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51.
We synthesized and evaluated by surface plasmon resonance 64 LNA/2'-O-methyl sequences corresponding to all possible combinations of such residues in a kissing aptamer loop complementary to the 6-nt loop of the TAR element of HIV-1. Three combinations of LNA/2'-O-methyl nucleoside analogues where one or two LNA units are located on the 3' side of the aptamer loop display an affinity for TAR below 1nM, i.e. one order of magnitude higher than the parent RNA aptamer. One of these combinations inhibits the TAR-dependent luciferase expression in a cell assay. 相似文献
52.
McNally DJ Lamoureux MP Karlyshev AV Fiori LM Li J Thacker G Coleman RA Khieu NH Wren BW Brisson JR Jarrell HC Szymanski CM 《The Journal of biological chemistry》2007,282(39):28566-28576
In this study we investigated the commonality and biosynthesis of the O-methyl phosphoramidate (MeOPN) group found on the capsular polysaccharide (CPS) of Campylobacter jejuni. High resolution magic angle spinning NMR spectroscopy was used as a rapid, high throughput means to examine multiple isolates, analyze the cecal contents of colonized chickens, and screen a library of CPS mutants for the presence of MeOPN. Sixty eight percent of C. jejuni strains were found to express the MeOPN with a high prevalence among isolates from enteritis, Guillain Barré, and Miller-Fisher syndrome patients. In contrast, MeOPN was not observed for any of the Campylobacter coli strains examined. The MeOPN was detected on C. jejuni retrieved from cecal contents of colonized chickens demonstrating that the modification is expressed by bacteria inhabiting the avian gastrointestinal tract. In C. jejuni 11168H, the cj1415-cj1418 cluster was shown to be involved in the biosynthesis of MeOPN. Genetic complementation studies and NMR/mass spectrometric analyses of CPS from this strain also revealed that cj1421 and cj1422 encode MeOPN transferases. Cj1421 adds the MeOPN to C-3 of the beta-d-GalfNAc residue, whereas Cj1422 transfers the MeOPN to C-4 of D-glycero-alpha-L-gluco-heptopyranose. CPS produced by the 11168H strain was found to be extensively modified with variable MeOPN, methyl, ethanolamine, and N-glycerol groups. These findings establish the importance of the MeOPN as a diagnostic marker and therapeutic target for C. jejuni and set the groundwork for future studies aimed at the detailed elucidation of the MeOPN biosynthetic pathway. 相似文献
53.
Changes in marine biodiversity through the Phanerozoic correlate much better with hyperbolic model (widely used in demography and macrosociology) than with exponential and logistic models (traditionally used in population biology and extensively applied to fossil biodiversity as well). The latter models imply that changes in diversity are guided by a first-order positive feedback (more ancestors, more descendants) and/or a negative feedback arising from resource limitation. Hyperbolic model implies a second-order positive feedback. The hyperbolic pattern of the world population growth arises from a second-order positive feedback between the population size and the rate of technological growth. The hyperbolic character of biodiversity growth can be similarly accounted for by a feedback between the diversity and community structure complexity. The similarity between the curves of biodiversity and human population probably comes from the fact that both are derived from the interference of the hyperbolic trend with cyclical and stochastic dynamics. 相似文献
54.
Villard V Agak GW Frank G Jafarshad A Servis C Nébié I Sirima SB Felger I Arevalo-Herrera M Herrera S Heitz F Bäcker V Druilhe P Kajava AV Corradin G 《PloS one》2007,2(7):e645
To identify malaria antigens for vaccine development, we selected alpha-helical coiled coil domains of proteins predicted to be present in the parasite erythrocytic stage. The corresponding synthetic peptides are expected to mimic structurally "native" epitopes. Indeed the 95 chemically synthesized peptides were all specifically recognized by human immune sera, though at various prevalence. Peptide specific antibodies were obtained both by affinity-purification from malaria immune sera and by immunization of mice. These antibodies did not show significant cross reactions, i.e., they were specific for the original peptide, reacted with native parasite proteins in infected erythrocytes and several were active in inhibiting in vitro parasite growth. Circular dichroism studies indicated that the selected peptides assumed partial or high alpha-helical content. Thus, we demonstrate that the bioinformatics/chemical synthesis approach described here can lead to the rapid identification of molecules which target biologically active antibodies, thus identifying suitable vaccine candidates. This strategy can be, in principle, extended to vaccine discovery in a wide range of other pathogens. 相似文献
55.
Roman M Baevsky Victor M Baranov Irina I Funtova André Diedrich Andrey V Pashenko Anja G Chernikova Jürgen Drescher Jens Jordan Jens Tank 《Journal of applied physiology》2007,103(1):156-161
Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41-50 yr, body-mass index of 22-28 kg/m2) during long-term missions (flight lengths of 162-196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight (P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight (P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances. 相似文献
56.
57.
Taras Antal Ivan Konyukhov Alena Volgusheva Tatyana Plyusnina Sergei Khruschev Galina Kukarskikh Sergey Goryachev Andrey Rubin 《Physiologia plantarum》2019,165(3):476-486
The development of high‐performance photobioreactors equipped with automatic systems for non‐invasive real‐time monitoring of cultivation conditions and photosynthetic parameters is a challenge in algae biotechnology. Therefore, we developed a chlorophyll (Chl) fluorescence measuring system for the online recording of the light‐induced fluorescence rise and the dark relaxation of the flash‐induced fluorescence yield (Qa? ? re‐oxidation kinetics) in photobioreactors. This system provides automatic measurements in a broad range of Chl concentrations at high frequency of gas‐tight sampling, and advanced data analysis. The performance of this new technique was tested on the green microalgae Chlamydomonas reinhardtii subjected to a sulfur deficiency stress and to long‐term dark anaerobic conditions. More than thousand fluorescence kinetic curves were recorded and analyzed during aerobic and anaerobic stages of incubation. Lifetime and amplitude values of kinetic components were determined, and their dynamics plotted on heatmaps. Out of these data, stress‐sensitive kinetic parameters were specified. This implemented apparatus can therefore be useful for the continuous real‐time monitoring of algal photosynthesis in photobioreactors. 相似文献
58.
Vasily N. Danilevich Andrey L. Mulyukin Andrey V. Machulin Vladimir V. Sorokin Sergey A. Kozlov 《Journal of biomolecular structure & dynamics》2019,37(4):918-930
Our previous studies demonstrated the formation of structurally diverse DNA-containing microparticles (DNA MPs) in PCR with Mg-pyrophosphate (MgPPi) as the structure-forming component. These DNA MPs were referred to major structural types: microdisks (2D MPs) with nanometer thickness and 3D MPs with sophisticated morphology and constructed from intersecting disks and their segments. Little is known about factors that influence both the morphology and size of DNA MPs, and the present study was aimed at fulfilling this gap. We showed that the addition of Mn2+ cations to PCR mixtures caused the profound changes in MPs morphology, depending on DNA polymerase used (KlenTaq or Taq). Asymmetric PCR with 20-fold decrease in the concentration of one of two primers facilitated the predominant formation of microdisks with unusual structure. The addition of 1 mM Na-pyrophosphate to PCR mixtures with synthesized DNA and subsequent thermal cycling (10–15 cycles) were optimal to produce microdisks or nanometer 3D particles. Using electron microscopy, we studied also the structure of inorganic micro- and nanoparticles from MgPPi, formed during multiple heating and cooling cycles of a mixture of Mg2+ and Na-pyrophosphate in various regimes. Also, we found the conditions to yield planar (Mg·Mn)PPi nanocrystals (diameter ~100 nm and thickness ~10 nm) which efficiently adsorbed exogenous DNA. These inorganic nanoparticles are promising for DNA delivery in transfection studies. Mechanisms to be involved in structural modifications of MPs and perspectives of their practical application are discussed. 相似文献
59.
Journal of Plant Growth Regulation - The original version of this article unfortunately contained a mistake in Fig. 5. The dot lines are missing and some unnecessary circles are filled in... 相似文献
60.
Ilya Borisenko Maria Daugavet Alexander Ereskovsky Andrey Lavrov Olga Podgornaya 《Open biology》2022,12(2)
Sponges (phylum Porifera) are early-branching animals, whose outwardly simple body plan is underlain by a complex genetic repertoire. The transition from a mobile larva to an attached filter-feeding organism occurs by metamorphosis, a process accompanied by a radical change of the body plan and cell transdifferentiation. The continuity between larval cells and adult tissues is still obscure. In a previous study, we have produced polyclonal antibodies against the major protein of the flagellated cells covering the larva of the sponge Halisarca dujardini, used them to trace the fate of these cells and shown that the larval flagellated cells transdifferentiate into the choanocytes. In the present work, we identified the sequence of this novel protein, which we named ilborin. A search in the open databases showed that multiple orthologues of the newly identified protein are present in sponges, cnidarians, flatworms, ctenophores and echinoderms, but none of them has been described yet. Ilborin has two conserved domains: triosephosphate isomerase-barrel, which has enzymatic activity against macroergic compounds, and canonical EF-hand, which binds calcium. mRNA of ilborin is expressed in the larval flagellated cells. We suggest that the new protein is involved in the calcium-mediated regulation of energy metabolism, whose activation precedes metamorphosis. 相似文献