AME - Vol. 47, No. 2 - Feature article

The ciliate Favella sp. Left: light micrograph of a cell fixed with Lugol’s iodine; center: scanning electron micrograph showing lorica structure; right: epifluorescence micrograph showing macronuclei. Photos: Gordon Wolfe

Strom SL, Wolfe GV, Bright KJ

 

Responses of marine planktonic protists to amino acids: feeding inhibition and swimming behavior in the ciliate Favella sp.

 

Feeding by the tintinnid Favella sp., a common coastal planktonic ciliate, was inhibited by dissolved free amino acids (DFAA) in laboratory experiments. The most inhibitory compounds (valine, cysteine, proline, alanine, and serine) were those with small side chains; these reduced feeding to <20% of the control rate at 20 µM added concentration. Inhibition was dose-dependent, with a threshold below DFAA concentration maxima in natural waters. Our work suggests that chemical signaling, which affects predator–prey interactions among crustacean zooplankton and fishes, may also play a role in structuring the microbial realm at the base of the ocean’s food web.

 

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