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  • 11
    Electronic Resource
    Electronic Resource
    Spatial and temporal variability of phytoplankton biomass and taxonomic composition around Elephant Island, Antarctica, during the summers of 1990–1993 (1995)
    Springer
    Marine biology 123 (1995), S. 677-686 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the austral summers of 1990–1993, phytoplankton studies were conducted in the vicinity of Elephant Island, Antarctica, to investigate the spatial and temporal variability of phytoplankton biomass and taxonomic composition. There was much intraannual variability, with a trend for increasing biomass from January–February (Leg I) to February–March (Leg II), except in the 1993 studies. There was also a change in phytoplankton composition between the two legs. During 1990–1991 the increase was due mostly to diatoms, during 1992 mostly to an increase of flagellates; during 1993 there was a decrease in total biomass between the two legs, with diatoms decreasing, so that dinoflagellates, which increased slightly in numbers, dominated the biomass during the second leg. There was also much inter-annual variability, with the summers of 1990–1991 having greater biomass and higher proportions of microplanktonic diatoms than that of 1992–1993, which had a higher proportion of flagellates. Cluster analyses revealed the presence of four major phytoplankton assemblages, with varying geographical distributions. The northwestern portion of the grid (Drake Passage waters), was characterized by nanoplanktonic diatoms during 1990–1991 and 1993, but by nanoplanktonic flagellates during 1992. The central area (Drake-Bransfield confluence) was characterized by microplanktonic diatoms in 1990–1991, but by cryptophytes or flagellates in 1992–1993. The south and southeastern portion of the area (Bransfield Strait waters) was characterized mainly by either cryptophytes or other flagellates during all 4 yr. The spatial and temporal variability of phytoplankton could not be ascribed specifically to the geographical extent of the different water masses found in the study area, but appears to be due to changing growth conditions in the upper water column as influenced by physical mixing and meteorological conditions, as well as to effects of differential grazing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349110
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  • 12
    Electronic Resource
    Electronic Resource
    Heterogeneity of Na+/K+-ATPase from rectal gland of Squalus acanthias is not due to α isoform diversity (1999)
    Springer
    Pflügers Archiv 437 (1999), S. 517-522 
    Details
    ISSN: 1432-2013
    Keywords: Key words Electronic autoradiography ; Enzyme heterogeneity ; α Isoforms ; Isoform-specific antibodies ; Na+/K+-ATPase ; [3H]Ouabain binding ; Shark rectal gland ; Squalus acanthias
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Purified Na+/K+-ATPase (EC 3.6.1.37) isolated from the rectal gland of Squalus acanthias was characterized in ouabain-binding studies and with respect to isoform(s) of the α peptide. To avoid enzyme inactivation [3H]ouabain equilibrium binding was carried out at 20°C. The heterogeneity of Na+/K+-ATPase isolated from shark rectal gland was similar in [3H]ouabain binding as previously seen in hydrolytic studies. The binding isotherms were compatible with the existence of a high-affinity (K dis 0.69 nM) and a low-affinity (K dis 42 nM) component of 1.46 and 0.79 nmol.(mg protein)–1, respectively. In Western blots the α peptide of the enzyme hybridized with an isoform-specific polyclonal antibody raised to an α3-specific region of the large intracellular domain of rat Na+/K+-ATPase, but not with the supposed α3-specific monoclonal antibody MA3-915 with its epitope near the N-terminus. Semi-quantitative analysis of the reaction of the α3-specific polyclonal antibody with the α peptide from the shark enzyme compared to the reaction with α peptide from rat brain enzyme indicated that this region is not exactly the same in the two species. The α peptide of shark enzyme was not recognized by α1- or α2-specific polyclonal antibodies, or by the α1-specific monoclonal antibodies 3B and F6. The large intracellular domain of Na+/K+-ATPase from shark rectal gland thus seems to be α3-like and no α isoform heterogeneity seems able to account for the heterogeneity seen in ouabain binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008089
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  • 13
    Electronic Resource
    Electronic Resource
    Physiology and chemical composition of nitrogen-fixing phytoplankton in the central North Pacific Ocean (1977)
    Springer
    Marine biology 41 (1977), S. 213-227 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The magnitude and physiological characteristics of biological nitrogen fixation have been studied in the oligotrophic waters of the North pacific gyre. The filamentous blue-green algae Trichodesmium spp. and Richelia intracellularis were the important nitrogen-fixing phytoplankton. Most of the nitrogen fixation occurs in the upper 40 m of the water column, with detectable fixation as deep as 90 m, which corresponds to about the 1 % light depth. There was no evidence of photoinhibition of nitrogen fixation, although CO2 reduction was depressed slightly at the highest light levels. The rate of nitrogen fixation in the water column varied throughout the day, being highest in mid-morning and in late afternoon. Relatively high fixation rates were also found during periods of darkness. Elevated oxygen concentrations had a marked inhibitory effect on rates of nitrogen fixation, a pO2 of 0.4 atm causing a 75% inhibition. Data from studies of nitrogen fixation and assimilation rates of 15N-labelled nitrate, ammonium, and urea indicate that nitrogen fixation furnished about 3% of the total daily fixed nitrogen requirement for phytoplankton growth. Studies with isolated colonies of Trichodesmium spp. indicated that 100% of their nitrogen requirement was met by nitrogen fixation. Chemical composition of the Trichodesmium colonies showed that the C:N ratio was 4.1 and that their phosphorus content relative to carbon or nitrogen was much lower than that of the total particulate material in the water column. Elevated ratios of carbon: adenosine triphosphate (ATP) also suggest that phosphorus deficiency may be limiting the growth of Trichodesmium. The magnitude of nitrogen fixation in the gyre is seasonally dependent, with high rates in late summer and autumn. At these times the water column is stratified, with phosphate and nitrate barely detectable in the upper 100 m. Our data suggest that during these months of stratification, biological fixation of nitrogen amounts to about 33 μg-at N/m2/day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394908
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  • 14
    Electronic Resource
    Electronic Resource
    Methodology and measurement of adenylate energy charge ratios in environmental samples (1978)
    Springer
    Marine biology 48 (1978), S. 185-197 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00395018
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  • 15
    Electronic Resource
    Electronic Resource
    Distribution of phytoplankton and nutrients in relation to different water masses in the area around Elephant Island, Antarctica (1997)
    Springer
    Polar biology 18 (1997), S. 145-153 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During January March 1996 the U.S. Antarctic Marine Living Resources program carried out an extensive multidisciplinary study in a 40,000 km2 sampling grid around Elephant Island, Antarctica. The physical, chemical, optical, and biological characteristics of the upper water column (0–750 m) were determined at 91 hydrographic stations. Analysis of the temperature and salinity data showed that six different hydrographic zones could be differentiated. The biological (phytoplankton distribution and abundance) and chemical (inorganic nutrient concentrations) data also showed characteristic differences within each of these six zones. In spite of high concentrations of inorganic N, P, and Si in all six zones, all stations in the northwest portion of the sampling grid (Drake Passage waters) showed very low chlorophyll-a concentrations in surface waters and a sub-surface maximum at increased depth. As stations in this zone have a relatively stable upper mixed layer of 40 m, excess macro-nutrients, and adequate solar radiation for maximal photosynthetic rates, this suggests that rates of primary production in this zone are limited by a micro-nutrient such as Fe. Phytoplankton abundance was much greater in the Bransfield Strait, in waters influenced by Bellingshausen Sea Water, and in the frontal zones where these water masses mix with Drake Passage waters. Relatively low and deeply distributed phytoplankton abundance was found at all stations in the southeastern portion of our sampling grid, where the upper water column was very weakly stratified and showed the characteristics of Weddell Sea water. The areas of enhanced phytoplankton biomass in the AMLR sampling grid roughly correspond to the areas where krill are generally also found in greater abundance. The overall biological productivity of the Elephant Island region would thus appear to be dependent upon the circulation patterns of the major water masses that intrude into this area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050169
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  • 16
    Electronic Resource
    Electronic Resource
    Spätabsceß nach laparoskopischer Cholecystektomie durch verlorene Gallensteine (1996)
    Springer
    Der Chirurg 67 (1996), S. 1047-1049 
    Details
    ISSN: 1433-0385
    Keywords: Key words: Cholecystolithiasis ; Laparoscopic cholecystectomy ; Gallstone loss ; Abdominal abscess.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Zu den möglichen intraoperativen Komplikationen der laparoskopischen Cholecystektomie gehört die Eröffnung der Gallenblase mit nachfolgendem Steinverlust. Wir berichten über den Fall einer 61 jährigen Patientin, die mit einer unklaren subhepatischen Raumforderung aufgenommen und laparotomiert wurde. Intraoperativ fand sich ein Absceß auf dem Boden von zurückgebliebenen Gallensteinen nach laparoskopischer Cholecystektomie vor 3 Jahren. Die Incidenz von Spätabscessen nach zurückgelassenen Gallensteinen ist zwar gering, kann jedoch aufgrund der langen Latenz und unspezifischen Symptomatik diagnostische Probleme bereiten. In Anbetracht der möglichen Komplikationen bei intraoperativem Steinverlust sollten möglichst alle Konkremente geborgen werden; eine Indikation zur Konversion besteht jedoch nicht.
    Abstract: Schlüsselwörter: Cholecystolithiasis – laparoskopische Cholecystektomie – verlorener Gallenstein – intraabdomineller Absceß.
    Notes: Summary. A possible intraoperative complication of laparoscopic cholecystectomy is opening of the gallbladder with subsequent loss of gallstones. We report on a 61-year-old woman who was hospitalised with an obscure subhepatic tumor. Intraoperatively an abscess was found that had been caused by lost gallstones following after laparoscopic cholecystectomy 3 years previously. There is a low incidence of late abscesses caused by loss of gallstones, but because of the long latency and unspecific symptoms there may be problems in diagnosis. Taking into consideration possible complications caused by intraoperative loss of gallstones, all concrements should be retrieved, even though there is no indication for changing to an open procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001040050102
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