Development and function of the midbrain dopamine system: what we know and what we need to

The past two decades have seen an explosion in our understanding of the origin and development of the midbrain dopamine system. Much of this work has been focused on the aspects of dopamine neuron development related to the onset of movement disorders such as Parkinson's disease, with the intent of hopefully delaying, preventing or fixing symptoms. While midbrain dopamine degeneration is a major focus for treatment and research, many other human disorders are impacted by abnormal dopamine, including drug addiction, autism and schizophrenia. Understanding dopamine neuron ontogeny and how dopamine connections and circuitry develops may provide us with key insights into potentially important avenues of research for other dopamine‐related disorders. This review will provide a brief overview of the major molecular and genetic players throughout the development of midbrain dopamine neurons and what we know about the behavioral‐ and disease‐related implications associated with perturbations to midbrain dopamine neuron development. We intend to combine the knowledge of two broad fields of neuroscience, both developmental and behavioral, with the intent on fostering greater discussion between branches of neuroscience in the service of addressing complex cognitive questions from a developmental perspective and identifying important gaps in our knowledge for future study.     

Chlorophyll a is the crucial redox sensor and transmembrane signal transmitter in the cytochrome b6f complex. Components and mechanisms of state transitions from the hydrophobic mismatch viewpoint

The cytochrome (cyt) b₆f complex is involved in the transmembrane redox signaling that triggers state transitions in cyanobacteria and chloroplasts. However, the components and molecular mechanisms are still unclear. In an attempt to solve this long-standing problem, we first focused on the unknown role of a single chlorophyll a (Chla) in cyt b₆f with a new approach based on Chla structural properties. Various b₆f X-ray crystal structures were analyzed to identify their differences, which correlate with differences in Chla molecular volume. We found that the distance of the Rieske [2Fe-2S] cluster to Chla correlates with the distance between a pair of residues at the Q_o-site and the distance between a pair of residues at the opposite membrane side. These correlations were accompanied by the rotation of a key peripheral residue and by changes in the hydrophobic thickness of cyt b₆f. Parallel analysis of cyt bc₁ crystal structures allowed us to conclude that Chla acts as the crucial redox sensor and transmembrane signal transmitter in b₆f for changes in the plastoquinone pool redox state. The hydrophobic mismatch induced by the changed hydrophobic thickness of cyt b₆f is the driving force for the structural reorganizations of the photosynthetic apparatus during induction and the progression of state transitions in cyanobacteria and chloroplasts. A mechanism for LHCII kinase activation in chloroplasts is also proposed. Our understanding of the dynamic structural changes in bc-complexes during turnover at the Q_o-site and state transitions is augmented by the time-sequence ordering of 56 bc crystal structures.     

Comparative analyses of quaternary arrangements in homo‐oligomeric proteins in superfamilies: Functional implications

A comprehensive analysis of the quaternary features of distantly related homo‐oligomeric proteins is the focus of the current study. This study has been performed at the levels of quaternary state, symmetry, and quaternary structure. Quaternary state and quaternary structure refers to the number of subunits and spatial arrangements of subunits, respectively. Using a large dataset of available 3D structures of biologically relevant assemblies, we show that only 53% of the distantly related homo‐oligomeric proteins have the same quaternary state. Considering these homologous homo‐oligomers with the same quaternary state, conservation of quaternary structures is observed only in 38% of the pairs. In 36% of the pairs of distantly related homo‐oligomers with different quaternary states the larger assembly in a pair shows high structural similarity with the entire quaternary structure of the related protein with lower quaternary state and it is referred as “Russian doll effect.” The differences in quaternary state and structure have been suggested to contribute to the functional diversity. Detailed investigations show that even though the gross functions of many distantly related homo‐oligomers are the same, finer level differences in molecular functions are manifested by differences in quaternary states and structures. Comparison of structures of biological assemblies in distantly and closely related homo‐oligomeric proteins throughout the study differentiates the effects of sequence divergence on the quaternary structures and function. Knowledge inferred from this study can provide insights for improved protein structure classification and function prediction of homo‐oligomers. Proteins 2016; 84:1190–1202. © 2016 Wiley Periodicals, Inc.     

8种绿化树种光合特性及叶片解剖结构比较

城市绿化不仅包含了园林绿化的美化作用,还具有重要的生态功能,其生态功能是通过植物的生理活动实现的。光合能力在种间和基因型间的变化很大,这些差异通常与代谢和(或)叶片的解剖结构的性质有关。本研究选择8种哈尔滨常见树种,采用Li-6400便携式光合测定系统对叶净光合速率(P_n)、呼吸速率(R_d)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO_2浓度(C_i)等进行测定,并利用显微镜观察测定叶片厚度、表皮厚度、栅栏组织厚度、海绵组织厚度,从而探讨叶片结构对光合生理的影响。结果表明:8个树种间叶片最大光合速率、气孔导度、胞间CO_2浓度、蒸腾速率、光饱和点差异显著(P <0.05);表皮厚度、栅栏组织厚度、上表皮气孔密度和下表皮气孔密度差异显著(P <0.05)。虽然8个树种间光合能力和叶片解剖结构的差异较大,但分析发现其间也存在一定的相关性。其中,光饱和点与叶表皮厚度显著正相关(P <0.01),相关系数为0.78。胞间CO_2浓度与上表皮气孔密度显著负相关(P <0.05),相关系数为-0.65。而最大光合速率、呼吸速率、蒸腾速率和光补偿点与表皮厚度、栅栏组织厚度、海绵组织厚度、上表皮气孔密度和下表皮气孔密度相关均不显著(P> 0.05)。胞间CO_2浓度与表皮厚度、栅栏组织厚度、海绵组织厚度和下表皮气孔密度相关均不显著(P> 0.05)。光饱和点与栅栏组织厚度、海绵组织厚度、上表皮气孔密度和下表皮气孔密度相关均不显著(P> 0.05)。虽然对叶片结构对生理过程的影响的机理还需要进一步研究,但是我们认为叶片解剖结构的研究可以更好地理解生理指标的变化。     

Twist and Degrade—Impact of Molecular Structure on the Photostability of Nonfullerene Acceptors and Their Photovoltaic Blends

Nonfullerene acceptors (NFAs) dominate organic photovoltaic (OPV) research due to their promising efficiencies and stabilities. However, there is very little investigation into the molecular processes of degradation, which is critical to guiding design of novel NFAs for long‐lived, commercially viable OPVs. Here, the important role of molecular structure and conformation in NFA photostability in air is investigated by comparing structurally similar but conformationally different promising NFAs: planar O‐IDTBR and nonplanar O‐IDFBR. A three‐phase degradation process is identified: i) initial photoinduced conformational change (i.e., torsion about the core–benzothiadiazole dihedral), induced by noncovalent interactions with environmental molecules, ii) followed by photo‐oxidation and fragmentation, leading to chromophore bleaching and degradation product formation, and iii) finally complete chromophore bleaching. Initial conformational change is a critical prerequisite for further degradation, providing fundamental understanding of the relative stability of IDTBR and IDFBR, where the already twisted IDFBR is more prone to degradation. When blended with the donor polymer poly(3‐hexylthiophene), both NFAs exhibit improved photostability while the photostability of the polymer itself is significantly reduced by the more miscible twisted NFA. The findings elucidate the important role of NFA molecular structure in photostability of OPV systems, and provide vital insights into molecular design rules for intrinsically photostable NFAs.     

Rational Design of Hierarchical “Ceramic‐in‐Polymer” and “Polymer‐in‐Ceramic” Electrolytes for Dendrite‐Free Solid‐State Batteries

Solid polymer electrolytes as one of the promising solid‐state electrolytes have received extensive attention due to their excellent flexibility. However, the issues of lithium (Li) dendrite growth still hinder their practical applications in solid‐state batteries (SSBs). Herein, composite electrolytes from “ceramic‐in‐polymer” (CIP) to “polymer‐in‐ceramic” (PIC) with different sizes of garnet particles are investigated for their effectiveness in dendrite suppression. While the CIP electrolyte with 20 vol% 200 nm Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) particles (CIP‐200 nm) exhibits the highest ionic conductivity of 1.6 × 10^?4 S cm^?1 at 30 °C and excellent flexibility, the PIC electrolyte with 80 vol% 5 µm LLZTO (PIC‐5 µm) shows the highest tensile strength of 12.7 MPa. A sandwich‐type composite electrolyte (SCE) with hierarchical garnet particles (a PIC‐5 µm interlayer sandwiched between two CIP‐200 nm thin layers) is constructed to simultaneously achieve dendrite suppression and excellent interfacial contact with Li metal. The SCE enables highly stable Li plating/stripping cycling for over 400 h at 0.2 mA cm^?2 at 30 °C. The LiFePO₄/SCE/Li cells also demonstrate excellent cycle performance at room temperature. Fabricating sandwich‐type composite electrolytes with hierarchical filler designs can be an effective strategy to achieve dendrite‐free SSBs with high performance and high safety at room temperature.     

2D Layered Double Hydroxides for Oxygen Evolution Reaction: From Fundamental Design to Application

The oxygen evolution reaction (OER) has aroused extensive interest from materials scientists in the past decade by virtue of its great significance in the energy storage/conversion systems such as water splitting, rechargeable metal–air batteries, carbon dioxide (CO₂) reduction, and fuel cells. Among all the materials capable of catalyzing OER, layered double hydroxides (LDHs) stand out as one of the most effective electrocatalysts owing to their compositional and structural flexibility as well as the tenability and the simplicity of their preparation process. For this reason, numerous efforts have been dedicated to adjusting the structure, forming the well‐defined morphology, and developing the preparation methods of LDHs to promote their electrocatalytic performance. In this article, recent advances in the rational design of LDH‐based electrocatalysts toward OER are summarized. Specifically, various tactics for the synthetic methods, as well as structural and composition regulations of LDHs, are further highlighted, followed by a discussion on the influential factors for OER performance. Finally, the remaining challenges to investigate and improve the catalyzing ability of LDH electrocatalysts are stated to indicate possible future development of LDHs.     

Secondary metabolites,secretory structures and biological activity of water celery (Apium nodiflorum (L.) Lag.) growing in central Italy

Apium nodiflorum (L.) Lag. (water celery) is an hydrophytic plant forming dense submerged populations occurring along streams and rivers of Europe. In the present work we provided new insights into the phytochemistry and biology of A. nodiflorum. In particular, we studied the chemical profile of essential oil and polar extracts obtained from the flowering aerial parts of water celery growing in central Italy, together with the essential oil biological activities, namely antimicrobial, antioxidant and cytotoxicity on tumour cells. In addition, we correlated the productivity in secondary metabolites to the secreting structures through a detailed micromorphological study. The essential oil was dominated by two main chemotypes, characterized by myristicin and limonene, respectively. The oils showed significant toxicity on tumour cells, as evidenced by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, with IC₅₀ values in the range 3.8–15.9 μg mL^?1, together with inhibitory effects on Candida albicans (inhibition zones of 10–11 mm). HPLC-MS analysis showed the caffeoylquinic acids and quercetin-3-O-glucoside as the most abundant phenolic compounds. Ducts and vittae were the principal secretory structures of vegetative (leaves and stems) and reproductive (fruits) parts, respectively, storing mainly essential oil. Results of this work provide scientific evidences for the possible valorization and exploitation of water celery.     

天然间苯三酚的化学结构和药理活性研究进展

天然的间苯三酚类化合物来源广泛、结构新颖,具有多种药理活性,是目前天然药物化学的研究热点之一。本文对近十年发现的天然间苯三酚类化合物的化学结构和药理活性的研究进展做了调研和综述,以期对该类化合物进一步的研究提供参考。