ISSN:
1615-6102
Keywords:
ATP
;
Ca2+-dependance
;
Contraction
;
Glycerination
;
Macronuclei
;
Paramecium bursaria
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The addition of 2 mM-3 mM ATP to macronuclei ofParamecium bursaria suspended in a glycerol buffer medium causes a decrease in their volume up to 23% within 3 minutes. The infiltration medium must not only contain Ca2+, but must also be of low ionic strength for ATP to be effective. A slow, careful exchange of the glycerol medium for the contraction solution is also necessary. Ca2+ present alone in the standard contraction buffer can likewise induce a limited volume decrease; in the presence of low concentrations of Ca2+, Mg2+ shows no detectable effect on glycerinated nuclei. When the nuclear volume has been reduced by ATP in the presence of Ca2+, the addition of EGTA induces a reexpansion of the nuclei. Salyrgan, an organic mercurial, either prevents or abolishes the ATP-induced contraction. Other nucleotide triphosphates such as guanosine triphosphate (GTP), inosine triphosphate (ITP) or uridine triphosphate (UTP) likewise induce a volume decrease of the glycerinated macronuclei, but to a distinctly lesser extent than ATP. The results indicate that the volume decrease caused by the ATP-contraction solution is not a passive osmotic process. The resemblance to actomyosin contractions suggests that the volume decrease reported here might also be the result of the reaction of nuclear actomyosin and ATP.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01276947
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