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81.
A kinetic analysis was made of the relationship between salicylate production from naphthalene and growth of Pseudomonas fluorescens in semicontinuous dialysis culture. The specific rates both of product formation and growth initially were increased by the diffusional withdrawal of salicylate, but subsequently were reduced to low levels despite continued salicylate removal. Productivity and growth were correlated by the Luedeking-Piret equation in an initial nondialysis period and in the early stages of dialysis fermentation, when specific growth rates exceeded. 005 hr?1. Below this level of growth at later stages of dialysis fermentation, the specific production rate was correlated only with total cell mass by a proportionality constant of .035 hr?1, which was attributed to maintenance metabolism. Maintenance accounted for about 84% of the total salicylate produced, while growth-associated metabolism accounted for the remainder. 相似文献
82.
83.
Ulrich Gerhardt 《Zoomorphology》1928,10(4):576-675
Ohne Zusammenfassung 相似文献
84.
Ulrich Gerhardt 《Development genes and evolution》1929,118(1):11-39
Zusammenfassung Die wissenschaftliche Vergleichung sexualbiologischer Geschehnisse kann von zwei verschiedenen Standpunkten aus geschehen: es können analoge Erscheinungen verglichen werden, es können aber auch phyletische Momente zur Erforschung echter Homologien in den Vordergrund gestellt werden, wie es in dieser Betrachtung geschieht.Für die am besten bekannten Tiergruppen, dieSäugetiere, einige Ordnungen derInsekten und dieSpinnen, werden die bisher bekannt gewordenen Ergebnisse sexualbiologischer Untersuchungen zusammengestellt und die für die einzelnen Gruppen charakteristischen Punkte erörtert.Es sind die Erscheinungen der Werbung, der Begattung und, bei Tieren mit akzessorischen Kopulationsorganen, der Bereitmachung dieser Organe, die untereinander bei Tieren gleicher morphologischer Organisation verglichen werden können. Nicht zu trennen von ihrer Betrachtung ist die der Morphologie und Physiologie der Sexualorgane.Wie deren Bau eine Fülle von Varianten zeigt, die sich nicht aus einem zwingenden physiologischen Bedarf in ihrer Ausgestaltung im einzelnen verstehen lassen, so ist auch das sexualbiologische Benehmen des tierischen Organismus nur teilweise aus der allgemeinen Lebensweise zu erklären. Ein Teil der Erscheinungen wird aus der Morphologie und Physiologie und aus Einflüssen der Außenwelt verständlich werden, aber für andere Erscheinungen versagen diese Möglichkeiten. Gerade diese Handlungskomplexe sind, weil verhältnismäßig unabhängig von dem täglichen Lebensbedarf des Tieres, äußerst variabel und daher für die Art sehr charakteristisch. Ihre Vergleichung bei Arten einer Gattung und mit denselben Erscheinungen in übergeordneten Einheiten des Systems (in mehreren Gattungen einer Familie und Familien einer Ordnung) zeigt deutliche biologische Reihen, die, wie morphologische Reihen, in sich in phyletische Beziehungen gebracht werden können. Bei der Aufstellung solcher Reihen werden biologische Typen in verschiedenen Varianten gezeigt werden können; es wird ferner festzustellen sein, wieweit diese Typen durch Faktoren der Außenwelt verwischt werden können. So wird die oft durch das Bedürfnis der möglichst günstigen Unterbringung der Keime geregelte Eiablage der Weibchen die endogen bedingten ursprünglichen biologischen Typen häufig nur schwer erkennen lassen.Von einer ausgedehnten Vergleichung biologischer Merkmale (die sich über alle Zweige der tierischen Lebensweise erstrecken müßte) ist eine Bereicherung unserer Kenntnisse der wesentlichen Merkmale der tierischen Arten, eine Möglichkeit der Auffindung von Zusammenhängen zwischen den verschiedenen Varianten eines biologischen Typus, der Aussonderung von Konvergenzerscheinungen und endlich einer durch die Morphologie allein nicht gegebenen und ihre Befunde kontrollierenden Betrachtungsweise des tierischen Systems gegeben. 相似文献
85.
The role of glutamate signaling in incentive salience: second‐by‐second glutamate recordings in awake Sprague‐Dawley rats
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Seth R. Batten Francois Pomerleau Jorge Quintero Greg A. Gerhardt Joshua S. Beckmann 《Journal of neurochemistry》2018,145(4):276-286
86.
H. C. Gerhardt J. Schul 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1999,185(1):33-40
The selectivity of female phonotactic responses to synthetic advertisement calls was tested in choice situations. Preferences
based on differences in the linear rise-time of synthetic pulses depended on intensity and carrier frequency. When the carrier
frequency was 1.1 kHz, simulating the low-frequency peak in the advertisement call, females preferred alternatives with slower
rise-time pulses that differed by 5 ms at playback levels of 75 dB SPL and higher. A rise-time difference of 10 ms was discriminated
at 65 dB SPL. When the carrier frequency was 2.2 kHz, simulating the high-frequency peak in the call, females discriminated
a 5-ms difference in rise-time only at 85 dB SPL. Females showed no preference when the difference was 10 ms at lower playback
levels. The difference in the thresholds (about 15–20 dB) for discriminating differences in rise-time at the two carrier frequencies
was greater than the difference in behavioral thresholds for these two frequencies (about 10 dB). This result suggests that
rise-time discrimination can be mediated solely by the neural channel mainly tuned to the low-frequency peak in the call.
Females probably assess differences in rise-time by comparing the first few pulses of each call rather than by averaging over
the entire call.
Accepted: 30 March 1999 相似文献
87.
Robo4 stabilizes the vascular network by inhibiting pathologic angiogenesis and endothelial hyperpermeability 总被引:1,自引:0,他引:1
Jones CA London NR Chen H Park KW Sauvaget D Stockton RA Wythe JD Suh W Larrieu-Lahargue F Mukouyama YS Lindblom P Seth P Frias A Nishiya N Ginsberg MH Gerhardt H Zhang K Li DY 《Nature medicine》2008,14(4):448-453
The angiogenic sprout has been compared to the growing axon, and indeed, many proteins direct pathfinding by both structures. The Roundabout (Robo) proteins are guidance receptors with well-established functions in the nervous system; however, their role in the mammalian vasculature remains ill defined. Here we show that an endothelial-specific Robo, Robo4, maintains vascular integrity. Activation of Robo4 by Slit2 inhibits vascular endothelial growth factor (VEGF)-165-induced migration, tube formation and permeability in vitro and VEGF-165-stimulated vascular leak in vivo by blocking Src family kinase activation. In mouse models of retinal and choroidal vascular disease, Slit2 inhibited angiogenesis and vascular leak, whereas deletion of Robo4 enhanced these pathologic processes. Our results define a previously unknown function for Robo receptors in stabilizing the vasculature and suggest that activating Robo4 may have broad therapeutic application in diseases characterized by excessive angiogenesis and/or vascular leak. 相似文献
88.
Hormonal levels fluctuate during the breeding season in many anurans, but the identity of the hormones that modulate breeding behavior and their effects remain unclear. We tested the influence of a combined treatment of progesterone and prostaglandin on phonotaxis, the key proceptive reproductive behavior of female anurans. First, we found that female gray treefrogs (Hyla versicolor) treated with progesterone and prostaglandin exhibited phonotaxis to synthetic male advertisement signals significantly more often than animals treated with ringers vehicle or uninjected controls. Responsive females had greater levels of plasma progesterone and estradiol compared to both control groups, suggesting that these steroids may be promoting phonotaxis. Second, we found that the selectivity of hormonally-induced phonotaxis in H.versicolor was similar to that observed in freshly captured breeding animals. Females made the same choices between acoustic signals after hormone treatments in tests of frequency, call rate and pulse rate, compared to their responses without treatment immediately after collection from the breeding chorus. The preference for a longer call was, however, significantly weaker after hormonal induction of phonotaxis. Hormonally primed females were also less likely to respond in any test and took longer to respond than did freshly collected females. Consequently, our study shows how progesterone-prostaglandin induced phonotaxis in female treefrogs influences both the quality and quantity of phonotaxis, relative to that exhibited by naturally breeding females. 相似文献
89.
Nabil Asaad Paul A. Bethel Michelle D. Coulson Jack E. Dawson Susannah J. Ford Stefan Gerhardt Matthew Grist Gordon A. Hamlin Michael J. James Emma V. Jones Galith I. Karoutchi Peter W. Kenny Andrew D. Morley Keith Oldham Neil Rankine David Ryan Stuart L. Wells Linda Wood Martin Augustin Stephan Krapp Stefan Steinbacher 《Bioorganic & medicinal chemistry letters》2009,19(15):4280-4283
A series of potent Cathepsin L inhibitors with good selectivity with respect to other cysteine Cathepsins is described and SAR is discussed with reference to the crystal structure of a protein-ligand complex. 相似文献
90.
Carina Loffredo Nilson A. Assunção Juergen Gerhardt M. Terêsa Machini Miranda 《Journal of peptide science》2009,15(12):808-817
Several conditions have been used in the coupling reaction of stepwise SPPS at elevated temperature (SPPS‐ET), but we have elected the following as our first choice: 2.5‐fold molar excess of 0.04–0.08 M Boc or Fmoc‐amino acid derivative, equimolar amount of DIC/HOBt (1:1) or TBTU/DIPEA (1:3), 25% DMSO/toluene, 60 °C, conventional heating. In this study, aimed to further examine enantiomerization under such condition and study the applicability of our protocols to microwave‐SPPS, peptides containing L ‐Ser, L ‐His, L ‐Cys and/or L ‐Met were manually synthesized traditionally, at 60 °C using conventional heating and at 60 °C using microwave heating. Detailed assessment of all crude peptides (in their intact and/or fully hydrolyzed forms) revealed that, except for the microwave‐assisted coupling of L ‐Cys, all other reactions occurred with low levels of amino acid enantiomerization (<2%). Therefore, herein we (i) provide new evidences that our protocols for SPPS at 60 °C using conventional heating are suitable for routine use, (ii) demonstrate their appropriateness for microwave‐assisted SPPS by Boc and Fmoc chemistries, (iii) disclose advantages and limitations of the three synthetic approaches employed. Thus, this study complements our past research on SPPS‐ET and suggests alternative conditions for microwave‐assisted SPPS. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. 相似文献