The inter-monomer interface of the major light-harvesting chlorophyll a/b complexes of photosystem II (LHCII) influences the chlorophyll triplet distribution

Under strong light conditions, long-lived chlorophyll triplets (³Chls) are formed, which can sensitize singlet oxygen, a species harmful to the photosynthetic apparatus of plants. Plants have developed multiple photoprotective mechanisms to quench ³Chl and scavenge singlet oxygen in order to sustain the photosynthetic activities. The lumenal loop of light-harvesting chlorophyll a/b complex of photosystem II (LHCII) plays important roles in regulating the pigment conformation and energy dissipation. In this study, site-directed mutagenesis analysis was applied to investigate triplet–triplet energy transfer and quenching of ³Chl in LHCII. We mutated the amino acid at site 123 located in this region to Gly, Pro, Gln, Thr and Tyr, respectively, and recorded fluorescence excitation spectra, triplet-minus-singlet (TmS) spectra and kinetics of carotenoid triplet decay for wild type and all the mutants. A red-shift was evident in the TmS spectra of the mutants S123T and S123P, and all of the mutants except S123Y showed a decrease in the triplet energy transfer efficiency. We propose, on the basis of the available structural information, that these phenomena are related to the involvement, due to conformational changes in the lumenal region, of a long-wavelength lutein (Lut2) involved in quenching ³Chl.     

Identification of species in the angiosperm family Apiaceae using DNA barcodes

Apiaceae (Umbelliferae) is a large angiosperm family that includes many medicinally important species. The ability to identify these species and their adulterants is important, yet difficult to do so because of their subtle fruit morphological differences and often lack of diagnostic features in preserved specimens. Moreover, dried roots are often the official medical organs, making visual identification to species almost impossible. DNA barcoding has been proposed as a powerful taxonomic tool for species identification. The Consortium for the Barcode of Life (CBOL) Plant Working Group has recommended the combination of rbcL+matK as the core plant barcode. Recently, the China Plant BOL Group proposed that the nuclear ribosomal DNA internal transcribed spacer (ITS), as well as a subset of this marker (ITS2), be incorporated alongside rbcL+matK into the core barcode for seed plants, particularly angiosperms. In this study, we assess the effectiveness of these four markers plus psbA‐trnH as Apiaceae barcodes. A total of 6032 sequences representing 1957 species in 385 diverse genera were sampled, of which 211 sequences from 50 individuals (representing seven species) were newly obtained. Of these five markers, ITS and ITS2 showed superior results in intra‐ and interspecific divergence and DNA barcoding gap assessments. For the matched data set (173 samples representing 45 species in five genera), the ITS locus had the highest identification efficiency (73.3%), yet ITS2 also performed relatively well with 66.7% identification efficiency. The identification efficiency increased to 82.2% when using an ITS+psbA‐trnH marker combination (ITS2+psbA‐trnH was 80%), which was significantly higher than that of rbcL+matK (40%). For the full sample data set (3052 ITS sequences, 3732 ITS2 sequences, 1011 psbA‐trnH sequences, 567 matK sequences and 566 rbcL sequences), ITS, ITS2, psbA‐trnH, matK and rbcL had 70.0%, 64.3%, 49.5%, 38.6% and 32.1% discrimination abilities, respectively. These results confirm that ITS or its subset ITS2 be incorporated into the core barcode for Apiaceae and that the combination of ITS/ITS2+psbA‐trnH has much potential value as a powerful, standard DNA barcode for Apiaceae identification.     

Increased 90-kDa ribosomal S6 kinase (Rsk) activity is protective against mutant huntingtin toxicity

Uncovering the underlying genetic component of any disease is key to the understanding of its pathophysiology and may open new avenues for development of therapeutic strategies and biomarkers. In the past several years, there has been an explosion of genome-wide association studies (GWAS) resulting in the discovery of novel candidate genes conferring risk for complex diseases, including neurodegenerative diseases. Despite this success, there still remains a substantial genetic component for many complex traits and conditions that is unexplained by the GWAS findings. Additionally, in many cases, the mechanism of action of the newly discovered disease risk variants is not inherently obvious. Furthermore, a genetic region with multiple genes may be identified via GWAS, making it difficult to discern the true disease risk gene. Several alternative approaches are proposed to overcome these potential shortcomings of GWAS, including the use of quantitative, biologically relevant phenotypes. Gene expression levels represent an important class of endophenotypes. Genetic linkage and association studies that utilize gene expression levels as endophenotypes determined that the expression levels of many genes are under genetic influence. This led to the postulate that there may exist many genetic variants that confer disease risk via modifying gene expression levels. Results from the handful of genetic studies which assess gene expression level endophenotypes in conjunction with disease risk suggest that this combined phenotype approach may both increase the power for gene discovery and lead to an enhanced understanding of their mode of action. This review summarizes the evidence in support of gene expression levels as promising endophenotypes in the discovery and characterization of novel candidate genes for complex diseases, which may also represent a novel approach in the genetic studies of Alzheimer's and other neurodegenerative diseases.     

双齿锤角叶蜂研究及亚洲锤角叶蜂科分属检索表

根据模式标本和新采集的标本,重新描述了齿锤角叶蜂属和双齿锤角叶蜂Odontocimbex svenhedini Malaise, 1934,其中双齿锤角叶蜂的雌虫是首次报道。简要讨论了齿锤角叶蜂属Odontocimbex 和锤角叶蜂属Cimbex Olivier、壮锤角叶蜂属 Palaeocimbex Semenov以及毛锤角叶蜂属Trichiosoma Leach的区别。重新指定了双齿锤角叶蜂Odontocimbex svenhedini Malaise的正选模。编制了锤角叶蜂科亚洲分布属分属检索表。     

Immune response of Japanese flounder Paralichthys olivaceus to outer membrane protein of Edwardsiella tarda

The humoral and cellular immune responses of Japanese flounder, Paralichthys olivaceus, were investigated following intraperitioneal injection with outer membrane protein (OMP) of Edwardsiella tarda in Freund's incomplete adjuvant (FIA). The specific serum antibody titre against OMP of E. tarda were measured using ELISA for 14 weeks, and the total serum antibody concentrations were also determined according to the sandwich ELISA standard model constructed using purified IgM. Both of the specific and total antibodies had an increase and reached their peaks 4 weeks after immunization. Simultaneously, the percentages of sIg + lymphocytes in blood, spleen, pronephros and mesonephros were detected by flow cytometry. It was shown that the percentages of sIg + lymphocytes in all lymphoid organs reached their peak levels 4 weeks after immunization, and then decreased gradually. To investigate the protection against infection, three challenges were performed in the same way at day 14, 30 and 100 after immunization, fish challenged at day 30 showed a higher relative percentage survival (RPS) of 71 compared to the 14-day group (30) and 100-day group (53), which indicated a positive correlation between the survival and the levels of the antibody.     

Dipeptidyl aminopeptidase IV from Stenotrophomonas maltophilia exhibits activity against a substrate containing a 4-hydroxyproline residue

The crystal structure of dipeptidyl aminopeptidase IV from Stenotrophomonas maltophilia was determined at 2.8-A resolution by the multiple isomorphous replacement method, using platinum and selenomethionine derivatives. The crystals belong to space group P4(3)2(1)2, with unit cell parameters a = b = 105.9 A and c = 161.9 A. Dipeptidyl aminopeptidase IV is a homodimer, and the subunit structure is composed of two domains, namely, N-terminal beta-propeller and C-terminal catalytic domains. At the active site, a hydrophobic pocket to accommodate a proline residue of the substrate is conserved as well as those of mammalian enzymes. Stenotrophomonas dipeptidyl aminopeptidase IV exhibited activity toward a substrate containing a 4-hydroxyproline residue at the second position from the N terminus. In the Stenotrophomonas enzyme, one of the residues composing the hydrophobic pocket at the active site is changed to Asn611 from the corresponding residue of Tyr631 in the porcine enzyme, which showed very low activity against the substrate containing 4-hydroxyproline. The N611Y mutant enzyme was generated by site-directed mutagenesis. The activity of this mutant enzyme toward a substrate containing 4-hydroxyproline decreased to 30.6% of that of the wild-type enzyme. Accordingly, it was considered that Asn611 would be one of the major factors involved in the recognition of substrates containing 4-hydroxyproline.     

黑皮质素受体-4调节通路的研究进展

黑皮质素系统来自阿片-促黑素细胞皮质素原,在中枢摄食行为和能量平衡代谢中起到重要作用,此系统生理功能的发挥主要通过与下丘脑神经元细胞上特定膜受体（黑皮质素受体）结合完成。黑皮质素受体（MCR）有五种亚型（MC1R-MC5R）,其中参与体重调节的受体主要是黑皮质素受体3（MC3R）和黑皮质素受体4（MC4R）。MC4R属于G蛋白耦联受体,具有七次跨膜结构。作为一种膜受体,MC4R发挥体重调节作用,一方面受外界激动剂或拮抗剂的调节;另一方面,此受体活化后会影响到细胞内的信号调节通路。研究MC4R的功能首先要了解受体的结构,本文对G蛋白耦联受体的结构进行了较详细的叙述,MC4R经信号调节通路,激活腺苷酸环化酶,增加cAMP的浓度,最终通过影响细胞内基因的转录和翻译,来调节体重和能量的消耗。     

Demonstration of improvements to the bioluminescence resonance energy transfer (BRET) technology for the monitoring of G protein-coupled receptors in live cells

The bioluminescence resonance energy transfer (BRET) technique has become extremely popular for studying protein-protein interactions in living cells and real time. Of particular interest is the ability to monitor interactions between G protein-coupled receptors, such as the thyrotropin-releasing hormone receptor (TRHR), and proteins critical for regulating their function, such as beta-arrestin. Using TRHR/beta-arrestin interactions, we have demonstrated improvements to all 3 generations of BRET (BRET(1), BRET(2), and eBRET) by using the novel forms of luciferase, Rluc2 and Rluc8, developed by the Gambhir laboratory. Furthermore, for the 1st time it was possible to use the BRET2 system to detect ligand-induced G protein-coupled receptor/beta-arrestin interactions over prolonged periods (on the scale of hours rather than seconds) with a very stable signal. As demonstrated by our Z'-factor data, these luciferases increase the sensitivity of BRET to such an extent that they substantially increase the potential applicability of this technology for effective drug discovery high-throughput screening.