Anabaena is known around the world for its formation of specialized cells.  The largest of these is the heterocyst cells that form along its Image from Wikipedia Commons.long chains.  These cells are large vegetative cells that have lost the ability to photosynthesize in exchange for a thin cell wall and the ability to fix nitrogen in the absence, or low amounts, of oxygen.  Heterocysts can form either inside the chain, known and intercalary heterocysts, or on the ends, known as terminal heterocysts. However in Anabaena they are only found intercalary in the trichome.


Another type of specialized cell that Anabaena have are akinetes.  These are another vegetative cell that enlarges and fills with food reserves.  These cells have been found to form about midway between two heterocysts andImage courtesy of Mike Clayton and UW-Madison Botany proceeds towards the heterocysts.  At maturity these cells are found next to the heterocysts, and provide all the necessary food for them.  Since the heterocysts cannot photosynthesize, it is very important for these cells to be near.  Also, the enzyme nitrogenase, which is what allows the heterocyst to perform nitrogen fixation, is unstable in the presence of oxygen, so akinetes help to keep these two essential components separated.


To learn how Anabaena acquires other nutrients head over to the nutrition page.

Image taken by Dr. Greg Sandland.

If you have already seen the nutrition page lets see how they use these nutrients to grow and develop, or head back to the main page!