Chemosensory response of marine flagellate towards L- and D- dissolved free amino acids generated during heavy grazing on bacteria Authors Begoña Ayo Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Aitziber Txakartegi Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Zuriñe Baña Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Itxaso Artolozaga Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Juan Iriberri Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Keywords: Rhynchomonas nasuta, marine flagellates, L- and D-amino acids, chemosensory response, grazing, bacterivore activity Abstract This study investigated the generation of dissolved free amino acids (DFAA) by the bacterivorous flagellate Rhynchomonas nasuta when feeding on abundant prey. Specifically, it examined whether this flagellate protist exhibits a chemosensory response towards those amino acids. The concentrations of glycine and the L- and D-enantiomers of glutamate, serine, threonine, alanine, and leucine were determined in co-cultures of the flagellate and bacteria. Glycine, L- and D-alanine, and L-serine were found to accumulate under these conditions in amounts that correlated positively with flagellate abundance, suggesting that protists are involved in their generation. Investigations of the chemotactic response of young and old foraging protists to the same amino acids, offered in concentrations similar to those previously generated, showed that glycine elicited the strongest attraction in both age groups. Young protists were strongly attracted to all the assayed amino acids, whereas older protists maintained a high level of attraction only for glycine. These results suggest that glycine generated by protists actively grazing in bacterially enriched patches functions as an infochemical, signaling to foraging protists the presence of available prey in the aquatic environment. [Int Microbiol 2010; 13(3):151-158] Author Biographies Begoña Ayo, Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Aitziber Txakartegi, Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Zuriñe Baña, Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Itxaso Artolozaga, Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Juan Iriberri, Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Department of Immunology, Microbiology and Parasitology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain Downloads PDF Published 2010-09-28 Issue Vol. 13 No. 3 (2010) Section Research Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. 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