ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Introduction (2000)
    Springer
    Cellular and molecular life sciences 57 (2000), S. 183-185 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00000682
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Microorganisms from composting leaves: Ability to produce extracellular degradative enzymes (1975)
    Springer
    Microbial ecology 2 (1975), S. 296-308 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mixed populations of bacteria, fungi, and actinomycetes in a leaf compost pile were examined over a 100-day test period for their ability to produce extracellular proteolytic, lipolytic, amylolytic, cellulolytic, pectolytic, and ureolytic enzymes and ability to utilize alkanes. Urea was added to the leaves to adjust the carbon to nitrogen ratio but was of little value in maintaining the proper ratio since it was degraded within the first few days. The degradative enzymes excreted by microorganisms was dependent on the temperature of the pile. In many cases organisms able to produce specific extracellular enzymes at medium temperatures were able to grow at high temperatures, but either did not excrete the specific enzymes or the enzymes were inactivated by the high temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02011649
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Experimental and modeling studies of a four-trophic level predator-prey system (1982)
    Springer
    Microbial ecology 8 (1982), S. 217-232 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experimental studies of a microbial food chain involving organic carbon substrates,Enterobacter aerogenes, and ciliate protozoansParamecium primaurelia andDldinium nasutum were conducted in stirred, aerated batch cultures. Quantitative measurements were made of organic carbon levels and of cell numbers, mean cell volumes, and total biovolumes for all three microbial populations. A mathematical model based on Monod kinetics was developed to describe this four-trophic level predator-prey system. The model was formulated in terms of biovolume, which is the product of cell numbers and mean cell size, and includes terms for bio-volume decay. Batch culture data were used to derive parameter values, and model simulations were compared to experimental results. Despite the significance ofParamecium-Didinium studies in ecological literature, the entire food chain has not been previously studied or modeled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02011426
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Upper temperature limits for growth and diazotrophy in the thermophilic cyanobacterium HTF Chlorogloeopsis (1993)
    Springer
    Archives of microbiology 159 (1993), S. 423-427 
    Details
    ISSN: 1432-072X
    Keywords: Chlorogloeopsis ; Continuous culture ; Cyanobacterium ; Nitrogen fixation ; Oxygen effects ; Photosynthesis ; Respiration ; Temperature effects ; Thermophile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature and oxygen on diazotrophic growth of the thermophilic cyanobacterium HTF (High Temperature Form) Chlorogloeopsis was investigated using cells grown in light-limited continuous culture at a dilution rate of 0.02 h-1. Diazotrophy was more sensitive to elevated temperatures than growth with combined nitrogen. The maximum temperature for growth of cultures gassed with CO2-enriched air was more than 55 °C but less than 60 °C with N2 as the sole nitrogen source, but between 60°C and 65°C when nitrate was present in the medium. The effect of temperature on nitrogenase activity, photosynthesis and respiration in the dark was determined using cells grown at 55°C. Maximal rates of all three processes were observed at 55°C and rates at 60°C during shortterm incubations were not less than 75% of the maximum. However, nitrogenase activity at 60°C was unstable and decayed at a rate of 2.2 h-1 under air and at 0.3 h-1 under argon. Photosynthesis and respiration were more stable at 60°C than anoxic nitrogen fixation. The upper temperature limits for diazotrophic growth thus seem to be set by the stability of nitrogenase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00288588
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effect of oxygen concentration on dark nitrogen fixation and respiration in cyanobacteria (1983)
    Springer
    Archives of microbiology 135 (1983), S. 287-292 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Respiration ; Nitrogen fixation ; Heterocysts ; K m for O2 ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of acetylene reduction by Anabaena variabilis and the concentration of dissolved oxygen in the suspension were made using a specially designed vessel which allowed measurements under steady-state conditions. The rate of acetylene reduction in the dark increased with increasing oxygen concentrations until a maximum value was reached at 300 μM O2 (corresponding to 30% O2 in the gas phase at 35°C). This presumably results from a requirement for energy provided by respiration. Measurements of the dependence of respiration rate on dissolved oxygen concentration were made under comparable conditions using an open system to allow conditions close to steady-state to be obtained. The respiration rate of diazotrophically grown Anabaena variabilis had a dependence on oxygen concentration corresponding to the sum of two activities. These had K m values of 1.0 μM and 69 μM and values of V max of similar magnitude. Only the high affinity activity was observed in nitrate-grown cyanobacteria lacking heterocysts, and this presumably represent activity in the vegetative cells. The oxygen concentration dependence of the low affinity activity resembled that for the stimulation of acetylene reduction. We interpret this as the result of oxygen uptake by the heterocysts. The results are consistent with the idea that in intact filaments of cyanobacteria O2 enters heterocysts much more slowly than it enters the vegetative cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00413483
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Incorporation of exogenous long-chain alcohols into bacteriochlorophyll c homologs by Chloroflexus aurantiacus (1995)
    Springer
    Archives of microbiology 163 (1995), S. 119-123 
    Details
    ISSN: 1432-072X
    Keywords: Bacteriochlorophyll ; Chloroflexus ; Chlorosome ; Green bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroflexus aurantiacus grown in batch culture took up exogenous alcohols and incorporated these into bacteriochlorophyll c as the esterifying alcohol. It was possible to change the distribution of the naturally occurring homologs of bacteriochlorophyll c esterified with phytol, hexadecanol, and octadecanol by adding the appropriate alcohol. The corresponding homolog then made up at least 60% of the cellular bacteriochlorophyll c. It was also possible to obtain novel bacteriochlorophyll homologs not found in detectable amounts in control cells by adding fatty alcohols with short chains (C10, C12) or long chains (C20). These changes in bacteriochlorophyll composition had no detectable effects on the spectral properties of the chlorosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381785
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Isolation of cyanobacterial heterocysts with high and sustained dinitrogen-fixation capacity supported by endogenous reductants (1986)
    Springer
    Archives of microbiology 145 (1986), S. 241-247 
    Details
    ISSN: 1432-072X
    Keywords: Heterocyst isolation ; Osmoregulators ; Cyanobacteria ; Nitrogen fixation ; Anabaena variabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method is described for the preparation of cyanobacterial heterocysts with high nitrogen-fixation (acetylene-reduction) activity supported by endogenous reductants. The starting material was Anabaena variabilis ATCC 29413 grown in the light in the presence of fructose. Heterocysts produced from such cyanobacteria were more active than those from photoautotrophically-grown A. variabilis, presumably because higher reserves of carbohydrate were stored within the heterocysts. It proved important to avoid subjecting the cyanobacteria to low temperatures under aerobic conditions, as inhibition of respiration appeared to lead to inactivation of nitrogenase. Low temperatures were not harmful in the absence of O2. A number of potential osmoregulators at various concentrations were tested for use in heterocyst isolation. The optimal concentration (0.2M sucrose) proved to be a compromise between adequate osmotic protection for isolated heterocysts and avoidance of inhibition of nitrogenase by high osmotic strength. Isolated heterocysts without added reductants such as H2 had about half the nitrogen-fixation activity expected on the basis of intact filaments. H2 did not increase the rate of acetylene reduction, suggesting that the supply of reductant from heterocyst metabolism did not limit nitrogen fixation under these conditions. Such heterocysts had linear rates of acetylene reduction for at least 2 h, and retained their full potential for at least 12 h when stored at 0°C under N2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00443652
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Hydrogenase activity in nitrate-grown cells of the unicellular cyanobacterium Cyanothece PCC 7822 (1988)
    Springer
    Archives of microbiology 151 (1988), S. 40-43 
    Details
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity of hydrogenase in intact cells of the unicellular cyanobacterium Cyanothece PCC 7822 was investigated using a mass spectrometer with a permeable membrane inlet. A small hydrogenase-catalyzed hydrogen production was observed with nitrate-grown cells under anoxic conditions in the dark. The same cells were also capable of a much greater rate of hydrogen uptake, induced by oxygen as well as light. Light-induced hydrogen uptake was inhibited by uncoupler. In contrast, addition of uncoupler caused a four-fold stimulation of anoxic hydrogen production in the dark. It is suggested that anoxic hydrogen production is the result of fermentative metabolism. Cyanobacteria are generally considered to have at least two distinct hydrogenases (Houchins 1984). One is a membrane-bound uptake hydrogenase which appears to be associated with nitrogen fixation, removing the hydrogen produced by nitrogenase with the concomitant production of reductant or ATP (Eisbrenner et al. 1978). The second is a reversible hydrogenase located in the cytoplasm and not closely linked to nitrogen metabolism. The reversible character of this enzyme can be demonstrated in the presence of suitable electron donors or acceptors; hydrogen consumption and evolution occur at similar rates (Lambert and Smith 1980). A reversible hydrogenase capable of reducing protons with the artificial electron donor couple dithionite and methyl viologen is widely distributed amongst cyanobacteria. However its physiological role remains unclear. The enzyme appears to be sensitive to oxygen, and consequently in vivo activity can only be demonstrated under anoxic conditions (Houchins 1984). On the basis of in vivo measurements with tritium and the observed low K m for hydrogen, the function of the reversible hydrogenase of the heterocystous cyanobacterium Anabaena has been proposed to be the uptake of hydrogen as a means of collecting additional reducing power during growth in light-limited anoxic environments (Spiller et al. 1983; Houchins 1984). However, Hallenbeck et al. (1981) reported a modest production of hydrogen by intact filaments of Anabaena. An example of a function of the reversible hydrogenase in the production of hydrogen is provided by the nonheterocystous filamentous cyanobacterium Oscillatoria limnetica. This organism is capable of shifting between oxygenic and anoxygenic photosynthesis (Oren and Padan 1978). In the latter case sulfide is the electron donor supporting photoreduction of CO2 via photosystem I only. However when CO2 is limiting, excess reducing equivalents are removed by a reversible hydrogenase (Belkin and Padan 1978). This hydrogen production probably enables the organism to continue photophosphorylation under these conditions. We recently reported that the unicellular cyanobacterium Cyanothece 7822 is capable of hydrogenase-catalyzed hydrogen production in vivo, without the addition of artificial reductants (Van der Oost et al. 1987). In this paper we have investigated the in vivo activity of the hydrogenase in Cyanothece by monitoring the concentrations of dissolved H2 and O2 in the cell suspension using a mass spectrometer with a permeable membrane inlet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00444666
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Measurement of Glass Transition Temperatures in Freeze Concentrated Solutions of Non-Electrolytes by Electrical Thermal Analysis (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 1023-1029 
    Details
    ISSN: 1573-904X
    Keywords: freeze drying ; collapse ; differential scanning calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electrical resistance (R) of frozen aqueous solutions was measured as a function of temperature in order to determine whether this technique can be applied for determination of glass transition temperatures of maximally freeze concentrated solutions (Tg′) of non-electrolytes which do not crystallize during freezing. Electrical thermal analysis (ETA) thermograms of frozen solutions containing the solute alone show a gradual change in slope over the temperature range of interest, with no inflection point which corresponds to Tg′. However, addition of low levels (about 0.1%) of electrolyte changes the shape of the thermogram into a biexponential function where the intersection of the two linear portions of the log (R) vs. T plot corresponds to the glass transition region. The total change in log (R) over the temperature range studied increases as the ionic radius of the reporter ion increases. The sharpest inflection points in the log (R) vs T curves, and the best correlation with DSC results, were obtained with ammonium salts. Tg′ values measured by ETA were compared with values measured by DSC. DSC thermograms of solutes with and without electrolyte (0.1%) show that the electrolyte decreases Tg′ by about 0.5 to 1.0°C. However, Tg′ values measured by ETA are somewhat higher than those measured by DSC, and difference between the two methods seems to increase as Tg′ decreases. Tg′ as measured by ETA is less heating rate dependent than DSC analysis, and ETA is a more sensitive method than DSC at low solute concentrations and at low heating rates. Results of electrical thermal analysis of frozen solutions are compared and contrasted with the electrical resistance vs. temperature behavior of polymer-electrolytes. ETA appears to be a useful complementary technique to DSC for characterizing formulations intended for freeze drying.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018991505659
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Tau as a nucleolar protein in human nonneural cells in vitro and in vivo (1996)
    Springer
    Chromosoma 105 (1996), S. 20-30 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The Tau-1 monoclonal antibody was localized to the nucleolus of interphase cells and the nucleolar organizing regions (NORs) of acrocentric chromosomes in cultured human cells. Putative nucleolar and NOR tau was found in HeLa cells and lymphoblasts as well as in nontransformed fibroblasts and lymphocytes. To confirm the presence of tau in the nuclei of these nonneural cells, immunoblotting analysis was performed on isolated nuclei from lymphoblasts. Several tau bands were noted on the blot of the nuclear extract suggesting the presence of multiple tau isoforms. Tau-1 immunostaining demonstrated variable staining intensities between individual acrocentric chromosomes in all cells tested. In cultured peripheral lymphocytes, these staining patterns were the same from one chromosome spread to the next within an individual. This consistency of Tau-1 staining and its variability among NORs was reminiscent of staining patterns obtained using the silver-NOR procedure. Comparisons of Tau-1 immunostaining with silver staining of chromosome spreads from human lymphocytes demonstrated that Tau-1 did not immunostain all of the NORs that were silver stained. The intensity of Tau-1 fluorescence in nucleoli was further shown to be increased in phytohemagglutinin-stimulated lymphocytes, indicating an upregulation of nuclear tau when cells reentered the cell cycle. These results contribute to a growing body of evidence defining tau as a multifunctional protein that may be involved in ribosomal biogenesis and/or rRNA transcription in the nucleus of all cells as well as microtubule-stabilizing functions in the neuronal cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050155
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...