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Journal of Cell Science, Vol 91, 523-529, Copyright © 1988 by Company of Biologists

Submitted on June 1, 1988
Accepted on August 26, 1988

Chemical signal-response in diatoms of the genus Amphora

BARBARA COOKSEY 1 and KEITH E. COOKSEY 1

1 Department of Microbiology, Montana State University, Bozeman, MT 59717, USA

The marine diatom Amphora coffeaeformis is positively chemotactic to glucose and sugars of similar structure. A free hydroxyl group is required at the 2-position of the ring; however, D-mannose (a toxic sugar) and L-glucose promote negative chemotaxis. Sugar metabolism is not necessary for a chemosensory response. When the direction of higher concentration in a D-glucose gradient is reversed, cells already orientated reverse their direction of movement. Pretreatment of diatoms with a uniform concentration of D-glucose before exposure to a concentration gradient eliminates the chemotactic response. When diatom cells attached to surfaces in the presence of 5mM-Ca2+ are exposed to 0.25-0.625 mM Ca2+, their motility drops rapidly. However, when this experiment is carried out in the presence of a uniform concentration of D-glucose or 3.O-methyl-D-glucose, motility is sustained for 25-30 min before falling. Speed of motility is also increased during this period. These results can be interpreted in terms of an agonist binding-secretion coupling model for diatom chemotaxis.

Key words: chemical signal response, diatom, chemotaxis, secretion model, calcium, sugars, Amphora

Submitted on June 1, 1988
Accepted on August 26, 1988






© The Company of Biologists Ltd 1988