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Diversity and Utilization of Marine Cyanobacteria
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
Many heterocystous cyanobacteria also form a second cell type, ‘akinetes’, which can germinate into trichomes when conditions are suitable for growth. The filaments are either unbranched (Nodularia; Figure 14.1, l) or branched (Mastigocoleus; Figure 14.1, q) or even with false branching (Scytonema; Figure 14.1, n). The forms with heterocysts can have them as intercalary heterocysts (Hormothomnion; Figure 14.1, p) or basal heterocysts (Calothrix; Figure 14.1, o).
Saxitoxin and Related Paralytic Shellfish Toxins
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Leanne Andrea Pearson, Brett Anthony Neilan
The vegetative cells of most PST-producing cyanobacteria are also capable of differentiating into spore-like cells known as akinetes. Like dinoflagellate resting cysts, akinetes are able to withstand low temperatures, desiccation, and oxidative stress.48 Akinetes are much larger than the vegetative cells and are characterized by a thickened cell wall and a multilayer extracellular envelope.49 They are also rich in reserve materials, such as glycogen and the nonribosomally produced amino acid polymer cyanophycin.49
The Azolia-Anabaena Symbiosis
Published in Peter M. Gresshoff, Molecular Biology of Symbiotic Nitrogen Fixation, 2018
Differentiation of akinetes usually occurs adjacent to heterocysts and is accompanied by the formation of thick, often pigmented envelopes around the walls of vegetative cells.47 The cells, as a rule, enlarge considerably and may become considerably longer and wider than vegetative cells.47
An overview on cyanobacterial blooms and toxins production: their occurrence and influencing factors
Published in Toxin Reviews, 2022
Isaac Yaw Massey, Muwaffak Al osman, Fei Yang
Weather conditions such as temperature and wind have demonstrated involvement in the growth of cyanoblooms. While warm and calm weather enhance the production of cyanoblooms (Paerl and Huisman 2008), cold and windy conditions favor other species development (Kanoshina et al.2003). In temperate regions, cyanoblooms usually occur in summer and last for the entire period (Johnk et al.2008, Davis et al.2009) or less. Conversely, at any time of the year, cyanoblooms are capable to occur in tropical regions and generally last for a few weeks at a time (Huszar et al.2000, Figueredo and Giani 2009, Prakash et al.2009). El-Shehawy et al. (2012) reported that global warming and temperature gradients also contribute to cyanoblooms formation and the subsequent production of different cyanotoxins. In addition, possible consequences of global warming on physiological and molecular changes in cyanobacteria and resulting effects on microcystin generation were demonstrated (El-Shehawy et al.2012). Anabaena sp. and Microcystis sp. were also shown to produce microcystins between temperatures 18 °C and 25 °C (Sivonen and Jones 1999). At higher temperatures, Anabaena sp. produced MC-RR while MC-LR was generated at temperatures below 25 °C (Rapala et al.1997). Studies indicated that higher temperatures favored Cylindrospermopsis sp. (Bouvy et al.2000, Huszar et al.2000, Briand et al.2002, Figueredo and Giani 2009). For instance a Cylindrospermopsis blooms in a shallow pond in France was found to be affected by high temperature indentified as key factor in germination of akinetes (Briand et al.2002).