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  • Springer  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Nanoplanktonic siliceous cysts from Antarctica are algae (1986)
    Springer
    Marine biology 92 (1986), S. 53-57 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Siliceous cysts, in the size range 2.0 to 5.5 μm are an important component of the nanoplankton of the Antarctic seas and the sub-arctic Pacific Ocean. It has been suggested that these organisms may be cysts in the life cycle of choanoflagellates (Acanthoecidae, Protozoa). We conclude that these organisms are algae, based on finding that living cells from Prydz Bay, Antarctica, autofluoresce red, indicating the presence of chlorophyll and that transmission electron microscopy of sectioned cells shows the presence of chloroplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392745
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  • 2
    Electronic Resource
    Electronic Resource
    The seasonal occurrence of chroococcoid cyanobacteria at an Antarctic coastal site (1989)
    Springer
    Polar biology 9 (1989), S. 193-196 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chroococcoid cyanobacterium Synechococcus was found at 5 m depth at a site 6 km off the Antarctic coast where the water depth was 30 m. These cells reached a peak concentration of 140 cells ml-1 in August at the time of maximum rate of development of seaice. They were accompanied in the water column by detritus consisting of diatom frustules and sediment particles. A smaller peak of abundance occurred at the time the sea-ice was breaking up. Cyanobacteria were seen only in very low numbers at one, and were absent at the other, of two deep water sampling sites. We propose that the two peaks of cyanobacterial abundance in the water column result from the suspension of a benthic population by ice crystals during the winter and their release from the sea-ice in summer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297175
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  • 3
    Electronic Resource
    Electronic Resource
    UV-B protecting compounds in the marine algaPhaeocystis pouchetii from Antarctica (1991)
    Springer
    Marine biology 109 (1991), S. 391-395 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phaeocystis pouchetii (Hariot) Lagerheim is widely distributed in polar waters, and forms massive near-surface blooms in the marginal ice-edge zone around Antarctica during spring and summer. UV irradiance in the Antarctic marine environment is reportedly as high in October and November as in mid-summer due to stratospheric ozone depletion. Because of the location and timing of theP. pouchetii bloom, this prymnesiophyte will be exposed to high levels of UV-B (280 to 320 nm) radiation. Colourless water-soluble compounds, produced by the colonial stage in the life cycle of this alga, absorb strongly between 250 and 370 nm, with absorbance maxima at 271 and 323 nm. The concentration of these compounds in culturedP. pouchetii depends on the strain, stage in the life cycle, and presence of bacteria. As well as conferring substantial protection to this alga, these substances may also provide UV protection to other organisms present in the water column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313504
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of UV-B irradiation on growth and survival of Antarctic marine diatoms (1994)
    Springer
    Marine biology 119 (1994), S. 507-515 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth rate, survival, and stimulation of the production of UV-B (280 to 320 nm) absorbing compounds were investigated in cultures of five commonly occurring Antarctic marine diatoms exposed to a range of UV-B irradiances. Experimental UV-B exposures ranged from 20 to 650% of the measured peak surface irradiance at an Antarctic coastal site (0.533 J m-2 s-1). The five diatom species (Nitzschia lecointei, Proboscia alata, P. inermis, Thalassiosira tumida and Stellarima microtrias) appear capable of surviving two to four times this irradiance. In contrast to Phaeocystis cf. pouchetii, another major component of the Antarctic phytoplankton, the concentrations of pigments with discrete UV absorption peaks in diatoms were low and did not change significantly under increasing UV-B irradiance. Absorbance of UV-B by cells from which pigments had been extracted commonly greatly exceeded that of the pigments themselves. Most of this absorbance was due to oxidisable cell contents, with the frustule providing the remainder. Survival of diatoms did not correlate with absorption by either pigments, frustules or oxidisable cell contents, indicating that their survival under elevated UV-B irradiances results from processes other than screening mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00354312
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  • 5
    Electronic Resource
    Electronic Resource
    Binding of manganese by Antarctic Phaeocystis pouchetii and the role of bacteria in its release (1987)
    Springer
    Marine biology 95 (1987), S. 481-487 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Antarctic Phaeocystis pouchetii and associated bacteria in culture, and the binding and release of manganese were investigated using cultures derived from three clonal isolates collected from Prydz Bay, Antarctica, in November and December 1982. The cultured strains accumulated manganese from the culture medium. The concentration of Mn2+ in the alga was up to 58 times that of the medium. The Mn2+ apparently binds to the mucilage secreted by the cells and gives the alga its characteristic brown colour. Oxidation or complexing of Mn2+ by P. pouchetii was also indicated. Bacterial growth on the mucilage is inhibited in rapidly growing cultures by acrylic acid produced in the mucilage. Once the growth of P. pouchetii and production of ccrylic acid slow, bacterial numbers increase, leading to the solubilization of the mucilage and the release of Mn2+. In cool-temperate, subpolar and polar seas where P. pouchetii may form dense blooms, the binding and subsequent release of manganese may have important consequences for competing phytoplankton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409577
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  • 6
    Electronic Resource
    Electronic Resource
    Seasonal variation in marine phytoplankton and ice algae at a shallow antarctic coastal site (1987)
    Springer
    Hydrobiologia 146 (1987), S. 33-46 
    Details
    ISSN: 1573-5117
    Keywords: seasonal variation ; phytoplankton ; ice algae ; antarctic ; chlorophyll ; diatoms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytoplankton population near Davis, Vestfold Hills, Antarctica was monitored throughout 1982. Chlorophyll-a determinations and counts of living cells in both the water column and sea ice demonstrated a marked seasonality in phytoplankton abundane and species composition. From April to October nanoplanktonic organisms contributed most of the chlorophyll-a in both the sea ice and water column. Blooms of diatoms occurred in May, November and December in the bottom of the sea-ice and in January and February in the water column. Phaeocystis pouchetii was dominant during December in the water column. Large numbers of dead diatoms were found in winter. The concentrations of nitrate, dissolved inorganic phosphate and dissolved silicate increased throughout the year until December, when the concentrations of nitrate and silicate fell sharply, followed a month later by a reduction in phosphate concentration. The diversity of phytoplankton was greatest during the summer months.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007575
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  • 7
    Electronic Resource
    Electronic Resource
    Colony formation and inversion in the green algaEudorina elegans (1977)
    Springer
    Protoplasma 93 (1977), S. 325-339 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During development of daughter coenobia in the volvocalean algaEudorina a rapid synchronized series of mitotic divisions and cytokineses gives rise to a slightly cup-shaped, patterned array of 16 or 32 cells, the plakea; the nuclei and centrioles of each cell lying at the concave face and the plastids at the convex face. Each cell is connected to its neighbours by cytoplasmic bridges. All cells within a plakea simultaneously elongate and enlarge their nuclear poles; while remaining interconnected by the cytoplasmic bridges at their plastid poles. The result is inversion of the developing coenobia so that the nuclei and centrioles come to lie on the convex, outer surface. Inversion is inhibited by colchicine and cytochalasin B. Both lengthening of the cells and expansion of their nuclear end is apparently mediated by microtubules. Striations on the plasmalemma encircling the bridges are thought to stablize the membrane at these sites during inversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275663
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  • 8
    Electronic Resource
    Electronic Resource
    Motility and microtubule stability of Antarctic algae at sub-zero temperatures (1983)
    Springer
    Protoplasma 115 (1983), S. 240-242 
    Details
    ISSN: 1615-6102
    Keywords: Algae ; Antarctic ; Microtubules ; Motility ; Sub-zero temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Most ectothermic organisms become immobile at a few degrees above zero. The unicellular planktonic algaeDunaliella sp., andChlamydomonas sp. from Antarctic hypersaline lakes remain motile at temperatures as low as −14 °C.Pyramimonas gelidicola from the same habitat stops swimming at −10 °C but its flagella continue to beat at −14 °C. Further, the characteristic shape ofPyramimonas, which is maintained by cytoskeletal microtubules, is unaffected by such low temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279815
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  • 9
    Electronic Resource
    Electronic Resource
    Microtubular determination of cell shape during colony formation by the algaPediastrum (1979)
    Springer
    Protoplasma 98 (1979), S. 1-14 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubules, which underlie the plasmalemma of zoospores ofPediastrum at the time of their aggregation to form daughter colonies, determine the shape of individual zoospores, and, as a consequence play a vital role in the patterned arrangement of cells in the colonies. Microtubules are also involved in extension of the characteristic horns on peripheral cells of colonies of this alga. Two densely staining plaques from which microtubules arise, are appressed to the plasmalemma at sites where horns emanate following adhesion of the zoospores. These plaques, which remain at the tips of the developing horns, are apparently microtubule organizing centres (MTOCs). IPC, a drug thought to affect MTOCs, interferes with the normal development of horns and the zoospores fail to aggregate in ordered arrays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01676659
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