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  • 1
    Electronic Resource
    Electronic Resource
    Regulation of the mechanism for HCO3 − use by the inorganic carbon level in Porphyra leucosticta Thur. in Le Jolis (Rhodophyta) (1997)
    Springer
    Planta 201 (1997), S. 319-325 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Carbonic anhydrase ; Inorganic carbon ; Macroalga ; pH ; Photosynthesis ; Porphyra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The capacity for HCO3 − use by Porphyra leucosticta Thur. in Le Jolis grown at different concentrations of inorganic carbon (Ci) was investigated. The use of HCO3 − at alkaline pH by P. leucosticta was␣demonstrated by comparing the O2 evolution rates measured with the O2 evolution rates theoretically supported by the CO2 spontaneously formed from HCO3 − . Both external and internal carbonic anhydrase (CA; EC 4.2.1.1) were implied in HCO3 − use during photosynthesis because O2 evolution rates and the increasing pH during photosynthesis were inhibited in the presence of azetazolamide and ethoxyzolamide (inhibitors for external and total CA respectively). Both external and internal CA were regulated by the Ci level at which the algae were grown. A high Ci level produced a reduction in total CA activity and a low Ci level produced an increase in total CA activity. In contrast, external CA was increased at low Ci although it was not affected at high Ci . Parallel to the reduction in total CA activity at high Ci is a reduction in the affinity for Ci, as estimated from photosynthesis versus Ci curves, was found. However, there was no evident relationship between external CA activity and the capacity for HCO3 − use because the presence of external CA became redundant when P. leucosticta was cultivated at high Ci. Our results suggest that the system for HCO3 − use in P. leucosticta is composed of different elements that can be activated or inactivated separately. Two complementary hypotheses are postulated: (i) internal CA is an absolute requirement for a functioning Ci-accumulation mechanism; (ii) there is a CO2 transporter that works in association with external CA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050073
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of turbulence and inorganic carbon supply on growth ofDunaliella viridis Teodoresco (1995)
    Springer
    International journal of salt lake research 4 (1995), S. 223-232 
    Details
    ISSN: 1573-8590
    Keywords: Dunaliella viridis ; subsidiary energy ; turbulence ; carbon supply ; photosynthetic efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Turbulence is known to enhance growth in microalgae. We studied the possible effects of the extra inorganic carbon supplied to the cultures when air bubbling is the source of turbulence. A set of experiments was carried out to separate the effects of the subsidiary action of agitation on growth from those due to possible carbon enrichment from air CO2 when air bubbling was the source of mixing. It was found that air bubbling does not induce an increase of the concentration of inorganic carbon in HCO 3 − -enriched growth media, and that no differences appear between air-bubbled and CO2-free air-bubbled cultures. On the other hand, photosynthetic O2 was accumulated in the medium in non-mixed cultures, which showed higher respiration and lower photosynthetic rates, probably due to photoinhibition induced by oversaturation of O2. Growth rate, maximal cell density and photosynthetic efficiency were higher in aerated cultures than in non-aerated ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02001492
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    Paper (German National Licenses)
    Fulltext
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