The energetic state of the thermogenic appendix of the voodoo lily inflorescence. A 31P-NMR study
1992
Skubatz, H. | Hardin, C.D. | Wiseman, R.W. | Meeuse, B.J.D. | Kushmerick, M.J.
Using 31P-NMR, we have monitored the metabolic changes in the phosphorus compounds of the appendix, the upper thermogenic part of the inflorescence, of Sauromatum guttatum (voodoo lily). Qualitatively, in vivo spectra from D-6 (6 days before heat-production: the day of heat-production is designated D-day), D-3, D-2, D-1, D-day, D + 1 and D + 2, revealed fluctuations in the concentration of the vacuolar and cytoplasmic inorganic phosphate (Pi) relative to an internal standard. From D-6 to D-2 the vacuolar Pi peak was not prominent relative to the other peaks. In the morning of D-1, an increase occurred in the vacuolar and the cytoplasmic Pi levels. Later on, during development, these levels gradually declined. On D-day, changes in vacuolar and cytoplasmic pH were detected during heat-production. The cytoplasmic pH decreased from 7.7 to 7.2 while that of the vacuole increased by almost one pH unit from 5.8 to 6.7. Perchlorate extract spectra from D-4, D-1 and D-day appendices confirmed the observed changes in Pi intensity. These spectra also revealed qualitative changes in the content of ATP and ADP. Their sum decreased during development, reaching its lowest level on D-day at the peak of heat-production between 11:00 and 14:00 (as determined by high performance liquid chromatography of the perchlorate extracts). This suggests that in the early morning of D-day, when heat-production starts, around 9:00, phosphofructokinase, the key enzyme in glycolysis. is not activated by a change in the intracellular ATP/ADP ratio, but by other effector(s).
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