Gravity-induced absorbance changes in Phycomyces: a novel method for detecting primary responses of gravitropism |
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Authors: | Werner Schmidt Paul Galland |
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Institution: | Fachbereich Biologie/Botanik, Philipps-Universit?t, Lahnberge, D-35032 Marburg, Germany, DE
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Abstract: | The negative gravitropism of the sporangiophores of Phycomyces blakesleeanus Burgeff is elicited by different sensory inputs, which include flexure of the growing zone, buoyance of lipid globules and
sedimentation of paracrystalline proteins, so-called octahedral crystals (C. Schimek et al., 1999a, Planta 210: 132–142).
Gravity-induced absorbance changes (GIACs), which are associated with primary events of gravity sensing, were detected in
the growing zones of sporangiophores. After placing sporangiophores horizontally, GIACs were detected after a latency of about
5 min, i.e. 15–25 min prior to gravitropic bending. The spectroscopic properties of the GIACs indicate that gravitropic stimulation
could imply the reduction of cytochromes. The GIACs were spectrally distinct from light-induced absorbance changes (LIACs),
showing that the primary responses of the light and gravity transduction chains are different. A dual stimulation with gravity
and light generated GIAC-LIACs which were distinct from the absorbance changes occurring after the single stimuli and which
indicate that light and gravity interact early in the respective transduction chains.
Received: 2 September 1999 / Accepted: 9 November 1999 |
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Keywords: | : Buoyance – Gravitropism – Gravity-induced absorbance change – Light-induced absorbance change – Statolith – Phycomyces |
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