Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1985-1989  (5)
  • 1980-1984  (4)
Datenquelle
Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Uptake of CO2 by aquatic vegetation (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 8 (1985), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract Photosynthesis by aquatic plants based on the supply of CO2 from air-equilibrated solutions may be limited by the low diffusion coefficient of CO2 in water. For plants in which the transport of CO2 from the bulk medium is by diffusion, and the initial carboxylation uses RUBISCO, CO2 supply can be increased by growth in habitats with fast water flow over the surface (reducing unstirred layer thickness), or with heterotrophically-augmented CO2 levels, including the direct use of sediment CO2. Many aquatic plants using RUBISCO as their initial carboxylase counter the limitations on CO2 supply via the operation of biophysical CO2 concentrating mechanisms which are based on active transport of HCO−3, CO2 or H+ at the plasmalemma, and use bulk-phase HCO−3 or CO2 as the C source. A final group of aquatic plants use biochemical CO2 concentrating mechanisms based on auxiliary carboxylation by PEPc: C4-like and Crassulacean Acid Metabolism–like processes are involved. These various mechanisms for increasing CO2 supply to RUBISCO also help to offset the low specific reaction rate of aquatic plant RUBISCOs at low [CO2] and low [CO2]: [CO2]. In addition to overcoming restrictions on CO2 supply, the various methods of increasing inorganic C availability may also be important in alleviating shortages of nitrogen or photons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3040.1985.tb01677.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Water balance of N2-fixing root nodules: Can phloem and xylem transport explain it? (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract Analysis of nodule inputs via the phloem and outputs via the xylem leads to the conclusion that water fluxes along those conduits alone would give a xylem sap osmolality in excess of that of sieve tubes and would thus plasmolyse the latter unless N2 fixation involved a very high respiratory consumption of organic C entering in the phloem, or there is significant water influx from soil through the nodule surface. Whether N2 fixation by attached nodules not in contact with an external water supply is energetically inefficient (and hence also, at a whole plant level, inefficient in terms of water-use) is as yet untested. However, the hypothesis which we prefer involves the shortfall in water entry via the phloem being made up the parenchymatic water flux from the root to the nodule.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01628.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    The utilization of bicarbonate ions by the macroalga Ascophyllum nodosum (L.) Le Jolis (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract A comparison of some of the methods used to determine whether aquatic plants have the ability to utilize bicarbonate ions as a source of inorganic carbon for photosynthesis has been applied to the intertidal macroalga Ascophyllum nodosum. These include: observing photosynthesis at a high pH (below the alga's CO2 compensation point), pH compensation point determinations, comparing the photosynthetic characteristics at low pH (5.20) and at high pH (7.95), estimating the maximal rates at which CO2 can diffuse through the unstirred layer and the rate at which CO2 can be produced from bicarbonate dehydration in the unstirred layer. All indicated that Ascophyllum nodosum can use bicarbonate ions for photosynthesis, though some were not always consistent. Calculating the total inorganic carbon concentration from pH measurements and acidification CO2 determinations revealed that the assumption that the alkalinity remains constant during pH drift experiments is not always valid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1365-3040.ep11611615
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Acid-base regulation during ammonium assimilation in Hydrodictyon africanum (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract The acid-base balance during ammonium (used to mean NH 4+ and/or NH3) assimilation in Hydrodictyon africanum has been measured on cells growing with about 1 mol m−3 ammonium at an external pH of about 6.5. Measurements made included (1) ash alkalinity (corrected for intracellular ammonium) which yields net organic negative charge, (2) the accumulation of organic N in the cells and (3) the change in extracellular H+ (from the pH change and the buffer capacity). These measurements showed that some 0.25 excess organic negative charge (half in the cell wall, half inside the plasmalemma) accumulates per organic N synthesized, while some 1.25H+ accumulate in the medium per organic N synthesized. Granted a permeability (PNH3) of some 10−3 cm s−1, and a finite [NH3] in the cytoplasm of these N-assimilating cells it is likely that most of the ammonium entering these growing cells is as NH 4+. This means that most of the H + appearing in the medium must have originated from inside the cell and have been subjected to active efflux at the plasmalemma: H+ accumulates in the medium equivalent to any NH3 entry by requilibration from exogenous NH 4+. The cell composition (net organic negative charge, organic N content) is very similar in these ammonium-grown cells to that of NO3+grown cells, suggesting that there is no action of a ‘biochemical pH stat’ during longterm assimilation of NO3+in H. africanum.Short-term experiments were carried out at an external pH of 7.2 in which ammonium at various concentrations were supplied to NO3+-grown cells. There was in all cases a rapid influx followed by a slower uptake; at least at the lower concentrations (less than 100 μmol dm−3) the net influx was all attributable to NH4+influx via a uniporter, probably partly short-circuited by a passive NH3 efflux due to intrinsic membrane permeability to NH3. The net ammonium influx was in all cases associated with H+ accumulation in the medium. (1.3-1.7 H + per ammonium taken up); as in the growth experiments, most of the ammonium taken up was assimilated.Determinations of cytoplasmic pH showed either no effect on, or a slight decrease in, pH during ammonium assimilation; the changes that occurred were in the direction expected for actuating a ‘pH-regulating’ change in H+ fluxes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1365-3040.ep11581869
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Source—sink characteristics of carbon transport in Chara hispida (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract Rates of uptake of 14C-labelled inorganic carbon were measured for whole Chara hispida plants, detached parts of the shoot and isolated (split-chamber technique) apices, lateral branchlets and rhizoid—node complexes.The rates of inorganic carbon uptake by the rhizoid—node complex expressed per gram fresh weight whole plant were three to four orders of magnitude less than the uptake for the whole plant. Up to 70% of the carbon taken up by the rhizoid—node complex was translocated to the shoot. After 12 h exposure to 14C-labelled inorganic carbon the concentration of 14C was greater in apices than in uppermost or central internodal cells and in all lateral branchlets, regardless of whether label was supplied to the whole plant or isolated rhizoid—node complexes. Measurement of inorganic carbon uptake by detached internodal cells and detached and isolated apices and lateral branchlets showed that lateral branchlets had the greatest rates of inorganic carbon uptake. During 12 h exposure to 14C, isolated lateral branchlets translocated to the attached shoot 55% of the labelled carbon taken up; for isolated apices this value was only 13%.It is concluded that it is highly unlikely that the rhizoid of Chara hispida could acquire a significant fraction of the whole plant requirement for inorganic carbon and that apices are sink regions for photosynthate while lateral branchlets are source regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1365-3040.ep11572119
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    BIOLOGY OF NONVASCULAR PLANTS (Book). (1984)
    Oxford, UK : Blackwell Publishing
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1365-3040.ep11589483
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Endogenous ion currents traverse growing roots and root hairs of Trifolium repens (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract The patterns of naturally growing ion currents associated with horizontally growing roots of Trifolium repens L. seedlings were measured in a simple low-salt bathing medium using a highly sensitive vibrating electrode. Current consistently enters the main elongation zone of the root and leaves from mature, elongated tissue. This current enters and leaves with densities of ca. 4.0–11.0 mA m−2 and 4.0 mA m−2, respectively. Current was also delected entering the zone of emerging root hairs and also the root-hair tips themselves.These results are a further example of the involvement of self-generated electrical fields in plant developmental processes. Possible, secondary rhizosphere-associated effects of the extracellular loop of the developmental current are also suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/1365-3040.ep11614353
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Inorganic carbon assimilation in the Isoetids, Isoetes lacustris L. and Lobelia dortmanna L. (1984)
    Springer
    Oecologia 61 (1984), S. 115-121 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The inorganic carbon fixation patterns of Isoetes lacustris and Lobelia dortmanna from an oligotrophic Scottish loch have been examined by following titratable acidity changes in plant sap and light/dark 14CO2 incorporation by roots and shoots. The diurnal pattern of titratable acidity changes in I. lacustris suggests crassulacean acid metabolism (CAM) while the lack of any change in titratable acidity in L. dortmanna suggests C3 metabolism. Of the carbon fixed by L. dortmanna, 99.9% was taken up through the roots and fixation occurred primarily during the day. In Isoetes, CO2 was taken up by both roots and shoots and during both day and night. Regardless of the site of CO2 uptake, fixation occurred only in the shoots of both plants. Analysis of carbon isotope ratios of plant organic material was used to further investigate the photosynthetic mechanisms of these Isoetids. Considering the absence of a nighttime peak in titratable acidity in L. dortmanna, the Δ13C (Δ=δ13C plant-δ13C source) value of the shoots of L. dortmanna (-14.2‰) is indicative of C3 photosynthesis limited by the rate of CO2 diffusion. The less negative Δ of I. lacustris (-6.0‰) is consistent with both dark acidification of CAM and CO2 limited C3 photosynthesis. This is in contrast to the terrestrial Isoetes durieui which is shown to have a Δ value which is similar to a terrestrial C3 plant. The carbon fixation patterns of these Isoetids suggest that the CO2 concentration in the loch may be growth limiting, and that root uptake and/or dark acidification are means of optimising CO2 supply. However, in view of the relatively high levels of CO2 in sediment and bulk water, it is suggested that low levels of nutrients may also limit growth in these plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00379096
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Stomatal mechanism as the basis of evolution of crassulacean acid metabolism (1985)
    [s.l.] : Nature Publishing Group
    Nature 314 (1985), S. 200-200 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] KEELEY ET AL. REPLY-We agree with Cockburn that, although the presence of CAM in astomatous Stylites does not support his theory on the stomatal origin of CAM, it does not necessarily falsify the theory either. We also agree with Thomas that Stylites most reasonably should be included with ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/314200c0
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...