Discrimination of Mineral Particles in Test Formation by Thecamoebae

Stout, J. D.; Walker, Graham D.

doi:10.2307/3225141

Cited by 14 publications

(4 citation statements)

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“…E. rotunda contained traces of Ti. These results are similar to those for Euglyphida reported previously (Stout and Walker, 1976;Jeanson and Coûteaux, 1977;Coûteaux and Jeanson, 1977;Peschke, 1988, 1990).…”

Section: Analysis Of Amoeban Biosilicasupporting

confidence: 94%

“…Thus, one can expect amoeban tests to be an active silica pool in the terrestrial cycle. Various elements, e.g., Ca, Al, K, Fe P, S, Cl and Cu, were detected other than the abundant Si in amoeban tests (Stout and Walker, 1976;Jeanson and Coûteaux, 1977;Coûteaux and Jeanson, 1977;Peschke, 1988, 1990). To evaluate amoeban biosilica, we have to confirm with a purification method of amoeban scales whether these elements other than Si are derived from scales or contaminants.…”

Section: Introductionmentioning

confidence: 95%

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Silica and testate amoebae in a soil under pine–oak forest

2007

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Section: Analysis Of Amoeban Biosilicasupporting

confidence: 94%

Section: Introductionmentioning

confidence: 95%

Silica and testate amoebae in a soil under pine–oak forest

2007

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“…Using these techniques, Saucin-Meulenberg et al (1973) determined the occurrence of silicic material in Arcella spp., Arcella hemisphaerica , Difflugia acuminata , Pontigulasia bigibbosa tests, and in Plagiopyxis callida , and Plagiopyxis declivis with the additional use of RX-spectrography. Stout and Walker (1976) observed the surface of Difflugia , Centropyxis , Cyclopyxis , and Euglypha with an X-ray micro-analyzer. They distinguished between major constituents (mostly Si, and Al only in the case of Difflugia ), significant constituents (Al, K, and Ca), and trace constituents (Na, Cl, Ca, and Al).…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensional Morphological and Mineralogical Characterization of Testate Amebae

2013

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Testate amebae are unicellular shelled protozoa commonly used as indicators in ecological and paleoecological studies. We explored the potential application of three-dimensional (3D) X-ray micro-tomography used in addition to 2D techniques (environmental scanning electron microscopy, electron probe micro-analysis, and cathodoluminescence) for detailed characterization of agglutinated shells of protozoa. We analyzed four specimens of the aquatic testate ameba Difflugia oblonga (Arcellinida), to test whether size distribution and mineral composition of shell grains diverged from sediment size distribution and mineralogical composition. From the 3D images, the geometry of the specimens (size and mass) and of the individual grains forming the specimen (grain size distribution and volume) were calculated. Based on combined chemical, mineralogical, and morphological analyses we show that D. oblonga is able to selectively pick up the small size fraction of the sediment with a preference for low-density silicates close to quartz density (~2.65). The maximum size of the grains matches the size of the pseudostome (shell aperture), suggesting the existence of a physical limit to grain size used for building the shell. This study illustrates the potential of this combined approach to characterize agglutinated shells of protozoa. This data can be useful for detailed morphological studies with applications in taxonomy and ecology.

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“…A preliminary study on the discrimination of mineral particles in test formation was carried out by Stout and Walker (Stout and Walker, 1976). X-ray qualitative analysis allowed the authors to precise that variations exist in the composition of the tests in the size range of the particles and their chemical composition.…”

Section: Introductionmentioning

confidence: 99%