Publication: Roles of cyclic AMP in regulation of phototaxis in chlamydomonas reinhardtii
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Issued Date
2009-10-01
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ISSN
13369563
00063088
00063088
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2-s2.0-70350551849
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Mahidol University
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SCOPUS
Bibliographic Citation
Biologia. Vol.64, No.6 (2009), 1058-1065
Suggested Citation
Maskiet Boonyareth, Jureepan Saranak, Darawan Pinthong, Yupin Sanvarinda, Kenneth W. Foster Roles of cyclic AMP in regulation of phototaxis in chlamydomonas reinhardtii. Biologia. Vol.64, No.6 (2009), 1058-1065. doi:10.2478/s11756-009-0194-4 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/26976
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Title
Roles of cyclic AMP in regulation of phototaxis in chlamydomonas reinhardtii
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Abstract
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. © 2009 Versita Warsaw and Springer-Verlag Berlin Heidelberg.