Home / Cyanobacteria / Filaments / Unbranched / Untapered / Heterocysts / No_visible_sheath / Anabaena
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Name derivation:
Classification:
Order Nostocales; Family Nostocaceae
Morphology:
Trichomes with spherical cells and intercalary heterocysts (frequency varies inversely with available dissolved nitrogen mainly as nitrate, nitrite or ammonium ions). Occasionally a "watery" sheath forms, although in this key it is classified as having no visible sheath. Staining is needed to see the thin sheaths when present. The blue-green to yellow-green colored cells may be cylindrical, or bent, but overall look much like a string of beads. Some species have colorless mucilage. Clusters of gas vesicles provide bouyancy in eutrophic or turbid waters for planktonic species. Can be solitary or form into groups of 2-5, and be spherical, ellipsoidal, cylindrical, or curved in shape, and are sometimes found adjacent to the heterocysts. Provides a model for the study of gene differentiation in the formation of heterocysts.
Similar genera:
Similar in morphology to the colonial Nostoc that essentially is a collection of Anabaena trichomes embedded in an extracellular gelatinous matrix.
N-fixation:
Nitrogenase activity has been demonstrated to occur only in heterocysts in Anabaena sp. L-31, at the same time as PS in vegetative cells (Thomas and David 1972). Anabaena torulosa requires sodium and molybdenum for nitrogenase activity but can differentiate heterocysts in the absence of sodium (Apte and Thomas 1984).
Known toxins:
Anatoxin (Devlin et al. 1977).
Inhibition of Daphnia:
In Lake Rotongaio, New Zealand, the presence of Anabaena minutissima var. attenuata apparently excluded Daphnia carinata based on Anabaena-rich lakewater enclosures (20 L, suspended in the lake with added D. carinata ). All Daphnia were extinguished within six days (Burns et al. 1989). Even the filtrate from A. minutissima var. attenuata inhibits filtering rate of D. carinata by 50% (Haney et al. 1994).
Habitat:
Freshwater plankton
References:
Apte, S.K. and J. Thomas 1984. Effect of sodium on nitrogen fixation in Anabaena torulosa and Plectonema boryanum. Journal of General Microbiology 130:1161-1168. Bornet, É. and C. Flahault 1886 '1888'. Revision des Nostocacées hétérocystées contenues dans les principaux herbiers de France. Annales des Sciences Naturelles, Botanique, Septième Série 7: 177-262. Burns, C.W., E.J. Forsyth, J.F. Haney, M.R. James, W. Lampert and R.D. Pridmore 1989. Coexistence and exclusion of zooplankton by Anabaena minutissima var. attenuate in Lake Rotongaio, New Zealand. Archiv fur Hydrobiology 32;63-82. Devlin, J.P., O.E., Edwards, P.R. Gorham, N.R. Hunter, R.K. Pike and B. Stavric 1977. Anatoxin-a, a toxic alkaloid from Anabaena flos aquae NEC-44h. Canadian Journal of Chemistry 55:1367-1371. Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 04 September 2013. Haney, J.F., D.J. Forsyth and M.R. James 1994. Inhibition of zooplankton filtering rates by dissolved inhibitors produced by naturally occurring cyanobacteria. Archiv fur Hydrobiology 132(1):1-13. Thomas, J. and K.A.V. David 1972. Nature New Biology 238:219-221.
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