases (SIKs) and CREB-regulated transcription co-activators (CRTCs). We hypothesised that the SIK-CRTC system in the PVN might contribute to the pathogenesis of depression. Thus, the present study employed chronic social defeat stress (CSDS) and chronic unpredictable mild stress (CUMS) models of depression, various behavioural tests, virus-mediated gene transfer, enzyme-linked immunosorbent assay, western blotting, co-immunoprecipitation, quantitative real-time reverse transcription polymerase chain reaction, and immunofluorescence to investigate this connection. Our results revealed that both CSDS and CUMS induced significant changes in SIK1-CRTC1 signalling in PVN neurons. Both genetic knockdown of SIK1 and genetic overexpression of CRTC1 in the PVN simulated chronic stress, producing a depression-like phenotype in naive mice, and the CRTC1-CREB-CRH pathway mediates the pro-depressant actions induced by SIK1 knockdown in the PVN. In contrast, both genetic overexpression of SIK1 and genetic knockdown of CRTC1 in the PVN protected against CSDS and CUMS, leading to antidepressant-like effects in mice. Moreover, stereotactic infusion of TAT-SIK1 into the PVN also produced beneficial effects against chronic stress. Furthermore, the SIK1-CRTC1 system in the PVN played a role in the antidepressant actions of fluoxetine, paroxetine, venlafaxine, and duloxetine. Collectively, SIK1 and CRTC1 in PVN neurons are closely involved in depression neurobiology, and they could be viable targets for novel antidepressants.

7.
J Phys Chem A ; 127(22): 4888-4896, 2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37235389

RESUMO

Copper has been found to be able to mediate the formation of bilayer borophenes. Copper-boron binary clusters are ideal model systems to probe the copper-boron interactions, which are essential to understand the growth mechanisms of borophenes on copper substrates. Here, we report a joint photoelectron spectroscopy and theoretical study on two di-copper-doped boron clusters: Cu2B3- and Cu2B4-. Well-resolved photoelectron spectra are obtained, revealing the presence of a low-lying isomer in both cases. Theoretical calculations show that the global minimum of Cu2B3- (C2v, 1A1) contains a doubly aromatic B3- unit weakly interacting with a Cu2 dimer, while the low-lying isomer (C2v, 1A1) consists of a B3 triangle with the two Cu atoms covalently bonded to two B atoms at two vertexes. The global minimum of Cu2B4- (D2h, 2Ag) is found to consist of a rhombus B4 unit covalently bonded to the two Cu atoms at two opposite vertexes, whereas in the low-lying isomer (Cs, 2A'), one of the two Cu atoms is bonded to two B atoms.

8.
J Chem Phys ; 159(11)2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37712786

RESUMO

We report a study on the electronic structure and chemical bonding of the BiB molecule using high-resolution photoelectron imaging of cryogenically cooled BiB- anion. By eliminating all the vibrational hot bands, we can resolve the complicated detachment transitions due to the open-shell nature of BiB and the strong spin-orbit coupling. The electron affinity of BiB is measured to be 2.010(1) eV. The ground state of BiB- is determined to be 2Π(3/2) with a σ2π3 valence electron configuration, while the ground state of BiB is found to be 3Σ-(0+) with a σ2π2 electron configuration. Eight low-lying spin-orbit excited states [3Σ-(1), 1Δ(2), 1Σ+(0+), 3Π(2), 3Π(1), 1Π(1)], including two forbidden transitions, [3Π(0-) and 3Π(0+)], are observed for BiB as a result of electron detachment from the σ and π orbitals of BiB-. The angular distribution information from the photoelectron imaging is found to be critical to distinguish detachment transitions from the σ or π orbital for the spectral assignment. This study provides a wealth of information about the low-lying electronic states and spin-orbit coupling of BiB, demonstrating the importance of cryogenic cooling for obtaining well-resolved photoelectron spectra for size-selected clusters produced from a laser vaporization cluster source.

9.
BMC Cancer ; 21(1): 704, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34130659

RESUMO

BACKGROUND: Our previous studies have reported the down-regulation of EGFL8 correlates to the development and prognosis of colorectal and gastric cancer. The present study is carried out to explore the expression pattern and role of EGFL8 in hepatocellular carcinoma (HCC). METHODS AND MATERIALS: EGFL8 expression in 102 cases of HCC tissues matched with adjacent non-tumorous liver tissues, a normal liver cell line and three liver cancer cell lines with different metastatic capacity was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot. Moreover, the clinicopathological features and prognosis of HCC patients were correlated with expression of EGFL8. Subsequently, the gain-and loss-of-function experiments were carried out to investigate the biological function of EGFL8 in HCC. We also used N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-(S)- phenylglycine t-butyl ester (DAPT), an inhibitor for Notch signaling pathway, in these experiments to verify the involvement of Notch signaling pathway in the effects of EGFL8. Additionally, a mouse model was established to investigate the effect of EGFL8 on metastasis of HCC cells. The expression of Notch signaling pathway in HCC cells and xenograft mouse tumors were detected by Western blot and immunohistochemistory. RESULTS: The expression of EGFL8 was significantly decreased in HCC tissues and cell lines and EGFL8 down-regulation correlated to multiple nodules, vein invasion, high TNM stage and poor prognosis of HCC. Interestingly, the expression levels of EGFL8 in three liver cancer cell lines were negatively associated with their metastatic capacity. In vitro and in vivo experiments indicated that EGFL8 obviously suppressed metastasis and invasion of HCC cells but slightly promoted apoptosis. Meanwhile, the expression of Notch signaling pathway was obviously suppressed in EGFL8 overexpressed HCCLM3 cells and xenograft mouse tumors generated from these cells but markedly elevated in EGFL8 depleted Hep3B cells. Furthermore, the up-regulated expression of Notch signaling pathway and effects induced by EGFL8 knockdown in Hep3B cells could be counteracted by DAPT treatment. CONCLUSION: The down-regulation of EGFL8 was correlated to progression and poor prognosis of HCC and regulates HCC cell migration, invasion and apoptosis through activating the Notch signaling pathway, suggesting EGFL8 as a novel therapeutic target and a potential prognostic marker for HCC.


Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Carcinoma Hepatocelular/genética , Família de Proteínas EGF/metabolismo , Neoplasias Hepáticas/genética , Receptores Notch/genética , Idoso , Animais , Apoptose , Carcinoma Hepatocelular/patologia , Movimento Celular , Modelos Animais de Doenças , Regulação para Baixo , Humanos , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Invasividade Neoplásica , Transdução de Sinais , Transfecção
10.
J Phys Chem A ; 125(21): 4606-4613, 2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34014680

RESUMO

The strong relativistic effects result in many interesting chemical and physical properties for gold and gold compounds. One of the most surprising findings has been that small gold clusters prefer planar structures. Dopants can be used to tune the electronic and structural properties of gold nanoclusters. Here we report an experimental and theoretical investigation of a Zn-doped gold cluster, Au9Zn-. Photoelectron spectroscopy reveals that Au9Zn- is a highly stable electronic system with an electron binding energy of 4.27 eV. Quantum chemical studies show that the global minimum of Au9Zn- has a D3h structure with a closed-shell electron configuration (1A1'), which can be viewed as replacing the central Au atom by Zn in the open-shell parent Au10- cluster. The high electronic stability of Au9Zn- is corroborated by its extremely large HOMO-LUMO gap of 3.3 eV. Chemical bonding analyses revealed that the D3h Au9Zn- are bonded by two sets of delocalized σ bonds, giving rise to double σ aromaticity and its remarkable stability. Two planar low-lying isomers are also observed, corresponding to a similar triangular structure with the Zn atom on the edge and another one with one of the corner Au atoms moved to the edge of the triangle.

11.
J Phys Chem A ; 125(31): 6751-6760, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34333984

RESUMO

Because of its low toxicity, bismuth is considered to be a "green metal" and has received increasing attention in chemistry and materials science. To understand the chemical bonding of bismuth, here we report a joint experimental and theoretical study on a series of bismuth-doped boron clusters, BiBn- (n = 6-8). Well-resolved photoelectron spectra are obtained and are used to understand the structures and bonding of BiBn- in conjunction with theoretical calculations. Global minimum searches find that all three BiBn- clusters have planar structures with the Bi atom bonded to the edge of the planar Bn moiety via two Bi-B σ bonds as well as π bonding by the 6pz orbital. BiB6- is found to consist of a double-chain B6 with a terminal Bi atom. Both BiB7- and BiB8- are composed of a Bi atom bonded to the planar global minima of the B7- and B8- clusters. Chemical bonding analyses reveal that BiB6- is doubly antiaromatic, whereas BiB7- and BiB8- are doubly aromatic. In the neutral BiBn (n = 6-8) clusters, except BiB6 which has a planar structure similar to the anion, the global minima of both BiB7 and BiB8 are found to be half-sandwich-type structures due to the high stability of the doubly aromatic B73- and B82- molecular wheel ligands.

12.
J Phys Chem A ; 125(12): 2622-2630, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33739102

RESUMO

Inverse-sandwich structures have been observed recently for dilanthanide boride clusters, in which two Ln atoms sandwich a monocyclic Bx ring for x = 7-9. An interesting question is if larger Bx rings are possible to form such inverse-sandwich clusters. Here we address this question by investigating La2B10- and La2B11- using photoelectron spectroscopy and ab initio quantum chemical calculations. Photoelectron spectra of La2B10- and La2B11- show complicated, but well-resolved, spectral features that are used to compare with theoretical calculations. We have found that global minimum structures of the two clusters are based on the octa-boron ring. The global minimum of La2B10- consists of two chiral enantiomers with C1 symmetry, which can be viewed as adding a B2 unit off-plane to the B8 ring, whereas that of La2B11- can be viewed as adding a B3 unit in-plane to the B8 ring in a second coordination shell. Chemical bonding analyses reveal localized B-B bonds on the edge of the clusters and delocalized bonds in the expanded boron frameworks. The interactions between the La atoms and the boron frameworks include the unique (d-p)δ bonding, which was found to be the key for inverse-sandwich complexes with monocyclic boron rings. The current study confirms that the largest monocyclic boron ring to form the inverse-sandwich structures is B9 and provide insights into the structural evolutions of larger lanthanide boride clusters.

13.
J Headache Pain ; 22(1): 38, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34000998

RESUMO

OBJECTIVES: In this study, we investigated the possible analgesic effects of Botulinum toxin type A (BoNT/A) on trigeminal neuralgia (TN). A modified TN mouse model was established by chronic constriction injury of the distal infraorbital nerve (dIoN-CCI) in mice, and the possible roles of microglia toll-like receptor 2 (TLR2) and neuroinflammation was investigated. METHODS: Male C57BL/6 mice were divided into 3 groups, including sham group, vehicle-treated TN group and BoNT/A-treated TN group. Bilateral mechanical pain hypersensitivity, anxiety-like and depressive-like behaviors were evaluated by using von Frey test, open field, elevated plus-maze testing, and forced swimming test in mice, respectively. The mRNA or protein expression levels of toll-like receptors (TLRs), glia activation markers and proinflammatory factors in the trigeminal nucleus caudalis (TNC) were tested by RT-qPCR, immunofluorescence and Western blotting. We also tested the pain behaviors of TN in Tlr2-/- mice. RESULTS: We found that unilateral subcutaneous injection of BoNT/A into the whisker pad on the ipsilateral side of dIoN-CCI mice significantly attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors induced by dIoN-CCI surgery in mice. The dIoN-CCI surgery significantly up-regulated the expression of TLR2, MyD88, CD11b (a microglia marker), IL-1ß, TNF-α and IL-6 in the ipsilateral TNC in mice, and BoNT/A injection significantly inhibited the expression of these factors. Immunostaining results confirmed that BoNT/A injection significantly inhibited the microglia activation in the ipsilateral TNC in dIoN-CCI mice. TLR2 deficiency also alleviated bilateral mechanical pain hypersensitivity and the up-regulation of MyD88 expression in the TNC of dIoN-CCI mice. CONCLUSION: These results indicate that unilateral injection of BoNT/A attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors in dIoN-CCI mice, and the analgesic effects of BoNT/A may be associated with the inhibition of TLR2-mediated neuroinflammation in the TNC.


Assuntos
Toxinas Botulínicas Tipo A , Neuralgia , Neuralgia do Trigêmeo , Animais , Ansiedade/tratamento farmacológico , Toxinas Botulínicas Tipo A/uso terapêutico , Hiperalgesia/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neuralgia/tratamento farmacológico , Ratos , Ratos Sprague-Dawley , Receptor 2 Toll-Like/genética , Neuralgia do Trigêmeo/tratamento farmacológico
14.
Zhongguo Zhong Yao Za Zhi ; 46(14): 3678-3686, 2021 Jul.
Artigo em Zh | MEDLINE | ID: mdl-34402292

RESUMO

This study aimed to investigate the antidepressant effects of total alkaloids of Fibraurea recisa in HT22 cells damaged by corticosterone (CORT) in vitro and in a mouse model of chronic unpredictable mild stress (CUMS) as well as the underlying mechanisms.In cellular experiments,the viability of CORT-damaged HT22 cells was detected using cell counting kit-8 (CCK-8),and the cell apoptosis was detected by Hoechst 33258 staining.In animal experiments,C57BL/6N mice were randomly divided into the control group,model group,low (100 mg·kg~(-1)),medium (200 mg·kg~(-1)) and high (400 mg·kg~(-1))-dose of total alkaloids of F.recisa groups,and positive control group.After 21 days of CUMS exposure,their depressive behaviors were observed in behavioral and Morris water maze tests.The serum levels of 5-hydroxytryptamine (5-HT),dopamine (DA),and norepinephrine (NE) were assessed by ELISA.The expression levels of apoptosis-related proteins Bcl-2,Bax and cleaved caspase-3 in HT22 cells and mouse hippocampus were detected by Western blot.The results suggested that total alkaloids of F.recisa alleviated the damage of HT22 cells induced by CORT in a dose-dependent manner.The Hoechst 33258 staining uncovered that total alkaloids of F.recisa better reduced the blue spots and inhibited cell apoptosis.The results of animal experiments showed that total alkaloids of F.recisa significantly improved the depression-like behaviors of mice and increased the serum levels of 5-HT,DA and NE as compared with those in the model group.The Western blot assays revealed a significant up-regulation of Bcl-2 protein expression,but an obvious reduction in Bax and cleaved caspase-3protein expression in the total alkaloids of F.recisa group.In conclusion,total alkaloids of F.recisa inhibited depression possibly by regulating the apoptosis-related protein expression or elevating the monoamine neurotransmitter levels in the brain.


Assuntos
Alcaloides , Depressão , Alcaloides/farmacologia , Animais , Antidepressivos/farmacologia , Depressão/tratamento farmacológico , Modelos Animais de Doenças , Hipocampo , Camundongos , Camundongos Endogâmicos C57BL , Estresse Psicológico
15.
Angew Chem Int Ed Engl ; 59(35): 15260-15265, 2020 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-32424965

RESUMO

Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal dπ →BR back-donation, despite the electron deficiency of boron. An electron-precise metal-boron triple bond was first observed in BiB2 O- [Bi≡B-B≡O]- in which both boron atoms can be viewed as sp-hybridized and the [B-BO]- fragment is isoelectronic to a carbyne (CR). To search for the first electron-precise transition-metal-boron triple-bond species, we have produced IrB2 O- and ReB2 O- and investigated them by photoelectron spectroscopy and quantum-chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB2 O- has a closed-shell bent structure (Cs , 1 A') with BO- coordinated to an Ir≡B unit, (- OB)Ir≡B, whereas ReB2 O- is linear (C∞v , 3 Σ- ) with an electron-precise Re≡B triple bond, [Re≡B-B≡O]- . The results suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems.

16.
Chem Rev ; 117(2): 860-898, 2017 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-28072519

RESUMO

Photosynthesis begins when a network of pigment-protein complexes captures solar energy and transports it to the reaction center, where charge separation occurs. When necessary (under low light conditions), photosynthetic organisms perform this energy transport and charge separation with near unity quantum efficiency. Remarkably, this high efficiency is maintained under physiological conditions, which include thermal fluctuations of the pigment-protein complexes and changing local environments. These conditions introduce multiple types of heterogeneity in the pigment-protein complexes, including structural heterogeneity, energetic heterogeneity, and functional heterogeneity. Understanding how photosynthetic light-harvesting functions in the face of these fluctuations requires understanding this heterogeneity, which, in turn, requires characterization of individual pigment-protein complexes. Single-molecule spectroscopy has the power to probe individual complexes. In this review, we present an overview of the common techniques for single-molecule fluorescence spectroscopy applied to photosynthetic systems and describe selected experiments on these systems. We discuss how these experiments provide a new understanding of the impact of heterogeneity on light harvesting and thus how these systems are optimized to capture sunlight under physiological conditions.


Assuntos
Fotossíntese , Espectrometria de Fluorescência/métodos , Pigmentos Biológicos/química , Proteínas/química
17.
J Phys Chem A ; 123(25): 5317-5324, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31204479

RESUMO

Transition-metal-centered monocyclic boron wheel clusters (M©B n q) represent a family of interesting borometallic compounds with double aromaticity. A variety of early and late transition metal atoms have been found to form such structures with high symmetries and various B n ring sizes. Here we report a combined photoelectron spectroscopy and quantum-chemistry theoretical study of two M©B n- clusters from the middle of the transition metal series: Re©B8- and Re©B9-. Global minimum structure searches revealed that ReB8- adopts a pseudo- C8 v structure while ReB9- is a perfectly planar D9 h molecular wheel. Chemical bonding analyses showed that both clusters exhibit σ and π double aromaticity and obey the electronic design principle for metal-centered borometallic molecular wheels. The central Re atoms are found to possess unusually low oxidation states of +I in Re©B8- and +II in Re©B9-, i.e., the Re atom behaves similarly to late transition metal elements (Ru, Fe, Co, Rh, Ir) in the M©B n- molecular wheels. These two clusters become new members of the family of transition-metal-centered monocyclic borometallic molecular wheels, which may be viable for chemical syntheses with appropriate ligands.

19.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(4): 956-60, 2015 Apr.
Artigo em Japonês | MEDLINE | ID: mdl-26197582

RESUMO

A stable mouse model of hyperuricemia was established by intraperitoneal injection of xanthine and oxonate, comparing the water extracts (containing crude drug 360 mg · mL(-1)) of Ermiao pill categorized formula (The ratio of atractylodes lancea to cortex phellodendri was 1:1, 1:2 and 2:1, respectively) and Ermiao pill (360 mg · mL(-1)) administered to different groups of animals continuously for two weeks and assessing the protection or treatment of drug on hyperuricemia. The xanthine oxidase (XOD) activities in serum and liver were detected by ultraviolet-visible spectroscopy at 570 nm wavelength, The results showed that as compared with each group, the XOD activity of the model group was significantly increased in serum (p < 0.01), XOD activity showed no significant difference in liver (p > 0.05), but compared with the model group, the XOD activity of each treatment group was significantly lower in serum and liver (p < 0.01), especially for the group treated with Ermiao pill categorized formula with the ratio of Atractylodes lancea to Cortex Phellodendri being 1:2. The morphological changes of glomerular and tubular interstitial fibrosis were measured by Hematoxylin-eosin staining (HE staining) and Masson trichrome staining (Masson staining)for kidney paraffin sections. The results showed that the glomerular atrophy, vascular loops confusion, a certain degree of inflammatory cell infiltration, interstitial fibrosis and other phenomena appeared in the model group. Compared to model group, these pathological phenomena of the treatment groups were significantly improved. The area showed that compared with each group, the fibrosis of the model group was significantly increased (p < 0.01 or p < 0.05), but compared with Ermiao pill categorized formula, the differences for the group of Ermiao pill was lower (p < 0.01), especially for the group treated with Ermiao pill categorized formula with the ratio of Atractylodes lancea to Cortex Phellodendri being 1 : 2. In this experiment, the damage of kidney and XOD activity serve as the index to evaluate the protection or treatment of drug on hyperuricemia, providing a scientific basis for the development of Ermiao pill categorized formula.


Assuntos
Medicamentos de Ervas Chinesas/uso terapêutico , Hiperuricemia/tratamento farmacológico , Animais , Modelos Animais de Doenças , Rim/patologia , Fígado/enzimologia , Camundongos , Ratos , Xantina Oxidase/sangue , Xantina Oxidase/metabolismo
20.
Pharmacol Biochem Behav ; 242: 173820, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38996926

RESUMO

BACKGROUND: Emerging data has demonstrated that in mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Thus, it is possible that SorCS2 plays a role in the pathophysiology of depression by regulating the BDNF-TrkB system. METHODS: In the present study, SorCS2 expression in different brain regions [hippocampus, medial prefrontal cortex (mPFC), hypothalamus, amygdala, ventral tegmental area (VTA), and nucleus accumbens (NAc)] was thoroughly investigated in the chronic social defeat stress (CSDS) and chronic unpredictable mild stress (CUMS) models of depression. The changes in depressive-like behaviors, the hippocampal BDNF signaling cascade, and amounts of hippocampal immature neurons were further investigated after SorCS2 overexpression by microinjection of the adenovirus associated virus vector containing the coding sequence of mouse SorCS2 (AAV-SorCS2) into the hippocampus of mice exposed to CSDS or CUMS. RESULTS: It was found that both CSDS and CUMS significantly decreased the protein and mRNA expression of SorCS2 in the hippocampus but not in other brain regions. Chronic stress also notably downregulated the level of hippocampal SorCS2-TrkB binding in mice. In contrast, AAV-based genetic overexpression of hippocampal SorCS2 fully reversed the chronic stress-induced not only depressive-like behaviors but also decreased SorCS2-TrkB binding, BDNF signaling pathway, and amounts of immature neurons in the hippocampus of mice. CONCLUSION: All these results suggest that enhancing the hippocampal SorCS2 expression protects against chronic stress, producing antidepressant-like actions. Hippocampal SorCS2 may participate in depression neurobiology and be a potential antidepressant target. SIGNIFICANCE STATEMENT: Targeting of proteins to distinct subcellular compartments is essential for neuronal activity and modulated by VPS10P domain receptors which include SorCS2. In mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Our study is the first direct evidence preliminarily showing that SorCS2 plays a role in depression neurobiology. It was found that chronic stress induced not only depressive-like behaviors but also decreased SorCS2 expression in the hippocampus. Chronic stress did not affect SorCS2 expression in the mPFC, hypothalamus, amygdala, VTA, or NAc. In contrast, genetic overexpression of hippocampal SorCS2 prevented against chronic stress, producing antidepressant-like actions in mice. Thus, hippocampal SorCS2 is a potential participant underlying depression neurobiology and may be a novel antidepressant target. Our study may also extend the knowledge of the neurotrophic hypothesis of depression.


Assuntos
Fator Neurotrófico Derivado do Encéfalo , Depressão , Hipocampo , Camundongos Endogâmicos C57BL , Receptor trkB , Estresse Psicológico , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Fator Neurotrófico Derivado do Encéfalo/genética , Hipocampo/metabolismo , Estresse Psicológico/metabolismo , Camundongos , Masculino , Receptor trkB/metabolismo , Depressão/metabolismo , Transdução de Sinais , Modelos Animais de Doenças , Comportamento Animal , Proteínas Tirosina Quinases/metabolismo , Proteínas Tirosina Quinases/genética , Neurônios/metabolismo
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