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FischerellaRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Terrabacteria group -> Cyanobacteria/Melainabacteria group -> Cyanobacteria -> Stigonematales -> Fischerella OVERVIEW: The true branches of these organisms are uniseriate and composed of cells, particularly those distal from the base, that are generally longer than broad. The axis (primary trichome) from which they arise is also mainly uniseriate, but may become multiseriate in part, with divisions in more than one plane. The axis in these regions, however, is seldom more than 2–3 cells in thickness. In addition, the cells of the axes become enlarged, often semispherical in shape. The older cells of a main axis may become separated from each other by sheath material and may act as akinetes (Martin and Wyatt, 1974). Most of the widened cells of the axial trichome, however, display a true filamentous nature, with only a peptidoglycan septum separating cells (Nierzwicki et al., 1982; Balkwill et al., 1984). The main axis forms when a hormogonium comes to rest, cells enlarge, and cell divisions that are parallel to the long axis or diagonal (oblique) begin; some of the resulting cells elongate to form branches (secondary trichomes) (Balkwill et al., 1984; Nierzwicki-Bauer et al., 1984) . Extracellular sheaths are absent. |