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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution and activity of bacterioplankton, and the turnover of dissolved organic matter (DOM) were examined in McMurdo Sound, Antarctica. On the eastern side of the Sound, bacteria averaged 6.5×108 l-1, and turnover rates of dissolved adenosine triphosphate, D-glucose and l-leucine averaged 16, 116 and 124 h, respecitvely. These molecules as well as thymidine were taken up maximally from 0° to 5°C and near-maximally from -1.5° to 0°C, indicating bacterial adaptation to rapid turnover of dissolved organic matter at the ambient temperature. On the west side of the Sound, bacteria averaged only 0.65×108 l-1, and turnover times for adenosine triphosphate, D-glucose and lleucine averaged 59, 20454, and 3070 h, respectively. Total microbial adenosine triphosphate (an indicator of total microbial biomass) and chlorophyll a were also much lower at the western than at the eastern side stations. Moreover, no primary production could be detected at one western side station (New Harbor). Thus, in McMurdo Sound, the western side is highly oligotrophic, but the eastern side has an abundant active bacterioplankton, comparable to that of temperate coastal waters.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurement of rates of microbial (bacteria and unicellular algae) ribonucleic acid (RNA) synthesis in environmental samples by radioactive tracers requires several assumptions that we test and evaluate herein. After addition of 3H-adenine to water samples from eutrophic freshwater or pelagic and oceanic ecosystems, microorganisms assimilate it without (1) any luxury uptake or (2) any expansion of intracellular adenine nucleotide pools. The calculated rate of stable RNA synthesis tends to be overestimated during the initial time periods of labeling (i.e., less than 30 s for cultures of Serratia marinorubra, and less than 20 min for most environmental samples) due to kinetic compartmentalization of the nucleic acid precursor (ATP) pool. Time-series analyses are recommended because the effects of compartmentalization decrease with increasing incubation. The kinetics of 3H-adenine uptake and aspects of its subsequent assimilation, intermediary metabolism and breakdown are described in bacteria and natural assemblages of microorganisms. Mass-balance radioactivity inventories greatly facilitate interpretation of nucleic acid precursor assimilation. Finally, we demonstrate that independent measurements of precursor (ATP) specific radioactivity are required for any elucidation of rates of stable RNA synthesis (and thus microbial growth) in nature.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 64 (1981), S. 13-21 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of stable ribonucleic acid (RNA) synthesis have been calculated from time-series measurements of the uptake of 3H-adenine and labeling of the intracellular adenosine triphosphate (ATP) and stable RNA pools for microbial communities from a variety of freshwater and marine ecosystems. Total rates of microbial RNA synthesis ranged from 6.6 pmol to 3.8x105 pmol of adenine incorporated into RNA l−1 h−1. Most of the variation was attributable to differences in microbial biomass; if total rate data are normalized to living microbial carbon (based on ATP measurements), the variation in specific rates of RNA synthesis is decreased by a factor of 100 to 1 000 for microbial communities from diverse environments. Light/dark experiments indicated that the uptake and incorporation of 3H-adenine are uncoupled from photophosphorylation. The measurement of rates of stable RNA synthesis of microbial assemblages in nature can yield useful information concerning in situ growth rates and the response of communities to changes in environmental conditions such as nutrient additions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 83 (1984), S. 129-139 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A technique for measuring rates of RNA and DNA synthesis in sedimentary microbial communities has been adapted from methods developed for marine and freshwater microplankton research. The procedure measures the uptake, incorporation and turnover of exogenous [2, 3H]-adenine by benthic microbial populations. With minor modification, it is applicable to a wide range of sediment types. Measurement of nucleic acid synthesis rates are reported from selected benthic marine environments, including coral reef sediments (Kaneohe Bay, Oahu, Hawaii), intertidal beach sands (Oahu and southern California) and California borderland basin sediment (San Pedro Basin), and comparisons are made to selected water-column microbial communities. Biomass-specific rates of nucleic acid synthesis in sediment microbial communities were comparable to those observed in water-column assemblages (i.e., 0.02 to 2.0 pmol deoxyadenine incorporated into DNA [ng ATP]-1 h-1 and 0.2 to 8.9 pmol adenine incorporated into RNA [ng ATP]-1 h-1). DNA synthesis rates were used to calculate carbon production estimates ranging from 2 μg C cm-3 h-1 in San Pedro Basin sediment (880 m water depth) to 807 μg C cm-3 h-1 in coral reef sediment from the Kaneohe Bay. Microbial community specific growth rate, μ(d-1), estimated from DNA synthesis rates in surface sediments ranged from 0.1 in San Pedro Basin to 4.2 in Scripps Beach (La Jolla, California) intertidal sand.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 48 (1978), S. 185-197 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for measuring ATP, ADP and AMP levels in environmental samples was devised, and applied to seawater and bacterial cell extracts. This procedure is specifically designed for measuring the extremely low concentrations of total adenine nucleotides ([AT]=[ATP]+[ADP]+[AMP]) that are apt to occur in most natural ecosystems (i.e., ≤10 ng AT ml-1 of sample extract). Although the current assay methodology can be used with purified firefly luciferase reagents, it has been suitably modified to accept crude luciferase preparations as well. ATP, ADP and AMP levels have been measured, and the corresponding energy charge (EC) ratios determined for seawater samples collected off the Southern California coast. The EC ratios ranged from 0.50 to 0.89, with peak values corresponding to the subsurface maxima in ATP and chlorophyll a concentrations, and the minimum values corresponding to the deepest water sampled (1500 m). The measurement of adenylate energy charge ratios in environmental samples can be a useful indicator of mean community metabolic activity and potential for cell growth.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 335 (1988), S. 532-535 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Two hydrothermal fields were found in 1987 on the upper portion of Loihi's south rift zone. Both fields are located on the eastern flanks of prominent pillow lava cones (Figs 1 and 2). Lavas from the venting areas are brecciated and strongly vesicular (20-35 volume per cent). The lavas from the ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 309 (1984), S. 54-56 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In order to reconcile the mesopelagic zone carbon budget, chemolithotrophic production of organic matter was proposed as a possible mechanism7. During the Vertex III sediment trap experiment, we had an opportunity to examine the possibility of bacterial chemolithotrophic production at a station, ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] As part of the US Joint Global Ocean Flux Study (JGOFS) and World Ocean Circulation Experiment (WOCE) programmes, we established a deep-water hydrostation8 (station ALOHA) -100 km north of Oahu, Hawaii at 22° 45' N, 158° W to assess and interpret annual- to decadal-scale ecosystem ...
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 289 (1981), S. 287-289 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our studies were conducted at McMurdo Sound, Antarctica, located in the southwest corner of the Ross Sea at latitude 77 S and longitude 166E (Fig. 1). The Sound is approximately 50 km wide; however, its eastern and western sides differ greatly in water column productivity and benthic biomass due to ...
    Type of Medium: Electronic Resource
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