Anabaena gallery

Anabaena soft cushions

The charming Anabaena ‘plush dolls’ shown above are made in the UK by ‘GIANTmicrobes‘ and are available for purchase directly from them or from Amazon.

The following images show Azolla’s cyanobacterial symbiont Anabaena azollae (images 7-12) and its free-living relatives which are assigned to various species of Anabaena and Nostoc (images 1-6)

Note the increased number of atmospheric nitrogen-fixing cells (heterocysts) in Anabaena azollae (e.g. images 10 and 11) compared to free-living species of Anabaena and Nostoc (e.g. images 3, 4, 5). This reflects the long period of co-evolution of Azolla and Anabaena azollae, during which the number of heterocysts increased so that they could fix the larger amounts of atmospheric nitrogen needed to provide nitrogen-based fertilizer compounds to the Azolla host plant.

Both free-living and symbiotic species also possess akinetes (thick-walled dormant cells derived from the enlargement of a vegetative cell). These were retained in Anabaena azollae because the endosymbiont is transmitted to successive generations of Azolla plants as akinete cells.

Details of images

  1. Diagram showing differentiated heterocyst and akinete cells that occur in both free-living Anabaena and Azolla’s symbiont Anabaena azollae. Source http://ulsfmovie.org/images/anabaena_with_labels.jpg
  2. Free-living Anabaena showing its differentiated heterocyst and akinete cells. The heterocysts can be identified by a paler green color due to the limited photosynthesis they can perform. Source https://quizlet.com/77668847/bio-314-lab-final-flash-cards/
  3. Free-living Anabaena scheremetievi showing heterocysts and akinetes. Note that it has fewer heterocysts than Azolla’s symbiont Anabaena azollae. Source: http://www-cyanosite.bio.purdue.edu/images/images2.html
  4. Nostoc, a free-living cyanobacterium that is similar to Anabaena in having differentiated heterocyst and akinete cells. Source: http://www.doctortee.com/dsu/tiftickjian/bio100/cell-lab.html
  5. Scanning electron micrograph of a free-living Anabaena showing that it has fewer heterocysts than Azolla’s symbiont Anabaena azollae. Source: http://www.scivit.de/blog/?p=349
  6. Torn section of Azolla with the filaments exposed, showing Anabaena azollae occurring in cavities inside of the leaves of Azolla Source: http://www.hsu.edu/Academics/ARNatureTrivia/plant-azolla.html
  7. Anabaena azollae: 400x photomicrograph of strands at the edge of a torn Azolla mexicana leafSource Russ Kleinman, Karen Blisard & Andy Anderson: http://wnmu.edu/academic/nspages/gilaflora/anabaena_azollae.html
  8. Anabaena azollae: 400x photomicrograph of strands at the edge of a torn Azolla mexicana leaf. Source Russ Kleinman, Karen Blisard & Andy Anderson: http://wnmu.edu/academic/nspages/gilaflora/anabaena_azollae.html
  9. Anabaena azollae and a torn Azolla mexicana leaf. Source: http://www.hsu.edu/Academics/ARNatureTrivia/plant-azolla.html
  10. Anabaena azollae separated from the Azolla host plant. Source: http://genome.jgi.doe.gov/anaaz/anaaz.home.html
  11. Anabaena azollae separated from the Azolla host plant. Source: http://genome.jgi.doe.gov/anaaz/anaaz.home.html
  12. Azolla filiculoides and Anabaena azollae. Source: http://theazollafoundation.org/azolla/
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