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Extra- and intra-cellular carbonic anhydrase in relation to culture age in a high-calcifying strain of Emiliania huxleyi Lohmann.

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Title: Extra- and intra-cellular carbonic anhydrase in relation to culture age in a high-calcifying strain of Emiliania huxleyi Lohmann.
Authors: Nimer, N. A.1, Guan, Q.1, Merrett, M. J.1
Source: New Phytologist. Apr94, Vol. 126 Issue 4, p601-607. 7p.
Subjects: Carbonic anhydrase, Calcification, Chloroplasts, Centrifugation, Cytoplasm, Lyases
Abstract: The relationships between extra- and intra-cellular carbonic anhydrase, calcification rate, utilization of dissolved inorganic carbon (DIC) and culture age were investigated in a high-calcifying strain of Emiliania huxleyi. The detection of carbonic anhydrase was dependent on culture age; neither the extra-cellular activity of intact cells nor activity in crude homogenates was detected until the stationary phase. By the stationary phase DIC in the medium was totally depleted and the calcification rate had decreased by 60%. Extra- and intra-cellular carbonic anhydrase was stimulated by Na+ but not Cl ions. The isolation of intact organelles by isopycnic gradient centrifugation from exponential and stationary phase cultures of high calcifying cells showed high carbonic anhydrase activity in the chloroplast fraction but carbonic anhydrase was not detected in low-calcifying cells even after gradient centrifugation. Although 50 μM ethoxyzolamide was an effective inhibitor of carbonic anhydrase activity in vitro, photosynthetic 14CO2 fixation was only inhibited 30%, calcification rate 10% and the internal inorganic carbon pool unaffected in intact cells. It is proposed that chloroplast carbonic anhydrase maintains the steady state flux of CO2 from the chloroplast envelope to Rubisco, much of the CO2 arising by release from HCO3-, in the cytosol, required to maintain cytoplasmic pH near neutrality in high-calcifying cells. [ABSTRACT FROM AUTHOR]
Copyright of New Phytologist is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
An: 12613867
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  Data: Extra- and intra-cellular carbonic anhydrase in relation to culture age in a high-calcifying strain of <em>Emiliania huxleyi</em> Lohmann.
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  Data: <searchLink fieldCode="AR" term="%22Nimer%2C+N%2E+A%2E%22">Nimer, N. A.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Guan%2C+Q%2E%22">Guan, Q.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Merrett%2C+M%2E+J%2E%22">Merrett, M. J.</searchLink><relatesTo>1</relatesTo>
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  Data: <searchLink fieldCode="JN" term="%22New+Phytologist%22">New Phytologist</searchLink>. Apr94, Vol. 126 Issue 4, p601-607. 7p.
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  Data: <searchLink fieldCode="DE" term="%22Carbonic+anhydrase%22">Carbonic anhydrase</searchLink><br /><searchLink fieldCode="DE" term="%22Calcification%22">Calcification</searchLink><br /><searchLink fieldCode="DE" term="%22Chloroplasts%22">Chloroplasts</searchLink><br /><searchLink fieldCode="DE" term="%22Centrifugation%22">Centrifugation</searchLink><br /><searchLink fieldCode="DE" term="%22Cytoplasm%22">Cytoplasm</searchLink><br /><searchLink fieldCode="DE" term="%22Lyases%22">Lyases</searchLink>
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  Data: The relationships between extra- and intra-cellular carbonic anhydrase, calcification rate, utilization of dissolved inorganic carbon (DIC) and culture age were investigated in a high-calcifying strain of <em>Emiliania huxleyi</em>. The detection of carbonic anhydrase was dependent on culture age; neither the extra-cellular activity of intact cells nor activity in crude homogenates was detected until the stationary phase. By the stationary phase DIC in the medium was totally depleted and the calcification rate had decreased by 60%. Extra- and intra-cellular carbonic anhydrase was stimulated by Na+ but not Cl ions. The isolation of intact organelles by isopycnic gradient centrifugation from exponential and stationary phase cultures of high calcifying cells showed high carbonic anhydrase activity in the chloroplast fraction but carbonic anhydrase was not detected in low-calcifying cells even after gradient centrifugation. Although 50 μM ethoxyzolamide was an effective inhibitor of carbonic anhydrase activity <em>in vitro</em>, photosynthetic 14CO2 fixation was only inhibited 30%, calcification rate 10% and the internal inorganic carbon pool unaffected in intact cells. It is proposed that chloroplast carbonic anhydrase maintains the steady state flux of CO2 from the chloroplast envelope to Rubisco, much of the CO2 arising by release from HCO3-, in the cytosol, required to maintain cytoplasmic pH near neutrality in high-calcifying cells. [ABSTRACT FROM AUTHOR]
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  Data: <i>Copyright of New Phytologist is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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      – Type: doi
        Value: 10.1111/j.1469-8137.1994.tb02954.x
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      – Code: eng
        Text: English
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      Pagination:
        PageCount: 7
        StartPage: 601
    Subjects:
      – SubjectFull: Carbonic anhydrase
        Type: general
      – SubjectFull: Calcification
        Type: general
      – SubjectFull: Chloroplasts
        Type: general
      – SubjectFull: Centrifugation
        Type: general
      – SubjectFull: Cytoplasm
        Type: general
      – SubjectFull: Lyases
        Type: general
    Titles:
      – TitleFull: Extra- and intra-cellular carbonic anhydrase in relation to culture age in a high-calcifying strain of <em>Emiliania huxleyi</em> Lohmann.
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            NameFull: Nimer, N. A.
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            NameFull: Guan, Q.
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            NameFull: Merrett, M. J.
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              M: 04
              Text: Apr94
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              Y: 1994
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              Value: 126
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