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Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum

Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum
Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum
?Vegetative adults of Acetabularia acetabulum (L.) Silva were studied as a model system for subcellular patterning in plants, and a description of several phenotypic and physiological characteristics that reveal patterns of subcellular differentiation in this unicellular macroalga was undertaken. Initially, calcification patterns were studied. Under favorable conditions, the rhizoid and most of the stalk calcified. Only the apical 10–20% of the stalk and a small region adjacent to the rhizoid remained uncalcified. Calcification in algae has been reported to result from a biologically mediated local increase in alkalinity. To test this model extracellular pH and extracellular hydrogen ion gradients were examined with ion-selective, self-referencing, electrodes. In the light, A. acetabulum displayed a general pattern of extracellular alkalinity around the entire alga, although in some individuals the region near the rhizoid and the rhizoid itself displayed extracellular acidity. Acetabularia acetabulum also displayed net hydrogen ion influx at the rhizoid and the apical half of the stalk, variable flux in the lower part of the stalk, and net hydrogen ion efflux at the base of the stalk next to the rhizoid. The lack of complete correlation between external pH patterns and calcification suggests that other factors contribute to the control of calcification in this alga. To examine whether net hydrogen ion flux patterns correlated with photosynthetic or respiration patterns, oxygen flux was measured along the stalk using self-referencing O2 electrodes. Photosynthetic oxygen evolution occurred at comparable levels throughout the stalk, with less evolution in the rhizoid. Respiration mainly occurred near and in the rhizoid, with less O2 consumption occurring more apically along the stalk. Our studies of calcification patterns, net hydrogen ion flux and O2 flux revealed several overlapping patterns of subcellular differentiation in A. acetabulum.
acetabularia (subcellular differentiation), calcification, oxygen flux, proton flux, subcellular differentiation
0032-0935
474-483
Serikawa, Kyle A.
4c247847-5c98-4a51-bfd6-7fb0115fb8b2
Porterfield, D. Marshall
ad367ffb-cd69-4c9e-ac0c-f7f048538518
Smith, Peter J. S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
Mandoli, Dina F.
846f756b-7777-4810-9b58-35763fb3c283
Serikawa, Kyle A.
4c247847-5c98-4a51-bfd6-7fb0115fb8b2
Porterfield, D. Marshall
ad367ffb-cd69-4c9e-ac0c-f7f048538518
Smith, Peter J. S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
Mandoli, Dina F.
846f756b-7777-4810-9b58-35763fb3c283

Serikawa, Kyle A., Porterfield, D. Marshall, Smith, Peter J. S. and Mandoli, Dina F. (2000) Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum. Planta, 211 (4), 474-483. (doi:10.1007/s004250000318).

Record type: Article

Abstract

?Vegetative adults of Acetabularia acetabulum (L.) Silva were studied as a model system for subcellular patterning in plants, and a description of several phenotypic and physiological characteristics that reveal patterns of subcellular differentiation in this unicellular macroalga was undertaken. Initially, calcification patterns were studied. Under favorable conditions, the rhizoid and most of the stalk calcified. Only the apical 10–20% of the stalk and a small region adjacent to the rhizoid remained uncalcified. Calcification in algae has been reported to result from a biologically mediated local increase in alkalinity. To test this model extracellular pH and extracellular hydrogen ion gradients were examined with ion-selective, self-referencing, electrodes. In the light, A. acetabulum displayed a general pattern of extracellular alkalinity around the entire alga, although in some individuals the region near the rhizoid and the rhizoid itself displayed extracellular acidity. Acetabularia acetabulum also displayed net hydrogen ion influx at the rhizoid and the apical half of the stalk, variable flux in the lower part of the stalk, and net hydrogen ion efflux at the base of the stalk next to the rhizoid. The lack of complete correlation between external pH patterns and calcification suggests that other factors contribute to the control of calcification in this alga. To examine whether net hydrogen ion flux patterns correlated with photosynthetic or respiration patterns, oxygen flux was measured along the stalk using self-referencing O2 electrodes. Photosynthetic oxygen evolution occurred at comparable levels throughout the stalk, with less evolution in the rhizoid. Respiration mainly occurred near and in the rhizoid, with less O2 consumption occurring more apically along the stalk. Our studies of calcification patterns, net hydrogen ion flux and O2 flux revealed several overlapping patterns of subcellular differentiation in A. acetabulum.

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Published date: 2000
Keywords: acetabularia (subcellular differentiation), calcification, oxygen flux, proton flux, subcellular differentiation

Identifiers

Local EPrints ID: 190517
URI: http://eprints.soton.ac.uk/id/eprint/190517
ISSN: 0032-0935
PURE UUID: 7fa5654a-e71f-4d3c-b148-8944938483f6
ORCID for Peter J. S. Smith: ORCID iD orcid.org/0000-0003-4400-6853

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Date deposited: 17 Jun 2011 09:03
Last modified: 21 Nov 2021 03:04

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Contributors

Author: Kyle A. Serikawa
Author: D. Marshall Porterfield
Author: Dina F. Mandoli

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