uu.seUppsala University Publications
Change search
Refine search result
78910 451 - 473 of 473
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 451.
    Vrede, T
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Vrede, K
    Contrasting “top-down” effects of crustacean zooplankton grazing on bacteria and phytoflagellates2005In: Aquatic Ecology, Vol. 39, p. 283-293Article in journal (Refereed)
  • 452.
    Vrede, Tobias
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Limnology.
    Elemental composition (C : N : P) and growth rates of bacteria and Rhodomonas grazed by Daphnia1998In: JOURNAL OF PLANKTON RESEARCH, ISSN 0142-7873, Vol. 20, no 3, p. 455-470Article in journal (Refereed)
    Abstract [en]

    The elemental composition and growth rate of Rhodomonas and heterotrophic bacteria were studied in batch cultures in the presence and absence of Daphnia and at two different levels of phosphorus limitation. The elemental content of single cells was measur

  • 453.
    Vrede, Tobias
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Limnology.
    Andersen, Tom
    Hessen, Dag O
    Phosphorus distribution in three crustacean zooplankton species1999In: LIMNOLOGY AND OCEANOGRAPHY, ISSN 0024-3590, Vol. 44, no 1, p. 225-229Article in journal (Refereed)
    Abstract [en]

    The distribution of phosphorus (P) was assessed in homogeneously P-33-labeled Daphnia magna, Daphnia galeata and Eudiaptomus gracilis. The specific P contents were 1.48, 1.41, and 0.50% of dry weight (DW), respectively. The results support the view of low

  • 454.
    Vrede, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Ballantyne, Ashley P.
    Mille-Lindblom, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Algesten, Grete
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Gudasz, Cristian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Lindahl, Sandra
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Brunberg, Anna-Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Effects of N:P loading ratios on phytoplankton community composition, primary production, and N fixation in a eutrophic lake2009In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 54, no 2, p. 331-344Article in journal (Refereed)
    Abstract [en]

    1. The aim of this study was to assess the effects of different nitrogen (N) to  phosphorus (P) loading ratios on phytoplankton community composition and primary production in a naturally eutrophic lake. Furthermore, the sources of N fuelling primary production were estimated using 15N stable isotope tracers.

    2. A mesocosm experiment was performed with the same amount of P added to all mesocosms (similar to internal loading rates) but with a range of N additions (0–86 μm N), resulting in a gradient of N : P supply ratios.

    3. Low N : P supply ratios resulted in a significant shift in the phytoplankton assemblage to a community dominated by N-fixing cyanobacteria and a supply of atmospheric N2 estimated to be up to 60% of total supply.

    4. The N : P loading ratio had no significant effect on primary production, total nitrogen (TN) concentration or particulate N concentration.

    5. Our results imply that a reduced N : P ratio of the nutrient load does not necessarily result in a lower TN concentration and downstream N export due to compensation by N-fixing cyanobacteria.

     

     

  • 455.
    Vrede, Tobias
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Dobberfuhl, Dean R.
    Kooijman, S. A. L. M.
    Elser, James J.
    FUNDAMENTAL CONNECTIONS AMONG ORGANISM C:N:P STOICHIOMETRY, MACROMOLECULAR COMPOSITION, AND GROWTH2004In: Ecology, Vol. 85, no 5, p. 1217–1229-Article in journal (Refereed)
    Abstract [en]

    Whereas it is acknowledged that the C:N:P stoichiometry of consumers and their resources affects both the structure and the function of food webs, and eventually influences broad-scale processes such as global carbon cycles, the mechanistic basis for the variation in stoichiometry has not yet been fully explored. Empirical evidence shows that the specific growth rate is positively related to RNA concentration both between and within taxa in both unicellular and multicellular organisms. Since RNA is rich in P and constitutes a substantial part of the total P in organisms, a high growth rate is also connected with a high P content. We argue that the reason for this pattern is that the growth of all biota is closely linked with their protein synthesis rate, and thus with the concentration of ribosomal RNA. Dynamic energy budget theory supports the positive relationship between RNA and specific growth rate in microorganisms, whereas the predictions concerning multicellulars only partially agrees with the observed pattern. In a simple model of consumer growth, we explore the consequences of various allocation patterns of RNA, protein, carbohydrates/lipids, and other biochemical constituents on organism potential growth rate and C:N:P stoichiometry. According to the model the percentage of N and especially percentage of P per dry mass increases with increasing specific growth rate. Furthermore, the model suggests that macromolecule allocation patterns and thus N:P stoichiometry are allowed to differ substantially at low growth rates whereas the stoichiometry at high growth rates is much more constricted at low N:P. The model fits empirical data reasonably well, but it is also acknowledged that complex life cycles and associated physiological constraints may result in other patterns. We also use a similar approach of modeling organism growth from basic biochemical principles to illustrate fundamental connections among biochemical allocation and C:N stoichiometry in autotroph production, which is based on allocation patterns between carbohydrates and rubisco. Similar to the RNA–protein model, macromolecular composition and C:N ratios are more constrained at high than at low growth rates. The models and the empirical data together suggest that organism growth is tightly linked with the organisms' biochemical and elemental composition. The stoichiometry of growth impinges on nutrient cycles and carbon fluxes at the ecosystem level. Thus, focus on the biological basis of organism C:N:P stoichiometry can mechanistically connect growth strategy and biochemical and cellular mechanisms of biota to major ecological consequences.

  • 456.
    Vrede, Tobias
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Limnology.
    Persson, Jonas
    Department of Ecology and Evolution, Limnology.
    Aronsen, Grete
    The influence of food quality (P:C ratio) on RNA:DNA ratio and somatic growth rate of Daphnia2002In: Limnology & Oceanography, Vol. 47, no 2, p. 487-494Article in journal (Refereed)
    Abstract [en]

    Growth experiments with juvenile Daphnia galeata were

  • 457.
    Vrede, Tobias
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Rydin, Emil
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Milbrink, Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Zooekologi.
    Restoration of fish stocks in oligotrophicated regulated reservoirs2006In: Dams under DebateArticle in journal (Refereed)
  • 458.
    Vrede, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Iron constraints on planktonic primary production in oligotrophic lakes2006In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 9, no 7, p. 1094-1105Article in journal (Refereed)
    Abstract [en]

    Phototrophic primary production is a fundamental ecosystem process, and it is ultimately constrained by access to limiting nutrients. Whereas most research on nutrient limitation of lacustrine phytoplankton has focused on phosphorus (P) and nitrogen (N) limitation, there is growing evidence that iron (Fe) limitation may be more common than previously acknowledged. Here we show that P was the nutrient that stimulated phytoplankton primary production most strongly in seven out of nine bioassay experiments with natural lake water from oligotrophic clearwater lakes. However, Fe put constraints on phytoplankton production in eight lakes. In one of these lakes, Fe was the nutrient that stimulated primary production most, and concurrent P and Fe limitation was observed in seven lakes. The effect of Fe addition increased with decreasing lake water concentrations of total phosphorus and dissolved organic matter. Possible mechanisms are low import rates and low bioavailability of Fe in the absence of organic chelators. The experimental results were used to predict the relative strength of Fe, N, and P limitation in 659 oligotrophic clearwater lakes (with total phosphorus <= 0.2 mu M P and total organic carbon < 6 mg C l(-1)) from a national lake survey. Fe was predicted to have a positive effect in 88% of these lakes, and to be the nutrient with the strongest effect in 30% of the lakes. In conclusion, Fe, along with P and N, is an important factor constraining primary production in oligotrophic clearwater lakes, which is a common lake-type throughout the northern biomes.

  • 459.
    Waldeback, Monica
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Rydin, Emil
    Department of Evolutionary Biology. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Markides, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Physical and Analytical Chemistry, Analytical Chemistry. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Use of accelerated solvent extraction for determination of ecological important phosphorus in lake sediments1998In: INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY, ISSN 0306-7319, Vol. 72, no 4, p. 257-266Article in journal (Refereed)
    Abstract [en]

    Phosphorus has been identified as one of the most important elements in eutrophication of lakes. and the bulk of phosphorus compounds stored in lake sediment contribute to a large extent to this process. It is therefore of great interest to get an adequa

  • 460.
    Weisse, Thomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Stadler, Peter
    Lindström, Eva S.
    Kimmance, Susan A.
    ontagnes, David J. S.
    Interactive effect of temperature and food concentration on growth rate: A test case using the small freshwater ciliate Urotricha farcta2002In: Limnol. Oceanogr., Vol. 47, no 5, p. 1447-1455Article in journal (Refereed)
    Abstract [en]

    The combined effect of temperature and food

  • 461. Weyhenmeyer, G.A.
    et al.
    Psenner, R.
    Tranvik, L.J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Lakes of Europe2009In: Encyclopedia of inland waters / [ed] Gene E. Likens, Academic Press , 2009, p. 567-576Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

     Lakes of Europe show a great variability in their characteristics, with boreal lakes at northern latitudes as the most abundant lake type. The variability is a result of large gradients in climate, geological history, land use, and atmospheric deposition, mainly along a north–south axis. Worldwide, the best known lakes are probably Europe's lakes in the Alp region, most likely due to their spectacular surroundings and their long tradition of providing good research facilities with all necessary infrastructure. Lakes of Europe, including very remote lakes, are subjected to multiple stressors, climate change and atmospheric deposition being examples. These stressors can cause water quality problems. One of the most common water quality problems occurring in all European countries have been and still are harmful algal blooms

  • 462.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Do warmer winters change variability patterns of physical and chemical lake conditions in Sweden?2009In: Aquatic Ecology, ISSN 1386-2588, E-ISSN 1573-5125, Vol. 43, no 3, p. 653-659Article in journal (Refereed)
    Abstract [en]

    In this study, the effect of a warmer winter climate on variability patterns of physical and chemical lake conditions was examined by using monthly air temperature data from 72 meteorological Swedish sites, ice breakup data from 77 Swedish lakes and monthly data of 17 water chemical variables from 11 nutrient-poor Swedish reference lakes during 1988–2005. The results showed significantly increasing variations of lake ice breakup dates and nitrate concentrations over Sweden along with increasing winter air temperatures. Variability patterns of other water chemical variables were not affected by warmer winters. Nitrate concentrations increased their variability in spring and early summer not only between lakes but also within lakes, which was attributed to a climate-induced increase in spring nitrate concentrations in particular in southern Sweden, while summer nitrate concentrations remained rather constant and low all over Sweden (median 10 μg l−1). Since nitrate concentrations play an important role for primary production, highly varying concentrations will be a challenge for biota to adapt.

  • 463.
    Weyhenmeyer, Gesa A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Jeppesen, Erik
    Adrian, Rita
    Arvola, Lauri
    Blenckner, Thorsten
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Jakanowski, Thomas
    Jennings, Eleanor
    Noges, Peter
    Noges, Tiina
    Straile, Dietmar
    Nitrate-depleted conditions on the increase in shallow northern European lakes2007In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 52, no 4, p. 1346-1353Article in journal (Refereed)
    Abstract [en]

    We determined relative nitrate-nitrogen (NO3- N) loss rates in 100 north-mid-European lakes from late spring to summer by using the exponential function N-2 5 N-1e(-k)( (t)(2) - (t)(2)), where N-1 and N-2 are NO3- N concentrations at the beginning (t(1)) and the end (t(2)) of the time interval, respectively, and k is the specific NO3- N loss rate. We found that k decreased with increasing lake depth. Adjusting k to the lake depth (k(adj)), we observed that k(adj) was positively related to spring NO3-N concentrations, but this relationship became insignificant at mean lake depths exceeding 12.5 m. A relationship between k(adj) and spring NO3- N concentrations in lakes shallower than 12.5 m implies that changes in spring NO3-N concentrations influence the NO3- N loss rate and thereby summer NO3- N concentrations. Time series from one Estonian, one German, and 14 Swedish lakes shallower than 12.5 m since 1988 revealed that May to August NO3-N concentrations have decreased over time everywhere, and the number of time periods exhibiting a NO3-N depleted condition, i.e., NO3-N levels below 10 mu g L-1, in these lakes has tripled since 1988. We explained the decreasing NO3-N concentrations by a reduction in external nitrogen loading including atmospheric deposition, and by changes in climate. The observed prolongation of NO3- N depleted conditions might be one possible explanation for the increasing occurrence of nitrogen- fixing cyanobacteria in a variety of lake ecosystems.

  • 464.
    Weyhenmeyer, Gesa A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Meili, Markus
    Hypolimnetic lake sediments in frequent motion2001In: Ver. Internat. Verein. Limnol., Vol. 27, no 4, p. 2317-2322Article in journal (Refereed)
  • 465. Widenfalk, Anneli
    et al.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Sundh, Ingvar
    Goedkoop, Willem
    Effects of pesticides on community composition and activity of sediment microbes: responses at various levels of microbial community organization2008In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 152, no 3, p. 576-584Article in journal (Refereed)
    Abstract [en]

    A freshwater sediment was exposed to the pesticides captan, glyphosate, isoproturon, and pirimicarb at environmentally relevant and high concentrations. Effects on sediment microorganisms were studied by measuring bacterial activity, fungal and total microbial biomass as community-level endpoints. At the sub-community level, microbial community structure was analysed (PLFA composition and bacterial 16S rRNA genotyping, T-RFLP). Community-level endpoints were not affected by pesticide exposure. At lower levels of microbial community organization, however, molecular methods revealed treatment-induced changes in community composition. Captan and glyphosate exposure caused significant shifts in bacterial community composition (as T-RFLP) at environmentally relevant concentrations. Furthermore, differences in microbial community composition among pesticide treatments were found, indicating that test compounds and exposure concentrations induced multidirectional shifts. Our study showed that community-level end points failed to detect these changes, underpinning the need for application of molecular techniques in aquatic ecotoxicology.

  • 466. Wilczek, Sabine
    et al.
    Fischer, Helmut
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Brunke, Matthias
    Pusch, Martin T.
    Microbial activity within a subaqueous dune in a large lowland river (River Elbe, Germany)2004In: AQUATIC MICROBIAL ECOLOGY, Vol. 36:, p. 83–97-Article in journal (Refereed)
    Abstract [en]

    Microbial processes within subaqueous dunes of large rivers are important for organic

    matter retention and decomposition but have rarely been examined. We investigated 3 morphodynamically

    defined zones (stoss side, crestal plateau, and lee side) within a subaqueous dune in the

    8th-order River Elbe. Analysis of flow velocity, vertical hydraulic gradient, concentration of mobile

    fine interstitial particles, and the quantity and biochemical quality of sedimentary organic matter

    indicated that the stoss and the lee sides of the dune were focal zones of particulate matter retention

    due to infiltration and sedimentation processes. Bacterial abundance and most measures of microbial

    activity (sediment community respiration and activities of the extracellular enzymes β-glucosidase,

    leucine aminopeptidase, β-xylosidase, and exo-1,4-β-glucanase) were significantly higher in these

    zones than in the plateau. Increases in bacterial abundance and microbial activity were closely correlated

    with protein, carbohydrates, nitrogen and phaeopigments associated with high-quality particulate

    organic matter. Our findings showed that the morphodynamic differentiation of the subaqueous

    dune resulted in the formation of distinct functional zones in the sediment. The underlying

    mechanisms can be conceptually summarized by a 2-stage regulatory hierarchy. Microbial activities

    were controlled directly by the input of dissolved oxygen and easily degradable microbial substrates,

    and indirectly by hydromorphological processes. We conclude that the subaqueous dune functioned

    as an efficient filter of particulate organic matter, and that the stoss and the lee sides of this river bedform

    were focal sites of microbial carbon mineralisation in the large river ecosystem.

  • 467. Wong, Bob
    et al.
    Candolin, Ulrika
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Lindström, Kai
    Environmental deterioration compromises socially enforced signals of male quality in three-spined sticklebacks2007In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 170, no 2, p. 184-189Article in journal (Refereed)
    Abstract [en]

    Social costs are often important in promoting the honesty of sexually selected traits. What happens, then, when social costs are relaxed? In species that breed in shallow coastal waters, increases in the frequency and severity of phytoplankton blooms may undermine the value of visual signals by reducing visibility and, in so doing, lead to dishonest signaling by relaxing the social consequences of high signaling effort for poor-quality individuals. Here, we experimentally test the effects of algally induced water turbidity on the role of male-male competition in facilitating reliable sexual displays in three-spined sticklebacks. We found that males in poor condition reduced their courtship effort in the presence of competition in turbid water. This reduction, however, was to a much lesser extent than that observed in clear water. Thus, courtship under conditions of algal turbidity did not reflect male condition as honestly as courtship in clear water. Algal turbidity also influenced breeding coloration, with males in poor condition reducing their area of red nuptial coloration in turbid conditions. Our findings suggest that anthropogenic disturbance to the signaling environment can potentially reduce the evolutionary potential of sexual selection by diminishing the efficacy of visual displays and weakening socially enforced signals of male quality.

  • 468.
    Worm, B
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Lotze, H K
    Hillebrand, H
    Sommer, U
    Consumer versus resource control of species diversity and ecosystem functioning.2002In: Nature, Vol. 417, p. 848-851Article in journal (Refereed)
  • 469. Zheng, Zongli
    et al.
    Advani, Abdolreza
    Melefors, Ojar
    Glavas, Steve
    Nordström, Henrik
    Ye, Weimin
    Engstrand, Lars
    Andersson, Anders F.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Titration-free massively parallel pyrosequencing using trace amounts of starting material2010In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 38, no 13, p. e137-Article in journal (Refereed)
    Abstract [en]

    Continuous efforts have been made to improve next-generation sequencing methods for increased robustness and for applications on low amounts of starting material. We applied double-stranded library protocols for the Roche 454 platform to avoid the yield-reducing steps associated with single-stranded library preparation, and applied a highly sensitive Taqman MGB-probe-based quantitative polymerase chain reaction (qPCR) method. The MGB-probe qPCR, which can detect as low as 100 copies, was used to quantify the amount of effective library, i.e. molecules that form functional clones in emulsion PCR. We also demonstrate that the distribution of library molecules on capture beads follows a Poisson distribution. Combining the qPCR and Poisson statistics, the labour-intensive and costly titration can be eliminated and trace amounts of starting material such as precious clinical samples, transcriptomes of small tissue samples and metagenomics on low biomass environments is applicable.

  • 470. Zibordi, G.
    et al.
    Strömbeck, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Melin, F.
    Berthon, J. -F
    Tower-based radiometric observations at a coastal site in the Baltic Proper2006In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 69, no 3-4, p. 649-654Article in journal (Refereed)
    Abstract [en]

    An autonomous above-water radiometer was operated during the summer of 2005 on the Gustaf Dalen Lighthouse Tower (GDLT) off the Swedish coast in the Baltic Proper. Normalized water leaving radiances, L-WN(lambda), produced from measurements performed with the autonomous system at various center-wavelengths lambda in the 412-675 nm spectral range, were applied within the context of water quality monitoring and satellite ocean color validation activities. Specifically these in situ radiometric data were used to determine the chlorophyll a concentration through a regional band-ratio algorithm and to assess L-WN(lambda) derived from top-of-atmosphere Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The in situ measurements collected during a bloom occurring in July 2005 were also used to investigate the spectral and small scale temporal-spatial variability of L-WN(lambda) in the presence of cyanobacteria.

  • 471. Zwart, G.
    et al.
    van Hannen, E. J
    Kamst-van Agterveld, M. P.
    Van der Gucht, K.
    Lindström, E.S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    van Wichelen, J.
    Lauridsen, T
    Crump, B. C.
    Han, S.-K.
    Declerck, S.
    Rapid Screening for Freshwater Bacterial Groups by Using Reverse Line Blot Hybridization2003In: Applied and Environmental Microbiology,, Vol. 69, p. 5875-5883Article in journal (Refereed)
  • 472.
    Östlund, C
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Flink, P
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Strömbeck, N
    Pierson, D
    Lindell, T
    Mapping of the water quality of Lake Erken, Sweden, from Imaging Spectrometry and Landsat Thematic Mapper2001In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 268, no 1-3, p. 139-154Article in journal (Refereed)
    Abstract [en]

    Hyperspectral data have been collected by the Compact Airborne Spectrographic Imager (CASI) and multispectral data by the Landsat Thematic Mapper (TM) instrument for the purpose of mapping lake water quality. Field campaigns have been performed on Lake Erken

  • 473. Öztürk, Murat
    et al.
    Croot, Peter L.
    Bertilsson, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Abrahamsson, Katarina
    Karlsone,, Bengt
    David, Roland
    Fransson, Agneta
    Sakshaug, Egil
    Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: implications for phytoplankton growth in the Southern Ocean2004In: Deep Sea Research Part II:: Topical Studies in Oceanography, Vol. 51, p. 2841-2856Article in journal (Refereed)
    Abstract [en]

    Iron(III) photoreduction and the responses of phytoplankton under ultraviolet (UV) and photosynthetically available radiation (PAR) were investigated with the presence of hydroxycarboxylic acid (glucaric acid (GA), a model compound for organic acids excreted by phytoplankton). The incubation experiments were carried out on board using seawater samples collected in the location of the winter ice edge (WIE) and the spring ice edge (SIE) of the Southern Ocean. In this paper, we focus on the results of experiment in WIE. Throughout the experiments, dissolved Fe(II), major nutrients and in vivo fluorescence were monitored regularly. In addition, Chl-a, POC/PON, cell densities of phytoplankton and bacteria, bacterial production, organic peroxide, hydrogen peroxide and total CO2 were measured.

    The results from the WIE show that iron enrichment had a substantial effect on phytoplankton growth rate. Fe(III) addition in the presence of GA (FeGA) gave higher Fe(II) concentration and higher growth rate of phytoplankton than those in controls. Our results suggest that hydroxycarboxylic acid had a significant chemical and biological impact. The presence of GA influenced iron photochemistry and iron availability to phytoplankton. Phytoplankton growth responses to iron enrichments in incubations under UV and PAR were completely dissimilar. It seems that FeGA addition prominently changes the harmful effect of UV on the phytoplankton population. This study provides preliminary information on how the photoreduction of iron(III) and the phytoplankton growth are affected by iron enrichment in the presence of hydroxycarboxylic acid.

78910 451 - 473 of 473
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf