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  • 1
    Electronic Resource
    Electronic Resource
    Acclimation of brown algal photosynthesis to ultraviolet radiation in Arctic coastal waters (Spitsbergen, Norway) (1998)
    Springer
    Polar biology 20 (1998), S. 388-395 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In field studies conducted at the Kongsfjord (Spitsbergen) changes of the irradiance in the atmosphere and the sublittoral zone were monitored from the beginning of June until the end of August 1997, to register the minimum and maximum fluxes of ultraviolet and photosynthetically active radiation and to characterise the underwater light climate. Measurements of photosynthesis in three abundant brown algal species (Alaria esculenta, Laminaria saccharina, Saccorhiza dermatodea) were conducted to test whether their photosynthetic performance reflects changing light climate in accordance with depth. Plants sampled at various depths were exposed to controlled fluence rates of photosynthetically active radiation (400–700 nm), UV-A (320–400 nm) and UV-B (280–320 nm). Changes in photosynthetic performance during the treatments were monitored by measuring variable chlorophyll fluorescence of photosystem II. In each species, the degree of inhibition of photosynthesis was related to the original collection depth, i.e. shallow-water isolates were more resistant than plants from deeper waters. The results show that macroalgae acclimate effectively to increasing irradiance levels for both photosynthetically active and ultraviolet radiation. However, the kinetics of acclimation are different within the different species. It is shown that one important strategy to cope with higher irradiance levels in shallow waters is the capability for a faster recovery from high light stress compared to isolates from deeper waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050319
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  • 2
    Electronic Resource
    Electronic Resource
    Adaptation and acclimation of growth and photosynthesis of five Antarctic red algae to low temperatures (2000)
    Springer
    Polar biology 23 (2000), S. 609-618 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Temperature requirements for growth, photosynthesis and dark respiration were determined for five Antarctic red algal species. After acclimation, the stenothermal species Gigartina skottsbergii and Ballia callitricha grew at 0 or up to 5 °C, respectively; the eurythermal species Kallymenia antarctica, Gymnogongrus antarcticus and Phyllophora ahnfeltioides grew up to 10 °C. The temperature optima of photosynthesis were between 10 and 15 °C in the stenothermal species and between 15 and 25 °C in the eurythermal species, irrespective of the growth temperature. This shows that the temperature optima for photosynthesis are located well below the optima from species of other biogeographical regions, even from the Arctic. Respiratory rates rose with increasing temperatures. In contrast to photosynthesis, no temperature optimum was evident between 0 and 25 °C. Partial acclimation of photosynthetic capacity to growth temperature was found in two species. B. callitricha and Gymnogongrus antarcticus acclimate to 0 °C, and 5 and 0 °C, respectively. But acclimation did in no case lead to an overall shift in the temperature optimum of photosynthesis. B. callitricha and Gymnogongrus antarcticus showed acclimation of respiration to 5 °C, and P. ahnfeltioides to 5 and 10 °C, resulting in a temperature independence of respiration when measured at growth temperature. With respect to the acclimation potential of the species, no distinction can be made between the stenothermal versus the eurythermal group. (Net)photosynthetic capacity:respiration (P:R) ratios showed in all species highest values at 0 °C and decreased continuously to values lower than 1.0 at 25 °C. In turn, the low P:R ratios at higher temperatures are assumed to determine the upper temperature growth limit of the studied species. Estimated daily carbon balance reached values between 4.1 and 30.7 mg C g−1 FW day−1 at 0 °C, 16:8 h light/dark cycle, 12–40 μmol m−2 s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000000130
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  • 3
    Electronic Resource
    Electronic Resource
    Low-molecular-weight organoiodine and organobromine compounds released by polar macroalgae – The influence of abiotic factors (2000)
    Springer
    Fresenius' journal of analytical chemistry 368 (2000), S. 297-302 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of temperature, light, salinity and nutrient availability on the release of volatile halogenated hydrocarbons was investigated in the Antarctic red macroalgal species Gymnogongrus antarcticus Skottsberg. Compared to standard culture condition, an increase in the release rates of iodocompounds was generally found for the exposure of the alga to altered environmental conditions. Macroalgae exhibited higher release rates after adaptation for two months to the changed factors, than after short-term exposure. Monitoring the release rates during a 24 h incubation period (8.25 h light, 15.75 h darkness) showed that changes between light and dark periods had no influence on the release of volatile halocarbons. Compounds like bromoform and 1-iodobutane exhibited constant release rates during the 24 h period. The formation mechanisms and biological role of volatile organohalogens are discussed. Although marine macroalgae are not considered to be the major source of biogenically-produced volatile organohalogens, they contribute significantly to the bromine and iodine cycles in the environment. Under possible environmental changes like global warming and uncontrolled entrophication of the oceans their significance may be increase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160000491
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of ultraviolet radiation on photosynthesis and related enzyme reactions of marine macroalgae (2000)
    Springer
    Planta 211 (2000), S. 555-562 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Macroalgae – Photosynthesis – Ribulose-1, 5-bisphosphate carboxylase/oxygenase – UV radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Changes in physiological parameters related to photosynthesis were studied in five macroalgal species from Spitsbergen (Monostroma arcticum, Laminaria solidungula, Alaria esculenta, Palmaria palmata, Phycodrys rubens) during a 72-h exposure to UV radiation. Maximal quantum yield of photochemistry (Fv/Fm) and maximal electron transport rate (ETRmax) were measured with a pulse-amplitude-modulated fluorometer; the activity of the Calvin cycle enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) were estimated using a photometric test. Proteins of crude extracts were separated by SDS gel electrophoresis and changes in cellular concentrations of Rubisco were determined. Moreover, the concentration of chlorophyll a (Chl a), and protein content, were measured photometrically. In all species, Chl a content, maximal quantum yield as well as ETRmax decreased during the UV treatment. Changes in ETRmax were related to the changes in the overall activity of Rubisco. Analysis of SDS gels showed that in P. rubens, L. solidungula, M. arcticum and A. esculenta decreasing Rubisco activity partly resulted from a degradation of the enzyme. However, in A. esculenta, the formation of a high-molecular-weight polypeptide was observed. In all species, the activity of Rubisco was more strongly impaired than that of G3PDH. Exposure to UV resulted in loss of total protein only in the deepwater species L. solidungula and P. rubens. The different sensitivities to UV exposure of the species tested reflect their zonation pattern in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000313
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  • 5
    Electronic Resource
    Electronic Resource
    Tonoplast fine structure and osmotic regulation in Porphyra umbilicalis (1983)
    Springer
    Planta 159 (1983), S. 342-346 
    Details
    ISSN: 1432-2048
    Keywords: Osmotic regulation ; Porphyra ; Tonoplast (fine structure)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Porphyra, an intertidal red alga, the fine structure of the tonoplast was studied by freeze-fracture electron microscopy. It was shown that density and size of intramembraneous particles on the protoplasmic fracture face vary with external osmotic potential. The frequency of particles grouped in size classes (calculated per cell) increases with increasing osmotic stress and shows a maximum in 3 to 4 x artificial seawater medium ASP12. It is concluded that the intensity of tonoplast transport, which probably is enhanced with increasing osmotic stress from 1 to 4 x media, is most likely correlated with a change in membrane fine structure of the tonoplast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393173
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  • 6
    Electronic Resource
    Electronic Resource
    Ion compartmentation in Porphyra umbilicalis determined by electron-probe X-ray microanalysis (1983)
    Springer
    Planta 159 (1983), S. 336-341 
    Details
    ISSN: 1432-2048
    Keywords: Ion compartmentation ; Osmotic stress ; Porphyra ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ion composition of cell compartments in the intertidal red alga Porphyra umbilicalis adapted for two weeks in 3.5 x artificial seawater was determined by X-ray microanalysis of unfixed, frozen, bulk specimens. A procedure is described for the calculation of ion concentrations in the main cell compartment, cytoplasm, vacuoles and plastid. The results indicate high K+ and low Na+ concentrations in cytoplasm and plastid. Sodium ions are preferentially localized in vacuoles. Both, vacuoles and plastid contain high Cl- concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393172
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  • 7
    Electronic Resource
    Electronic Resource
    Growth, cell volume, and fine structure of Porphyra umbilicalis in relation to osmotic tolerance (1980)
    Springer
    Planta 150 (1980), S. 303-311 
    Details
    ISSN: 1432-2048
    Keywords: Carbon balance ; Fine structure ; Growth ; Osmotic regulation ; Porphyra ; Volume regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Porphyra umbilicalis, a marine red alga occurring in the intertidal zone of the cold North Sea, tolerates a wide range of osmotic conditions from 0.2 x to 6 x artificial seawater medium ASP12. In cells osmotically adapted for two weeks, photosynthesis and respiration are progressively inhibited in media more concentrated than 2 x. In both hypo- and hyperosmotic stress ranges, the most striking fine structural change is the development of vacuoles. In comparison to 1 x medium, where vacuoles are virtually lacking, the vacuolar part of the protoplasm increases 6-fold in 0.2 x and 10-fold in 3.5 x medium, respectively. However, at extreme hyperosmotic stress (6 x medium) the vacuolar part is extremely small. The largest cell volumes are found in 0.2 x and 3.5 x media, the smallest one in 6 x medium. In the osmotically regulated range (0.2–3.5 x medium), the regulated parameter is the volume of the protoplasm without the vacuolar system. It is suggested that at hyperosmotic stress the vacuoles may serve as osmotically active compartment, probably by accumulation of inorganic ions. The intracellular content of Floridean starch granules decreases with increasing osmotic pressure, possibly indicating the significance of soluble organic constituents as osmotically active solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384660
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  • 8
    Electronic Resource
    Electronic Resource
    Natural ultraviolet radiation and photosynthetically active radiation induce formation of mycosporine-like amino acids in the marine macroalga Chondrus crispus (Rhodophyta) (1998)
    Springer
    Planta 205 (1998), S. 257-262 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Chondrus ; Palythene ; Palythine ; Palythinol ; Shinorine ; UV-sunscreens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The UV-absorbing mycosporine-like amino acids (MAAs) are hypothesized to protect organisms against harmful UV radiation (UVR). Since the physiology and metabolism of these compounds are unknown, the induction and kinetics of MAA biosynthesis by various natural radiation conditions were investigated in the marine red alga Chondrus crispus collected from Helgoland, Germany. Three photosynthetically active radiation (PAR, 400–700 nm) treatments without UVR and three UV-A/B (290–400 nm) treatments without PAR were given. Chondrus crispus collected from 4–6 m depth contained only traces of the MAA palythine. After 24 h exposure to 100% ambient PAR, traces of three additional MAAs, shinorine, palythinol and palythene, were detected, and their concentrations increased strongly during a one-week exposure to all PAR treatments. The concentration of all MAAs varied directly with PAR dose, with palythine and shinorine being four- to sevenfold higher than palythinol and palythene. Likewise, naturally high doses of both UV-A and UV-B resulted in a strong accumulation of all MAAs, in particular shinorine. While shinorine accumulation was much more stimulated by UVR, the content of all other MAAs was more affected by high PAR, indicating an MAA-specific induction triggered by UVR or PAR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050319
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  • 9
    Electronic Resource
    Electronic Resource
    Distribution of macroalgae and macroalgal communities in gradients of physical conditions in Potter Cove, King George Island, Antarctica (1996)
    Springer
    Hydrobiologia 333 (1996), S. 1-17 
    Details
    ISSN: 1573-5117
    Keywords: macroalgae ; distribution ; sublittoral ; exposition ; communities ; Antarctic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vegetation of a small fjord and its adjacent open shore was documented by subaquatic video. The distribution of individual species of macroalgae and the composition of assemblages were compared with gradients of light availability, hydrography, slope inclination, substratum, and exposition to turbulence and ice. The sublittoral fringe is usually abraded by winterly ice floes and devoid of large, perennial algae. Below this zone, the upper sublittoral is dominated by Desmarestia menziesii on steep rock faces, where water movements become irregular, or by Ascoseira mirabilis and Palmaria decipiens on weakly inclined slopes with steady rolling water movements. In the central sublittoral above 15 m, where turbulence is still active, Desmarestia anceps is outcompeting all other species on solid substratum, However, the species is not able to persist on loose material under these conditions. Instead, Himantothallus grandifolius may occur. Deeper, where turbulence usually is negligible, Desmarestia anceps also covers loose material. The change of dominance to Himantothallus grandifolius in the deep sublittoral cannot completely be explained at present. Himantothallus grandifolius also prevails in a mixed assemblage under the influence of grounding icebergs. Most of the smaller algae are opportunists with different degrees of tolerance for turbulence, but some apparently need more stable microhabitats and thus are dependent from continuing suppression of competitive large phaeophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020959
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  • 10
    Electronic Resource
    Electronic Resource
    Ultraviolet sunscreen compounds in epiphytic red algae from mangroves (2000)
    Springer
    Hydrobiologia 432 (2000), S. 159-171 
    Details
    ISSN: 1573-5117
    Keywords: MAAs ; mangrove algae ; mycosporine-like amino acids ; UV-radiation ; UV-sunscreens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Epiphytic red algae of the order Ceramiales from mangroves and salt marshes (nine species from Bostrychia, three from Stictosiphonia and four from Caloglossa) produce varying levels of the UV-absorbing compounds mycosporine-glycine, shinorine, porphyra-334, palythine, asterina-330 and palythinol, a suite of substances chemically assigned as mycosporine-like amino acids (MAAs). Mean MAA levels varied from 0.02 to 12.8 mg g−1 DW in field-collected and laboratory cultured specimens. While in field samples of Bostrychia montagneiHarvey, Bostrychia radicans (Montagne) Montagne and Caloglossa apomeiotica J.West et G.Zuccarello MAA concentrations were generally higher compared to cultured plants of the same taxa, Bostrychia tenella(Lamouroux) J.Agardh did not show such a difference. Catenella caespitosa (Withering) L.Irvine, Catenella impudica (Montagne) J.Agardh and Catenella nipae Zanardini (Gigartinales, Caulacanthaceae) produce two novel UV-absorbing compounds: MAA-1 (1.4–4.3 mg g −1 DW) and MAA-2 (0.1–1.0 mg g−1 DW), which absorb at 334 nm and 320 nm, respectively. In laboratory culture of Bostrychia moritziana when photosynthetically active radiation (PAR) was increased from 20 to 40 μmol photons m−2 s−1, the total level of palythinol increased by 85% (from 2.0 to 3.7 mg g−1 DW). In a culture of Caloglossa leprieurii when PAR was increased from 40 to 80 μmol m−2 s−1the porphyra-334 content increased by 77% (from 3.1 to 5.5 mg g−1 DW). Extremely high MAA contents of 〉30 mg g−1 DW were detected in mature tetrasporangial sori prepared from two isolates of laboratory-cultured reproductive Caloglossa apomeiotica compared to vegetative plants (about 10 mg MAAs g−1 DW) indicating tetraspores loaded up with UV-sunscreens. All data demonstrate that mangrove red algae contain high MAA concentrations, particularly the reproductive structures, and hence these compounds may act as biochemical photoprotectants against exposure to UV-radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004046909810
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