Document Detail

β-cyclocitral, a grazer defence signal unique to the cyanobacterium Microcystis.
MedLine Citation:
PMID:  21072572     Owner:  NLM     Status:  In-Process    
β-Cyclocitral is often present in eutrophic waters and is a well known source of airborne and drinking water malodor, but its production and functional ecology are unresolved. This volatile organic compound (VOC) is derived from the catalytic breakdown of β-carotene, and evidence indicates that it is produced by the activation of a specific carotene oxygenase by all species of the bloom-forming cyanobacterium Microcystis. Previous work has shown that β-cyclocitral affects grazer behavior, but the nature of this interaction and its influence on predator-prey dynamics was unresolved. The present study combined analytical and behavioral studies to evaluate this interaction by using Microcystis NRC-1 and Daphnia magna. Results showed that β-cyclocitral was undetectable in live Microcystis cells, or present only at extremely low concentrations (2.6 amol /cell). In contrast, cell rupture activated a rapid carotene oxygenase reaction, which produced high amounts (77 ± 5.5 amol β-cyclocitral/cell), corresponding to a calculated maximum intracellular concentration of 2.2 mM. The behavioral response of Daphnia magna to β-cyclocitral was evaluated in a bbe© Daphnia toximeter, where β-cyclocitral treatments induced a marked increase in swimming velocity. Acclimation took place within a few minutes, when Daphnia returned to normal swimming velocity while still exposed to β-cyclocitral. The minimum VOC concentration (odor threshold) that elicited a significant grazer response was 750 nM β-cyclocitral, some 2,900 times lower than the per capita yield of a growing Microcystis cell after activation. Under natural conditions, initial grazer-related or other mode of cell rupture would lead to the development of a robust β-cyclocitral microzone around Microcystis colonies, thus acting as both a powerful repellent and signal of poor quality food to grazers.
Friedrich Jüttner; Susan B Watson; Eric von Elert; Oliver Köster
Publication Detail:
Type:  Journal Article     Date:  2010-11-12
Journal Detail:
Title:  Journal of chemical ecology     Volume:  36     ISSN:  1573-1561     ISO Abbreviation:  J. Chem. Ecol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7505563     Medline TA:  J Chem Ecol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1387-97     Citation Subset:  IM    
University of Zürich, Limnological Station, Kilchberg, Switzerland.
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