Roles of cyclic AMP in regulation of phototaxis in chlamydomonas reinhardtii

Maskiet Boonyareth, Jureepan Saranak, Darawan Pinthong, Yupin Sanvarinda, Kenneth W. Foster

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Chlamydomonas reinhardtii swims toward or away from light (phototaxis) in a graded way depending on various conditions. Activation of rhodopsin provides signals to control the steering of this unicellular organism relative to a light source and to up-regulate rhodopsin biosynthesis. Intracellular cAMP and cGMP concentrations were measured in positive (1117, swims toward light) and negative (806, swims away from light) phototactic strains with and without light stimulation or 3-isobutyl-1-methylxanthine (IBMX). In the dark, the levels of cAMP and cGMP were significantly higher in the strain with positive phototaxis than in the strain with negative phototaxis. To test whether either cyclic nucleotide influenced the direction, their pre-stimulus levels were pharmacologically manipulated. Higher pre-stimulus levels of cAMP biased the cells to swim toward green light and lower levels biased the cells to swim away. In addition, green-light activation of rhodopsin or addition of IBMX causes a sustained increase in cAMP in both strains. As a consequence of this increase in cAMP, carotenogenesis is induced, as shown by recovery of phototaxis in a carotenoid mutant. Thus, two functions for cAMP were identified: High pre-stimulus level biases swimming toward a light source and sustained elevation following rhodopsin activation increases rhodopsin biosynthesis.

Original languageEnglish (US)
Pages (from-to)1058-1065
Number of pages8
Issue number6
StatePublished - Oct 2009


  • Adenylyl cyclase
  • Carotenogenesis
  • Phosphodiesterase
  • Phototaxis
  • Rhodopsin
  • cAMP

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics
  • Plant Science
  • Cell Biology


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