ACETATE IS A CHEMOATTRACTANT FOR THE COLONIAL GREEN ALGA ASTREPHOMENE GUBERNACULIFERA (CHLOROPHYCEAE)1

• Published in: Journal of phycology Vol. 38; no. 6; pp. 1099 - 1105
• Main Authors: Hoops, Harold J., Cocina, Amy E., Binder, David S., Widjaja, Armand
• Format: Journal Article
• Language: English
• Published: Boston, MA, USA Blackwell Science Inc 01.12.2002
• Subjects: Astrephomene gubernaculifera; behavior; chemoaccumulation; chemoresponse; chemotaxis; ciliary motility; flagellar motility; phototaxis; Volvocales
• ISSN: 0022-3646; 1529-8817
• DOI: 10.1046/j.1529-8817.2002.02016.x

Astrephomene gubernaculifera Pocock is capable of growth on sodium acetate, even in the absence of light. From an evolutionary standpoint, it would be beneficial for this motile heterotrophic organism to be able to sense and swim to such an energy source. We used three assays to test for chemoattraction of A. gubernaculifera. In each case, there was strong chemoattraction to acetate. Propionate, a molecule structurally similar to acetate, also elicited a strong chemoattraction response, even though it was incapable of supporting growth in the dark in this strain. This implies that chemoattraction in A. gubernaculifera is based on a receptor‐mediated signaling response. Video analysis of colonies exhibiting the attraction response indicated that most of them remained motile in the vicinity of the acetate. This rules out the simplest possible model for accumulation in which colonies stop when they encounter increased acetate concentrations. We also tested a variety of other organic molecules for their ability to chemoattract A. gubernaculifera. Of the 11 sugars, 18 amino acids, and three other organic molecules tested, only the amino acid phenylalanine elicited chemoattraction.