title: The coupling of cyclic GMP and photopolarization of Pelvetia zygotes.
abstract: Unidirectional blue light directs the rhizoid-thallus axis in the apolar zygotes of Fucus and Pelvetia. Here, it is shown that blue light (but not red light) increased cyclic GMP levels of Pelvetia zygotes by about a factor of 2. When the increase in cyclic GMP was blocked by a guanylyl cyclase inhibitor, photopolarization was also blocked. Bathing the cells in a permeant cyclic GMP analog, which should tend to collapse intracellular cyclic GMP gradients, reduced the degree of photopolarization. Growing the cells in the dark in a gradient of the analog caused the rhizoids to tend to form on the low concentration side. It appears that the stimulation of the blue light photoreceptors on the side nearer the light activates guanylyl cyclase and results in a transcytoplasmic cyclic GMP gradient that is necessary for polarization.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA. ken@video.bio.purdue.edu
authors.forename: K R
authors.initials: KR
authors.lastname: Robinson
authors.forename: B J
authors.initials: BJ
authors.lastname: Miller
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000634:Aminoquinolines / Q000494:pharmacology; D002455:Cell Division; D016764:Cell Polarity / Q000187:drug effects; D006152:Cyclic GMP / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D008027:Light; D000459:Phaeophyceae / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D015053:Zygote / Q000502:physiology
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D000634:Aminoquinolines; D004791:Enzyme Inhibitors; C017759:9-(tetrahydro-2-furyl)-adenine; C041715:6-anilino-5,8-quinolinedione; D010727:Phosphoric Diester Hydrolases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D000225:Adenine; D015056:1-Methyl-3-isobutylxanthine