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
Filter
Collection
Keywords
Publisher
Language
Years
  • 1
    facet.materialart.
    Unknown
    Authigenic Formation of Clay Minerals in the Abyssal North Pacific (2022)
    Details
    Publication Date: 2023-07-19
    Description: Present estimates of the biogeochemical cycles of calcium, strontium, and potassium in the ocean reveal large imbalances between known input and output fluxes. Using pore fluid, incubation, and solid sediment data from North Pacific multi‐corer cores we show that, contrary to the common paradigm, the top centimeters of abyssal sediments can be an active site of authigenic precipitation of clay minerals. In this region, clay authigenesis is the dominant sink for potassium and strontium and consumes nearly all calcium released from benthic dissolution of calcium carbonates. These observations support the idea that clay authigenesis occurring over broad regions of the world ocean may be a major buffer for ocean chemistry on the time scale of the ocean overturning circulation, and key to the long‐term stability of Earth's climate.
    Description: Key Points: North Pacific red clay sediments are a sink for marine calcium, strontium, and potassium. Authigenic formation of clay minerals is prevalent in pelagic sediments throughout the North Pacific. The main mechanism for clay formation is recrystallization of aluminosilicates, neoformation can occur in biogenic silica rich sediments.
    Description: EC H2020 PRIORITY “Excellent science” H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: Blavatnik Family Foundation http://dx.doi.org/10.13039/100011643
    Description: Isaac Newton Trust http://dx.doi.org/10.13039/501100004815
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.pangaea.de/10.1594/PANGAEA.946881
    Keywords: ddc:549 ; reverse weathering ; clay authigenesis ; calcium ; potassium ; porewater ; strontium
    Language: English
    Type: doc-type:article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    CITATION GEO-LEO
  • 2
    Electronic Resource
    Electronic Resource
    Transient outwardly rectifying potassium channel in the rabbit corneal endothelium (1992)
    Springer
    The journal of membrane biology 128 (1992), S. 123-132 
    Details
    ISSN: 1432-1424
    Keywords: cornea ; A-type potassium channel ; epithelium ; patch clamp ; perforated patch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Ionic currents from freshly dissociated rabbit corneal endothelial cells were examined using patch-clamp technology and a perforated patch technique. Whole-cell current recordings revealed a transient outward K+-selective current that was blockable in a dose-dependent manner by 4-aminopyridine (4-AP) and quinidine. This current is similar to the ‘A’-type current present in many excitable cells and is the first reported instance of such a current in any epithelial cell type. In addition to the transient current, an outwardly rectifying nonselective cation current was also observed. This current is also blocked by quinidine. To examine the possible role of these currents in the stromal volume regulatory function of the endothelium, corneas were perfused under a specular microscope with a glutathionebicarbonate Ringer's solution (GBR) or GBR plus either 1 mM quinidine or 10 mM 4-AP. For quinidine perfusions, control corneas swelled at a rate of 6 μm/hr, while quinidine-perfused corneas swelled at a rate of 48 μm/hr. For 4-AP perfusions, control corneas deswelled at a rate of −2 μm/hr, while 4-AP perfused corneas swelled at a rate of 24 μm/hr. One possible mechanism of the stromal swelling induced by these K+ channel blockers may be the result of loss of the K+ recycling pathway necessary for proper Na+/K+ ATPase function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231885
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Membrane and junctional properties of dissociated frog lens epithelial cells (1989)
    Springer
    The journal of membrane biology 111 (1989), S. 215-227 
    Details
    ISSN: 1432-1424
    Keywords: lens ; epithelium ; gap junctions ; membrane transport ; whole cell voltage clamp ; dye transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Individual cells and cell pairs were isolated from frog lens epithelium. Individual cells were whole cell voltage clamped and the current-voltage relationship was determined. The cells had a mean resting voltage of −54.3 mV and a mean input resistance of 1.4 GΩ. The current-voltage relationship was linear near the cell resting voltage, but showed decreased resistance with large depolarization or hyperpolarization. Junctional currents between pairs of cells were recorded using the dual whole cell voltage-clamp technique. The corrected junctional resistance was 15.5 MΩ (64.5 nS). The junctional current-voltage relationship was linear. A combination of ATP and cAMP, in the electodes, stabilized junctional resistance. Currents recorded when uncoupling was nearly complete, showed evidence of single connexon gating events. A single-channel conductance of about 100 pS was prominent. Dye spread between isolated cell pairs was demonstrated using Lucifer Yellow CH in a whole cell configuration. Photodamage to the cells due to the dye was apparent. Dye loaded cells, in the presence of exciting light, showed decreased resting voltages, decreased input resistances and morphological changes. Glutathione (20mm) delayed this damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871007
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Potassium channel in rabbit corneal endothelium activated by external anions (1990)
    Springer
    The journal of membrane biology 114 (1990), S. 29-36 
    Details
    ISSN: 1432-1424
    Keywords: cornea ; endothelium ; potassium channel ; HCO 3 − ; Cl− ; anions ; patch clamp ; rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The apical membrane of the rabbit corneal endothelium contains a potassium-selective ionic channel. In patch-clamp recordings, the probability of finding the channel in the open state (P o) depends on the presence of either HCO 3 − or Cl− in the bathing medium. In a methane sulfonate-containing bath,P o is 〈0.05 at all physiologically relevant transmembrane voltages. With 0mm [HCO 3 − ] o at +60 mV,P o was 0.085 and increased to 0.40 when [HCO 3 − ] o was 15mm. With 4mm [Cl−] o at +60 mV,P o was 0.083 and with 150mm Cl−,P o increased to 0.36. LowP o's are also found when propionate, sulphate, bromide, and nitrate are the primary bath anions. The mechanism of action of the anion-stimulated K+ channel gating is not yet known, but a direct action of pH seems unlikely. The alkalinization of cytoplasm associated with the addition of 10mm (NH4)2SO4 to the bath and the acidification accompanying its removal do not result in channel activation nor does the use of Nigericin to equilibrate intracellular pH with that of the bath over the pH range of 6.8 to 7.8. Channel gating also is not affected by bathing the internal surface of the patch with cAMP, cGMP, GTP-γ-s, Mg2+ or ATP. Blockers of Na/H+ exchange, Na+−HCO 3 − cotransport, Na+−K+ ATPase and carbonic anhydrase do not block the HCO 3 − stimulation ofP o. Several of the properties of the channel could explain some of the previously reported voltage changes that occur in corneal endothelial cells stimulated by extracellular anions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869382
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ion channel involvement in the temperature-sensitive response of the rabbit corneal endothelial cell resting membrane potential (1993)
    Springer
    The journal of membrane biology 135 (1993), S. 61-71 
    Details
    ISSN: 1432-1424
    Keywords: Corneal endothelium ; K+ channel ; Temperature sensitivity ; Resting voltage ; Patch clamp ; Perforated patch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Previous studies have shown that the resting potential (E m) of the corneal endothelium hyperpolarizes following an increase in temperature above 24°C. Whole-cell studies using the perforated-patch technique were used to compare currents and E mvalues from isolated corneal endothelial cells at 24 and 32°C. These studies revealed a small, outwardly rectifying, slowly activating, weakly voltage-dependent current with a reversal potential showing K+ selectivity (E rev = −80 mV). This current had features similar to the whole-cell current seen following addition of HCO3 − to these cells. E mmeasurements found an average 24 mV hyperpolarization following temperature elevation in NaCl Ringer. Single channel studies found the only change in channel activity following an elevation in temperature to be an increase in the open probability (P o) of a K+ channel previously reported in this cell type to be activated by external anions. P o(−30 mV) at 24 and 32°C equaled 0.003 and 0.06, respectively. Increases in P owere found at all voltages examined. This increased P ocan account for the magnitude of the hyperpolarization seen in these cells following temperature elevation. Addition of HCO3 − along with elevated temperature produced a synergistic effect on the increase in P oalong with an increased hyperpolarization of the cell, pointing to separate mechanisms of activation from these two stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234652
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Whole-cell potassium current in rabbit corneal epithelium activated by fenamates (1992)
    Springer
    The journal of membrane biology 129 (1992), S. 81-97 
    Details
    ISSN: 1432-1424
    Keywords: cornea ; epithelium ; patch clamp ; potassium current ; fenamates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Rabbit corneal epithelium contains a large-conductance, potassium-selective channel, which is a major contributor to the whole-cell current. In perforated-patch recordings of the macroscopic current, the isolated cells studied had resting voltages of −41±20 mV and capacitances of 5.8±2.6 pF (mean + sd for n=255). Activation of the channels was weakly voltage dependent. They opened at about −100 mV and reached an open probability of about 0.2 at +100 mV. The current was blocked by millimolar concentrations of external Ba2+ and quinidine. Diltiazem also blocked when applied to the external surface of the membrane. Nonsteroidal anti-inflammatory agents of the fenamate group were powerful activators of the channel at submillimolar concentrations when applied either to the inside or the outside of the channels. The mechanism of action which leads to his activation is not yet known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232057
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Cyclic GMP regulation of a voltage-activated K channel in dissociated Enterocytes (1991)
    Springer
    The journal of membrane biology 124 (1991), S. 159-167 
    Details
    ISSN: 1432-1424
    Keywords: cGMP ; charybdotoxin ; K recycling ; K secretion ; NaCl absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Enterrocytes from the intestinal epithelium of the winter flounder were isolated by collagenase digestion and incubated in flounder Ringer solution. Conventional whole-cell and amphotericin-perforated whole-cell recording techniques were used to characterize the properties of a voltage-activated K current present in dissociated cells. Resting membrane potentials and series resistances were significantly lower (from −23 to − 39 mV and 29 to 13 MΩ, respectively) when amphotericin was used to achieve the whole-cell configuration. When cells were placed in flounder Ringer solution, held at −80 mV and subsequently stepped to a series of depolarizing voltages (from−70 to 0 mV), an outward current was observed that exhibited inactivation at voltages above −20 mV. This current was sensitive to holding potential and was not activated when the cells were held at −40 mV or above. When cells were bathed in symmetric K Ringer solution and the same voltage protocol was applied to the cell, inward currents were observed in response to the negative intracellular potentials. Reversal potentials at two different extracellular K concentrations were consistent with K as the currentcarrying ion. BaCl2 (2 mM) and CsCl (0.5 mM) both produced voltage-dependent blockade of the current when added to the bathing solution. Charybdotoxin (300 nM extracellular concentration) completely blocked the current. The IC50 for charybdotoxin was 50 nM. Cyclic. GMP inhibited the voltage-activated current in flounder Ringer and in symmetric K Ringer solution. The cyclic GMP analog, 8-Br cGMP, lowered the threshold for voltage activation and potentiated inactivation of the current at voltages above−40 mV. Previous studies with intact flounder epithelium showed that K recycling and net K secretion were inhibited by Ba2+ and by cGMP. We suggest that the channel responsible for the whole-cell current described in this study may be important in K recycling and secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870460
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Electrophysiology of cultured human lens epithelial cells (1990)
    Springer
    The journal of membrane biology 117 (1990), S. 285-298 
    Details
    ISSN: 1432-1424
    Keywords: lens epithelium ; whole-cell recording ; cell culture ; K+ current ; Na+ current ; ion channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The lens epithelial K+ conductance plays a key role in maintaining the lens ionic steady state. The specific channels responsible for this conductance are unknown. We used cultured lens epithelia and patch-clamp technology to address this problem. Human lens epithelial explants were cultured and after 1–4 passages were dissociated and used in this study. The cells from which we measured had a mean diameter of 31±1 μm (sem,n=26). The resting voltage was −19±4 mV (sem,n=10) and the input resistance was 2.5±0.5 GΩ (sem,n=17) at −60 mV. Two currents were prominent in whole-cell recordings. An outwardly rectifying current was seen in nearly every cell. The magnitude of this current was a function of K+ concentration and was blocked by 3mm tetraethylammonium. The instantaneous current-voltage relationship was linear in symmetric K+, implying that the outward rectificiation was due to gating. The current showed complex activation and inactivation kinetics. The second current seen was a transient inward current. This current had kinetics very similar to the traditional Na+ current of excitable cells and was blocked by 0.1 μm tetrodotoxin. In single-channel recordings, a 150-pS K+ channel and a 35-pS nonselective cation channel were seen but neither account for the macroscopic currents measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868458
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Dye coupling in the corneal endothelium: effects of ouabain and extracellular calcium removal (1992)
    Springer
    Cell & tissue research 269 (1992), S. 57-63 
    Details
    ISSN: 1432-0878
    Keywords: Cornea ; Endothelium ; Gap junction ; Ouabain ; Calcium-free solution ; Phototoxicity ; Lucifer yellow ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of ouabain and extracellular calcium removal on gap junctional coupling of isolated rabbit corneal endothelium was examined using a modified dye-spread technique. This technique is a modification of a microelectrode procedure that now utilizes patch electrodes connected to a current-clamp circuit for dye iontophoresis and a shuttering system in the excitation light path to reduce phototoxic effects in the monolayer. It was found that a significant degree of junctional uncoupling occurred after 45 min of exposure to ouabain, quantified as a reduction in the effective diffusion coefficient of injected Lucifer yellow CH: 1.74×10-7 cm2/s (control) versus 0.43×10-7 cm2/s (ouabain-treated). It was also determined that no gap junctional uncoupling occurs after extended exposure (up to 3.5 h) to a calcium-free extracellular environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384726
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    facet.materialart.
    Unknown
    Distribution and ecology of planktic foraminifera in the North Pacific: Implications for paleo-reconstructions (2018)
    In:  EPIC3Quaternary Science Reviews, 191, pp. 256-274
    Details
    Publication Date: 2019-08-19
    Description: Planktic foraminifera census data have been used to reconstruct past temperatures through transfer functions, as well as changes in ocean ecosystems, chemistry and circulation. Here we present new multinet, plankton net and core-top census data from 20 sites in the Subpolar North Pacific. We combine these with previous data to provide an up to date compilation of North Pacific planktic foraminifera assemblage data. Our compilation is used to define 6 faunal zones: the subpolar zone; transitional zone; upwelling zone; subtropical zone; east equatorial zone; west equatorial zone; based on the distribution of 10 major species of planktic foraminifera. Two species of planktic foraminifera Neogloboquadrina pachyderma and Globigerina bulloides provide the basis for many subpolar paleo-reconstructions. Through the analysis of new multinet and CTD data we find that G. bulloides and N. pachyderma are predominantly found within 0–50 m of the water column and coincide with high food availability. N. pachyderma also shows a strong temperature control and can thrive in food poor waters where temperatures are low. Both species bloom seasonally, particularly during the spring bloom of March to June, with G. bulloides exhibiting greater seasonal variation. We suggest that percentage abundance of N. pachyderma in paleo-assemblages can be used to assess relative changes in past temperature, with G. bulloides abundance more likely to reflect changes in food availability. By comparing our core-top and multinet data, we also find a dissolution bias of G. bulloides over N. pachyderma in the North Pacific, which may enrich assemblages in the latter species.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...