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  • bacteria  (2)
  • 16S  (1)
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  • 1
    ISSN: 1573-5125
    Schlagwort(e): bacteria ; clones ; DNA ; FISH ; hybridization ; sequences
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract New molecular approaches relying on 16S rRNA sequences allow qualitative and quantitative analysis of marine microbial diversity. Here we report on (1) continued development of ‘lists’ of taxa present in marine environments, in temperate coastal waters, and (2) new fluorescent in situ hybridization (FISH) approaches to quantify taxonomic compositions, with an initial focus on archaea. Our cloning results come from Long Island Sound on the Atlantic coast (February and August), and Malibu (April) and offshore Monterey Bay (September), California. The clones were dominated (39 of 45 total clones) by proteobacteria, with the α subdivision (33 clones), and the SAR11 cluster (17) in particular, being quite abundant. There were also clones from the β (2) and γ (4) subdivisions, the cyanobacteria (4, from Monterey Bay only) and the Cytophaga group (2). Some clones were very similar to those previously reported from open ocean or deep sea environments, but others were not close relatives of any of those previously reported. The FISH results used doubly-labeled probes that were ‘universal’, bacterial, and archaeal (single and multiple), in combination with chloramphenicol treatment and probe detection by intensified video microscopy. Universal probes detected ca. 75–95% of total DAPI counts. Of 2 depth profiles from mesotrophic-oligotrophic California waters, a September one, to 300 m, indicated a low but detectable presence of archaea (about 10% above control values) as measured with single probes. A second profile in May with 4 archaeal probes showed 〈5% at 100 m depth, but the percentage relative to total DAPI counts increased to about 40% at 600 m depth. Samples from the French Mediterranean coast showed few detectable archaea (analyzed with single probes) in surface waters of Villefranche-sur-Mer Bay, but about 60% archaea at 200 m depth outside the bay. These results point in general to the suitability of this single cell FISH method to quantify taxonomic composition of marine samples, and the specific results indicate the high abundance of archaea in at least some midwater locations.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 159 (1988), S. 51-62 
    ISSN: 1573-5117
    Schlagwort(e): bacteria ; bacterivores ; feeding ; grazing ; marine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A variety of methods have been used to estimate the degree of control exercised upon marine bacterioplankton by grazing organisms. These include filtration or dilution of samples to reduce grazers, the use of specific inhibitors to prevent growth or grazing, and the use of artificial particles or radio-labelled bacteria as tracers for the natural bacterioplankton. Each of these techniques has drawbacks which may lead to under- or overestimates of grazing. In addition, they tell us little about which organisms are doing the grazing or the degree to which viruses or lytic bacteria compete with grazers for bacterial production. Because measurements of grazing and bacterioplankton growth rates are uncertain, exact comparisons are not presently possible. Thus measurements of bacterial and bacterivore abundance, concentrated on comparisons between seasons, on diel cycles and on spatial variations, have been used to evaluate mechanisms controlling bacterial populations. These give an idea of the degree of coupling between bacterial growth and bacterivore activity and of the time scales over which growth and grazing balance. Combined with laboratory studies of grazing, they currently provide the best insight into what controls populations of bacteria in the sea.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2022-05-26
    Beschreibung: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in mSystems 1 (2015): e00009-15, doi:10.1128/mSystems.00009-15.
    Beschreibung: Designing primers for PCR-based taxonomic surveys that amplify a broad range of phylotypes in varied community samples is a difficult challenge, and the comparability of data sets amplified with varied primers requires attention. Here, we examined the performance of modified 16S rRNA gene and internal transcribed spacer (ITS) primers for archaea/bacteria and fungi, respectively, with nonaquatic samples. We moved primer bar codes to the 5′ end, allowing for a range of different 3′ primer pairings, such as the 515f/926r primer pair, which amplifies variable regions 4 and 5 of the 16S rRNA gene. We additionally demonstrated that modifications to the 515f/806r (variable region 4) 16S primer pair, which improves detection of Thaumarchaeota and clade SAR11 in marine samples, do not degrade performance on taxa already amplified effectively by the original primer set. Alterations to the fungal ITS primers did result in differential but overall improved performance compared to the original primers. In both cases, the improved primers should be widely adopted for amplicon studies.
    Beschreibung: J.A.F. and A.P. are supported by the Gordon and Betty Moore Foundation (GMBF3779) and NSF grant 1136818. A.P. is supported by an NSF Graduate Fellowship. A.A. is supported by NSF grant OCE-1233612. J.K.J. is supported by the Microbiomes in Transition Initiative LDRD Program at the Pacific Northwest National Laboratory, a multiprogram national laboratory operated by Battelle for the DOE under contract DE-AC06-76RL01830. J.A.G. is supported by the U.S. Department of Energy under contract DE-AC02-06CH11357. J.G.C., J.A.G., and R.K. are supported by the Alfred P. Sloan Foundation. R.K. is supported by the Howard Hughes Medical Institute.
    Schlagwort(e): Microbial ecology ; Marker genes ; Primers ; 16S ; ITS
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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