ISSN:
1615-6102
Keywords:
Dictyostelium mucoroides
;
Cellular slime mold
;
Cytoplasmic pH
;
Ethylene
;
Cyclic AMP
;
Sexual development
;
Macrocyst
;
Sorocarp
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Dictyostelium mucoroides-7 (Dm 7) and a mutant MF 1 derived from it exhibit two developmental pathways: sorocarp formation occurs during the asexual process, and macrocyst formation during the sexual cycle. The two developmental pathways are mainly regulated by two chemical substances: 3′,5′-cyclic adenosine monophosphate (cAMP) and ethylene. Recently, we have demonstrated that cytoplasmic pH (pHi) has a critical role for the choice of developmental pathways, higher pHi being favourable to macrocyst formation. Thereupon, attention was riveted to the relation of pHi to biosynthesis of cAMP and ethylene. Effect of pHi on the production and release of ethylene, a potent inducer of macrocyst formation, was examined, using the two facing culture method. The result showed that lowered pHi inhibits ethylene production, thus resulting in a failure of cells to form macrocysts. The accumulation of cAMP, an inhibitor of macrocyst formation, was found to vary depending on extracellular pH (pHo), but diethylstilbestrol (DES) that is a proton pump inhibitor and also an inhibitor of macrocyst formation had no significant effect on the accumulation. Taken together these results indicate that higher pHi may induce macrocyst formation through enhancement of ethylene production rather than inhibition of cAMP synthesis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01539958
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