The role of lymphotoxin in development and maintenance of secondary lymphoid tissues

Secondary lymphoid organs provide the necessary microenvironment for the cooperation of antigen-specific T- and B-lymphocytes and antigen-presenting cells in order to initiate an efficient immune response. Remarkable progress in understanding of the mechanisms of lymphoid organogenesis was achieved due to the analysis of various gene-targeted mice. This review primarily focuses on the role of lymphotoxin (LT) in development, maturation and maintenance of secondary lymphoid organs.     

Cyanobacterial leader peptides for protein secretion

The leader peptide of the major secreted protein PilA1 of the cyanobacterium Synechocystis sp. strain PCC 6803 and several artificial leader peptides have been used to study secretion of the reporter protein lichenase to the culture medium. The strains of Synechocystis carrying lichenase with the leader sequences of PilA and with the leader sequence of Slr2016 efficiently secreted the reporter protein. The artificial leader sequence that was characterized by the overall positive charge (as PilA1 and Slr2016 leaders) also allowed secretion. The artificial leader with negative charge, however, did not allow secretion of the reporter protein. Moreover, no secreted proteins have been isolated from this strain using conventional techniques for preparation of secreted proteins. These data suggest that the general secretion pathway in cyanobacteria, at least for pilins, recognizes the overall charge of the leader sequences, and operates in a sequence-non-specific manner.     

Microbicidal properties of polymer films modified by five-membered polynitrogen heterocycles

The probability of a series of substituted 1,2,4-tri- and tetrazole compounds and by these modified polymer film materials to inhibit the process of microbiological corrosion of metals has been investigated. Fungi-toxicity of the studied compounds and materials has been observed for Aspergillus, Penicillium and Trichoderma fungi whose metabolites initiate corrosion of ferrous and nonferrous materials. For Thiobacillus ferrooxidans as an example, the bactericidal properties have been studied and azoles have been proven to suppress test-culture growth in culture medium. A comparative analysis of fungi and bactericidal activity of the studied compounds has been carried out. According to experimental results of kinetics of modifier desorption from the polymer matrix, the microbicidal effect of modified films is determined along with the corrosion inhibitor (CI) biocidal properties by its volatility and the intensity of the liquid phase (plasticizer + CI) syneresis from the material bulk. It has been concluded that there are fair prospects of application of azoles and by azoles modified materials as means of protection against both microbiological and electrochemical corrosion.     

Kindling fluorescent proteins for precise in vivo photolabeling

Photobleaching of green fluorescent protein (GFP) is a widely used approach for tracking the movement of subcellular structures and intracellular proteins. Although photobleaching is a powerful technique, it does not allow direct tracking of an object's movement and velocity within a living cell. Direct tracking becomes possible only with the introduction of a photoactivated fluorescent marker. A number of previous studies have reported optically induced changes in the emission spectra of fluorescent proteins. However, the ideal photoactivated fluorescent marker should be a nonfluorescent tag capable of "switching on" (i.e., becoming fluorescent) in response to irradiation by light of a particular wavelength, intensity, and duration. In this report, we generated a mutant of Anemonia sulcata chromoprotein asCP. The mutant protein is capable of unique irreversible photoconversion from the nonfluorescent to a stable bright-red fluorescent form ("kindling"). This "kindling fluorescent protein" (KFP1) can be used for precise in vivo photolabeling to track the movements of cells, organelles, and proteins. We used KFP1 for in vivo cell labeling in mRNA microinjection assays to monitor Xenopus laevis embryo development and to track mitochondrial movement in mammalian cells.     

Proton transfer in the photosynthetic reaction center of Blastochloris viridis

Photosynthetic reaction centers of Blastochloris viridis require two quanta of light to catalyse a two-step reduction of their secondary ubiquinone Q(B) to ubiquinol. We employed capacitive potentiometry to follow the voltage changes that were caused by the accompanying transmembrane proton displacements. At pH 7.5 and 20 degrees C, the Q(B)-related voltage generation after the first flash was contributed by a fast, temperature-independent component with a time constant of approximately 30 micros and a slower component of approximately 200 micros with activation energy (E(a)) of 50 kJ/mol. The kinetics after the second flash featured temperature-independent components of 5 micros and 200 micros followed by a component of 600 micros with E(a) approximately 60 kJ/mol.     

A new outbreak of fox rabies at the Russian–Mongolian border

<正>Dear Editor,Lake Baikal and its neighboring territories are an intermediate zone for thesteppeandarctic-likerabies virus lineages in Russia.After the elimination of dog-mediated rabies during the early 1980s,this area remained rabies-free for over 25–30 years.A sudden reappearance of rabies occurred in this zone in the Republic of Buryatia in 2011–2012.A marginal part of the Mongolian steppe penetrates the Siberian taiga forests in this area,and human and animal rabies have been repeatedly recorded in the Republic of Buryatia from the end of the     

Three-dimensional structure of ectatomin from Ectatomma tuberculatum ant venom

Summary Two-dimensional ¹H NMR techniques were used to determine the spatial structure of ectatomin, a toxin from the venom of the ant Ectatomma tuberculatum. Nearly complete proton resonance assignments for two chains of ectatomin (37 and 34 amino acid residues, respectively) were obtained using 2D TOCSY, DQF-COSY and NOESY experiments. The cross-peak volumes in NOESY spectra were used to define the local structure of the protein and generate accurate proton-proton distance constraints employing the MARDIGRAS program. Disulfide bonds were located by analyzing the global fold of ectatomin, calculated with the distance geometry program DIANA. These data, combined with data on the rate of exchange of amide protons with deuterium, were used to obtain a final set of 20 structures by DIANA. These structures were refined by unrestrained energy minimization using the CHARMm program. The resulting rms deviations over 20 structures (excluding the mobile N- and C-termini of each chain) are 0.75 ? for backbone heavy atoms, and 1.25 ? for all heavy atoms. The conformations of the two chains are similar. Each chain consists of two α-helices and a hinge region of four residues; this forms a hairpin structure which is stabilized by disulfide bridges. The hinge regions of the two chains are connected together by a third disulfide bridge. Thus, ectatomin forms a four-α-helical bundle structure.     

Electron and proton transfer in the <Emphasis Type="Italic">ba</Emphasis><Subscript>3</Subscript> oxidase from <Emphasis Type="Italic">Thermus thermophilus</Emphasis>

The ba ₃-type cytochrome c oxidase from Thermus thermophilus is phylogenetically very distant from the aa ₃–type cytochrome c oxidases. Nevertheless, both types of oxidases have the same number of redox-active metal sites and the reduction of O₂ to water is catalysed at a haem a ₃-Cu_B catalytic site. The three-dimensional structure of the ba ₃ oxidase reveals three possible proton-conducting pathways showing very low homology compared to those of the mitochondrial, Rhodobacter sphaeroides and Paracoccus denitrificans aa ₃ oxidases. In this study we investigated the oxidative part of the catalytic cycle of the ba ₃ -cytochrome c oxidase using the flow-flash method. After flash-induced dissociation of CO from the fully reduced enzyme in the presence of oxygen we observed rapid oxidation of cytochrome b (k ≅ 6.8 × 10⁴ s⁻¹) and formation of the peroxy (P_R) intermediate. In the next step a proton was taken up from solution with a rate constant of ~1.7 × 10⁴ s⁻¹, associated with formation of the ferryl (F) intermediate, simultaneous with transient reduction of haem b. Finally, the enzyme was oxidized with a rate constant of ~1,100 s⁻¹, accompanied by additional proton uptake. The total proton uptake stoichiometry in the oxidative part of the catalytic cycle was ~1.5 protons per enzyme molecule. The results support the earlier proposal that the P_R and F intermediate spectra are similar (Siletsky et al. Biochim Biophys Acta 1767:138, 2007) and show that even though the architecture of the proton-conducting pathways is different in the ba ₃ oxidases, the proton-uptake reactions occur over the same time scales as in the aa ₃-type oxidases. Smirnova and Zaslavsky contributed equally to the work described in this paper.