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A PHAGOTROPHICALLY DERIVABLE GROWTH FACTOR IN THE PLASTIDIC DINOFLAGELLATE GYRODINIUM RESPLENDENS (DINOPHYCEAE)
Author(s) -
Skovgaard Alf
Publication year - 2000
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.2000.00009.x
Subject(s) - dinoflagellate , biology , dinophyceae , photosynthesis , botany , mixotroph , chloroplast , darkness , heterotroph , bacteria , ecology , phytoplankton , biochemistry , nutrient , genetics , gene
The marine dinoflagellate Gyrodinium resplendens Hulburt is a mixotroph. It possesses chloroplasts and is photosynthetic, and it also feeds phagotrophically on another dinoflagellate, Prorocentrum minimum (Pavillard) Schiller. The species could be cultivated only in food‐replete cultures. When kept in cultures without food, cellular chl a content and photosynthetic activity of G. resplendens decreased and growth ceased after a few days. In food‐replete cultures, G. resplendens could grow strictly heterotrophically in darkness, but growth rate was then three times lower than in food‐replete cultures kept in light. It is suggested that the main importance of phagotrophy is to acquire a growth factor essential to photosynthetic growth. The addition of soil extract or amino acids to the growth medium induced enhanced photosynthetic growth of the species even without the presence of particulate food, but only for approximately 2 weeks. Long‐term starvation of G. resplendens led to loss of the ability to feed, and therefore starved cells eventually reached a point of no return where neither photosynthesis nor phagotrophy could sustain further growth. Light microscopical observations on G. resplendens revealed new morphological and behavioral details of the species.