Zellsaftgewinnung, AFS (apparent free space) und Vakuolenkonzentration der osmotisch wichtigsten mineralischen Bestandteile einiger Helgoländer Meeresalgen

Kesseler, Hanswerner

doi:10.1007/bf01612374

Cited by 11 publications

(4 citation statements)

References 15 publications

(2 reference statements)

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“…Our estimate of the fraction of extracellular space is derived from three nonelectrolytes of quite different sizes, and agrees with that of Kesseler (1964b), who used Li + as the extracellular marker. Errors in intracellular ionic concentrations and osmolalities can arise from at least three sources: (1)errors in our estimate of percent tissue water, (2) errors in either the volume or assumed composition of the extracellular fluid, and (3) existence of substantial amounts of "nonsolvent" water or "bound" ions in the tissue.…”

Section: Discussionsupporting

confidence: 86%

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Osmotic regulation in the marine alga,Codium decorticatum

Bisson

Gutknecht

1975

J. Membrain Biol.

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Codium decorticatum regulates its internal ionic composition and osmotic pressure in response to changes in external salinity. Over a salinity range of 23 to 37% (675 to 1120 mosmol/kg) Codium maintains a constant turgor pressure of 95 mosmol/kg (2.3 atm), observed as a constant difference between internal and external osmotic pressures. The changes in internal osmotic pressure are due to changes in intracellular inorganic ions. At 30 0/00 salinity the major intracellular ions are present in the following concentrations (mmol/kg cell H20): K+, 295; Na+, 255; Cl-, 450. At different salinities intracellular ion concentrations remain in constant proportion to the external ion concentrations, and thus the equilibrium potentials are approximately constant. The potential difference between the vacuole and seawater (-76 mV), whici is predominantly a K+ diffusion potential, is also constant with changing salinity. Comparison of the equilibrium potentials with the vacuole potential suggests that Cl- is actively absorbed and Na+ actively extruded, whereas K+ may be passively distributed between the vacuole and seawater. Turgor pressure does not change with environmental hydrostatic pressure, and increasing the external osmotic pressure with raffinose elicits a response similar to that obtained by increasing the salinity. These two results suggest that the stimulus for turgor regulation is a change in turgor pressure rather than a change in internal hydrostatic pressure or ion concentrations.

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Section: Discussionsupporting

confidence: 86%

“…The fraction of ECS is 0.13 _+ 0.01 liter/kg tissue (9), which agrees with the value of 0.145 obtained by Kesseler (1964b) using Li + as an ionic marker for ECS. Mannitol, sucrose and inulin gave similar values for ECS.…”

Section: Tissue Water and Extracellular Spacesupporting

confidence: 87%

Osmotic regulation in the marine alga,Codium decorticatum

Bisson

Gutknecht

1975

J. Membrain Biol.

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“…The measurements shown in Table 1 leave very little scope for any other non-measured inorganic anion (e.g. the sihcate present in Forsberg's medium, which can be found in soluble, ionic form in a number of algal cells: Kesseler, 1964;Fuhrman, Chisholm <& Guillard, 1978).…”

Section: Resultsmentioning

confidence: 99%

Acid‐base regulation during nitrate assimilation in Hydrodictyon africanum

Raven

Michelis

1979

Plant Cell & Environment

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The acid-base balance during NO3 assimilation in Hydrodictyon africanum has been investigated during growth from (1) an analysis of the elemental composition of the cells, (2) the alkalinity of the ash and (3) the net H"^ changes in the medium during growth. These investigations agree in showing that some 0.25 excess organic negative charges are generated per N assimilation from NO3 as N-source and CO2 as C-source; the excess OH" (0.75 0H~ per NOJ assimilated) appears in the medium. Approximately half of the excess organic negative charge is attributable to cell wall uronates; the remainder is intracellular. All of the excess 0H~ appearing in the medium must have crossed the plasmalemma (as net dovmhill H"^ influx or 0H~ efflux).Previous work has shown that the value of XJJQQ is more negative than 1//^^ during NO3 assimilation, suggesting that the active electrogenic H"*" extrusion pump is still operative despite the net downhill H"*^ infiux. The interpretation of this in terms of H'^-NOs symport which causes the entry of more H"^ than is consumed in NO3 metabolism, with extrusion of the excess H"*" via the active, electrogenic H"^ pump, was tested by measuring shortterm H"^ infiux upon addition of NOJ. A net H"^ infiux occurs before NO3 assimilation (as indicated by additional O2 evolution in the light) has commenced, suggesting a mechanistic relation of H"^ and NO3 infiuxes. This is consistent with the interpretation suggested above. Determinations of cytoplasmic pH showed no significant effect of NO3 assimilation, suggesting that cytoplasmic pH changes sufficient to change the 'pH-regulating' H"f luxes are smaller than the errors in the determination of cytoplasmic pH.

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“…Jacques and Osterhout (21) found that NO3-was concentrated in the sap ofValonia macryophysa by 2,000-fold and in the sap of H. osterhoutii by 500-fold over the concentration in natural seawater, which is less than 10 /xM. The accumulation of phosphate and SO4 = has been shown in several species of marine algae (23,24,35). Likewise, the active inward transport of phosphate (33,39) and of SO4 = (34) has been demonstrated in freshwater algae.…”

Section: Steady-state Ionic Distributionmentioning

confidence: 98%

Ion transport studies and determination of the cell wall elastic modulus in the marine alga Halicystis parvula.

Graves¹,

Gutknecht²

1976

The Journal of General Physiology

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A ~ S x 1~ A C X Using cultured cells of the marine alga, Halicystis parvula, we measured the concentrations of 11 inorganic ions in the vacuolar sap and the electrical potential difference (PD) between the vacuole and the external solution. In normal cells under steady-state conditions a comparison of the electrochemical equilibrium (Nernst) potential for each ion with the PD of -8~ mV (inside negative) indicates that Na + and K + are actively transported out of the vacuole whereas all anions are pumped into the cell. Although the [K +] in the vacuole is only 9 raM, the cytoplasmic [K +] is about 420 mM, which suggests that the outwardly directed pump is at the tonoplast. Using large Halicystis cells we perfused the vacuole with an artificial seawater and conducted a short-circuit analysis of ion transport. The short-circuit current (SCC) of 299 peq • cm-2.s -~ is not significantly different from the net influx of CI-. There is a small, but statistically significant net efflux of K + (<1 pmol-cm-2.-t), while the influx and efflux of Na + are not significantly different. Therefore, the SCC is a good measure of the activity of the C1-pump. Finally, we measured the volumetric elastic modulus (e) of the cell wall by measuring the change in cell volume when the internal hydrostatic pressure was altered, The Value of ~ at applied pressures between 0 and 0.4 atm is about 0.6 atm, which is at least 100-fold lower than the values of ~ for all other algae which have been studied,

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Zellsaftgewinnung, AFS (apparent free space) und Vakuolenkonzentration der osmotisch wichtigsten mineralischen Bestandteile einiger Helgoländer Meeresalgen

Cited by 11 publications

References 15 publications

Osmotic regulation in the marine alga,Codium decorticatum

Osmotic regulation in the marine alga,Codium decorticatum

Acid‐base regulation during nitrate assimilation in Hydrodictyon africanum

Ion transport studies and determination of the cell wall elastic modulus in the marine alga Halicystis parvula.

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