| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, Canada N9B 3P4
2Institute of Molecular Plant Sciences, Cell Biology Section, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, Netherlands
Author for correspondence: David A. Cotter. Tel: +1 519 253 3000. Fax: + 1 519 971 3609. e-mail: cotter1@uwindsor.ca
ABSTRACT
Signalling mechanisms involving cAMP have a well-documented role in the coordination of multicellular development and differentiation leading to spore formation in the social amoeba, Dictyostelium discoideum. The involvement of cAMP in the poorly understood developmental stages of spore dormancy and germination have been investigated in this study. Dormant spores contained up to 11-fold more cAMP than nascent amoebae. The spore cAMP levels were not constant, but typically underwent a surge at 14-18 d when spores acquired the ability to germinate spontaneously. The high cAMP levels decreased only during successful spore germination, i.e. emergence of nascent amoebae. The temporal pattern of cAMP decrease was complex and unique to the method of spore activation, supporting our hypothesis that exogenously (e.g. heat) activated and autoactivated spores germinate by different mechanisms. During heat-induced activation, transcription of acg (a gene encoding adenylyl cyclase associated with germination) correlated well with spore cAMP content. Young wild-type spores, incapable of spontaneous germination, maintained a uniformly high cAMP level, and spore cAMP levels also remained high if germination was inhibited. When activated spores were deactivated by applying increased osmotic pressure, cAMP concentrations rose and ultimately levelled off at the high levels typical of dormant spores. The correlation between high cAMP and failure to germinate was also evident when autoactivation was inhibited by the cAMP analogue, 8-bromo-cAMP. Also, spores from a strain (HTY217) with unrestrained protein kinase A activity were incapable of spontaneous germination. Overall, our experiments provide evidence for continued cAMP signalling in spores up to 18 d after sporulation and for linkages between elevated cAMP, spore deactivation and inhibition of spontaneous germination.
Abbreviations: ACA, adenylylcyclase for aggregation; ACG, adenylylcyclase regulating spore germination; PKA, protein kinase A.
This article has been cited by other articles:
|
|
 |
|
  R. Yoshino, T. Morio, Y. Yamada, H. Kuwayama, M. Sameshima, Y. Tanaka, H. Sesaki, and M. Iijima Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum Eukaryot. Cell, December 1, 2007; 6(12): 2419 - 2428. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Alvarez-Curto, S. Saran, M. Meima, J. Zobel, C. Scott, and P. Schaap cAMP production by adenylyl cyclase G induces prespore differentiation in Dictyostelium slugs Development, March 1, 2007; 134(5): 959 - 966. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Torija, J. J. Vicente, T. B. Rodrigues, A. Robles, S. Cerdan, L. Sastre, R. M. Calvo, and R. Escalante Functional genomics in Dictyostelium: MidA, a new conserved protein, is required for mitochondrial function and development J. Cell Sci., March 15, 2006; 119(6): 1154 - 1164. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Saran and P. Schaap Adenylyl Cyclase G Is Activated by an Intramolecular Osmosensor Mol. Biol. Cell, March 1, 2004; 15(3): 1479 - 1486. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Tekinay, H. L. Ennis, M. Y. Wu, M. Nelson, R. H. Kessin, and D. I. Ratner Genetic Interactions of the E3 Ubiquitin Ligase Component FbxA with Cyclic AMP Metabolism and a Histidine Kinase Signaling Pathway during Dictyostelium discoideum Development Eukaryot. Cell, June 1, 2003; 2(3): 618 - 626. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Kimura, Y. Mishima, H. Nakano, and K. Takegawa An Adenylyl Cyclase, CyaA, of Myxococcus xanthus Functions in Signal Transduction during Osmotic Stress J. Bacteriol., July 1, 2002; 184(13): 3578 - 3585. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. West, P. Zhang, A. C. McGlynn, and L. Kaplan Outside-In Signaling of Cellulose Synthesis by a Spore Coat Protein in Dictyostelium Eukaryot. Cell, April 1, 2002; 1(2): 281 - 292. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Anjard, F. Soderbom, and W. F. Loomis Requirements for the adenylyl cyclases in the development of Dictyostelium Development, September 15, 2001; 128(18): 3649 - 3654. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P Thomason and R Kay Eukaryotic signal transduction via histidine-aspartate phosphorelay J. Cell Sci., January 9, 2000; 113(18): 3141 - 3150. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
| J MED MICROBIOL | ALL SGM JOURNALS | |
