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61.
62.
Unusual behaviour of SPO1 DNA with respect to restriction and modification enzymes recognizing the sequence 5''-G-G-C-C 总被引:7,自引:0,他引:7
John N. Reeve Egon Amann Ravindra Tailor Ursula Günthert Klaus Scholz Thomas A. Trautner 《Molecular & general genetics : MGG》1980,178(1):229-231
Summary SPO1 DNA contains only 5 cleavage sites for restriction enzymes which recognize and cleave the sequence 5-G-G-C-C (HaeIII or BsuR). Fragments of SPO1 DNA cloned in E. coli to substitute 5-hydroxymethyluracil (HMU) by thymine (T) remain resistant to HaeIII indicating that this unexpectedly small number of cleavages by HaeIII is not correlated with the presence of HMU in the normal phage DNA. It was previously shown that SPO1 is neither subject to B. subtilis R restriction (Trautner et al., 1974) nor modification in vivo (Günthert et al., 1975). We now show that SPO1 DNA can however be restricted and modified in vitro. 相似文献
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65.
Bruno Studer Torben Asp Ursula Frei Stephan Hentrup Helena Meally Aurélie Guillard Susanne Barth Hilde Muylle Isabel Roldán-Ruiz Philippe Barre Carole Koning-Boucoiran Gerda Uenk-Stunnenberg Oene Dolstra Leif Skøt Kirsten P. Skøt Lesley B. Turner Mervyn O. Humphreys Roland Kölliker Niels Roulund Klaus K. Nielsen Thomas Lübberstedt 《Molecular breeding : new strategies in plant improvement》2008,21(4):533-548
An expressed sequence tag (EST) library of the key grassland species perennial ryegrass (Lolium perenne L.) has been exploited as a resource for microsatellite marker development. Out of 955 simple sequence repeat (SSR) containing
ESTs, 744 were used for primer design. Primer amplification was tested in eight genotypes of L. perenne and L. multiflorum representing (grand-) parents of four mapping populations and resulted in 464 successfully amplified EST-SSRs. Three hundred
and six primer pairs successfully amplified products in the mapping population VrnA derived from two of the eight genotypes
included in the original screening and revealed SSR polymorphisms for 143 ESTs. Here, we report on 464 EST-derived SSR primer
sequences of perennial ryegrass established in laboratory assays, providing a dedicated tool for marker assisted breeding
and comparative mapping within and among forage and turf grasses.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
66.
Gustav Kramer und Ursula von St. Paul 《Journal of Ornithology》1956,97(4):353-370
Zusammenfassung Schon veröffentlichte Feststellungen über verringertes Heimfindevermögen von Brieftauben im Winter werden bestätigt.Durch wiederholte Auflassungen über die gleiche Kurzstrecke (von NNW 22 km nach SSO) wird gezeigt, daß die Einzeltaube regelmäßig wesentlich schlechter abschneidet, wenn sie die gleiche, im Sommer durchflogene Strecke im Winter wiederholt. Durch Verwendung einer hinreichenden Anzahl von Erstfliegern in beiden Jahreszeiten wird der Wintereffekt auch durch Vergleich von Heimkehrschnelligkeiten verschiedener Individuen sichergestellt.Es wird gezeigt, daß die Verwandlung des Landschaftsbildes nicht die Ursache des winterlichen Versagens sein kann. Es ist auch unwahrscheinlich, daß die im Winter geringere Höhe des Sonnenstandes schuld ist. Entgegen einer früher vonKramer geäußerten Meinung können auch weder niedrige Temperaturen als solche noch direkt mit ihnen streng gekoppelte Faktoren verantwortlich gemacht werden.Der Einwand, daß es sich beim Wintereffekt nicht um eine Orientierungsbehinderung, sondern um eine jahreszeitlich, vielleicht mit der Taglänge korrelierte Schwächung des Heimkehrimpulses handeln möge, wird kritisch besprochen. Gegen diesen Einwand wird geltend gemacht, daß nach den bisherigen Erfahrungen der März noch zu den Winter-Monaten zählt; sogar ein Aprilflug trug intermediäre Züge. Dagegen funktioniert das Heimkehrvermögen im September noch gut. — Eine Korrelation mit der Intensität des Fortpflanzungsverhaltens kann deswegen nicht vorliegen, weil die Fortpflanzungsaktivität schon im Februar erheblich gesteigert ist. Es wird der Nachweis geführt, daß bei gleichen Temperaturen im Winter signifikant verschiedene Heimkehrerfolge an nahe beisammenliegenden Daten (3. 1. und 26. 1. 1956) erzielt werden können.Auch für andere Strecken (36 km S — N, 41 km O — W, 94 km S — N) werden Vergleiche von Heimflügen im Sommer mit solchen im Winter angestellt. Die Winterergebnisse sind durchweg erheblich schlechter.Das Bestehen des Wintereffekts zeigt, daß die Orientierung bei der Heimkehr auch über kurze Strecken nicht auf dem visuellen Erkennen von Landschaftsstrukturen beruht. Der Orientierungsmechanismus ist vielmehr unbekannt. Es ist vorläufig zu vermuten, daß er identisch ist mit dem, der über weitere Distanzen wirksam ist.Mit Unterstützung der Deutschen Forschungsgemeinschaft, welche das Fahrzeug zur Verfügung stellte und die Betriebsmittel dafür trug. 相似文献
67.
Novel fluid shear‐based dissociation device for improved single cell dissociation of spheroids and cell aggregates 下载免费PDF全文
Biological industries commonly rely on bioreactor systems for the large‐scale production of cells. Cell aggregation, clumping, and spheroid morphology of certain suspension cells make their large‐scale culture challenging. Growing stem cells as spheroids is indispensable to retain their stemness, but large spheroids (>500 µm diameter) suffer from poor oxygen and nutrient diffusion, ultimately resulting in premature cell death in the centers of the spheroids. Despite this, most large‐scale bioprocesses do not have an efficient method for dissociating cells into single cells, but rely on costly enzymatic dissociation techniques. Therefore, we tested a proof‐of‐concept fluid shear‐based mechanical dissociator that was designed to dissociate stem cell spheroids and aggregates. Our prototype was able to dissociate cells while retaining high viability and low levels of apoptosis. The dissociator also did not impact long‐term cell growth or spheroid formation. Thus, the dissociator introduced here has the potential to replace traditional dissociation methods. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:293–298, 2018 相似文献
68.
Thomas Mattern Ursula Ellenberg David M. Houston Miles Lamare Lloyd S. Davis Yolanda van Heezik Philip J. Seddon 《PloS one》2013,8(12)
Free-ranging marine predators rarely search for prey along straight lines because dynamic ocean processes usually require complex search strategies. If linear movement patterns occur they are usually associated with travelling events or migratory behaviour. However, recent fine scale tracking of flying seabirds has revealed straight-line movements while birds followed fishing vessels. Unlike flying seabirds, penguins are not known to target and follow fishing vessels. Yet yellow-eyed penguins from New Zealand often exhibit directed movement patterns while searching for prey at the seafloor, a behaviour that seems to contradict common movement ecology theories. While deploying GPS dive loggers on yellow-eyed penguins from the Otago Peninsula we found that the birds frequently followed straight lines for several kilometres with little horizontal deviation. In several cases individuals swam up and down the same line, while some of the lines were followed by more than one individual. Using a remote operated vehicle (ROV) we found a highly visible furrow on the seafloor most likely caused by an otter board of a demersal fish trawl, which ran in a straight line exactly matching the trajectory of a recent line identified from penguin tracks. We noted high abundances of benthic scavengers associated with fisheries-related bottom disturbance. While our data demonstrate the acute way-finding capabilities of benthic foraging yellow-eyed penguins, they also highlight how hidden cascading effects of coastal fisheries may alter behaviour and potentially even population dynamics of marine predators, an often overlooked fact in the examination of fisheries’ impacts. 相似文献
69.
Niels Westergaard Ursula Sonnewald Steffen B. Petersen Arne Schousboe 《Neurochemical research》1991,16(8):919-923
In the present investigation a method is described for culturing cerebellar granule cells (glutamatergic neurons), cerebral cortical neurons (GABAergic neurons) and cortical astrocytes on Cytodex 3 microcarriers. It was possible to obtain a high yield of attached neurons and astrocytes on the microcarriers and the cell specific characteristics such as the ability to release neurotransmitter (neurons) and a high activity of glutamine synthetase (astrocytes) were preserved. This system, allowing mixtures of neurons and astrocytes at any given ratio to be produced, may constitute an attractive model system by which the interaction between neurons and astrocytes with regard to exchange of neurotransmitter precursors as well as other compounds may be studied. 相似文献
70.
Melø TM Håberg AK Risa Ø Kondziella D Henry PG Sonnewald U 《Neurochemical research》2011,36(10):1801-1808
Evaluating early changes in cerebral metabolism in hydrocephalus can help in the decision making and the timing of surgical
intervention. This study was aimed at examining the tricarboxylic acid (TCA) cycle rate and 13C label incorporation into neurotransmitter amino acids and other compounds 2 weeks after rats were subjected to kaolin-induced
progressive hydrocephalus. In vivo and ex vivo magnetic resonance spectroscopy (MRS), combined with the infusion of [1,6-13C]glucose, was used to monitor the time courses of 13C label incorporation into the different carbon positions of glutamate in the forebrains of rats with hydrocephalus as well
as in those of controls. Metabolic rates were determined by fitting the measured data into a one-compartment metabolic model.
The TCA cycle rate was 1.3 ± 0.2 μmoles/gram/minute in the controls and 0.8 ± 0.4 μmoles/gram/minute in the acute hydrocephalus
group, the exchange rate between α-ketoglutarate and glutamate was 4.1 ± 2.5 μmoles/gram/minute in the controls and 2.7 ± 2.6 μmoles/gram/minute
in the hydrocephalus group calculated from in vivo MRS. There were no statistically significant differences between these
rates. Hydrocephalus caused a decrease in the amounts of glutamate, alanine and taurine. In addition, the concentration of
the neuronal marker N-acetyl aspartate was decreased. 13C Labelling of most amino acids derived from [1,6-13C]glucose was unchanged 2 weeks after hydrocephalus induction. The only indication of astrocyte impairment was the decreased
13C enrichment in glutamine C-2. This study shows that hydrocephalus causes subtle but significant alterations in neuronal metabolism
already early in the course of the disease. These sub-lethal changes, however, if maintained and if ongoing might explain
the delayed and programmed neuronal damage as seen in chronic hydrocephalus. 相似文献