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81.
Møller MS Fredslund F Majumder A Nakai H Poulsen JC Lo Leggio L Svensson B Abou Hachem M 《Journal of bacteriology》2012,194(16):4249-4259
82.
Bom Roeland A. van Gils Jan A. Molenaar Karen Kwarteng Andy Y. Victor Reginald Folmer Eelke O. 《Hydrobiologia》2021,848(3):751-752
Hydrobiologia - In the above mentioned publication, incorrect values for P. segnis are shown on the right hand side of Fig. 4. The correct version of Fig. 4 and its caption is... 相似文献
83.
Alexander Holm Viborg Folmer Fredslund Takane Katayama Stinne Kirketerp Nielsen Birte Svensson Motomitsu Kitaoka Leila Lo Leggio Maher Abou Hachem 《Molecular microbiology》2014,94(5):1024-1040
The Bifidobacterium genus harbours several health promoting members of the gut microbiota. Bifidobacteria display metabolic specialization by preferentially utilizing dietary or host‐derived β‐galactosides. This study investigates the biochemistry and structure of a glycoside hydrolase family 42 (GH42) β‐galactosidase from the probiotic Bifidobacterium animalis subsp. lactis Bl‐04 (BlGal42A). BlGal42A displays a preference for undecorated β1‐6 and β1‐3 linked galactosides and populates a phylogenetic cluster with close bifidobacterial homologues implicated in the utilization of N‐acetyl substituted β1‐3 galactosides from human milk and mucin. A long loop containing an invariant tryptophan in GH42, proposed to bind substrate at subsite + 1, is identified here as specificity signature within this clade of bifidobacterial enzymes. Galactose binding at the subsite ? 1 of the active site induced conformational changes resulting in an extra polar interaction and the ordering of a flexible loop that narrows the active site. The amino acid sequence of this loop provides an additional specificity signature within this GH42 clade. The phylogenetic relatedness of enzymes targeting β1‐6 and β1‐3 galactosides likely reflects structural differences between these substrates and β1‐4 galactosides, containing an axial galactosidic bond. These data advance our molecular understanding of the evolution of sub‐specificities that support metabolic specialization in the gut niche. 相似文献
84.
Todd A. Brugel Reed W. Smith Michael Balestra Christopher Becker Thalia Daniels Tiffany N. Hoerter Gerard M. Koether Scott R. Throner Laura M. Panko James J. Folmer Joseph Cacciola Angela M. Hunter Ruifeng Liu Philip D. Edwards Dean G. Brown John Gordon Norman C. Ledonne Mark Pietras Patricia Schroeder Linda A. Sygowski Matthew F. Peters 《Bioorganic & medicinal chemistry letters》2010,20(19):5847-5852
Initial high throughput screening efforts identified highly potent and selective kappa opioid receptor antagonist 3 (κ IC50 = 77 nM; μ:κ and δ:κ IC50 ratios >400) which lacked CNS exposure in vivo. Modification of this scaffold resulted in development of a series of 8-azabicyclo[3.2.1]octan-3-yloxy-benzamides showing potent and selectivity κ antagonism as well as good brain exposure. Analog 6c (κ IC50 = 20 nM; μ:κ = 36, δ:κ = 415) was also shown to reverse κ-agonist induced rat diuresis in vivo. 相似文献
85.
The conformational change of Li-DNA in water/ethanol mixtures is followed by the change in the CD spectrum in solutions containing various percentages of ethanol in the range from 0 to 95%. Two main transitions can be distinguished. The first occurs in the range from 0 to 70% and is represented by a large reduction of the intensity of the positive CD band around 275 nm, which is apparently related to a small change in the number of base pairs per turn. Secondly, at higher percentages of ethanol (> 80%) a conformational change is detected, which is expressed as a reduction of the 245-nm negative CD intensity. According to x-ray diffraction experiments of fibers of Li-DNA, the C-form is attained in 95% ethanol, while at 70% ethanol a B-like structure is observed. The CD experiments reported here also show that for DNA in solution the dependence on percentage of ethanol is composed of two main transition regions. The C-form would then be adopted at high (~ 95%) ethanol percentage. The 0–70% transition, although strongly expressed in optical CD experiments, has to be related to relatively small structural changes within the B-family of DNA structures, which probably induce an enhanced contribution of n → π* transitions to the CD spectrum. 相似文献
86.
Towards a solution of the plankton paradox: the importance of physiology and life history 总被引:5,自引:0,他引:5
Phytoplankton communities reveal an astonishing biodiversity, whereas classical competition theory seems to suggest that only a few competing species can survive. Recently we suggested a new solution to this plankton paradox. In theory, at least, competition between multiple species can generate complex dynamics that can support a large number of species. How likely is it then, in reality, that competitive chaos indeed promotes biodiversity? To obtain some insight, we simulated multispecies competition according to five different physiological scenarios. For random species parameters, biodiversity was generally low. Assuming plausible physiological trade‐offs, the simulations revealed switches back and forth between equilibrium and nonequilibrium dynamics, and a higher biodiversity. An extremely high biodiversity, with sometimes more than 100 species on three resources, was observed in simulations that assumed a cyclic relation between competitive abilities and resource contents. We conclude that physiological and life‐history patterns have a major impact on the likelihood of nonequilibrium dynamics and on the biodiversity of plankton communities. 相似文献
87.
F. Bokma 《Journal of evolutionary biology》2002,15(6):1048-1056
Abstract The theory of ‘punctuated equilibrium’ hypothesises that most morphological change in species takes place in rapid bursts triggered by speciation. Eldregde and Gould postulated the theory in 1972, as an alternative to the idea that morphological change slowly accumulates in the course of time, a then common belief they dubbed ‘phyletic gradualism’. Ever since its introduction the theory of punctuated equilibrium has been the subject of speculation rather than empirical validation. Here I present a method to detect punctuated evolution without reference to fossil data, based on the phenotypes of extant species and on their relatedness as revealed by molecular phylogeny. The method involves a general mathematical model describing morphological differentiation of two species over time. The two parameters in the model, the rates of punctual (cladogenetic) and gradual (anagenetic) change, are estimated from plots of morphological diversification against time since divergence of extant species. 相似文献
88.
G. I. Garris B. H. Bokma R. K. Strickland G. P. Combs 《Experimental & applied acarology》1989,6(1):67-76
A cooperative effort between the United States Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, the Agricultural Research Service, and the Department of Agriculture, Commonwealth Government of Puerto Rico has been successful in eardicatingAmblyomma variegatum (Fabricius) from the islands of Puerto Rico and Vieques (an island municipality of Puerto Rico). Application of acaricides to livestock and dogs at 14-day intervals for an 18-month period eliminated foci of tick infestation on 188 farms in four different locations without additional aerial or ground treatment. Reasons for the success and some of the costs associated with the eradication program on Puerto Rico are presented. 相似文献
89.
Voltaire Sant’Anna Ana Paula Folmer Correa Amanda de Souza da Motta 《Preparative biochemistry & biotechnology》2016,46(8):838-843
Antimicrobial peptide P34 is a promising biopreservative for utilization in the food industry. In this work, aqueous biphasic systems (ABS) and aqueous biphasic micellar systems (ABMS) were studied as prestep for purification of peptide P34. The ABS was prepared with polyethylene glycol (PEG) and inorganic salts and the ABMS with Triton X-114 was chosen as the phase-forming surfactant. Results indicate that peptide P34 partitions preferentially to PEG-rich phase and extraction with ammonium sulfate [(NH4)2SO4], yielding a 75% recovery of the antimicrobial activity, specific activity of 1,530 antimicrobial units per mg of protein, and purification fold of 2.48. Protein partition coefficient and partition coefficient for the biological activity with (NH4)2SO4 system were 0.48 and 64, respectively. Addition of sodium chloride did not affect recovery, but decreased protein amount in the PEG-rich phase, indicating a higher partition of biomolecules. ABMS did not yield good recovery of antimicrobial activity. Purification fold using PEG–(NH4)2SO4 and 1.0?mol l?1 sodium chloride was twice higher than that obtained by conventional protocol, indicating a successful utilization of ABS as a step for purification of peptide P34. 相似文献