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161.
Alberto V. Borges Gaëlle Speeckaert Willy Champenois Mary I. Scranton Nathalie Gypens 《Ecosystems》2018,21(4):583-599
Dissolved CH4 concentrations in the Belgian coastal zone (North Sea) ranged between 670 nmol l?1 nearshore and 4 nmol l?1 offshore. Spatial variations of CH4 were related to sediment organic matter (OM) content and gassy sediments. In nearshore stations with fine sand or muddy sediments, the CH4 seasonal cycle followed water temperature, suggesting methanogenesis control by temperature in these OM-rich sediments. In offshore stations with permeable sediments, the CH4 seasonal cycle showed a yearly peak following the chlorophyll-a spring peak, suggesting that in these OM-poor sediments, methanogenesis depended on freshly produced OM delivery. This does not exclude the possibility that some CH4 might originate from dimethylsulfide (DMS) or dimethylsulfoniopropionate (DMSP) or methylphosphonate transformations in the most offshore stations. Yet, the average seasonal CH4 cycle was unrelated to those of DMS(P), very abundant during the Phaeocystis bloom. The annual average CH4 emission was 126 mmol m?2 y?1 in the most nearshore stations (~4 km from the coast) and 28 mmol m?2 y?1 in the most offshore stations (~23 km from the coast), 1260–280 times higher than the open ocean average value (0.1 mmol m?2 y?1). The strong control of CH4 by sediment OM content and by temperature suggests that marine coastal CH4 emissions, in particular in shallow areas, should respond to future eutrophication and warming of climate. This is supported by the comparison of CH4 concentrations at five stations obtained in March 1990 and 2016, showing a decreasing trend consistent with alleviation of eutrophication in the area. 相似文献
162.
Isolation and characterization of lectins and lectin-alliinase complexes from bulbs of garlic (Allium sativum) and ramsons (Allium ursinum) 总被引:1,自引:0,他引:1
Koen Smeets Els J.M Van Damme Fred Van Leuven Willy J Peumans 《Glycoconjugate journal》1997,14(3):331-343
A procedure developed to separate the homodimeric and heterodimeric mannose-binding lectins from bulbs of garlic (Allium sativum
L.) and ramsons (Allium ursinum L.) also enabled the isolation of stable lectin-alliinase complexes. Characterization of the
individual lectins indicated that, in spite of their different molecular structure, the homomeric and heteromeric lectins
resemble each other reasonably well with respect to their agglutination properties and carbohydrate-binding specificity. However,
a detailed analysis of the lectin-alliinase complexes from garlic and ramsons bulbs demonstrated that only the heterodimeric
lectins are capable of binding to the glycan chains of the alliinase molecules (EC 4.4.1.4). Moreover, it appears that only
a subpopulation of the alliinase molecules is involved in the formation of lectin-alliinase complexes and that the complexed
alliinase contains more glycan chains than the free enzyme. Finally, some arguments are given that the lectin-alliinase complexes
do not occur in vivo but are formed in vitro after homogenization of the tissue.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
163.
Hillyard Stanley D.; Cantiello Horacio F.; Van Driessche Willy 《American journal of physiology. Cell physiology》1997,273(6):C1995
Skin from larval bullfrogs was mounted in an Ussing-type chamberin which the apical surface was bathed with a Ringer solution containing 115 mM K+ and thebasolateral surface was bathed with a Ringer solution containing 115 mMNa+. Ion transport was measured asthe short-circuit current(Isc) with alow-noise voltage clamp, and skin resistance(Rm) wasmeasured by applying a direct current voltage pulse. Membrane impedance was calculated by applying a voltage signal consisting of 53 sine wavesto the command stage of the voltage clamp. From the ratio of theFourier-transformed voltage and current signals, it was possible tocalculate the resistance and capacitance of the apical and basolateralmembranes of the epithelium(Ra andRb,Ca and Cb,respectively). With as the anion,Rm decreasedrapidly within 5 min following the addition of 150 U/ml nystatin to theapical solution, whereasIsc increasedfrom 0.66 to 52.03 µA/cm2 over a60-min period. These results indicate that nystatin becomes rapidlyincorporated into the apical membrane and that the increase inbasolateral K+ permeabilityrequires a more prolonged time course. Intermediate levels ofIsc were obtainedby adding 50, 100, and 150 U/ml nystatin to the apical solution. Thisproduced a progressive decrease in Ra andRb whileCa andCb remainedconstant. With Cl as theanion, Isc valuesincreased from 2.03 to 89.57 µA/cm2 following treatment with150 U/ml nystatin, whereas with gluconate as the anionIsc was onlyincreased from 0.63 to 11.64 µA/cm2. This suggests that theincrease in basolateral K+permeability produced by nystatin treatment, in the presence of morepermeable anions, is due to swelling of the epithelial cells of thetissue rather than the gradient for apicalK+ entry. Finally,Cb was notdifferent among skins exposed toCl,, or gluconate, despite the largedifferences inIsc, nor didinhibition of Iscby treatment with hyperosmotic dextrose cause significant changes inCb. These resultssupport the hypothesis that increases in cell volume activateK+ channels that are alreadypresent in the basolateral membrane of epithelial cells. 相似文献
164.
Isolation,characterization and molecular cloning of the mannose-binding lectins from leaves and roots of garlic (Allium sativum L.) 总被引:4,自引:0,他引:4
Smeets Koen Van Damme Els J.M. Verhaert Peter Barre Annick Rougé Pierre Van Leuven Fred Peumans Willy J. 《Plant molecular biology》1997,33(2):223-234
Two novel lectins were isolated from roots and leaves of garlic. Characterization of the purified proteins indicated that the leaf lectin ASAL is a dimer of two identical subunits of 12 kDa, which closely resembles the leaf lectins from onion, leek and shallot with respect to its molecular structure and agglutination activity. In contrast, the root lectin ASARI, which is a dimer of subunits of 15 kDa, strongly differs from the leaf lectin with respect to its agglutination activity. cDNA cloning of the leaf and root lectins revealed that the deduced amino acid sequences of ASAL and ASARI are virtually identical. Since both lectins have identical N-terminal sequences the larger Mr of the ASARI subunits implies that the root lectin has an extra sequence at its C-terminus. These results not only demonstrate that virtually identical precursor polypeptides are differently processed at their C-terminus in roots and leaves but also indicate that differential processing yields mature lectins with strongly different biological activities. Further screening of the cDNA library for garlic roots also yielded a cDNA clone encoding a protein composed of two tandemly arrayed lectin domains. Since the presumed two-domain root lectin has not been isolated yet, its possible relationship to the previously described two-domain bulb lectin could not be studied at the protein level. 相似文献
165.
Isolation,characterization and molecular cloning of a leaf-specific lectin from ramsons (Allium ursinum L.). 总被引:1,自引:0,他引:1
Smeets Koen Van Damme Els J.M. Van Leuven Fred Peumans Willy J. 《Plant molecular biology》1997,35(4):531-535
Lectins were isolated from roots and leaves of ramsons and compared to the previously described bulb lectins. Biochemical analyses indicated that the root lectins AUAIr and AUAIIr are identical to the bulb lectins AUAI and AUAII, whereas the leaf lectin AUAL has no counterpart in the bulbs. cDNA cloning confirmed that the leaf lectin differs from the bulb lectins. Northern blot analysis further indicated that the leaf lectin is tissue-specifically expressed. Sequence comparisons revealed that the ramsons leaf lectin differs considerably from the leaf lectins of garlic, leek, onion and shallot. 相似文献
166.
167.
Walter Finsinger Oliver Heiri Verushka Valsecchi Willy Tinner André F. Lotter 《Global Ecology and Biogeography》2007,16(5):567-582
Aim and Location Our aim is to develop pollen–climate inference models for southern Europe and to test their performance and inference power by cross‐validation with modern climate data. Surface sediments collected from lakes along a climate gradient from the winter‐cold/summer‐wet Alps to winter‐wet/summer‐dry Sicily were analysed for modern pollen assemblages. Methods For each lake, mean monthly temperatures, seasonal precipitation and site‐specific climate uncertainties have been estimated. Pollen–climate relationships were studied using numerical analyses, and inference models were derived by partial least squares (PLS) and weighted‐averaging PLS (WA‐PLS) regressions for January and July temperatures (T), and for winter, spring and summer precipitation (P). In order to assess whether these variables are also of ecological importance for vegetation in the subregions, we split the data set into an Alpine and a Mediterranean subset. Results Low bootstrap cross‐validated root mean square errors of prediction (RMSEP) for January T (1.7 °C), July T (2.1 °C) and summer P (38 mm), as well as low RMSEPs expressed as a percentage of the gradient length (8–9%), indicate a good inference power. Models revealed excellent to good performance statistics for January T, July T and summer P (r2= 0.8), and for winter and spring P (r2=c. 0.5). We show that the variables with the highest explanatory power differ between the two subregions. These are summer T and P for the Alpine set, and January T, winter P and July T for the Mediterranean set. Main conclusions The study reveals the influence of climatic conditions during the growing season on modern pollen assemblages and indicates the potential of pollen data for long‐term climate reconstructions of parameters such as winter precipitation and temperature, which seem to be the main factors having an influence on the variability of Mediterranean climate. These models may therefore provide important information on past regional climate variability in southern Europe. 相似文献
168.
Silvano De Bernardo Manfred Weigele Voldemar Toome Karin Manhart Willy Leimgruber Peter Böhlen Stanley Stein Sidney Udenfriend 《Archives of biochemistry and biophysics》1974,163(1):390-399
Fluorescamine is a useful reagent for the fluorometric assay of primary amines. The extent of the reaction between fluorescamine and primary amines, as well as the fluorescence intensities of the resulting fluorophors depend on pH, solvent composition and reagent concentration. Optimum values for these variables further depend on the amine under study. The influence of these parameters on the fluorogenic reaction of representative amines, and on their fluorophoric derivatives has been investigated, and the results are reported here. 相似文献
169.
Willy Nolte 《Helgoland Marine Research》1968,17(1-4):156-167
Zusammenfassung 1. Weder in der Wesermündung noch vor dieser in der Deutschen Bucht kann erwartet werden, daß eingeleitete Abwässer immer eine schnelle und gute Durchmischung oder sogar eine totale Durchmischung erfahren. Es bilden sich sehr häufig Wasserschlieren, Wasserfahnen, Wasserblasen, Wasserkörper oder Wasserinseln, die sich — entgegen allen Theorien und Berechnungen — der totalen Durchmischung entziehen.2. Die schädlichen Stoffe können mangelhaft oder undurchmischt zusammenbleiben und in mehr oder weniger großen Gebieten biologische Schäden verursachen.3. Ein Schaden in der biologischen Kette kann weiterwirken auf die Nahrungstiere der Garnelen und Fische und damit mittelbar auf diese selbst oder auf deren Ei- und Jugendstadien, auf den Glasaalaufstieg oder auf Muschelkulturen (Korringa 1967).4. Es wäre wünschenswert, die Küstengewässer vor großen Abwassereinleitungen zu schützen. Wenn Großsiedlungen und Industrien darauf angewiesen sind, so muß jedenfalls gefordert werden, daß die Technik alle Möglichkeiten ausschöpft, um die Abwässer soweit unschädlich zu machen, wie es technisch heute möglich ist. Es muß erwartet werden, daß Wirtschaftlichkeitsberechnungen nicht nur die Rentabilität der Industrie, sondern auch die Fischerei (Abb. 3) und die Bedeutung der Küste als Erholungsgebiet einbeziehen (Caspers 1967).5. Die Fischerei erhebt die über 60 Jahre alten Forderungen für die Binnengewässer (Wundsch 1926) heute für die Küstengewässer und das Meer: (a) Das Gewässer darf durch die Abwassereinleitungen nicht so verändert werden, daß die Fischwelt gehindert wird zu leben und sich fortzupflanzen. (b) Die natürliche Fauna und Flora darf nicht vermindert oder in ihrer Zusammensetzung zum Nachteil der Nahrungskette verändert werden. (c) Die technische Durchführbarkeit der Fischerei darf nicht gestört oder unmöglich gemacht werden.
The inshore-fishery in the lower and outer Weser and the danger of water pollution
In earlier times the fishery of the lower and outer Weser was of a high commercial value. Todays fishery suffers from the development of the Weser River into a great shipping way and increasing water pollution. Many professional fishermen have been replaced by hobby fishermen; these fish in great numbers and, therefore, secure relatively great quantities of fish. In 1966 the value of the total catch of professional and hobby fishermen amounted to about 3 million DM. Such high yields can, however, hardly be expected in the future. Already now the Weser belongs to the-to-mesosaprob zone. The greatest danger is to be seen in the trend of the various industries to settle near the coast and to dump their wastes into rivers and littoral areas expecting fast and complete mixing of the waters. However, the Weser estuary is always stratified horizontally and vertically, hence total mixing wastes never occurs. In view of the great amounts of industrial wastes to be discharged and the hydrographic stratification, severe biological consequences are to be expected. Some of the potential water pollution damages are discussed.相似文献
170.
Willy Lange 《Journal of phycology》1974,10(4):411-414
Although domination of 1 species in an algal community has often been attributed to toxic effects, nutrient exhaustion can also lead to competitive exclusion among algal species. The bacteria-associated blue-green algae Microcystis aeruginosa, Nostoc muscorum, and Phormidium foveolarum were cultivated in Zehnder-Gorham's medium No. 11 individually and in their combinations. The growth rates of Microcystis and of Nostoc were reduced by the presence of Phormidium. This detrimental effect was apparently not due to formation of any toxic or allelopathic matter. It was caused by the reduction of iron and trace metal concentrations in the medium by Phormidium to levels too low for normal growth of Microcystis and Nostoc. Work with the axenic forms of the 3 algal species also indicated a lowering of iron and trace element concentrations by Phormidium to levels not sufficient for sustained growth of Microcystis and Nostoc. Thus, bacteria played no significant role in this example of competitive exclusion. 相似文献