M. Imaizumi et Y. Doida, CYCLIC-AMP IS A SIGNAL FOR REPRESSION OF DIFFERENTIATION INTO GAMETESIN MICRASTERIAS-THOMASIANA VAR NOTATA, PLANT SCI, 112(1), 1995, pp. 33-42
This study investigates the effects of adenosine 3':5'-cyclic monophos
phate (cAMP) and several chemicals which elevate the intracellular lev
el of cAMP on the induction of zygote formation in Micrasterias thomas
iana var. notata. When added at a concentration of 0.5-3 mM, cAMP repr
essed the induction of zygotes and simultaneously promoted cell prolif
eration, although at a concentration of 0.1 mM it merely delayed the i
nitiation of zygote induction. Methylxanthines caffeine (0.05-1 mM) an
d theophylline (0.05-1 mM), forskolin (10 mu M), which is a potent act
ivator of adenylate cyclase, and a membrane-permeable cAMP analog, 8-b
romo cAMP (0.1-3 mM), also repressed the induction of zygotes and simu
ltaneously promoted cell proliferation. In contrast, another cAMP anal
og used in this study, N-6,O-2'-dibutyryl cAMP (2-3 mM), repressed the
induction of zygotes but did not cause promotion of cell proliferatio
n. This analog also specifically blocked the cell division directly in
volved with gamete formation. The results obtained suggest that intrac
ellular cAMP may function as a signal which simultaneously represses z
ygote induction and causes proliferation of cells in Micrasterias.