Anabaena
| Anabaena | ||||||||||||
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Anabaena sp. |
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| Scientific name | ||||||||||||
| Anabaena | ||||||||||||
| Bory de St. Vincent 1886 |
Anabaena is a genus of filamentous cyanobacteria or "blue-green algae".
features
Anabaena forms unbranched, single-row threads of blue-green, gray-green to yellow-green color. The individual cells are spherical to cylindrical. At the cell boundaries, the threads are always constricted to a string of pearls. The threads can be surrounded by a jelly.
The growth occurs through cell division within the thread. Reproduction occurs asexually through fragmentation of the threads. Unfavorable periods are survived as permanent stages , as elongated oval akinetes.
In the thread there are often colorless, thick-walled, somewhat larger cells, the heterocysts . This Heterocysts are capable of atmospheric nitrogen to fix and ammonium to reduce.
Occurrence
Most species live in fresh water, a few also occur in sea water. The species live in plankton , on the bottom (benthic) and on aquatic plants in small and larger, nutrient-rich waters. They are also found in acidic moorland . They can rise and fall through the formation and reduction of gas vacuoles in the water.
ecology
Different Anabaena species form symbioses with other plants, for example with the algae fern ( Azolla ), and supply them with nitrogen compounds.
Some species can neurotoxins form: anatoxin-a (1- (8-amino-cyclooct-1-enyl) ethanone) can cause the animals dying.
Some types of anabaena are used in rice fields as an effective natural fertilizer .
genetics
A DNA sequencing project was carried out in 1999 that mapped the entire genome of Anabaena variabilis , which is 7.2 million base pairs long. The study focused on the heterocysts.
species
Around 100 species are known. The most common Central European species are:
- Anabaena circinalis in the plankton of standing water, can produce water blooms.
- Anabaena flos-aquae in ponds and lakes, forms water blossoms in the form of greasy mucus layers on the water surface.
- Anabaena spiroides , common in lakes and ponds.
- Anabaena cylindrica , on aquatic plants and on the bottom of ponds and lakes.
- Anabaena sphaerica , in pools, ponds, bog waters.
supporting documents
- Karl-Heinz Linne von Berg, Michael Melkonian u. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 .
- Heinz Streble , Dieter Krauter : Life in a drop of water. Microflora and microfauna of freshwater. An identification book. 10th edition. Kosmos, Stuttgart 2006, ISBN 3-440-10807-4 .
Web links
Individual evidence
- ↑ Sequencing the genome ( Memento of the original dated November 23, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
