New observations on the Coccolithophorid<i>Umbilicosphaera sibogae</i>var.<i>foliosa</i>(Prymnesiophyceae) with reference to cell covering, cell structure and flagellar apparatus

Inouye, Isao; Pienaar, Richard N.

doi:10.1080/00071618400650401

Cited by 47 publications

(51 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3); we suggest that the base-plate is located between the two. Our SEM observations suggest that this is also the case for species of Umbilicosphaera, although TEM (transmission electron microscopy) studies of them have indicated that the base-plate underlies the coccoliths (Manton and Leedale 1969;Inouye and Pienaar 1984). This suggests that TEM microtome observations of coccolith-scale relationship need to be assessed carefully, given the problems of coccolith disruption and dissolution during cytological preparation.…”

Section: Organic Scalesmentioning

confidence: 83%

Coccolith biomineralisation studied with atomic force microscopy

Henriksen¹,

Young²,

Bown³

et al. 2004

Palaeontology

View full text Add to dashboard Cite

ABSTRACT. Biomineralisation can only be understood as an interplay between organic and mineral phases. With this objective, we conducted an investigation of coccoliths using atomic force microscopy (AFM), an ultra-high resolution technique that requires no surface coating and can be used in air or under solution at ambient conditions of temperature and pressure. The detailed morphology, crystal structure, organic scales and organic coating of the coccolith species Coccolithus pelagicus, Helicosphaera carteri and Oolithotus fragilis were investigated. The ®ne structure of coccoliths is very complex, with the calcite either being smooth, dominated by steps or tuberculate; organic cover can be either granular or ®brous. Behaviour of coccolith surfaces during dissolution is in¯uenced both by mineral and organic material and different surface types show variable resistance to dissolution. The organic coating protects element faces against etching. Through atomic resolution AFM, it is possible to establish the crystallographic structure of the distal shields of C. pelagicus and O. fragilis. Though elements of both species are dominated by stable crystal faces, there are important differences between them, with the external edge of elements being parallel to a cleavage direction in C. pelagicus but parallel to the atomic rows in O. fragilis. Thus, there is evidence that the biomineralisation of each species, and also of select areas of coccoliths of the same species, is markedly different.

show abstract

Section: Organic Scalesmentioning

confidence: 83%

Coccolith biomineralisation studied with atomic force microscopy

Henriksen¹,

Young²,

Bown³

et al. 2004

Palaeontology

View full text Add to dashboard Cite

show abstract

“…foliosa on the basis that "extremely rare specimens having both types of coccoliths on a single coccosphere were observed". Curiously this taxonomic separation has been upheld by later researchers, even though research on Umbilicosphaera demonstrated a stable morphology under culture conditions and diagnostic cytological differences between the species (Inouye and Pienaar 1984). Our own research -with data from cultures, natural samples, and sediments -has now validated these findings and it seems likely that Okada and McIntyre (1977) distinguished the coccoliths of the two varieties using the expression of the suture lines, which is one of the least reliable criteria for species determination (see below and Young et al this volume).…”

Section: Quantitative and Qualitative Morphologymentioning

confidence: 99%

“…Cells are nonmotile, but flagellar bases are present, uncalcified body scales are absent (Inouye and Pienaar 1984). Although intensive research has been conducted on cultures both within CODENET, and by other researchers (Inouye and Pienaar 1984), no phase changes have been observed and the life-cycle associations of the Umbilicosphaera spp. remain unknown.…”

Section: Quantitative and Qualitative Morphologymentioning

confidence: 99%

“…For instance Umbilicosphaera sibogae, which by some authors has been subdivided into two varieties with alternative hypotheses that they represented ecotypes, life-cycle stages or closely related genotypes (Inouye and Pienaar 1984). Molecular evidence suggests that they have been genotypically independent for more than 5 Ma according to the molecular clock of Sáez et al (2003).…”

Section: Synthesis Speciation and Divergences (Plate 7)mentioning

confidence: 99%

“…Although intensive research has been conducted on cultures within CODENET, and also by other researchers (Inouye and Pienaar 1984) the life-cycle associations of the Umbilicosphaera spp. remain unknown.…”

Section: Culture Studies and Life-cyclesmentioning

confidence: 99%

See 2 more Smart Citations

Species level variation in coccolithophores

et al. 2004

View full text Add to dashboard Cite

Coccolithophores are an ideal test group for investigating fine-scale differentiation within the phytoplankton since their taxonomy is rather well-documented and their biomineralised periplasts -the coccoliths -provide a rich suite of qualitative and quantitative morphological characters and a uniquely extensive fossil record. In addition, extant coccolithophore species can be grown in culture and hence are available for studies of morphological variability under controlled conditions, molecular genetic studies and cytological research.For the CODENET project the following extant species with seemingly global occurrence and spanning the biodiversity of coccolithophores were selected: Coccolithus pelagicus, Calcidiscus leptoporus, Umbilicosphaera sibogae, Syracosphaera pulchra, Gephyrocapsa oceanica, and Helicosphaera carteri. These were used as case studies to elucidate their species level biodiversity. The key merit of our approach was the use of multiple, independent lines of evidence, so as to remove the ambiguity implicit in any one type of study. In each case morphotypes of previously uncertain significance have been shown to represent discrete genotypes and probably well-separated species, with divergence times ranging 314 Geisen et al. from about 100 kyrs to >10 myrs. The evolutionary significance of these results is discussed.

show abstract