Top-spraying soybean meal-based diets with phytase improves protein and mineral digestibilities but not lysine utilization in rainbow trout, Oncorhynchus mykiss (Walbaum)     

Jouni Vielma  Kari Ruohonen  Jacques Gabaudan  Kurt Vogel 《Aquaculture Research》2004,35(10):955-964

Two digestibility trials and two growth trials were carried out to evaluate the influence of top‐sprayed phytase on apparent digestibility coefficients (ADCs) of protein and mineral and utilization in rainbow trout fed with soybean meal‐based diets. In Trial 1, a semi‐purified diet containing 50% soybean meal was supplemented with graded levels of phytase (0, 500, 1000, 2000 and 4000 U kg^?1 diet), and fed to triplicate groups of fish. In Trial 2, commercial‐type extruded feeds containing 36% soybean meal with either 0 or 2000 U phytase kg^?1 were fed to five replicate groups of fish. Phytase clearly decreased phytic acid content of feces from 35 to 5 mg and from 34 to 14 mg phytic acid per g faecal dry matter in Trials 1 and 2 respectively. Apparent digestibility coefficient of P improved from 23% to 83% in Trial 1 and from 35% to 54% in Trial 2 by phytase. Apparent protein increased by 1.2% and 3.2%‐units by phytase in Trials 1 and 2. Zinc digestibility was significantly increased in Trial 1, but not in Trial 2. Trials 3 and 4 were conducted to evaluate the influence of phytase on dietary P (Trial 3) and lysine (Trial 4) utilization. Three diets were prepared for each trial: P (Trial 3)‐ or lysine (Trial 4)‐deficient basal diets, basal diets with phytase supplementation (2000 U kg^?1) and P (Trial 3)‐ or lysine (Trial 4)‐fortified diets. Rainbow trout (initial weight 20 g) were fed for 10 weeks using four and six replicates for Trials 3 and 4 respectively. Phytase increased P utilization in Trial 3 as demonstrated by an increase in vertebra ash from 24.1% to 45.4%, and by an increase in weight gain from 243% to 459% of the initial weight. Phytase did not increase lysine utilization, since neither protein retention nor weight gain were enhanced by phytase. Supplemental lysine increased protein retention and weight gain to 43.1% and 514%, respectively, and also decreased whole‐body lipid contents significantly from 120 to 123 g kg^?1 in fish fed the basal diet and phytase‐supplemented diet to 106 g kg^?1 in fish fed with lysine‐fortified diet.  相似文献   

Autorreferate demnächst crscheinender Arbeiten     

Kurt Zschau  Horst Böttcher 《Archives of Agronomy and Soil Science》2013,59(10):951-952

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Zur Frage der forstlichen Unterrichtsgestaltung     

Kurt Mantel 《Forstwissenschaftliches Centralblatt》1937,59(1):1-16

Ohne Zusammenfassung  相似文献   

Untersuchungen zum Einfluß des Matrixpotentials im Boden auf Stammdickenänderungen von Fichten (Picea abies (L.) Karst.)     

Jin-Chen Liu  Karl-Heinz Hberle  Kurt Loris 《植物养料与土壤学杂志》1995,158(3):231-234

Effects of soil water potential on stem radius changes of Norway spruce (Picea abies (L.) Karst.) The stem radius of 2 mature Norway spruce trees and the soil water potential were continuously measured in situ with dendrometers and tensiometers, respectively. In a period without growth and frost events the stem radius and the soil water potentials correlated closely. A young spruce tree grown under controlled conditions changed its radius in response to the soil water supply likewise. The shrinkage of the stem was reversible, even if the soil was very dry (soil water potential ± ? 1000 hPa). An estimate of the soil water potential seems to be possible even beyond ? 1000 hPa by measurements of stem radius changes.  相似文献   

Untersuchungen zur Entwicklung der apomiktischen Fortpflanzungsweise bei Futtergräsern II. Hybrideffekt und Fertilität von Art- und Gattungsbastarden     

Kurt Gröber  Fritz Matzk  Martin Zacharias 《Genetic Resources and Crop Evolution》1976,24(1):349-364

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Zytologische und embryologische Untersuchungen am Nucellus apomiktischer Sippen der Wiesenrispe (Poa pratensis L.)     

Kurt Gröber 《Genetic Resources and Crop Evolution》1986,34(2):147-158

Zusammenfassung Bei apomiktischen Sippen vonPoa pratensis wurden 165 Samenanlagen auf die Anzahl der in ihren Nucelli ausgebildeten Embryosäcke untersucht. Dabei wurden in 87 Nucelli ein, in 60 zwei und in 18 drei Embryosäcke gefunden. Im Einzelfall sind in diesem Stadium apomiktische von sexuellen Embryosäcken nicht zu unterscheiden; es kann aber aus der bekannten hohen Apomixierate bei Zuchtmaterial geschlossen werden, daß es sich dabei fast ausnahmslos um solche aposporen Ursprungs handelt.Die zahlenmäßige Erfassung keimfähiger mono-, bi- und polyembryonaler Karyopsen erfolgt im Keimapparat auf Filterpapier. Die auf diese Weise ermittelte Differenz zu den mittels embryologischer Methoden erfaßten Embryosäcken ist beträchtlich. Von der Anzahl aposporer Initialen je Nucellus über die Anzahl entwickelter Embryosäcke je Nucellus bis zur Ausbildung keimfähiger Embryonen je Karyopse, ist zahlenmäßig eine starke Verminderung festzustellen.In dem befruchtungsfähigen Embryosack bilden, wie zu erwarten, drei Kerne den Eiapparat, zwei die Polkerne und drei die Antipoden. Durch somatische Polyploidisierung erfahren die Antipoden stets eine auffällige Volumenzunahme, und es kann sich durch zusätzliche Teilungen auch ihre Anzahl erhöhen.

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Cytological and embryological studies in nucelli of apomictic specimens ofPoa pratensis L.

Summary In a total of 165 analysed nucelli of apomictic specimens ofPoa pratensis 87 contain only one embryo-sac, 60 two embryo-sacs and 18 three ones. In no case aposporous embryo-sacs could be distinguished from meiotic ones. However, from the high apomeiotic rate in breeding material the conclusion can be drawn that the majority of them are of aposporous origin.The numerical evaluation of the germinating capacity of mono-, bi- and polyembryonic caryopses was performed in a germinating apparatus. There are considerable differences between the values determined in this way and those ascertained by embryological methods. It was found that during the developmental pathway from the aposporous initial to the mature, full-grown embryo sequentially the number of embryo-sacs per nucellus and the number of embryos capable to germinate per caryopsis are diminished.As expected, in the mature, fertile embryo-sac three nuclei form the egg-apparatus, two ones the pole nuclei and three ones the antipodals. By somatic polyploidization the antipodals always undergo a considerable increase in volume, and in few cases by additional divisions the number of antipodals may be increased also.

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(Poa pratensis L.)

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Visualization and functional analysis of RNA-dependent RNA polymerase lattices     

Lyle JM  Bullitt E  Bienz K  Kirkegaard K 《Science (New York, N.Y.)》2002,296(5576):2218-2222

Positive-strand RNA viruses such as poliovirus replicate their genomes on intracellular membranes of their eukaryotic hosts. Electron microscopy has revealed that purified poliovirus RNA-dependent RNA polymerase forms planar and tubular oligomeric arrays. The structural integrity of these arrays correlates with cooperative RNA binding and RNA elongation and is sensitive to mutations that disrupt intermolecular contacts predicted by the polymerase structure. Membranous vesicles isolated from poliovirus-infected cells contain structures consistent with the presence of two-dimensional polymerase arrays on their surfaces during infection. Therefore, host cytoplasmic membranes may function as physical foundations for two-dimensional polymerase arrays, conferring the advantages of surface catalysis to viral RNA replication.  相似文献   

Planetary science. Sampling the Sun     

Marti K 《Science (New York, N.Y.)》2007,318(5849):401-402

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Widespread intense turbulent mixing in the Southern Ocean     

Garabato AC  Polzin KL  King BA  Heywood KJ  Visbeck M 《Science (New York, N.Y.)》2004,303(5655):210-213

Observations of internal wave velocity fluctuations show that enhanced turbulent mixing over rough topography in the Southern Ocean is remarkably intense and widespread. Mixing rates exceeding background values by a factor of 10 to 1000 are common above complex bathymetry over a distance of 2000 to 3000 kilometers at depths greater than 500 to 1000 meters. This suggests that turbulent mixing in the Southern Ocean may contribute crucially to driving the upward transport of water closing the ocean's meridional overturning circulation, and thus needs to be represented in numerical simulations of the global ocean circulation and the spreading of biogeochemical tracers.  相似文献   

Was there really an Archean phosphate crisis?     

Konhauser KO  Lalonde SV  Amskold L  Holland HD 《Science (New York, N.Y.)》2007,315(5816):1234

During the Archean, massive amounts of iron were deposited in the form of banded iron formations. It has been suggested that sedimenting particles of ferric oxyhydroxide may have stripped dissolved phosphate from the oceans, causing a reduction in phytoplankton productivity. However, that model does not take into account the high concentration of dissolved silica that was present in seawater at that time. We show experimentally that silica effectively competes with phosphate for sorption sites on ferrihydrite particles. Furthermore, coprecipitation of silica with ferrihydrite reduces particle reactivity toward phosphate. Hence, Archean oceans probably contained considerably more phosphate than previously predicted.  相似文献