Yoke algae
| Yoke algae | ||||||||||||
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Spirogyra sp. |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Zygnematales | ||||||||||||
| GM Smith , 1933 |
The yoke algae (Zygnematales) are unicellular or unbranched-filamentous algae from the Charophyta group . The cell walls can be surrounded by thick gelatinous layers. During their sexual reproduction, they form yoke-like copulation channels between two sexual partners, through which uncultivated gametes are subsequently transmitted (conjugation). The zygote makes before re-sprouting a meiosis through so that it is in the zygnematales to haploid organisms is. Occasionally all of the ornamental algae (Zygnemophyceae) including the ornamental algae are grouped together as yoke algae.
Some representatives of the filamentous yoke algae, for example from the genera Spirogyra or Mougeotia , form floating algae floods on the surface of water. Single-cell algae can also be found in terrestrial locations such as soils or damp rock surfaces ( Cylindrocystis , Mesotaenium ).
Zygnematales fossils have been known since the Carboniferous .
Systematic proximity to land plants
The taxonomic proximity of the yoke algae to the land plants , together with some other isolated groups such as the chandelier algae, is expressed in their summary in the Charophyta. These are not green algae in the traditional sense.
The molecular biological investigation of the sequences of 129 proteins from different plants and algae showed that the ancestors of the land plants are probably to be found among the yoke algae (Zygnematales). This finding was surprising, since the yoke algae are morphologically relatively simple and the more complex candelabrum algae are also being discussed as a sister group to the plants. Another molecular biological study, which took into account up to 852 nuclear-coded genes, confirmed a thesis in favor of the Zygnemophyceae.
Some example genera
- Family Mesotaeniaceae (mostly unicellular)
- Mesotaenium : chloroplast plate-shaped. Often as soil algae or aerophytic.
- Ancylonema : short threads. So far only known as ice algae on glacier surfaces.
- Netrium
- Family Zygnemaceae (all filamentous)
- Mougeotia : The chloroplasts of this genus are plate-shaped and can be positioned accordingly for optimal use of the incidence of light. In weak light, they turn perpendicular to the light, it now falls on the entire surface of the plastid. If the incidence of light is too strong, the chloroplast adjusts parallel to the light beam, only the edge is directly in the light.
- Spirogyra : screw algae. The species have one to several helical chloroplasts.
- Zygnema : Here the one or two chloroplasts per cell are star-shaped.
literature
- Christian van den Hoek, Hans M. Jahns, David G. Mann: Algae . 3. Edition. Thieme, Stuttgart 1993, ISBN 3-13-551103-0
Web links
Individual evidence
- ↑ Researchers find possible ancestors of all land plants today. Der Standard, April 18, 2011, accessed March 31, 2011 .
- ↑ idw-online.de of April 18, 2011: "Ancestors of the land plants determined."
- ↑ Norman J. Wickett, Siavash Mirarab, Nam Nguyen, Tandy Warnow, Eric Carpenter, Naim Matasci, Saravanaraj Ayyampalayam, Michael S. Barker, J. Gordon Burleigh, Matthew A. Gitzendanner, Brad R. Ruhfel, Eric Wafula, Joshua P. Der, Sean W. Graham, Sarah Mathews, Michael Melkonian, Douglas E. Soltis, Pamela S. Soltis, Nicholas W. Miles, Carl J. Rothfels, Lisa Pokorny, A. Jonathan Shaw, Lisa DeGironimo, Dennis W. Stevenson, Barbara Surek, Juan Carlos Villarreal, Béatrice Roure, Hervé Philippe, Claude W. dePamphilis, Tao Chen, Michael K. Deyholos, Regina S. Baucom, Toni M. Kutchan, Megan M. Augustin, Jun Wang, Yong Zhang, Zhijian Tian, Zhixiang Yan, Xiaolei Wu, Xiao Sun, Gane Ka-Shu Wong and James Leebens-Mack: Phylotranscriptomic analysis of the origin and early diversification of land plants . PNAS 2014 111 (45) E4859-E4868; published ahead of print October 29, 2014, doi : 10.1073 / pnas.1323926111