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    Cytoplasmic Streaming Regulated by Adenine Nucleotides and Inorganic Phosphates in Characeae
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    Keywords:
    Cytoplasmic streaming
    Nitella
    Chara
    Adenine nucleotide
    Adenosine triphosphate
    Plasmodesmata were recorded in vivo in Nitella furcata using polarization and differential interference-contrast light microscopy, techniques that could prove useful for further physiological experimentation on intercellular transport in characean cells.Freeze-fractured, deep-etch replicas of Nitella endoplasm were prepared without the use of cryoprotective agents. The endoplasm, in which rapid cytoplasmic streaming occurs, contains intricate three-dimensional networks of filaments of which two prominent size classes are characterized: 7- to 8-nm putative actin filaments and 4- to 5-nm putative myosin filaments. It is quite likely that the putative actin filaments are components of the endoplasmic filaments, and that these filaments interacting with the 4- to 5-nm filaments produce the motive force generating the observed cytoplasmic streaming.
    Nitella
    Cytoplasmic streaming
    Plasmodesma
    Citations (34)
    Distinct distribution patterns were observed for several species of charophytes during a survey in Chile. We attempted to link these patterns to climatic conditions, but no direct causality between specific climatic factors and charophyte growth conditions could be identified. In this paper, correlations between water chemistry and occurrence of charophytes were tested as an alternative approach to explain the distribution pattern. Datasets with information about conductivity, alkalinity, pH and concentrations of calcium, magnesium, sodium, potassium, sulphate and chloride from sites inhabited by at least one charophyte species were analysed by principal component analysis. The results show that the distribution patterns of at least some species can be explained by niche differences with respect to water chemistry. The genera Chara and Nitella are in general well separated by their preferences for a given pH, alkalinity and conductivity range. Within the genus Chara, Chara squamosa, Chara braunii, Chara fulgens, and a yet unidentified taxon Chara sp., differ from this genus-specific pattern with respect to at least one parameter, whereas Chara vulgaris occupies a broad niche, covering almost the full range of all parameters except conductivity. Within the genus Nitella, niche separation by water chemistry was only possible between Nitella tenuissima and Nitella asagrayana. The chemical niche of Chara braunii was more closely related to the niche of the genus Nitella than the niche of other Chara species.
    Nitella
    Chara
    Alkalinity
    The electrical 'cable' properties associated with the two membranes (plasmalemma and tonoplast) and the conductive cytoplasm present in plant cells are analysed for a cylindrical radially symmetric geometry. Calculations indicate that the interpretation of measurements made via vacuolar electrodes on the charophytes Chara and Nitella will not usually be significantly in error if the presence of a longitudinally conductive cytoplasm is neglected. However because of their different conductances, the individual cable properties of the plasmalemma and tonoplast will normally differ. Thus if current is injected into the vacuole at only a single point, the ratio of the consequent potential differences developed across the plasmalemma and tonoplast will vary with longitudinal position on the cell surface, and consequently caution should be exercised in calculating the resistances of the plasmalemma and tonoplast in long cylindrical cells which are not space-clamped. It is also shown that the presence of a longitudinally conductive cytoplasm will ensure that any current leakage around a cytoplasmic electrode will not significantly alter the interpretation of measurements.
    Chara
    Nitella
    Cytoplasmic streaming
    Plant cell
    Citations (8)
    New records to the Characean flora of Sicily are presented. Five species (Chara baltica, C. conimbrigensis, C. oedophylla, Nitella gracilis, Tolypella salina) are new to Sicily, two of them being also new to Italy (Chara conimbrigensis, C. oedophylla). Two species are confirmed for Sicily (Chara aspera, Nitella opaca), three (Chara braunii, C. canescens, Nitella capillaris) are rare taxa. The Characean flora of Sicily, updated with these records, currently includes 25 species, distributed in four genera: Chara (13 species), Nitella (eight species), Tolypella (three species) and Lamprothamnium (one species).
    Nitella
    Chara
    Flora