水生双翅目昆虫监测水体重金属污染的研究

水生双翅目昆虫是监测水体重金属污染的理想对象。文章归纳用于监测重金属污染的水生双翅目昆虫的种类,重点介绍水生双翅目昆虫在重金属污染下外部形态、内部结构、生化及分子水平的变化,以及相关生物标志物的研究,为水生双翅目昆虫用于水体重金属污染的生物监测提供科学依据。     

蜂王浆蛋白生物学功能的研究

蜂王浆是哺育蜂咽下腺与上颚腺分泌的供3日龄以内蜜蜂幼虫和蜂王食用的浆状物质,具有多种生物活性。王浆含有丰富的蛋白质,通过直接分离纯化王浆中的蛋白质分子,或通过王浆蛋白基因克隆表达以获得表达产物,进而研究王浆蛋白的功能。研究发现王浆中含有多种具有特定功能的蛋白质,如MRJP3具有免疫调节作用,Jelleine-I-IV及Royalisin具有抗菌作用,MRJP1具有抗肿瘤功能及可能的蜜蜂行为调节功能,57kDa蛋白及Apisimin的促细胞生长功能,57kDa蛋白具有抗疲劳功能等。随着王浆蛋白组分分离、基因克隆表达及其功能研究的深入,王浆蛋白将被应用到生物医药、细胞培养、组织工程等更多的研究领域。     

丝带凤蝶滞育与非滞育蛹及其成虫的形态学观察

丝带凤蝶Sericinus montelus是一种有开发价值的观赏昆虫,以蛹滞育越冬,成虫存在多型现象。本研究从体色、个体大小和蛹腹部刺突长度等方面比较了丝带凤蝶滞育与非滞育蛹及其成虫的形态差异。与非滞育蛹相比,滞育蛹体色较深,触角末端的淡黄色与体色差异明显,3日龄滞育蛹腹部第9节刺突长度是3日龄非滞育蛹的4倍左右,这些差异可以用于该虫蛹滞育早期判别。滞育蛹羽化成虫的翅展和尾突长度显著小于非滞育蛹羽化成虫,且腹部及翅面斑纹也存在明显的差异,这些差异与丝带凤蝶春型、夏型成虫的描述相一致,表明丝带凤蝶成虫季节多型是与滞育相关联的。     

Protein-protein docking by simulating the process of association subject to biochemical constraints

We present a computational procedure for modeling protein-protein association and predicting the structures of protein-protein complexes. The initial sampling stage is based on an efficient Brownian dynamics algorithm that mimics the physical process of diffusional association. Relevant biochemical data can be directly incorporated as distance constraints at this stage. The docked configurations are then grouped with a hierarchical clustering algorithm into ensembles that represent potential protein-protein encounter complexes. Flexible refinement of selected representative structures is done by molecular dynamics simulation. The protein-protein docking procedure was thoroughly tested on 10 structurally and functionally diverse protein-protein complexes. Starting from X-ray crystal structures of the unbound proteins, in 9 out of 10 cases it yields structures of protein-protein complexes close to those determined experimentally with the percentage of correct contacts >30% and interface backbone RMSD <4 A. Detailed examination of all the docking cases gives insights into important determinants of the performance of the computational approach in modeling protein-protein association and predicting of protein-protein complex structures.     

N,N′-Ethylene-bis(3-methoxysalicylideneimine) mononuclear (4f) and heterodinuclear (3d–4f) metal complexes: Synthesis, crystal structure and luminescent properties

The stepwise synthesis of mononuclear (4f) and heterodinuclear (3d–4f) Salen-like complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, reactions of ligand H₂L and Ln(NO₃)₃ · 6H₂O give rise to three mononuclear lanthanide complexes Ln(H₂L)(NO₃)₃ [H₂L = N,N′-ethylene-bis(3-methoxysalicylideneimine), Ln = Nd (1), Eu (2) and Tb (3)], in which N,N′-ethylene-bis(3-methoxysalicylideneimine) acts as tetradentate ligands with the O₂O₂ set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac)₂ · H₂O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO₃)₃ · H₂O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N₂O₂ cavity. Luminescent analysis reveals that complex 3 exhibits characteristic metal-centered fluorescence of Tb(III) ion. However, the characteristic luminescence of both Sm(III) and Eu(III) ions is not observed both in solution and solid state of the complexes.     

A suboptimal algorithm for de novo peptide sequencing via tandem mass spectrometry.

Tandem mass spectrometry has emerged to be one of the most powerful high-throughput techniques for protein identification. Tandem mass spectrometry selects and fragments peptides of interest into N-terminal ions and C-terminal ions, and it measures the mass/charge ratios of these ions. The de novo peptide sequencing problem is to derive the peptide sequences from given tandem mass spectral data of k ion peaks without searching against protein databases. By transforming the spectral data into a matrix spectrum graph G = (V, E), where |V| = O(k(2)) and |E| = O(k(3)), we give the first polynomial time suboptimal algorithm that finds all the suboptimal solutions (peptides) in O(p|E|) time, where p is the number of solutions. The algorithm has been implemented and tested on experimental data. The program is available at http://hto-c.usc.edu:8000/msms/menu/denovo.htm.     

工业乳酸发酵的近期进展

乳酸是一种重要的多用途有机酸。通过菌种改良和发酵工艺技术的改进,可以大大提升微生物发酵技术水平,降低成本。简要综述有关的研究进展。     

Grafting of antibacterial polymers on stainless steel via surface‐initiated atom transfer radical polymerization for inhibiting biocorrosion by Desulfovibrio desulfuricans

To enhance the biocorrosion resistance of stainless steel (SS) and to impart its surface with bactericidal function for inhibiting bacterial adhesion and biofilm formation, well‐defined functional polymer brushes were grafted via surface‐initiated atom transfer radical polymerization (ATRP) from SS substrates. The trichlorosilane coupling agent, containing the alkyl halide ATRP initiator, was first immobilized on the hydroxylated SS (SS‐OH) substrates for surface‐initiated ATRP of (2‐dimethylamino)ethyl methacrylate (DMAEMA). The tertiary amino groups of covalently immobilized DMAEMA polymer or P(DMAEMA), brushes on the SS substrates were quaternized with benzyl halide to produce the biocidal functionality. Alternatively, covalent coupling of viologen moieties to the tertiary amino groups of P(DMAEMA) brushes on the SS surface resulted in an increase in surface concentration of quaternary ammonium groups, accompanied by substantially enhanced antibacterial and anticorrosion capabilities against Desulfovibrio desulfuricans in anaerobic seawater, as revealed by antibacterial assay and electrochemical studies. With the inherent advantages of high corrosion resistance of SS, and the good antibacterial and anticorrosion capabilities of the viologen‐quaternized P(DMAEMA) brushes, the functionalized SS is potentially useful in harsh seawater environments and for desalination plants. Biotechnol. Bioeng. 2009;103: 268–281. © 2009 Wiley Periodicals, Inc.     

Effect of Gynostemma Pentaphyllum Polysaccharide on boar spermatozoa quality following freezing–thawing

Gynostemma Pentaphyllum Polysaccharide (GPP) was added at concentrations of 0.25, 0.5, 1.0, 1.5 and 2.0 mg/ml to the extenders used to freeze boar semen and its effects on the quality of frozen–thawed sperm were assessed. The sperm motility was significantly higher in the extenders containing 0.25 and 0.5 mg/ml GPP, as compared to other groups (P < 0.05). The extender supplemented with 0.5 mg/ml GPP favored the highest intact membrane and intact acrosome percentages in comparison with other groups (P < 0.05), respectively. The mitochondrial activity was significantly higher at the concentrations of 0.25, 0.5 and 1.0 mg/ml GPP than that of other treatments, and the control group (P < 0.05). In biochemical assays, the extender supplemented with 0.25 and 0.5 mg/ml GPP significantly improved SOD levels, compared to other groups (P > 0.05). However, the extenders supplemented with GPP did not cause significant differences in levels of CAT and GSH-Px, compared to the control (P > 0.05). In summary, GPP exhibited a dose-related response and the lower concentration produced greater protective effect. According to the standard semen quality parameters and antioxidant activities measured in this study, the concentration of 0.5 mg/ml GPP caused a beneficial cryoprotective effects on the quality of frozen–thawed boar semen. It is proposed that an extender containing 0.5 mg/ml GPP could be used as cryoprotective medium of better efficiency.