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41.
42.
Kurt Preissler 《Hydrobiologia》1980,73(1-3):199-203
Avoidance of shore by pelagic rotifers is considered to be the result of an optical orientation. Field experiments show that the spatial light distribution in the shore region determines the preferred direction of migration. The behaviour of Eudiaptomus gracilis was tested in comparison to that of rotifers.This publication is dedicated to Pater Dr. Josef Donner on the occasion of his 70th birthday 相似文献
43.
A strain of Acremonium kiliense (Fungi Imperfecti) produced a water-soluble, dialyzable, heat-stable agent that rendered Cladophora glomerata (Chlorophyta) chlorotic and inhibited its growth. 相似文献
44.
Kurt Mendgen 《Archives of microbiology》1979,122(2):129-135
A new species of anaerobic bacterium that degrades the even-numbered carbon fatty acids, butyrate, caproate and caprylate, to acetate and H2 and the odd-numbered carbon fatty acids, valerate and heptanoate, to acetate, propionate and H2 was obtained in coculture with either an H2-utilizing methanogen or H2-utilizing desulfovibrio. The organism could be grown only in syntrophic association with the H2-utilizer and no other energy sources or combination of electron donor and acceptors were utilized. It was a Gram-negative helical rod with 2 to 8 flagella, about 20 nm in diameter, inserted in a linear fashion about 130 nm or more apart along the concave side of the cell. It grew with a generation time of 84 h in co-culture with Methanospirillum hungatii and was present in numbers of at least 4.5×10-6 per g of anaerobic digestor sludge. 相似文献
45.
Aqueous samples containing labile substances are rapidly lyophilized after the frozen solutions are crushed in Nalgene plastic
bottles. Lyophilization time compares favorably with shell-frozen samples, and samples remain frozen at all times. 相似文献
46.
Kurt Schwarz 《Plant Systematics and Evolution》1979,131(3-4):193-209
47.
The 13C nmr chemical shifts of the common amino acid residues were measured in D2O solutions of the linear tetrapeptides H-Gly-Gly-X-L -Ala-OH. For Asp, Glu, Lys, Tyr and His, the titration shifts arising from the ionization of te amino acid side chains were also obtained. These data are compared with the corresponding 13C chemical shifts in the protected tetrapeptides CF3CO-Gly-Gly-X-L -Ala-OCH3, the linear pentapeptides H-Gly-Gly-X-Gly-Gly-OH, and the free amino acids. On this basism the selection of suitable “random coil” 13C chemical shifts for conformational studies of polypeptides chain is discussed. 相似文献
48.
Samit Kumar Dutta Pedro Serrano Michael Geralt Herbert L. Axelrod Qingping Xu Scott A. Lesley Adam Godzik Ashley M. Deacon Marc‐André Elsliger Ian A. Wilson Kurt Wüthrich 《Protein science : a publication of the Protein Society》2015,24(10):1600-1608
Flavodoxins in combination with the flavin mononucleotide (FMN) cofactor play important roles for electron transport in prokaryotes. Here, novel insights into the FMN‐binding mechanism to flavodoxins‐4 were obtained from the NMR structures of the apo‐protein from Lactobacillus acidophilus (YP_193882.1) and comparison of its complex with FMN. Extensive reversible conformational changes were observed upon FMN binding and release. The NMR structure of the FMN complex is in agreement with the crystal structure (PDB ID: 3EDO ) and exhibits the characteristic flavodoxin fold, with a central five‐stranded parallel β–sheet and five α‐helices forming an α/β‐sandwich architecture. The structure differs from other flavoproteins in that helix α2 is oriented perpendicular to the β‐sheet and covers the FMN‐binding site. This helix reversibly unfolds upon removal of the FMN ligand, which represents a unique structural rearrangement among flavodoxins. 相似文献
49.
Johnsen K Maier C Sanchez F Anderson P Butnor J Waring R Linder S 《Plant, cell & environment》2007,30(1):128-134
Quantifying below-ground carbon (C) allocation is particularly difficult as methods usually disturb the root-mycorrhizal-soil continuum. We reduced C allocation below ground of loblolly pine trees by: (1) physically girdling trees and (2) physiologically girdling pine trees by chilling the phloem. Chilling reduced cambium temperatures by approximately 18 degrees C. Both methods rapidly reduced soil CO2 efflux, and after approximately 10 days decreased net photosynthesis (P(n)), the latter indicating feedback inhibition. Chilling decreased soil-soluble C, indicating that decreased soil CO2 efflux may have been mediated by a decrease in root C exudation that was rapidly respired by microbes. These effects were only observed in late summer/early autumn when above-ground growth was minimal, and not in the spring when above-ground growth was rapid. All of the effects were rapidly reversed when chilling was ceased. In fertilized plots, both chilling and physical girdling methods reduced soil CO2 efflux by approximately 8%. Physical girdling reduced soil CO2 efflux by 26% in non-fertilized plots. This work demonstrates that phloem chilling provides a non-destructive alternative to reducing the movement of recent photosynthate below the point of chilling to estimate C allocation below ground on large trees. 相似文献
50.
ED Dean LM Mexas NL Cápiro JE McKeon MR DeLong KD Pennell JA Doorn V Tangpricha GW Miller ML Evatt 《PloS one》2012,7(7):e39227
Recent clinical evidence supports a link between 25-hydroxyvitamin D insufficiency (serum 25-hydroxyvitamin D [25(OH)D] levels <30 ng/mL) and Parkinson's disease. To investigate the effect of 25(OH)D depletion on neuronal susceptibility to toxic insult, we induced a state of 25(OH)D deficiency in mice and then challenged them with the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We found there was no significant difference between control and 25(OH)D-deficient animals in striatal dopamine levels or dopamine transporter and tyrosine hydroxylase expression after lesioning with MPTP. Additionally, we found no difference in tyrosine hydroxylase expression in the substantia nigra pars compacta. Our data suggest that reducing 25(OH)D serum levels in mice has no effect on the vulnerability of nigral dopaminergic neurons in vivo in this model system of parkinsonism. 相似文献