Topic
Sphaeroplea
About: Sphaeroplea is a research topic. Over the lifetime, 20 publications have been published within this topic receiving 357 citations.
Papers
TL;DR: In green algae, a branched helix I in the secondary structure of the ITS2 evolves past the 'Sphaeroplea' clade and is an apomorph characteristic within the monophyletic DO-group.
Abstract: Within Chlorophyceae the ITS2 secondary structure shows an unbranched helix I, except for the 'Hydrodictyon' and the 'Scenedesmus' clade having a ramified first helix. The latter two are classified within the Sphaeropleales, characterised by directly opposed basal bodies in their flagellar apparatuses (DO-group). Previous studies could not resolve the taxonomic position of the 'Sphaeroplea' clade within the Chlorophyceae without ambiguity and two pivotal questions remain open: (1) Is the DO-group monophyletic and (2) is a branched helix I an apomorphic feature of the DO-group? In the present study we analysed the secondary structure of three newly obtained ITS2 sequences classified within the 'Sphaeroplea' clade and resolved sphaeroplealean relationships by applying different phylogenetic approaches based on a combined sequence-structure alignment. The newly obtained ITS2 sequences of Ankyra judayi, Atractomorpha porcata and Sphaeroplea annulina of the 'Sphaeroplea' clade do not show any branching in the secondary structure of their helix I. All applied phylogenetic methods highly support the 'Sphaeroplea' clade as a sister group to the 'core Sphaeropleales'. Thus, the DO-group is monophyletic. Furthermore, based on characteristics in the sequence-structure alignment one is able to distinguish distinct lineages within the green algae. In green algae, a branched helix I in the secondary structure of the ITS2 evolves past the 'Sphaeroplea' clade. A branched helix I is an apomorph characteristic within the monophyletic DO-group. Our results corroborate the fundamental relevance of including the secondary structure in sequence analysis and phylogenetics.
63 citations
TL;DR: In this article, the metal ion uptake increased with initial metal ion concentration studied up to 500 µm2/L. Both the Freundlich and Langmuir adsorption models could fit the equilibrium data.
Abstract: Biosorption of nickel (II) and copper (II) ions from aqueous solution by dead sphaeroplea algae in natural and acid treated forms were studied as a function of concentration, pH, and adsorbent dose. The optimum pH for nickel (II) and copper (II) biosorption was found to be 6.0 and 4.0 respectively. The metal ion uptake increased with initial metal ion concentration studied up to 500 mg/L. Both the Freundlich and Langmuir adsorption models could fit the equilibrium data. The adsorption reasonably fitted the Lagergren kinetic model. Further the biomass was characterized by FTIR spectra. Surface area values are measured to be 0.9 and 2.1 m2/g for natural and acid treated forms respectively. The maximum adsorption capacity was found to be 3.40, 4.15 mmol/g for nickel (II) and 2.21, 3.41 mmol/g for copper (II) in natural and acid treated forms respectively.
49 citations
Journal Article•
TL;DR: Organic thalli of Ordovician calcareous algae Vermiporella fragilis Stolley and Palaeoporella variabilisStolley found for the first time are studied and are shown to be fundamentally different from that previously described by various authors.
Abstract: Organic thalli of Ordovician calcareous algae Vermiporella fragilis Stolley and Palaeoporella variabilis Stolley found for the first time are studied. The structure of V. fragilis is shown to be fundamentally different from that previously described by various authors. Its thallus consists of a central stem and lateral branches of three orders, arranged in regular whorls. Spores are preserved in stem segments, which are separated by septa. Morphologically they resemble the oospores of a Recent alga Sphaeroplea Fritsch. The structure of previously unknown filamentous central parts of thallus of P. variabilis is studied and their relation to subcortical and cortical threads penetrating the calcareous sheath are described. Revised diagnoses of Vermiporella Stolley and Palaeoporella Stolley and of their type species are given.
35 citations
TL;DR: The new genus Atractomorpha echinata is distinguished from Sphaeroplea primarily by its pattern of vegetative growth, and is further characterized by the regular formation of biflagellate zoospores in asexual reproduction.
Abstract: Atractomorpha echinata gen. et sp. nov. is described from isolates derived from zygotes present in a dry soil sample obtained from Texas. The new genus is distinguished from Sphaeroplea primarily by its pattern of vegetative growth. While Sphaeroplea is distinctly filamentous with numerous coenocytic cells uniseriately arranged, Atractomorpha grows as individual, multinucleate, spindle-shaped cells with sharply pointed extremities. Such cells may vary considerably in length (25–6000 μm, or more) and normally lack septa. In young, rapidly growing cultures the cells often attain lengths of 300–500 μm, but rarely exceed 1800 μm. The new species is further characterized by: (1) the regular formation of biflagellate zoospores in asexual reproduction, (2)anisogamy (occasionally oogamy) and (3) the size and ornamentation of its zygotes. Variations in vegetative morphology are discussed as are conditions for obtaining gametogenesis.
24 citations
TL;DR: Based on the structure of its male gametes, Atractomorpha clearly demonstrates affinity with the chlorophycean rather than the ulvaphycean line of evolution, and if phylogenetic affinities for the Sphaeropleaceae are to be sought among other groups of green algae, the Chlorococcales appears the most promising candidate.
Abstract: Many naked gametes are produced in each fusiform, male gametangium of Atractomorpha echinata Hoffman and are liberated through irregularly shaped pores in the gametangial wall They are typically biflagellate, pyriform or fusiform in shape, 6-11 μm long, and only a few micrometers wide A mature male gamete is characterized by: (i) a nucleus with condensed chromatin and no nucleoli, (ii) a reduced, starch filled chloroplast occupying a posterior position, and (iii) a cup shaped eyespot consisting of a single layer of plastoglobuli The flagellar apparatus includes two types of flagellar roots alternating in a cruciate pattern One type consists of two microtubules, while the other consists of microtubules of varying number, usually eight or nine, but rarely as many as eleven The paired basal bodies are connected anteriorly by a broad, striated distal fiber; there is no dense apical cap as reported in Sphaeroplea sperm A unique structure, consisting of three layers of small subunits (6–8 nm diameter) arranged in a paracrystalline array, is positioned beneath each basal body Based on the structure of its male gametes, Atractomorpha clearly demonstrates affinity with the chlorophycean rather than the ulvaphycean line of evolution Moreover, if phylogenetic affinities for the Sphaeropleaceae are to be sought among other groups of green algae, the Chlorococcales appears the most promising candidate
23 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
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| 2008 | 1 |
| 2006 | 1 |
| 2005 | 1 |
| 2002 | 1 |
| 2001 | 1 |
| 1995 | 1 |