scholarly journals Kinetics and energetics of growth of the marine choanoflagellate Stephanoeca diplocostata

1988 ◽  
Vol 47 ◽  
pp. 169-177 ◽  
Author(s):  
RJ Geider ◽  
BSC Leadbeater
Keyword(s):  
Stephanoeca Diplocostata

Silicification of 'cell walls’ of certain protistan flagellates

1984 ◽  
Vol 304 (1121) ◽  
pp. 529-536 ◽  
Keyword(s):  
Cell Cycle ◽  
Cell Wall ◽  
Cell Walls ◽  
Silica Deposition ◽  
Early Stages ◽  
A Cell ◽  
Stephanoeca Diplocostata

Silica deposition is described for two protistan flagellates, Synura petersenii (Chrysophyceae, algae) and Stephanoeca diplocostata (Choanoflagellida, Protozoa). Both taxa produce silica units intracellularly and subsequently assemble them outside the protoplast to form a ‘cell wall’. In Synura the cell wall consists of a scale case to which scales are added throughout the cell cycle. In Stephanoeca individual siliceous, costal strips are accumulated outside the protoplast and assembled into a lorica once sufficient strips have been produced. In both taxa silica is laid down within silica deposition vesicles (s.d.vs) of uncertain origin. Microtubules are involved in the orientation and support of s.d.vs during early stages of silica unit biogenesis. Detailed comparisons of silica deposition are made between Synura and Stephanoeca and between these and other silica-depositing protistans.

Preliminary Observations on the Chemistry and Biology of the Lorica in a Collared Flagellate (Stephanoeca Diplocostata Ellis)

1974 ◽  
Vol 54 (2) ◽  
pp. 269-276 ◽  
Author(s):  
B. S. C. Leadbeater ◽  
I. Manton
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Hydrofluoric Acid ◽  
Light And Electron Microscopy ◽  
Amorphous Form ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Biological Aspects ◽  
Stephanoeca Diplocostata

Evidence for the presence of silica in the costae of Stephanoeca diplocostata Ellis has been provided by a combination of light and electron microscopy. The solubility of costae in hydrofluoric acid has been demonstrated. The presence of silicon in the costae has been strongly confirmed by means of the X-ray analytical electron microscope (EMMA) but tests for a crystalline substructure by means of electron diffraction were negative; it is concluded that silicon is present in a crystallographically amorphous form. Preliminary observations on other biological aspects of the organism include the presence of a sac-like membrane between the lorica and protoplast, the presence of immature costal strips within the cytoplasm and the nature of ingested food. The phyletic position of the group is briefly discussed with special reference to mitochondrial substructure.

scholarly journals Phylogeny of Opisthokonta and the evolution of multicellularity and complexity in Fungi and Metazoa

2003 ◽  
Vol 2 (3) ◽  
pp. 203-211 ◽  
Author(s):  
Mónica Medina ◽  
Allen G. Collins ◽  
John W. Taylor ◽  
James W. Valentine ◽  
Jere H. Lipps ◽  
...  
Keyword(s):  
Ribosomal Dna ◽  
Special Interest ◽  
Sequence Data ◽  
Large Subunit ◽  
Sister Group ◽  
Ssu Rdna ◽  
Lsu Rdna ◽  
Evolutionary Transitions ◽  
Stephanoeca Diplocostata ◽  
Paraphyletic Assemblage

While early eukaryotic life must have been unicellular, multicellular lifeforms evolved multiple times from protistan ancestors in diverse eukaryotic lineages. The origins of multicellularity are of special interest because they require evolutionary transitions towards increased levels of complexity. We have generated new sequence data from the nuclear large subunit ribosomal DNA gene (LSU rDNA) and the SSU rDNA gene of several unicellular opisthokont protists – a nucleariid amoeba (Nuclearia simplex) and four choanoflagellates (Codosiga gracilis, Choanoeca perplexa, Proterospongia choanojuncta and Stephanoeca diplocostata) to provide the basis for re-examining relationships among several unicellular lineages and their multicellular relatives (animals and fungi). Our data indicate that: (1) choanoflagellates are a monophyletic rather than a paraphyletic assemblage that independently gave rise to animals and fungi as suggested by some authors and (2) the nucleariid filose amoebae are the likely sister group to Fungi. We also review published information regarding the origin of multicellularity in the opisthokonts.

Observations on the life-history and ultrastructure of the marine choanoflagellate Choanoeca perplexa Ellis

1977 ◽  
Vol 57 (2) ◽  
pp. 285-301 ◽  
Author(s):  
Barry S. C. Leadbeater
Keyword(s):  
Life History ◽  
Electron Microscope ◽  
Marine Species ◽  
Freshwater Species ◽  
Relative Ease ◽  
Ultrastructural Studies ◽  
Modern Methods ◽  
The Subject ◽  
Stephanoeca Diplocostata ◽  
Whole Mounts

In recent years the external morphology of marine choanoflagellates has been the subject of close scrutiny. This is a result of the attention given to marine nanoplankton, of which choanoflagellates are a part, and the relative ease with which choanoflagellates with loricae of costal construction can be observed in shadowcast whole mounts with an electron microscope. However, detailed ultrastructural studies of choanoflagellate protoplasts have been limited to one freshwater species Codosiga botrytis (Ehr.) Saville-Kent (Petersen & Hansen, 1954; Fjerdingstad, 1961; Hibberd, 1975) and four marine species Salpingoeca pelagica Laval (Laval, 1971), Stephanoeca diplocostata Ellis (Leadbeater & Manton, 1974), Savillea micropora (Norris) Leadbeater (Leadbeater, 1974) and Codosiga gracilis James-Clark (Leadbeater & Morton, 1974b). Of these only the recent studies by Hibberd (1975), Laval (1971), Leadbeater & Manton (1974), Leadbeater (1974) and Leadbeater & Morton (1974b) contain micrographs of material processed by modern methods.

High resolution electron microscopy studies of the silica lorica in the choanoflagellate Stephanoeca diplocostata Ellis

1982 ◽  
Vol 216 (1203) ◽  
pp. 137-146 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Amorphous Silica ◽  
High Resolution Electron Microscopy ◽  
Central Axis ◽  
Low Concentrations ◽  
Resolution Electron ◽  
Stephanoeca Diplocostata

The silica lorica of Stephanoeca diplocostata Ellis has been studied by ultra-high and high resolution electron microscopy. Ultra-high resolution electron microscopy reveals an extremely amorphous silica structure within costal strips. T-junctions between strips in intact loricae have been examined and in several cases strips of viscid connective material containing in part amorphous silica have been observed running between the two strips. Silica demineralization initiates from the central axis of the costal strips leaving tubular brittle rods. The surface of costal strips is shown to be active in binding low concentrations of cations (Co 2+ , Fe 3+ ) from external solutions.

scholarly journals Technical note: The silicon isotopic composition of choanoflagellates: implications for a mechanistic understanding of isotopic fractionation during biosilicification

2019 ◽  
Vol 16 (24) ◽  
pp. 4805-4813 ◽  
Author(s):  
Alan Marron ◽  
Lucie Cassarino ◽  
Jade Hatton ◽  
Paul Curnow ◽  
Katharine R. Hendry
Keyword(s):  
Isotopic Composition ◽  
Biogenic Silica ◽  
Sediment Cores ◽  
Isotopic Fractionation ◽  
Technical Note ◽  
Silicon Isotope ◽  
Transport Pathway ◽  
Dissolved Silica ◽  
Wide Range ◽  
Stephanoeca Diplocostata

Abstract. The marine silicon cycle is intrinsically linked with carbon cycling in the oceans via biological production of silica by a wide range of organisms. The stable silicon isotopic composition (denoted by δ30Si) of siliceous microfossils extracted from sediment cores can be used as an archive of past oceanic silicon cycling. However, the silicon isotopic composition of biogenic silica has only been measured in diatoms, sponges and radiolarians, and isotopic fractionation relative to seawater is entirely unknown for many other silicifiers. Furthermore, the biochemical pathways and mechanisms that determine isotopic fractionation during biosilicification remain poorly understood. Here, we present the first measurements of the silicon isotopic fractionation during biosilicification by loricate choanoflagellates, a group of protists closely related to animals. We cultured two species of choanoflagellates, Diaphanoeca grandis and Stephanoeca diplocostata, which showed consistently greater isotopic fractionation (approximately −5 ‰ to −7 ‰) than cultured diatoms (−0.5 ‰ to −2.1 ‰). Instead, choanoflagellate silicon isotopic fractionation appears to be more similar to sponges grown under similar dissolved silica concentrations. Our results highlight that there is a taxonomic component to silicon isotope fractionation during biosilicification, possibly via a shared or related biochemical transport pathway. These findings have implications for the use of biogenic silica δ30Si produced by different silicifiers as proxies for past oceanic change.

scholarly journals Biosilicification of loricate choanoflagellate: organic composition of the nanotubular siliceous costal strips of Stephanoeca diplocostata

2010 ◽  
Vol 213 (20) ◽  
pp. 3575-3585 ◽  
Author(s):  
N. Gong ◽  
M. Wiens ◽  
H. C. Schroder ◽  
E. Mugnaioli ◽  
U. Kolb ◽  
...  
Keyword(s):  
Organic Composition ◽  
Stephanoeca Diplocostata

scholarly journals Loricate Choanoflagellates from the South Atlantic coastal zone (~32 °S) including the description of Diplotheca tricyclica sp. nov.

2008 ◽  
Vol 8 (4) ◽  
pp. 111-122 ◽  
Author(s):  
Marli Bergesch ◽  
Clarisse Odebrecht ◽  
Øjvind Moestrup
Keyword(s):  
Coastal Zone ◽  
South Atlantic ◽  
The South ◽  
Patos Lagoon ◽  
High Salinity Water ◽  
Transmission Electron ◽  
Salinity Water ◽  
Lower Temperature ◽  
Stephanoeca Diplocostata ◽  
Atlantic Coastal

The biodiversity of marine heterotrophic protists is poorly known in the South Atlantic coastal zone (~32 °S) especially regarding the nanoflagellates. The presence of loricate choanoflagellates was reported for the first time in the Patos Lagoon estuary and the adjacent coastal zone. Seventeen species of eleven genera of loricate choanoflagellates were observed between October 1998 and May 2000 in fixed water samples (lugol's solution + glutaraldehyde) in a JEM 100-SX transmission electron microscope. Most species were recorded in euhaline and mixopolyhaline waters during the spring and summer, none in autumn and a few (four) in winter. The absence of choanoflagellates at the more sheltered inshore stations is due freshwater influence, and at the beach station, probably due the strong wave action. The probably cosmopolitan species Pleurasiga minima, Cosmoeca norvegica, C. ventricosa and Parvicorbicula circularis were present in spring or summer in the estuary channel and coastal area while Stephanoeca diplocostata which apparently prefers lower temperature, was recorded in winter. Calotheca alata and Campyloacantha spinifera are mainly temperate species and were present in spring. The new species Diplotheca tricyclica was recorded at the estuary channel in the summer 1999, in high salinity water.

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