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
    Role of Silicon in Diatom Metabolism (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 30 (1974), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The in vivo uptake of 31Si-silicic acid and 68Ge-germanic acid by cell organelles of Nitzschia alba Lewin and Lewin and Cylindrotheca fusiformis Reimann and Lewin was demonstrated. The organelles were isolated by fractionation of pre-labeled cells by differential centrifugation in 0.4 M sucrose medium. Electron micrographs showed that the isolated organelles were intact, with the exception of the N. alba mitochondria which appeared swollen and the C. fusiformis chloroplasts which had ruptured outer membranes and lacked stroma material. The amount of 31Si or 68Ge per mg protein of the subcellular fractions decreased in the following general order for both organisms: cell wall, mitochondria, chloroplasts, vesicles, and microsomes. A portion of the 31Si or 68Ge in the organelle fractions could be extracted into a distilled water wash. The uptake of silicon by the organelles suggests that silicon may be involved in some processes of the compartmentalized systems of the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1974.tb03654.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Parasitism ofAzotobacter andRhizobium species byBdellovibrio bacteriovorus (1968)
    Springer
    Antonie van Leeuwenhoek 34 (1968), S. 188-196 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Attempts to isolate, from soil, strains ofBdellovibrio bacteriovorus parasitic on variousAzotobacter andRhizobium species were not successful. However, a strain ofBdellovibrio bacteriovorus isolated from soil as a parasite ofEscherichia coli was shown to produce plaques onAzotobacter chroococcum as well but not onAzotobacter vinelandii or variousRhizobium species. The nutritive conditions required for thisBdellovibrio strain to yield discrete countable plaques onAzotobacter chroococcum plates were examined, and it was proposed thatAzotobacter slime be used as a preservative agent for the maintenance ofBdellovibrio bacteriovorus strains in frozen culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02046430
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Sea ice microbial communities (SIMCO) (1983)
    Springer
    Polar biology 2 (1983), S. 171-177 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Algal standing crops for the 1980 McMurdo Sound sea ice microbial communities (SIMCO) averaged 131 (±121) mg chl a·m-2 despite strong attenuation of downwelling irradiance by snow and ice cover. Using a C:chl a ratio of 31, annual sea ice production was estimated at 4.1 gC·m-2. SIMCO standing crops in the West Sound, previously considered a biologically depauperate region due to persistent ice cover and local current regimes, were greater than or equal to those of the East Sound when areas of similar ice thickness were compared. Biomass was located almost entirely in the bottom 20 cm of annual ice including over 99% of the chlorophyll a and ATP, and 93% of the particulate organic carbon. During the ice algal bloom, concentrations of chlorophyll a in the bottom 20 cm of ice averaged 656 mg ·m-3, 2000 times greater than under ice phytoplankton at 1 m depths. Phaeopigment: chlorophyll a ratios (P:C) were significantly higher in the upper ice column than in the bottom 20 cm. An hypothesis is presented that the ice contains a frozen record of P:C ratios in the surface seawater during ice formation. Photosynthetic rate of ice microalgae measured in the laboratory under simulated in situ conditions (-1.9°C; 0.3 to 13 μE·m-2·s-1) ranged from 0.6 to 7.5 mg C fixed·mg chl a -1·da-1. It was concluded that the bottom type SIMCO contributes a considerable amount of new carbon to McMurdo Sound during the austral spring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00448967
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Studies on the biochemistry and fine structure of silica shell formation in diatoms (1976)
    Springer
    Planta 130 (1976), S. 159-167 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell division in Navicula pelliculosa (Bréb.) Hilse, strain 668 was synchronized with an alternating regime of 5 h light and 7 h dark. Cell volume and dry weight increased only during the light period. DNA synthesis, which began during the third h of light, was followed sequentially by mitosis, cytokinesis, silicic acid uptake, cell wall formation, and cell separation. Silicification and a small amount of net synthesis of DNA, RNA and protein occurred during the dark at the expense of carbohydrate reserves accumulated during the light period. Cells kept in continuous light, after synchronization with the light-dark regime, remained synchronized through a second division cycle; the sequence of morphological events was the same as that in the light-dark division cycle, but the biosynthesis of macromolecular components changed from a stepwise to a linear pattern. The silicon-starvation synchrony was improved by depriving light-dark synchronized cells of silicic acid at the beginning of their division cycle, then resupplying silicic acid to cells blocked at wall formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384414
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Diatom mineralization of silicic acid (1979)
    Springer
    Archives of microbiology 123 (1979), S. 157-164 
    Details
    ISSN: 1432-072X
    Keywords: Active transport ; Binding ; Cell cycle ; Diatoms ; Germanium-68 ; Ion regulation ; Light dependent transport ; Nitzschia angularis ; Transport regulation ; Silicic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Silicic acid binding, possibly at a membrane site is suggested as the first step in Si(OH)4 metabolism in the marine diatom Nitzschia angularis. We estimate 1738±133 Si(OH)4 binding sites·μm-2 cell surface and a turnover of 4–12 Si(OH)4 molecules·s-1 at maximum transport velocity. All studies were carried out using 68Ge(OH)4 as a tracer for Si(OH)4. After Si(OH)4 uptake, rapid (〈1 min) transformation or intracellular binding was demonstrated; yet the extractable pool size after 1 min was indicative of transport against a concentration gradient. Initial uptake kinetics were linear for 150 s and saturation kinetics were demonstrated with kinetic parameters of 560 pmol Si(OH)4·106 cells-1·min-1 (V max) 4.2 μmol Si(OH)4·L-1(Ks). A metabolic energy requirement for transport was suggested by inhibition of uptake by agents that uncouple or inhibit phosphorylation; transport also was sensitive to agents that block sulfhydryl groups. Such characteristics are consistent with Si(OH)4 transport being an active carrier mediated process. Rates of Si(OH)4 transport were regulated during various growth stages and during the synchronized cell cycle. In Si(OH)4 starved cells, blocked at the initiation of silica frustule formation, cycloheximide treatment caused a rapid decline of transport rate. Blocked cells, placed in the dark, maintained high transport rates for 6 h after which there was a loss of activity during the following 18 h. Light dependent recovery of transport ability in 12 h predarkened cells was dependent on de novo protein synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446815
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Release of an ice-active substance by Antarctic sea ice diatoms (1994)
    Springer
    Polar biology 14 (1994), S. 71-75 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interstitial water from the diatom-rich ice platelet layer in McMurdo Sound, Antarctica contains a macromolecular, ice-active substance (IAS) that, at in situ concentrations, causes dense pitting on the basal surfaces of growing ice platelets. In this respect, it resembles several fish antifreezes that also cause pitting on ice surfaces, but unlike the antifreezes, it does not lower the freezing point. The IAS appeared to be released by diatoms, as extracts from the diatoms contained IAS, while seawater from a diatom-free area did not. No evidence of IAS was found in several species of temperate water diatoms. The ice-pitting activity of the IAS was destroyed by proteases and by incubation at 40° C, but not by periodate oxidation, or by incubation with galactosidase or endonuclease. Thus, activity appears to arise from a protein or protein component, and not from carbohydrate or nucleic acids. Potential roles of the IAS in the sea ice community are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240276
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Sea ice microbial communities. III. Seasonal abundance of microalgae and associated bacteria, Mcmurdo Sound, Antarctica (1984)
    Springer
    Microbial ecology 10 (1984), S. 231-242 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Numbers of bacteria in annual sea ice increased directly with numbers of algae during the 1981 spring ice diatom bloom in McMurdo Sound, Antarctica. Algae and bacteria in a control site grew at rates of 0.10 and 0.05 day−1, respectively, whereas in an experimentally darkened area neither increased after six weeks. Epiphytic bacteria grew at a rate twice that of the nonattached bacteria and were significantly larger, contributing approximately 30% of the total bacterial biomass after October. The microalgal assemblage was dominated by two species of pennate diatoms, anAmphiprora sp. andNitzschia stellata. Greater than 65% of epiphytic bacteria were associated withAmphiprora sp. after October.N. stellata, however, remained largely uncolonized throughout the study. We hypothesize that microalgae stimulate bacterial growth in sea ice, possibly by providing the bacteria with organic substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010937
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Community metabolism of adenylates by microheterotrophs from the Los Angeles Harbor and Southern California coastal waters (1981)
    Springer
    Marine biology 62 (1981), S. 217-226 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The natural concentration (S n) of dissolved total adenylates TA(=AMP+ADP+ATP) in coastal seawater from a depth of 1 m at 5 stations (California, USA) sampled periodically for 1 yr had a mean value ±1 SD of 2.8±1.7 nmol TA1-1. The specific uptake rates of TA by microheterotrophs at a station inside the Los Angeles Harbor and at a station 1.5 km offshore in the San Pedro Channel were studied by simple uptake and saturation-type kinetic analysis using 3H-AMP as a tracer. Within the harbor, the specific uptake rate (nmol TA 109 cell-1 h-1) at S n ranged 10-fold from 0.028 in December to 0.28 in August. K t (half-saturation constant) values always exceeded theS n concentrations in any given month, and were greater in the harbor than in the channel. Generally, over 80% of biological uptake of 3H-AMP was associated with organisms 〈1.0 μm, a size class accounting for about 20% of the total particulate adenylate concentration in the 0.2 to 203 μm size fraction. Assuming steady-state conditions for the dissolved adenylate pool, we propose a model in which losses from this pool are balanced by inputs to the pool through inefficient feeding, lysis and decomposition of particulate adenylates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388185
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Orthophosphate uptake by phytoplankton and bacterioplankton from the Los Angeles Harbor and Southern California coastal waters (1981)
    Springer
    Marine biology 64 (1981), S. 23-33 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Orthophosphate (P) uptake on a seasonal basis in surface waters and in vertical profiles was directly proportional to the standing stocks of phytoplankton and bacterioplankton in the outer Los Angeles Harbor and in southern California coastal waters during 1978–1979. A phytoplankton-enriched size fraction (PEF) which was retained on a 1 μm pore-size filter contained 83% of the total chlorophyll a but only 18% of the total bacteria. A bacterioplankton-enriched size fraction (BEF) which passed the 1 μm filter but was retained on a 0.2 μm filter contained 82% of the total bacteria but only 17% of the total chlorophyll a. PEF and BEF accounted for 91 and 9% of the microbial carbon, respectively. The differential uptake of 10 radiolabeled substrates more fully characterized PEF and BEF. 33P uptake occurred in both PEF and BEF, accounting for 47 and 53%, respectively, of the total uptake. 33P uptake by both size fractions was inhibited by low concentrations of 2,4-dinitrophenol (DNP), N-ethylmaleimide (NEM) and carbonyl cyanide, m-chlorophenylhydrozone (CCCP). Darkness and low levels of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) selectively inhibited 33P uptake by PEF; valinomycin selectively inhibited 33P uptake by BEF. An experiment measuring 33P uptake velocity versus P concentration produced sigmoidal saturation kinetics at high levels of exogenous P. Kinetic parameter analyses according to the Hill equation gave a V max of 7.12 nmol l−1 h−1 and aK t of 0.41 nmol l−1 for PEF, and a V max of 5.17 nmol l−1 h−1 and aK t of 112 nmol l−1 for BEF. Consideration of relative surface areas of phytoplankton and bacterioplankton, their 33P uptake rates in light and dark, and estimates of the population turnover times emphasizes the potential importance of bacterioplankton in community phosphorus metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394077
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effects of four environmental variables on photosynthesis-irradiance relationships in Antarctic sea-ice microalgae (1987)
    Springer
    Marine biology 94 (1987), S. 299-306 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of temperature, salinity, growth irradiance and diel periodicity of incident irradiance on photosynthesis-irradiance (P-I) relationships were examined in natural populations of sea-ice microalgae from McMurdo Sound in the austral spring of late 1984. Both P m b (photosynthetic rate at optimum irradiance) and α b (initial slope or P-I curve) were temperature-dependent reaching optimal rates at approximately +6° and +2°C, respectively. P-I relationships showed little difference at 20 and 33‰ S; however, no measurable photosynthesis by sea-ice microalgae was detected in a 60‰ S solution of brine collected from the upper layers of congelation ice. Although diel periodicity characteristic of the under-ice light field appeared to have little effect on P-I relationships, changes in growth irradiance had a profound effect. An increase in growth irradiance from 7 μE m-2 s-1 (ambient) to 35 or 160 μE m-2 s-1 resulted in a transient three-fold increase in P m b and I k (index of photoadaptation) during the first four days, followed by a sharp decline. The effects of these environmental factors on ice algal photosynthesis may influence the distribution of microalgae in sea-ice environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392944
    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...