Chemoreception in a marine cryptophyte: Behavioral plasticity in response to amino acids and nitrate
Limnol. Oceanogr., 44(6), 1999, 1571-1574 | DOI: 10.4319/lo.19126.96.36.1991
ABSTRACT: The behavioral responses of Chroomonas sp. to ammonium, nitrate, and 19 individual amino acids were examined by computer-assisted video motion analysis. Cells were cultured with either glycine or nitrate as the sole nitrogen source. Relative to seawater, rates at which glycine-grown cells stopped and turned were significantly reduced in response to 10-6 and 10-7 M glutamate, methionine, alanine, and aspartate. This response was akin to the tumbling behavior (chemotaxis) displayed by flagellated bacteria. When cultured in nitrate, Chroomonas sp. did not react to amino acids and ammonium but did significantly reduce stopping and turning in response to 10-6 M nitrate. These results are the first to demonstrate chemoreception in any cryptophyte species. Because Chroomonas sp. commonly lives in habitats where light and inorganic nutrients are limiting, behavioral mechanisms that maximize use of both amino acids and nitrate would seem particularly adaptive.