Discovery of symbiotic nitrogen-fixing cyanobacteria in corals.
Colonies of the Caribbean coral Montastraea cavernosa exhibit a solar-stimulated orange-red fluorescence that is spectrally similar to a variety of fluorescent proteins expressed by corals. The source of this fluorescence is phycoerythrin in unicellular, nonheterocystis, symbiotic cyanobacteria within the host cells of the coral. The cyanobacteria coexist with the symbiotic dinoflagellates (zooxanthellae) of the coral and express the nitrogen-fixing enzyme nitrogenase. The presence of this prokaryotic symbiont in a nitrogen-limited zooxanthellate coral suggests that nitrogen fixation may be an important source of this limiting element for the symbiotic association.
Department of Zoology and Center for Marine Biology, University of New Hampshire, Durham, NH 03824, USA. mpl@cisunix.unh.edu
Michael P
MP
Lesser
Charles H
CH
Mazel
Maxim Y
MY
Gorbunov
Paul G
PG
Falkowski
D000818:Animals; D037421:Anthozoa / Q000382:microbiology* / Q000502:physiology; D000458:Cyanobacteria / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology* / Q000648:ultrastructure; D004141:Dinoflagellida / Q000302:isolation & purification / Q000502:physiology; D005453:Fluorescence; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000235:genetics / Q000378:metabolism; D015388:Organelles / Q000648:ultrastructure; D010799:Phycoerythrin / Q000378:metabolism; D013559:Symbiosis; D020524:Thylakoids / Q000648:ultrastructure
D010799:Phycoerythrin; D009591:Nitrogenase